The geology of Svalbard

The Geology of Svalbard

To Svalbard Colleagues

Geological Society Memoirs Series Editor A. J. FLEET

View of Ny-.&lesund settlement seen from the west with three mountain peaks, Tre Kroner, in the distance. The peaks are capped by Carboniferous strata unconformably resting on Early Devonian rocks. They are 30 km distant from the buildings, being foreshortened by the telephoto lens. The glacier from which they emerge as nunataks extends about 15 km nearer. The remaining 15 km just visible is the eastern, inner part of Kongsfjorden. To the right in the foreground is a raised, insulated and heated utiliduct supplying water from a small lake. Photo M. J. Hambrey, CSE 1962 (SP.941e).

View WSW from the old road quay at Ny Alesund, with Scheteligf]ellet in the centre right formed mainly of Carboniferous and Permian strata. Typical low cloud is creeping half way up the mountain from the right. The middle foreshortened low tundra with snow is characteristic raised beach or strandflat topography. The cliffs in the foreground usually about 5-10 m high form the coastline of the shallow bay, Thiisbukta, where in somewhat deeper water motorboats have a sheltered anchorage. The ice in the foreground is 'bay ice', which forms each winter and melts in the early summer. After a hard winter (probably in June) this bay ice is grounded in shallow water at low tide. In a few days it would disintegrate and drift away with tide. Photo M. J. Hambrey (SP631).

The Geology of Svalbard By W. B R I A N H A R L A N D

(University of Cambridge, UK)

Assisted by LESTER M. ANDERSON and DAOUD MANASRAH (CASP, UK) With contributions by NICHOLAS J. BUTTERFIELD (University of Cambridge, UK) ANTHONY CHALLINOR (deceased formerly University of Cambridge, UK) PAUL A. DOUBLEDAY (CASP, UK) EVELYN K. DOWDESWELL (University of Aberystwyth, UK) JULIAN A. DOWDESWELL (University of Aberystwyth, UK) ISOBEL GEDDES (CASP, UK) SIMON R. A. KELLY (CASP, UK) EDA L. LESK (CASP, UK) ANTHONY M. SPENCER (Statoil, Norway) CLARE F. STEPHENS (CASP, UK)

M e m o i r 17 1997 P u b l i s h e d by The G e o l o g i c a l Society London

THE GEOLOGICAL SOCIETY The Society was founded in 1807 as The Geological Society of London and is the oldest geological society in the world. It received its Royal Charter in 1825 for the purpose of 'investigating the mineral structure of the Earth'. The Society is Britain's national society for geology with a membership of around 8000. It has countrywide coverage and approximately 1000 members reside overseas. The Society is responsible for all aspects of the geological sciences including professional matters. The Society has its own publishing house, which produces the Society's international journals, books and maps, and which acts as the European distributor for publications of the American Association of Petroleum Geologists, SEPM and the Geological Society of America. Fellowship is open to those holding a recognized honours degree in geology or cognate subject and who have at least two years' relevant postgraduate experience, or who have not less than six years' relevant experience in geology or a cognate subject. A Fellow who has not less than five years' relevant postgraduate experience in the practice of geology may apply for validation and, subject to approval, may be able to use the designatory letters C Geol (Chartered Geologist). Further information about the Society is available from the Membership Manager, The Geological Society, Burlington House, Piccadilly, London W1V 0JU, UK. The Society is a Registered Charity, No. 210161.

Published by The Geological Society from: The Geological Society Publishing House Unit 7 Brassmill Enterprise Centre Brassmill Lane Bath BA1 3JN UK (Orders: Tel. 01225 445046 Fax 01225 442836) First published 1997 The publishers make no representation, express or implied, with regard to the accuracy of the information contained in this book and cannot accept any legal responsibility for any errors or omissions that may be made. 9 The Geological Society 1998. All rights reserved. No reproduction, copy or transmission of this publication may be made without written permission. No paragraph of this publication may be reproduced, copied or transmitted save with the provisions of the Copyright Licensing Agency, 90 Tottenham Court Road, London W1P 9HE. Users registered with the Copyright Clearance Center, 27 Congress Street, Salem, MA 01970, USA: the item-fee code for this publication is 0435-4052/97/$10.00. British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library.

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Contents

List of figures List of tables List of photographs Preface Acknowledgements Participants Conventions

ix ..~ Xln

5.4

Xln

5.5 5.6 5.7 5.8 5.9

XV

xvii ixx xxi

PART 1 Introduction

CHAPTER 6

CHAPTER 1 SVALBARD 1.1 Geographical names 1.2 Topography and bathymetry 1.3 The physical environment 1.4 The biota 1.5 Political history 1.6 The Spitsbergen Treaty 1.7 Settlements 1.8 Official publications

Northeastern Spitsbergen, Wilhelmoya and Hinlopenstretet Southwestern Nordaustlandet Kong Karls Land (with S. R. A. Kelly) Barentsoya, Edgeoya and Tusenoyane Hopen Correlation of four exploratory wells: Edgeoya and Hopen

3 7 8 10 11 11 13 13

6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8

Early work Stratal succession Subjacent metamorphic complex Late tectonic plutons Minor igneous bodies Summary of isotopic ages Structure of Nordaustlandet The Lomonosov Ridge in relation to Nordaustlandet

CHAPTER 7 CHAPTER 2 2.1 2.2 2.3 2.4 2.5 2.6

Early exploration 1858 to 1920 1920 to 1945 1946 to 1960 1960 to 1975 1975 onwards

CHAPTER 3 3.1 3.2 3.3 3.4 3.5

CHAPTER 4

4.4 4.5 4.6 4.7 4.8 4.9

16 16 16 18 19 20 21 23 23 25 29 31 37

Regional descriptions THE CENTRAL BASIN

Geological frame Van Mijenfjorden Group (Paleogene) Adventdalen Group (Cretaceous-Jurassic) (by S. R. A. Kelly) Kapp Toscana and Sassendalen Groups (Liassic-Triassic) (with I. Geddes) Biinsow Land Supergroup (Permian-Carboniferous) Tempelfjorden Group (Permian) with I. Geddes & P.A. Doubleday Gipsdalen Group (Permian-Carboniferous) with I. Geddes & P. A. Doubleday Billefjorden Group (Early Carboniferous) with I. Geddes & P. A. Doubleday Structure and development of Central Basin

CHAPTER 5 5.1 5.2 5.3

SVALBARD'S G E O L O G I C A L F R A M E

The space frame: Svalbard's structural frame The time frame The rock frame Tectonostratigraphic sequences Geotectonic interpretations

PART 2 4.1 4.2 4.3

OUTLINE HISTORY OF G E O L O G I C A L RESEARCH

EASTERN SVALBARD P L A T F O R M

Platform strata Igneous rocks Submarine outcrops

7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 7.10

NORTHERN NORDAUSTLANDET

N O R T H E A S T E R N SPITSBERGEN

Geological frame Younger (cover) rocks Post-Permian deformation Ny Friesland plutons The Hecla Hoek Complex: the continuing debate Hinlopenstretet Supergroup Lomfj orden Supergroup Stubendorffbreen Supergroup: succession Stubendorffbreen Supergroup: genesis The Hecla Hoek Complex: mid-Paleozoic structure and metamorphism

77 80 83 86 91 93

96 96 96 104 105 106 106 107 108

110 110 112 112 112 113 116 118 121 125 128

CHAPTER 8 N O R T H W E S T E R N SPITSBERGEN

132

8.1 8.2 8.3 8.4 8.5 8.6

133 134 135 142 145 152

Cenozoic volcanic rocks of the Woodfjorden area Mesozoic, Permian and Carboniferous cover Liefde Bay Supergroup (Devonian) The 'crystalline' rocks of Northwestern Spitsbergen Structure Offshore geology (with P.A. Doubleday)

47 47 48 52 59 63 63 66 71 73 75 75 76 76

CHAPTER 9 9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8 9.9 9.10

Paleogene strata Mesozoic strata of Oscar II Land Late Paleozoic strata of Oscar II Land Early Paleozoic rocks Proterozoic strata of Oscar II Land Pre-Carboniferous rocks of Prins Karls Forland Structure of Oscar II Land (with P. A. Doubleday) Structure of Prins Karls Forland Structure of Forlandsundet Basin (with P. A. Doubleday) A tectonic interpretation of the West Spitsbergen Orogen: northern segment

CHAPTER 10 10.1 10.2

CENTRAL WESTERN SPITSBERGEN

SOUTHWESTERN A N D S O U T H E R N SPITSBERGEN

Paleogene strata Mesozoic strata in southwest Sorkapp Land

154 154 158 159 162 165 166 168 171 175 177

179 180 182

vi 10.3 10.4 10.5 10.6 10.7 10.8 10.9 10.10 10.11 10.12 10.13

CONTENTS Permian and Carboniferous strata of southern Spitsbergen Devonian strata Proterozoic strata of western Nordenski61d Land Proterozoic strata of western Nathorst and northwestern Wedel Jarlsberg Lands Early Paleozoic and Proterozoic strata of southwestern Wedel Jarlsberg Land Early Paleozoic and Proterozoic strata of Sorkapp Land Pre-Devonian correlation through southwest Spitsbergen Structure of western Nordenski61d Land Structure of western Nathorst Land Structure of Wedel Jarlsberg Land (with P. A. Doubleday) Structure of Sorkapp Land (with P. A. Doubleday)

CHAPTER 11

S O U T H E R N SVALBARD: BJORNOYA A N D SUBMARINE G E O L O G Y

11.1 11.2 11.3 11.4

Early work Geologic frame of Bjernoya Triassic strata of Bjornoya Late Paleozoic strata of Bjornoya (with I. Geddes) 11.5 Pre-Devonian strata of Bjornoya 11.6 Structural sequence of Bj~rnoya 11.7 Submarine outcrops 11.8 Submarine structure (with P. A. Doubleday)

PART 3

199 200 201

CHAPTER 17

201 205

~-~,~~,' nn 210 212 212 213 218 219 222 222

229 229 231 235 236 239 240

Vendian Vendian Vendian Vendian Vendian Vendian

time scale and correlation successions and correlation in Svalbard biotas environments international correlation palinspastic discussion C A M B R I A N - O R D O V I C I A N HISTORY

Cambrian-Ordovician Cambrian-Ordovician Cambrian-Ordovician Cambrian-Ordovician Cambrian-Ordovician

CHAPTER 15

time scale biotas and correlation sedimentary environments tectonic environments terranes and palinspastics

S I L U R I A N HISTORY

15.1 Silurian time 15.2 Silurian supracrustal events: sedimentation and tectonics 15.3 Silurian tectogenesis 15.4 Silurian petrogenesis of crystalline rocks 15.5 Silurian terranes, provinces and palinspastics 15.6 Sequence of Silurian (main Caledonian) events

17.1 17.2 17.3 17.4 17.5

244 244 246 248 249 252 254 257 260 260 264 266 268

17.6 17.7 17.8

D E V O N I A N HISTORY

Devonian time scale and correlation Devonian succession Devonian biotas ?Silurian and Devonian sedimentation Devonian tectonics The question of sinistral Paleozoic strike-slip faulting, transpression and transtension Sequence of events through Devonian time A Lomonosov conjecture

197

Precambrian time scales Pre-Vendian rock successions Pre-Vendian biotas (by N. J. Butterfield) Precambrian isotopic ages Tectonostratigraphic evidence for proto-basement Pre-Vendian correlation Palinspastic considerations V E N D I A N HISTORY

16.1 16.2 16.3 16.4 16.5 16.6 16.7 16.8

227

CHAPTER 14 14.1 14.2 14.3 14.4 14.5

191

PRE-VENDIAN HISTORY

CHAPTER 13 13.1 13.2 13.3 13.4 13.5 13.6

189

Historical Synthesis

CHAPTER 12 12.1 12.2 12.3 12.4 12.5 12.6 12.7

CHAPTER 16 183 187 188

CARBONIFEROUS-PERMIAN HISTORY

Early work Stratigraphic frame: Biinsow Land Supergroup Structural frame Carboniferous and Permian time scale Carboniferous-Permian sedimentary environments {1.~r, I . f"L~,..1,-.l~'~ ~ ,_,y ,_,~uu~) Carboniferous-Permian fossil record Carboniferous-Permian tectonic control of sedimentation (with I. Geddes) Carboniferous and Permian palaeogeology

289 289 291 291 296 299 303 306 309

310 310 312 314 316 318 324 328 335

CHAPTER 18 TRIASSIC HISTORY

340

18.1 18.2 18.3 18.4

340 343 344

18.5 18.6 18.7

Early work Structural frame Triassic rock units Triassic time scale and international correlation (with I. Geddes) Triassic biotas Sequence of Triassic environments (with I. Geddes) Triassic regional palaeogeology

350 353 356 36l

CHAPTER 19 J U R A S S I C - C R E T A C E O U S HISTORY

363

19.1 19.2 19.3 19.4

363 365 366

19.5 19.6 19.7 19.8

Early work Jurassic-Cretaceous structural frame stratigraphic scheme Jurassic-Cretaceous time scale and correlation (with S. R. A. Kelly) Jurassic-Cretaceous formations Jurassic-Cretaceous biotas Jurassic-Cretaceous events in Svalbard events (with S. R. A. Kelly) Svalbard in a Jurassic-Cretaceous regional context

CHAPTER 20 20.1 20.2 20.3 20.4 20.5 20.6 20.7 20.8 20.9

P A L E O G E N E HISTORY

Early work Structural and stratigraphic frame Paleogene time scale and correlation Paleogene biotas of Svalbard Paleogene sedimentation and tectonics Paleogene structures (with A. Challinor & P. A. Doubleday) Structural sequence Regional tectonic sequence Paleogene tectonosedimentary history

368 372 378 381 383 388 388 390 391 393 394 399 410 413 413

272 272 275 275 280 284 288

CHAPTER 21 21.1 21.2 21.3 21.4

N E O G E N E - Q U A T E R N A R Y HISTORY

Neogene--Quaternary time scale Plate motions (by C. F. Stephens) Deep structure of Svalbard Neogene-Holocene volcanism and thermal springs (by C.F. Stephens)

418 418 418 421 423

CONTENTS 21.5 21.6 21.7 21.8 21.9

Neogene and Pleistocene sedimentation (with C.F. Stephens) Neogene-Holocene uplift and erosion Glacial history of Svalbard: Neogene-Holocene (with C.F. Stephens) Pleistocene and Holocene surficial geology and geomorphic features Post-glacial sea-level and climatic changes

CHAPTER 22

22.1 22,2 22,3 22.4 22,5 22,6 22.7

PART 4 426 427 429 431 434

M O D E R N GLACIERS A N D CLIMATE C H A N G E (by E. K. Dowdeswell and J. A. Dowdeswell) 436

Introduction Modern ice cover Geophysical characteristics and ice dynamics Ice-ocean interaction Late Holocene glacial events and chronology Glaciers and climatic change Summary and conclusions

vii

436 436 438 442 443 444 445

23 23.1 23.2 23.3 23.4

APPENDIX: ECONOMIC G E O L O G Y Coal Petroleum (with A. M. Spencer) Metalliferous minerals Non-metalliferous minerals

449 449 251 253 254

I N D E X OF PLACE NAMES (by L. M. Anderson)

455

GLOSSARY OF S T R A T I G R A P H I C NAMES

463

REFERENCES

477

GENERAL INDEX

515

Figures Fig. 4.10 Geological map of Btinsow Land showing the distribution of Permo-Carboniferous formations (Btinsow Land Supergroup) Fig. 4.11 Summary of the stratigraphic schemes for Central Spitsbergen since 1950 Fig. 4.12 Schematic west-east stratigraphic profile showing lateral variations and structural controls on Carboniferous stratigraphy Fig. 4.13 Stratigraphic schemes for the Billefjorden Group Fig. 4.14 Simplified structural cross-sections of the Central Basin

CHAPTER 1 Fig. 1.1 Regional geographical setting of Svalbard Fig. 1.2 Principal islands and fjords of Svalbard Fig. 1.3 The 'lands' of Svalbard Fig. 1.4 Map showing the principal topographic features of Svalbard Fig. 1.5 Bathymetry of the western Barents Shelf Fig. 1.6 Prevailing surface currents of the Barents Sea and North Atlantic areas Fig. 1.7 Principal ice cover and valleys of Svalbard Fig. 1.8 Diagrammatic map to show boundaries of possible political interest Fig. 1.9 Map showing environmentally protected areas of Svalbard Fig. 1.10 Marine chart sheet coverage of Svalbard Fig. 1.11 Topographic and geological map coverage of Svalbard

12 12 14

Fig. 3.1 Svalbard in the Arctic (Polar projection) 23 Fig. 3.2 Generalized geological map of Svalbard 24-5 Fig. 3.3 Regions of Svalbard as used in this book for Chapters 4 to 11 25 Fig. 3.4 Principal discontinuities in Svalbard 26 Fig. 3.5 Major structural features of the western Barents Shelf 26 Fig. 3.6 Russian structural map of Svalbard 27 Fig. 3.7 Provisional time scale used in this book 28 Fig. 3.8 Svalbard chronometric record 30 Fig. 3.9 Tectonostratigraphic terranes of Svalbard 32 Fig. 3.10 (a) Simplified stratigraphy and geological evolution of Svalbard 39 (b) Schematic map of rock units and terranes 40 Fig. 3.11 Sequence of palinspastic reconstructions for the North Atlantic and Arctic from Cambrian to the present-day 41-2 Fig. 3.12 Summary of successive palaeolatitudes for Europe and North America for Silurian to Neogene time 43 Fig. 3.13 Plot of subsidence against time for western, central and eastern areas 44 CHAPTER 4

CHAPTER 6

CHAPTER 2 Fig. 2.1 Geological sketch map of Spitsbergen by A. G. Nathorst Fig. 2.2 Geological map of Spitsbergen by Hans Frebold

17 19

CHAPTER 3

Fig. 4.1 Reproduction of the Festningen profile as by Hoel & Orvin (1937) Fig. 4.2 Map of the Paleogene outcrops in the Central Basin Fig. 4.3 Stratigraphy of the Van Mijenfjorden Group Fig. 4.4 Geological map and cross-section of eastern Nordenski61d Land and Sabine Land Fig. 4.5 Geological map of the east coast of Spitsbergen from Agardhbukta to Hamburgfjellet Fig. 4.6 Geological map and cross sections of the Adventdalen Group in Wedel Jarlsberg Land and western Torell Lands Fig. 4.7 Geological map and cross sections of the Adventdalen Group in Sorkapp Land Fig. 4.8 Geological map and cross sections of the Adventdalen Group in Oscar II Land, Nordenski61d Land and Nathorst Land Fig. 4.9 Fence diagram showing the distribution and thickness variation of the Sassendalen and Kapp Toscana groups

49 50 51 54 55

56 56

58 60

65

66 72 73

CHAPTER 5 Fig. 5.1 Map of the eastern platform area of Svalbard showing the main place names and principal bathymetric features Fig. 5.2 Geological map of eastern Ny Friesland Fig. 5.3 Geological map of southwestern Nordaustlandet showing the known extent of Phanerozoic outcrops Fig. 5.4 Stratigraphical schemes for Permian and Triassic units of Nordaustlandet Fig. 5.5 Sketch map of Svenskoya, Kongsoya and Abeloya Fig. 5.6 Sketch map of Svenskoya showing principal topographic features and geology Fig. 5.7 Sketch map of Kongsoya showing principal topographic features and geology Fig. 5.8 Summary of schemes of rock units, and their ages, of Kong Karls Land Fig. 5.9 Correlation of the principal stratigraphic sections on Svenskoya Fig. 5.10 Correlation of the principal stratigraphic sections on Kongsoya Fig. 5.11 Proposed nomenclature for local rock units on Barentsoya and Edgeoya Fig. 5.12 Geological map of Barentsoya and Edgeoya Fig. 5.13 Interpretation of Raddedalen- 1 well (Edgeoya) Fig. 5.14 Interpretation of Plurdalen-1 well (Edgeoya) Fig. 5.15 Edgeoya and Barentsoya Triassic biostratigraphy Fig. 5.16 Generalized structural map of Barentsoya and Edgeoya, with structure contours for the top of the Barentsoya Formation Fig. 5.17 Geological map of Hopen and a longitudinal section along the island Fig. 5.18 Interpretation of Hopen-1 and Hopen-2 wells Fig. 5.19 Correlation of the Raddedalen-1, Plurdalen- 1, Hopen-1 and Hopen-2 wells

14

64

Fig. 6.1 Map of northern Nordaustlandet showing principal topographic features, ice-rock boundaries and major place names Fig. 6.2 Preferred names for rock units in Nordaustlandet and their approximate equivalents in Ny Friesland, with estimated thicknesses Fig. 6.3 Geological map of northwestern Nordaustlandet Fig. 6.4 Summary of isotopic ages from Nordaustlandet Fig. 6.5 Outline geological map of Nordaustlandet and adjacent areas of Ny Friesland

76 78 80 81 82 82 83 84 84 85 87 88 90 91 91

92 92 94 95

97

98 101 107 108

CHAPTER 7 Fig. 7.1 Topographic and place name map of Ny Friesland Fig. 7.2 Summary of the Hecla Hoek succession of Ny Friesland. Fig. 7.3 Generalized geological map of Ny Friesland outlining the distribution and subdivision of the Hecla Hoek Complex

111 114

115

x Fig. 7.4 Distribution of the Stubendorffbreen Supergroup in Ny Friesland Fig. 7.5 (a) Metamorphic rocks of the southern part of Ny Friesland (Lower Hecla Hoek) (b) M.B. Bayly's metamorphic zones as defined in Ny Friesland Fig. 7.6 Structural map of Ny Friesland Fig. 7.7 Diagrammatic cross-sections across Ny Friesland Fig. 7.8 Alternative structural interpretations across Ny Friesland

FIGURES

121

126 128 129 130

CHAPTER 8 Fig. 8.1 Geological map of NW Spitsbergen Fig. 8.2 Liefde Bay Supergroup units Fig. 8.3 Faunal divisions and lithological members of the Wood Bay Formation Fig. 8.4 Geological map of the Raudfjorden/Liefdefjorden area, Northwestern Spitsbergen, showing the distribution of the Siktefjellet and Red Bay groups Fig. 8.5 Schematic section showing the relationships between the units of the Siktefjellet and Red Bay groups Fig. 8.6 Caledonian basement rocks in northwest Spitsbergen Fig. 8.7 Generalized geological map of Biskayerhalvoya, northwest Spitsbergen Fig. 8.8 Principal structural elements (mainly Devonian) of northwest Spitsbergen Fig. 8.9 Map of central west Dickson Land Fig. 8.10 Generalized cross-section across northwest Spitsbergen, from the Albert I Land High to the Andr6e Land Basin Fig. 8.11 Structural profile across the Andr~e Land anticline between Gr~huken and Mushamna Fig. 8.12 Principal bathymetric features off northwest Spitsbergen

133 136 137

139 141 143 145 146 146

147 148 152

CHAPTER 9 Fig. 9.1 Topographic and place name map of Oscar II Land and Prins Karls Forland Fig. 9.2 Diagrammatic outcrop map of central west Spitsbergen Fig. 9.3 Geological map and stratigraphic section of the Ny-.~lesund coalfields Fig. 9.4 Summary of the Paleogene stratigraphic units in Forlandsundet Fig. 9.5 Fence diagram showing the stratigraphic relationships within the St Jonsfjorden Trough Fig. 9.6 Structural cross-section showing the major folds and thrusts in the Mediumfjellet-Lappdalen area Fig. 9.7 Alternative structural profiles across northern Prins Karls Forland to illustrate the different interpretations of the structure Fig. 9.8 Lithostratigraphic formations and geological map of south-central Prins Karls Forland Fig. 9.9 Simplified structural map and cross-sections of the Forlandsundet Graben Fig. 9.10 Schematic diagram of 'flower structure' within a convergent strike-slip fault zone

155 156 157 157 160 171

173 174

196 197

202 203 203

CHAPTER 11 Fig. 11.1 Bathymetric map of the western Barents Sea around southern Svalbard, with principal bathymetric features named 209 Fig. 11.2 Summary of stratigraphic schemes for Bjornoya 210 Fig. 11.3 Geological map of Bj~rnoya 211-2 Fig. 11.4 Summary plot of seismic velocity, porosity and estimated minimal subsidence rate 212 Fig. 11.5 Structure contour map of the base of the Roedvika Formation, with diagrammatic profile 213 Fig. 11.6 Schematic structural map of Bjornoya 220 Fig. 11.7 Geological map and sketch cross-section through basement rocks of southern Bjornoya 221 Fig. 11.8 Structure of the western Barents Sea showing the possible location of the Iapetus suture 223 CHAPTER 12 Fig. 12.1 Outcrops of pre-Vendian rocks (mainly Proterozoic) Fig. 12.2 Precambrian timescale comparing chronostratigraphic and chronometric scales Fig. 12.3 Correlation of pre-Vendian sequences of Ny Friesland and Nordaustlandet Fig. 12.4 Correlation of pre-Vendian sequences of the western terranes Fig. 12.5 Correlation of Precambrian sequences in the western, central and eastern terranes, with some age constraints Fig. 12.6 Map showing the distribution of proto-basement in Svalbard Fig. 12.7 Pressure-temperature plot for the metamorphic complex of Biskayer Peninsula Fig. 12.8 Correlation of East Greenland and Ny Friesland Proterozoic sequences Fig. 12.9 Schematic reconstruction of eastern Laurentia and Baltica for the period 1900-1600 Ma Fig. 12.10 Pre-Vendian aulacogen model showing the distribution of the Greenland, Barents and Baltica cratons Fig. 12.11 Global palinspastic reconstruction for Kanatia timeshowing the locations of rift margins and glacigenic deposits

228 229 230 231

236 237 238 240 240 241

242

176 CHAPTER 13 177

CHAPTER 10 Fig. 10.1 Topographic and place name map from Isfjorden to Sorkapp Fig. 10.2 Generalized outcrop map of central and southwestern Spitsbergen Fig. 10.3 Simplified tectonic map of central and southwestern Spitsbergen Fig. 10.4 Vendian geology of northwest Wedel Jarlsberg Land Fig. 10.5 Stratigraphic schemes for the Precambrian succession of southern Wedel Jarlsberg Land

Fig. 10.6 Comparison of stratigraphic schemes for southwest Spitsbergen Fig. 10.7 Correlation of Pre-Devonian units in southwest Spitsbergen Fig. 10.8 Structural map and representative cross-sections of Nordenski61d Land, illustrating the structure of Carboniferous to Cretaceous units Fig. 10.9 Simplified structural profile across the Midterhuken Peninsula Fig. 10.10 Schematic structural profile of northern Sorkapp Land

180 181 182 190 193

Fig. 13.1 Outcrop map showing the distribution of Vendian outcrops in Svalbard Fig. 13.2 Vendian biostratigraphy and isotopic variations of carbonate rocks Fig. 13.3 Correlation of Vendian successions in Svalbard Fig. 13.4 Secular variation in ~513Cplotted against stratigraphic depth (m) for the Varanger and Sturtian succession of Spitsbergen Fig. 13.5 Interpretation of Vendian environments from the successions of northeastern Spitsbergen Fig. 13.6 Vendian correlation chart for representative successions of Svalbard and adjacent areas of the North Atlantic-Arctic region

245 246 247

249 250

252

FIGURES Fig. 13.7 Correlation of the Vendian successions of East Greenland and northeast Svalbard 253 Fig. 13.8 Schematic palinspastic model for Vendian time showing the inferred positions of the Svalbard terranes and the postulated Iapetus Ocean 253 Fig. 13.9 Global palinspastic reconstruction for Rodinia time showing the distribution of Varanger glacigenic deposits 256

Fig. 16.9 Tectonic evolution and stratigraphic sequences in the Western, Central and Eastern Svalbard Precambrian to Devonian terranes Fig. 16.10 Geological provinces of the eastern part of the Canadian Arctic Archipelago and northern Greenland Fig. 16.11 Summary of strike-slip displacement along the major fault and shear zones of Svalbard to illustrate the possible amounts of sinistral displacement

xi

303 306

307

CHAPTER 14 Fig. 14.1 Cambrian and Ordovician rock units in contemporary nomenclature and classification Fig. 14.2 Map of Svalbard showing the distribution of Cambrian and Ordovician outcrops Fig. 14.3 Cambrian-Ordovician chronostratic time scale divisions with biostratigraphic correlations and estimated chronometric ages Fig. 14.4 Cambrian-Ordovician correlation chart for Svalbard Fig. 14.5 Approximate subsidence rates for the Cambrian-Ordovican sequence in Ny Friesland Fig. 14.6 Simplified geological map and representative profiles of the Motalafjella area (Oscar II Land) Fig. 14.7 Pressure-temperaturetime trajectory for the Motalafjella blueschist-eclogite complex Fig. 14.8 Cambrian-Ordovician tectonic events in Svalbard Fig. 14.9 Schematic correlation of North AtlanticArctic Early Paleozoic sequences Fig. 14.10 Schematic illustration of the CambrianOrdovician palinspastic configuration of Greenland and adjacent terranes according to the strike-slip hypothesis conjectured in this work Fig. 14.11 Ordovician palinspastic map

CHAPTER 17 257 258

259 261 265 267 268 269 269

270 270

CHAPTER 15 Fig. 15.1 Map of Svalbard showing the distribution of Silurian outcrops and areas of tectonism and metamorphism Fig. 15.2 Summary of Silurian time scales Fig. 15.3 Field sketch of the Stubendorff Mountains Fig. 15.4 Cartoon illustrating the elements in tectonic transitions in the Ny Friesland Orogen Fig. 15.5 Schematic profile of the pre-Red Bay Group structure as observed in Biskayerfonna-Holtedahlfonna terrane just south of Liefdefjorden Fig. 15.6 Quantitative petrographical classification of granitic rocks in Svalbard Fig. 15.7 Schematic illustration of terranes surrounding Greenland at approximately the beginning of Silurian time, with the closure of the Iapetus Ocean Fig. 15.8 (a) Late Ordovician to Early Silurian global palinspastic reconstruction, with glacigenic deposits; (b) Mid-Silurian palinspastic reconstruction

273 274 277 277

279 281

287

287

CHAPTER 16 Fig. 16.1 Outcrop map showing the distribution of Devonian deposits in Svalbard and locations of identified thermal events Fig. 16.2 Stratigraphic correlation chart for the (Devonian) Liefde Bay Supergroup of Svalbard Fig. 16.3 Devonian fossil fish reconstructions Fig. 16.4 Devonian fossil fish ranges Fig. 16.5 Distribution of Svalbard Devonian fish genera with time Fig. 16.6 Illustration of a Devonian landscape Fig. 16.7 Schematic diagrams to illustrate successive sedimentation patterns through Devonian time Fig. 16.8 True-scale cross-sections of fold and fault zones in the Devonian rocks of the Gronhorgdalen Belt, Eastern Boundary Belt and an EW cross-section from James I Land to the Balliolbreen Fault

290 292 293 294 295 296 297

302

Fig. 17.1 Map of Svalbard showing the distribution of Carboniferous and Permian rocks 311 Fig. 17.2 Chart illustrating successive classifications of rocks units 312 Fig. 17.3 Lithostratigraphic scheme for Carboniferous and Permian formations of the Bfinsow Land Supergroup 313 Fig. 17.4 Schematic map of Carboniferous and Permian structures 315 Fig. 17.5 Carboniferous and Permian time scale and biostratigraphy 317 Fig. 17.6 Some fossils recorded from Carboniferous and Permian formations of Svalbard 325 Fig. 17.7 Fence diagram illustrating lateral variations and tectonic controls on the Carboniferous stratigraphy 328 Fig. 17.8 Early Carboniferous lithofacies maps 329 Fig. 17.9 (a) Early Bashkirian lithofacies. (b) Moscovian lithofacies maps 331 Fig. 17.10 Gzelian lithofacies map 332 Fig. 17.11 (a) Asselian lithofacies. (b) Early Artinskian lithofacies maps 332 Fig. 17.12 Ufimian lithofacies 333 Fig. 17.13 Principal Carboniferous and Permian tectonic events 335 Fig. 17.14 International correlation of Carboniferous and Permian formations in the Arctic 336 Fig. 17.15 Carboniferous to Permian paleogeologic maps of the Barents Sea region 337-8 CHAPTER 18 Fig. 18.1 Outcrop map showing the distribution of Triassic deposits in Svalbard Fig. 18.2 Correlation chart to show the relationship of published Triassic stratigraphic names in Svalbard Fig. 18.3 Triassic structural framework Fig. 18.4 Triassic lithostratigraphic schemes for Svalbard Fig. 18.5 Sassendalen Group isopach map Fig. 18.6 Kapp Toscana Group isopach map Fig. 18.7 Localities and thickness of the Wilhelmoya Formation Fig. 18.8 Triassic time scales Fig. 18.9 Comparative zonation of Triassic Svalbard successions Fig. 18.10 Stratigraphic correlation chart Fig. 18.11 (a) Early, (b) Mid-(early Ladinian) and (c) Late Triassic sedimentary facies of Spitsbergen, Barentsoya and Edgeoya Fig. 18.12 Triassic sedimentation sequences on Barentsoya and Edgeoya Fig. 18.13 Regional Triassic tectonics Fig. 18.14 Comparison of Arctic shelf sequences in Svalbard and the Queen Elizabeth Islands plotted for the Tournaisian to Maastrichtian interval Fig. 18.15 Triassic palaeogeology of the Barents Sea. (a) Early to Mid-Triassic; (b) Late Triassic

341 342 344 346 347 348 349 351 352 353

357 359 359

360 361

CHAPTER 19 Fig. 19.1 Map of Svalbard showing the distribution of Jurassic and Cretaceous outcrops Fig. 19.2 Hydrocarbon potential and depositional environment of Triassic to Cretaceous rocks of Svalbard

364 365

xii

FIGURES

Fig. 19.3 Historical review of the principal stratigraphic schemes for the Jurassic and Cretaceous of Spitsbergen 366 Fig. 19.4 Jurassic and Cretaceous structural framework Fig. 19.5 Summary of the principal lithostratigraphic units of the Adventdalen and Kapp Toscana groups in Svalbard 367 Fig. 19.6 Jurassic-Cretaceous international time scale 369 Fig. 19.7 Summary of the biozonal schemes for Svalbard and the adjacent Barents Sea 370 Fig. 19.8 Biostratigraphic distribution of belemnite genera in Svalbard 372 Fig. 19.9 Summary of the Jurassic and Cretaceous stratigraphy of Svalbard and the adjacent Barents Sea 373 Fig. 19.10 Summary of the lateral development of the Helvetiafjellet Formation 375 Fig. 19.11 Fence diagram showing lateral variations in the Carolinefjellet Formation 376 Fig. 19.12 Map showing the distribution of JurassicCretaceous igneous rocks 377 Fig. 19.13 Summary of events in the Jurassic and Cretaceous history of Svalbard 381 Fig. 19.14 Lateral variation of the Agardhfjellet and Rurikfjellet formations across Spitsbergen 382 Fig. 19.15 Summary of structural and tectonic events in the Arctic in mid-Jurassic and mid-Cretaceous time 383 Fig. 19.16 Jurassic to Cretaceous palaeogeologic maps of the Barents Sea 384-5

CHAPTER 20 Fig. 20.1 Map of Svalbard showing the distribution of Paleogene deposits and deformation 389 Fig. 20.2 Sequence of classification of Paleogene deposits in the Central Basin 390 Fig. 20.3 Generalized Paleogene structural framework of Spitsbergen 391 Fig. 20.4 Paleogene time scale 392 Fig. 20.5 Successive interpretations of the age of Paleogene strata and events in Svalbard 393 Fig. 20.6 Map showing the geographic-stratigraphic distribution, preservation state and sedimentary facies of palynomorph assemblages 398 Fig. 20.7 Schematic cross-section of the northern part of the West Spitsbergen Orogen 399 Fig. 20.8 (a) Map showing the location of unpublished structural profiles of the West Spitsbergen Orogen 402 (b) Selection of unpublished cross-sections of the West Spitsbergen Orogen by A. Challinor 403-8 Fig. 20.9 Schematic model illustrating the various structural configurations within an area of strike-slip deformation 409 Fig. 20.10 Interpretation of the structural development of Paleogene structures in Nordenski61d Land 411 Fig. 20.11 Historical review of Paleogene tectonic models for Svalbard 411 Fig. 20.12 Paleogene time-scale 412 Fig. 20.13 Sequence of maps showing the motion of Svalbard relative to Greenland (fixed) for latest Cretaceous to Oligocene time 413 Fig. 20.14 Diagrammatic model for the Cenozoic sea-floor spreading, dextral strike-slip and transpression between Svalbard and Greenland 414

Fig. 20.15 Palaeogeologic map of Spitsbergen in Mid-Paleocene time Fig. 20.16 Paleogene palaeogeologic maps of Spitsbergen latest Paleocene to early Mid-Eocene

415 415-6

CHAPTER 21 Fig. 21.1 Neogene and Quaternary volcanics; Quaternary hydrothermal springs, seeps and microseismic zones Fig. 21.2 Neogene and Quaternary time scale Fig. 21.3 Bathymetric features and structures of the Norwegian-Greenland Sea and eastern Arctic Ocean Fig. 21.4 Present-day bathymetric structures in the North Atlantic Fig. 21.5 Map showing depth to basement in Spitsbergen as defined from aeromagnetic data Fig. 21.6 Map of the Bockfjorden area indicating the locations of hydrothermal springs Fig. 21.7 Compositions of Neogene plateau lavas Fig. 21.8 Simplified profiles and Tertiary stratigraphy of the Western Barents Shelf Fig. 21.9 Summary of the Neogene units of the western Barents Shelf margin Fig. 21.10 Interpretation of the Neogene fluvial drainage pattern in the Barents Sea Fig. 21.11 Map of the Barents Sea delineating the main erosion areas from mid-Miocene to Recent Fig. 21.12 Summit-height map of Svalbard Fig. 21.13 Diagrammatic model of the chronology of the deglaciation pattern of the Western Barents Sea Fig. 21.14 Diagrammatic illustrations of patterned ground Fig. 21.15 Late Pleistocene stratigraphy of inner Isfjorden

419 420 420 422 423 424 424 426 427 427 428 429 430 433 434

CHAPTER 22 Fig. 22.1 Map of Svalbard with the distribution of the modern glaciers and ice caps Fig. 22.2 (a) Map of estimated precipitation over Svalbard; (b) Map of estimated equilibrium line altitude over Svalbard Fig. 22.3 Landsat satellite image of Nordaustlandet with the interpretation of ice-cap drainage basins inset Fig. 22.4 Airborne radio-echo sounding data from Austfonna, Nordaustlandet Fig. 22.5 Ice surface and bedrock profiles from radio-echo sounding of Nordaustlandet Fig. 22.6 Fast-flowing glaciers on Vestfonna Fig. 22.7 Photographs of a surge of Bakaninbreen, Spitsbergen Fig. 22.8 The terminus of a tidewater glacier Fig. 22.9 Photographs of constrasting iceberg morphology: (a) tabular, (b) irregular Fig. 22.10 Temperature records from 1912 Fig. 22.11 Mass balance records for three Spitsbergen glaciers Fig. 22.12 Energy balance model predictions of glacier response to future global warming Fig. 22.13 Oxygen isotope ratios from Lomonosovfonna since about AD 1200

437

438 439 440 441 441 442 443 444 444 445 445 445

APPENDIX Fig. 23.1 Plot of major wells in Svalbard Fig. 23.2 Mesozoic petroleum source-rocks of the Arctic

451 453

Tables Table Table Table Table Table

1.1 Geographical nomenclature for Svalbard archipelago 5 1.2 Arctic summers and winters in Svalbard 8 3.1 Precambrian chronometric scale 28 15.1 Eastern and western outcrops of Ny Friesland 276 16.1 Divisions of the Devonian 289

Table 17.1 Divisions of the Kapp Starostin Formation Table 17.2 Carboniferous and Permian sedimentation rates Table 19.1 Average of chemical analysis made by Tyrrell & Sandford (1933) Table 23.1 Deep well data for Svalbard

327 334 378 452

Photographs Interior of south central Spitsbergen from the air Cover Ny-Alesund and Tre Kroner ii Bay ice in Thiisbukta and Scheteligfjellet seen from Ny-A.lesund ii Comfortlessbreen and Aavartsmarkbreen from near the shore 1 Crevassed Monacobreen snout seen from the east 1 Small bergs in inner Kongsfjorden with Broggerhalvoya beyond 2 Late summer in mid Kongsfjorden with Kapp Mitra and the motor boat Salterella 2 Snow camp in southwest Lomonosovfonna looking down Wilsonbreen 45 Snow-capped mountains of Ny Friesland from northern Lomonosovfonna 45 Snow scooter in the middle reaches of Tryggvebreen, Ny Friesland 46

Tracked amphibious vehicle hauling sledges at Draken, Ny Friesland Camp on Nordenski61dkysten, a strandflat on the west coast of Spitsbergen Camp by Siktefjellet on raised beach north of Liefderfjorden The motor boat Arctoceras equipped for living aboard and working ashore The motor boat Salterella helped on her way through pack ice A safe anchorage for easy access ashore below Alkhornet Routine boat passage through Smeerenburgfjorden en route to the north The motor boat Salterella in north Liefdefjorden anchored off Erikbeen Access up Hannabreen from Liefdefjorden with signs of the end of summer

46 225 225 226 226 447 447 448 448

Preface 'I think that we shall have to get accustomed to the idea that we must not look upon science as a "body of knowledge", but rather as a system of hypotheses; that is to say, as a system of guesses or anticipations which in principle cannot be justified, but with which we work as long as they stand up to tests, and of which we are never justified in saying that we know they are "true" or "more or less certain" or even "probable".' Karl A. Popper (From a paper that Popper read in 1934 when his Logik den Forschung was in proof. It was published in English in the new appendices of his Logic of Scientific Discovery 1959, p. 317).

This work attempts to present the geology of Svalbard in some detail, arranged systematically as a definitive study and so reflecting the present conjuncture of research. It may thus meet the needs of specialists with information on related fields or of any geoscientist wanting an indication of what is known about this key region. Spitsbergen (peaked mountains), the name earlier referred to the whole archipelago. It is now replaced by the name Svalbard (cold coasts), within which Spitsbergen is the principal landmass. Spitsbergen alone is about the size of Switzerland and the whole archipelago a little less than the area of Scotland. Geologically it has the wealth in variety and complexity in stratigraphy and structure no less than these classic areas. Moreover with an international history and present treaty status many nations have participated in research so the geological literature currently comprising far more than 3000 publications is widely scattered and rapidly increasing. There are indeed excellent published geological outlines, but no comprehensive work. Part 1 of this work is introductory, setting the stage. Chapter 3 in particular presents the principal geological conventions used throughout and outlines the main geological features and tectonic hypotheses. Part 2 divides Svalbard into eight somewhat arbitrary regions/sectors which are described with minimal interpretation. The rock successions are described briefly from the top down as observed, and the structures are outlined and to some extent illustrated. Part 3 interprets historical events and environments from oldest to youngest in successive time-slices. Part 4 comprises an appendix on economic geology and four alphabetical lists (place names, stratigraphic names, references and general index). Small type has been used throughout the text for detail that may be skipped when only the main argument is of interest. My interest in the project stems from about 50 years of research in many aspects of Svalbard geology with some 50 colleagues and collaborators listed below. However this book purports to be an objective study of contributions from international sources. Where there are differences of opinion alternative views are presented. Obviously, however, no single person could comprehend the whole literature nor avoid some personal bias when making a coherent synthesis that has been thought through. These objectives would take more than a life-time to fulfil. This work is presented as a contemporary statement in the spirit of the quotation at the head of this preface. By venturing conjectures and exposing them freely in graphic form as well as in the text it is intended that they shall be subject to critical assessment. Lack of appropriate evidence does not vitiate an hypothesis nor can abundant supporting evidence establish it. Only contradictory evidence provides effective criticism. This work presents a challenge and a platform for further research and will be superseded in the normal course of science. The philosophy behind this study is that all geological data may be integrated in space and time, that is stratigraphy in the broad sense. This regional synthesis is offered as a contribution to Earth history. It is a two way interaction. Understanding of process enables and demands the interpretation of historical data and the attempt to understand history leads to further modifications in the theory of the Earth. For example: the attempt to make sense of the field data led to early hypotheses of continental drift; of cooling and heating of the mantle with regional subsidence and uplift; of compression leading to lateral escape, transpression and transtension; of large scale paleo-strike-slip of former provinces and allochthonous terranes; and of global Vendian glaciation.

This is a personal synthesis at the conclusion of work epitomizing a journey that began for me in Spitsbergen on graduation in 1938. I have been privileged as a student and teaching officer in a great University and as a member and Fellow of an ancient Cambridge College. These positions require specified duties in teaching and administration, but with freedom to pursue investigations whenever and wherever they may lead, provided the necessary resources can be found. I came into a culture where the older generation worked out their own research as individuals with little or no organized cooperation. After two abortive research lines I decided in 1948 both to attempt to tie up some unfinished work in Spitsbergen and at the same time to try out a pattern of cooperative research with our students. All I have learned about research was gained through such interaction and that is why I dedicate this work to those colleagues. Some, hardly junior, have long achieved distinction. About 400 persons have in diverse ways contributed to our joint enterprises. I draw attention to the early decades when fieldwork involved long boat journeys to Spitsbergen and then transport by small open boats, manhauled sledges and always much pack-carrying to the study area. Equipment was primitive and conditions often harsh. We thought ourselves fortunate indeed to share the experience of our predecessors in Svalbard exploration. I mention only two colleagues. Colin B. Wilson worked with me in N y Friesland contributing greatly to the work in Chapter 7. His contribution, first in our systematic survey of Ny Friesland and later on his private solo excursions by small boat with outboard, carrying sledges and supplies from Longyearbyen round the northwest to N y Friesland where he recorded exemplary observations across enormous distances. His motivation was the shear joy of discovery and only with difficulty was he persuaded to prepare work for publication. His death in 1959, not in Spitsbergen, but by an accident in Cambridge, deprived us of a remarkable investigator. C. John B. Kirton a brilliant first year student was killed in 1958 by a flying stone while holding a fossil at a new locality on a mountain later named after him. A service was held in 1959 at his remote grave and memorial cairns were built nearby and by the shoreside base. He represents the best in our university tradition. Our research group was never an official university project and we paid our way as best we could in the early days, contributing personally. The need for independence led to the formation of Cambridge Spitsbergen Expeditions, (later Cambridge Svalbard Exploration). This then led to the formation of the Cambridge Arctic Shelf Programme to give more security of employment and to spread our interests so as not to compete for limited funds in Britain or Norway. Finally I acknowledge one colleague, my wife Elisabeth, who in the early years looked after our family taking domestic responsibility single handed. In the middle years she assisted in Svalbard on 13 field seasons and has latterly given invaluable support to my writing of this work for which I alone must bear full responsibility. W. B. Harland July 1997

Department of Earth Sciences University of Cambridge Downing Street Cambridge CB2 3EQ

Acknowledgements Two kinds of acknowledgement relate to the research and to this publication. First paying tribute to those to whom the book is dedicated the research has benefited from the participation of many colleagues during 45 field seasons as well as in Cambridge. They contributed greatly to my education and determination to write this book. It may be of interest to other Svalbard geologists to note who have published from this experience. In list A those names with asterisks worked on Svalbard material for their research degrees, others participated, some over long periods. It would, however, be wrong to think only of the geologists whose reward was in their work. We depended throughout on logistic support. Of the hundred or more who supported the work in this way list C names those who took responsibility for more than one season, for example captaining boats. More than a hundred geology undergraduates joined as assistants and many have gone on to distinguish themselves. They often asked the most penetrating questions, made unlikely observations and were rewarding companions. Whereas the above thanks are for my own personal indebtedness to those who have shared in the work I gladly acknowledge the immense debt due to the larger scientific community whose published work is the basis of this book as may be noted from the list of publications cited. At the same time I should declare that by no means have the extensive files of CSE and CASP unpublished work been abstracted here. I remembered only what seemed relevant to the arguments. Nevertheless to have traversed the ground myself enabled the literature to be better appreciated. For help with the many aspects of the book it is both a pleasure and a duty to acknowledge the following: D. Manasrah's patient committal to disc of my scribble and good tempered acceptance of the need for innumerable revisions. L. M. Anderson helped manage the later stages of the book, executing most of the figures, listing place names and checking the whole for submission on disc. Both were employed by CASP on this work, (Cambridge Arctic Shelf Programme, West Building, Gravel Hill, Huntingdon Road, Cambridge C B 3 0 D J ) . Whereas I drafted most of the text and sketched most of the figures others contributed of their expertise as indicated in

the chapter headings. The late Dr A. Challinor gave permission to include the serial cross sections of the West Spitsbergen Orogen from his dissertation and later CSE reports (Section 20.6); D. I. M. Macdonald, Chief Geologist of CASP, supported this work throughout and seconded CASP staff at different times to this project. I. Geddes helped with the proofs. The place name list was compiled by Mr L.M. Anderson The lexicon of stratigraphic names begun in the fifties was abbreviated and checked recently in co-operation with W. K. Dallmann (Norsk Polarinstitutt Geologist and Chairman of the SKS) The more comprehensive bibliography (the basis of the reference list here) has a long history beginning with the earliest research. Managed for many years as a card index by K.N. Herod it was in due course computerised initially by R. A. Scott (CASP) and subsequently updated at regular intervals with the continuing help of D. Manasrah (CASP), and E. L. Lesk, Information Officer in CASP, who scanned new literature for me through this work. Publications were listed as met in the work and not sought out for a comprehensive bibliography. Unless otherwise stated in the captions, the figures were devised and sketched by me and then executed on disc by those who have initialled the diagrams, mainly L. M. Anderson, C. F. Stephens, S. R. A. Kelly, D. Manasrah and P. A. Doubleday. M. J. Hambrey, P. W. Webb and N. I. Cox provided most of the supplementary photographs that appear as the frontispiece and on the cover page for each of the four parts of the book. At a late stage in preparation of the manuscript I owe much to help from those who made useful improvements, especially to M. J. Wells (University College London) for correcting my Norwegian (and English), to F. Cooley (CASP) for checking most of the Russian transliterations in the reference list. The remaining mistakes would not be due to any failure on their parts. Named referees contributed significantly: in addition to A. M. Spencer's contribution in the Appendix, P. F. Friend, A. J. Martin and J. R. Parker suggested where improvements could be made. Finally the work has benefited from the professionalism of the staff of the Geological Society Publishing House in Bath, particularly the Staff Editor Angharad Hills.

(A) Geologists accompanying Cambridge field parties (and/or) who have had Svalbard research published * K. C. Allen L. M. Anderson K. A. Auckland * D. J. Batten * M. B. Bayly * D. E. T. Bidgood G. S. Boulton S. H. Buchan * H. J. Campbell * A. Challinor * C. Croxton * J. L. Cutbill * M. Dettmann J. A. D. Dickson P. W. Ditchfield E. K. Dowdeswell J. A. Dowdeswell * M. Dowling P. Doyle I. J. Fairchild * C. L. Forbes * R. A. Fortey * P. F. Friend

* M. D. Fuller * R. A. Gayer I. Geddes * D. G. Gee E . R . Gee * D. J. Gobbet A. Hallam M . J . Hambrey M. Head A . P . Heafford W . G . Henderson K . N . Herod * D. W. Holliday * W. T. Horsfield * K. Howells N . F . Hughes * P. F. Hutchins * L. K a n a t S . R . A . Kelly A . H . Knoll J. Laing U. Lehmann B . E . Lock

J. Lowry S . R . Lu D . I . M . Macdonald * A. J. M c C a n n * J. R. H. McWhae * G. M. M a n b y * A. M a n n * D. Masson-Smith * P. I. M a t o n * M. Moody-Stuart * A. P. Morris J . E . Odell * J. R. Parker C . A . G . Pickton * G. Playford * D. J. W. Piper S . P . Price M. Quest P . F . Rawson A . B . Reynolds W. Schwarzacher R . A . Scott * D. G. Smith

. . .

xvm M. P. Smith I. Snape 9 H. Spall C. F. Stephens K. Swett

ACKNOWLEDGEMENTS F. Thiedig R . S . W . Thornley C. Townsend G. Vallance R . H . Wallis

* P. Waddams * C. B. Wilson T . S . Winsnes N . J . R . Wright R . T . Wu

* Svalbard research students at one time

(B) Some of those who contributed to the field work and later in other ways M. J. Allderidge T. R. Astin P. B. H. Bailey M. H. P. Bott D. D. Clark-Lowes A. P. R. Cooper L. E. Craig T. A. Davies

J . G . Elbo N. Golenko G . E . Groom B. Harte E . M . Himsworth C . A . Jourdan R. Mason D . P . McKenzie

B. Moore M.J. O'Hara P . C . Parks C . V . Reeves O . P . Singleton J . C . Tippen F . J . Vine P . T . Warren

(C) Logistic leaders (e.g. boat captains) for more than one season R. A. Browne M. F. Chantrey N. I. Cox

W . D . H . Fairbairn R N J. H Gammage A . H . Neilson

A. C. Smith M. Tuson

Participants W. B. HARLAND

Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK L. M. ANDERSON

CASP, West Building, Gravel Hill, Huntingdon Road, Cambridge CB3 0DJ, UK D. MANASRAH

CASP, West Building, Gravel Hill, Huntingdon Road, Cambridge CB3 0DJ, UK N. J. BUTTERFIELD

Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK A. CHALLINOR (DECEASED)

Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK P. A. DOUBLEDAY

CASP. Present address: Amerada Hess Ltd, 33 Grosvenor Place, London SW1 X7HY, UK E. K. DOWDESWELL

Centre for Glaciology, Institute of Geography and Earth Sciences, University of Wales, Aberystwyth, Cardigan SY23 3DB, UK J. A. DOWDESWELL

Centre for Glaciology, Institute of Geography and Earth Sciences, University of Wales, Aberystwyth, Cardigan SY23 3DB, UK I. GEDDES

CASP. Present address." 1 School Close, Keevil, Trowbridge BA14 6SB, UK S. R. A. KELLY

Consultant with CASP, 10 Belvoir Road, Cambridge CB4 1JJ, UK E. L. LESK

CASP, West Building, Gravel Hill, Huntingdon Road, Cambridge CB3 0DJ, UK A. M. SPENCER

Statoil, Forushagen, 4035 Stavanger, Norway C. F. STEPHENS

CASP. Present address." Amoco (UK), Amoco House, West Gate, London W5 1XL, UK

Conventions Geological conventions employed throughout the work are treated in Chapter 3. These include the international time scale, principles for lithostratigraphic nomenclatures, the uses of some technical terms and the descriptive names for Svalbard structures. Place names are explained in Chapter 1 and listed in Part 4.

Acronyms in common use

Authority It is intended that any positive statement be supported by a reference at the end of the paragraph or subsection. If none it may be assumed either that the statement is common knowledge or that it is the original contribution (opinion) of this work. The names of up to three authors may be cited in the text and 'et al.' generally refers to four or more.

CSE: Cambridge Spitsbergen Expeditions, Cambridge Svalbard Exploration. CASP: Cambridge Arctic Shelf Programme. GSSP: Global stratotype section and point. IKU: Continental Shelf Institute, Trondheim. lUGS: International Union of Geological Sciences. NP: Norsk Polarinstitutt. SKS: Stratigrafisk Komit6 for Svalbard.

Use of contemporary nomenclature and compass orientation

Contractions in figures where space is critical

Transfiteration

-fjt (-fjellet); -fdn; fin (-fjorden); -fja (-fjella); -bn (-breen)

The Norwegian alphabet places symbols o and 6 ~t a~ at the end whereas they are placed here as though unmodified in the English language alphabetical order. For Chinese: Pinyin For Cyrillic: The system used was jointly recommended by the Permanent Committee on Geographical Names (PCGN) for British Official use and the United States Board on Geographical Names (USBGN), as revised in 1970 and 1972. It is used in the Times Atlas of the World, the Scott Polar Research Institute and the Geographical Names Division of the US Army Topographic Command, which has published perhaps the most comprehensive gazeteer of the FSU. The ISO system has advantages but requires the addition to normal type of accurate diacritical symbols unfamiliar in the west.

Time conventions Three-letter abbreviation of age names follow Harland et al. (1990), see Chapter 3.2. Formal use of subscript numbers 1, 2 & 3 = Early, Mid- and Late, which are not abbreviated. Ma is the usual symbol for the age in millions of years as also ka for thousands of years before present (BP).

In recording earlier work, unless original wording is quoted (in quotes), the present usage (for example of place and stratigraphic names) is generally substituted. Original names may be added in parentheses. Compass directions for earlier geological ages are expressed in the present orientation without implication as to what was the ancient orientation.

Rock units U, M & L upper, middle and lower for rock units only. 'Thickness' in metres is not added to numbers i.e. 100m to indicate 100m thick unless otherwise specified.

Lithologies Lst, dst, sst, slst, sh, cgl (conglomerate), qi (quartzite); aren. (arenaceous); dol (dolomite-except. dst); unto. (unconformity, unconformable).

Use of stratigraphic nomenclature (as explained in Section 3) The problem of divergent stratigraphic nomenclature and classification has been met by a discussion arriving at a conclusion generally early in each historical chapter. That discussion, often seemingly of miniscule interest, may then be confined to that particular section. The conclusions may be applied in the rest of the work both in earlier or later parts. Therefore, the reader who finds a different scheme employed and is possibly irritated thereby, should find the reasoning behind such a choice in a section in each of the historical chapters. The Stratigraphic Glossary may help.

PART 1 Introduction Chapter 1 Chapter 2 Chapter 3

Svalbard, 3 Outline history of geological research, 16 Svalbard's geological frame, 23

Mid-season view of the glaciers Comfortlessbreen (on the left) and Aavartsmarkbreen (beyond). The rocks are Early Vendian with Varanger tillites. Stratigraphic sections are generally worked along the glacier margins either by porterage from the shore (in this case Egelskbukta) or by sledge from the interior. Photo M. J. Hambrey (SP. 455).

Late season view from the east over the terminal crevassed glacier Monacobreen. In this case access up the glacier is almost impossible because the lower reaches are deeply crevassed and the glacier terminates in ice-cliffs in inner Liefdefjorden. The glacier beyond offers an easy route westward. Photo P. W. Webb, CSE 1989.

View from Ossian Sarsfjellet at the eastern end of Kongsfjorden towards the mountains of Broggerhalvoya which are reflected in the fjord. The intervening fjord carries a scatter of small bergs which have calved from the glacier cliffs of Kronebreen and Kongsbreen respectively to north and south of the photographer. The concentration of ice depends on wind and tide and is navigable with care in a slow moving boat. The small bergs melt rapidly in the summer. Photo M. J. Hambrey (SP96.122) 1996.

The CSE motorboat Salterella in mid-Kongsfjorden seen when looking out to sea with the landmark K a p p Mitra to the right where the rocks are Caledonian metamorphosed basement of pre-Vendian rocks. This is a late summer scene in an outer fjord. Snow on land and floating ice have gone. Weather generally deteriorates at this time so this is unusually a calm evening scene. Eider duck are flying and on the water. Photo P. W. Webb, CSE 1989.

Chapter 1 Svalbard W. B R I A N 1.1 1.1.1 1.1.2 1.1.3 1.2 1.3 1.3.1 1.3.2 1.3.3 1.3.4 1.3.5 1.3.6 1.4 1.5 1.6 1.6.1 1.6.2

Geographical names, 3 Principal islands and fjords, 3 The lands, 7 Norwegian place names, 7 Topography and bathymetry, 7 The physical environment, 8 Latitude and daylight, 8 Marine influences, 8 Weather, 8 Sea ice, 8 Snow and ice cover, 10 Frozen ground, 10 The biota, 10 Political history, 11 The Spitsbergen Treaty, 11 Administrative consequences of the Treaty, 11 Strategic consequences of the Treaty, 11

An introduction to Svalbard is as necessary for a geoscientist as for any other student of the archipelago. The section on geographical nomenclature is illustrated by maps which are designed to locate many of the commonly used names. These and others are listed at the end of the volume where additional names used later are referred to. The regional context of Svalbard is shown in Fig. 1.1. The present-day physical environment is mentioned, but treated more fully in Chapters 21 and 22.

HARLAND 1.6.3 1.6.4 1.7 1.7.1 1.7.2 1.7.3 1.7.4 1.7.5 1.7.6 1.7.7 1.8 1.8.1 1.8.2 1.8.3 1.8.4 1.8.5

The section on the present-day Svalbard biota is not by a specialist for specialists, but is intended to list those organisms commonly encountered in the field and of interest to most workers. The political and treaty considerations are interwoven and have sometimes left the Norwegian administration in an ambivalent position. Happily however the resources forthcoming from the petroleum industry to the nation has enabled the administration to fulfil its responsibility admirably and latterly without the pressures from the Cold War. Svalbard for its size has a small population, less than 4000 concentrated in relatively few settlements, but numbers are augmented by summer arrivals of construction/maintenance staff, tourists, students and scientists, while the residents often take their summer holidays on the mainland. The environmental threat from this expanding seasonal population presents one of the most serious challenges, while at the same time tourism is replacing coal mining as the principal economic resource. Provision of shipping facilities supplemented by air travel is transforming the economy, which however still requires substantial subsidy. The international community has generated more than 3500 geoscientific publications of which about 2500 are listed in the references. The official publication series are outlined at the end of this chapter. This work attempts to encompass the present geological nature of Svalbard and to interpret its history. It is mainly concerned with evidence from above sea level and this may be justified in part by some more recent interpretations of the Spitsbergen Treaty which claims for Svalbard not more than about 4 nautical miles offshore. The immense area of the submarine Barents Sea floor, the exploration of which resulted in enormous resources, is not treated here except for occasional mention. That would require another work on this scale and by another author. A recent convenient survey of what is known was provided by A. N. Nystad (1996) on the geology and petroleum resources of the Barents Sea; but as with so much knowledge obtained industrially, references to sources are not given. However this volume is mainly concerned with published information together with original thinking.

1.1

Fig. 1.1. Regional geographical setting of Svalbard, with typical maximum and minimum limits of pack ice. Simplified and redrawn from Harland (in press) Norway. Svalbard in Encyclopedia of Worm Regional Geology, fig. 1.

Economic/political consequences of the Treaty, 11 Environmental consequences of the Treaty, 12 Settlements, 13 Longyearbyen, 13 Sveagruva, 13 Ny-Alesund, 13 Barentsburg, 13 Pyramiden, 13 Other settlements, 13 Manned Norwegian radio and meteorological stations, 13 Official publications, I3 Bathymetric charts, 14 Topographic maps, 14 Geological maps, 15 Thematic maps, 15 Scientific serials of the Norsk Polarinstitutt, 15

1.1.1

Geographical names Principal islands and fjords

The archipelago, whose geology is the subject of this work, lies on the northwest corner of the Barents Shelf 650 km north of Norway.

4

CHAPTER 1

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SVALBARD The name Spitsbergen was given by the Dutch captain, Barents, who is generally credited with the modern discovery of the islands in 1596 and after whom the Barents Sea is named. Barents did not know that the name Svalbard (cool coast) was mentioned in the Islandske Annaler in A D 1194 and in the Landndmabbk (approximately AD 1230) from Viking exploration. It was supposed that this archipelago was the northern land referred to, although it was only much later that a clear distinction was made between Spitsbergen and Greenland. Also Russian hunters are claimed to have built huts in the fifteenth century and possibly earlier (Baron 1986). The name Spitsbergen refers to the pointed mountain peaks that the main island exhibits on approach from the sea. It had been used for the whole archipelago or for the main part of it excluding the outlying islands. Spitsbergen was the name for the whole archipelago in the Treaty of S6vres in 1920, and in the Spitsbergen Treaty, which came into effect in 1925. The main island had been known as West Spitsbergen. The name Svalbard was formally introduced by A. K. Orvin in Place Names of Svalbard (1942), by the Norsk Polarinstitutt (the Norwegian Polar Institute in Oslo) in the first systematic and descriptive gazeteer. In Place Names of Svalbard Spitsbergen was redefined to comprise the main group of islands, excluding the outlying islands Storoya, Kong Karls Land, Hopen (Hope island) and Bjornoya (Bear Island). The nomenclature was revised again (Hjelle 1970) so that Spitsbergen now refers only to the main island and excludes Nordaustlandet (North East Land), Barentsoya, Edgeoya, and Prins Karls Forland (Fig. 1.2). Place Names was supplemented in 1958. Until the Spitsbergen Treaty, which awarded the administration of the archipelago to Norway, the islands had been, in the words of Sir Martin Conway (1906), a 'no man's land'. There was no sovereignty and the principal competing nations first for whaling (1600 until the whale population was decimated around 1750) were Dutch and British; then for mineral rights American, British, Norwegian, Russian and Swedish. Scientific exploration went hand in hand with penetration beyond the coastline in a series of expeditions from Britain, (e.g. Scoresby 1820, Parry 1827), Norway (Keilhau 1831), Sweden (Torell 1859, Nordenski61d 1863, Nathorst 1910), Monaco (1899) with increasingly international participation. Consequently most prominent features were named in various languages. Whereas systematization and Norwegianization of older place names led to a single standard for scientific and cartographic description, for geological use once a rock unit name has been established, its original name remains unchanged except for change of rank etc. For example, in the literature before 1940 a common name in English for a fjord in the northwest was Red Bay. This was Norwegianized to Raudfjorden in i940 but the name Red Bay Conglomerate etc. still stands even if changed to Red Bay Formation or Group. Place names of Svalbard (Anon 1942) is a mine of historical information as well as a systematic Norwegianization of place names, and some principal geographical suffixes from that work are listed below. In addition to names for physical features (islands, mountains, glaciers, fjords etc.) the larger areas of Svalbard are divided into lands which are convenient for descriptive purposes (Fig. 1.3). Place names used in this work are listed at the end of the volume with figure numbers of some maps where they may be found. It is generally a scientific convention (as in this work) to follow the official geographical nomenclature of the Norsk Polarinstitutt (Table 1.1). Geological nomenclature will, as far as possible, follow generally recognized international principles taking into account recommendations of the Stratigraphic Committee for Svalbard (SKS). Even when discussing early work present nomenclature is generally employed here. Until about the middle of the nineteenth century there was little exploratory interest in the land. Indeed the prime concern was exploiting marine wealth. Fjords, anchorages and coastal hazards were the main concern. Thus the names of the principal accessible fjords were of great use in navigation. The Place Names of Svalbard recounts their early history. Therefore Fig. 1.2 also plots the present nomenclature of islands and coastal waterways.

5

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Table 1.1. Geographicalnomenclativefor Svalbard

Present nomenclature

1942-1960

pre- 1942*

Svalbard

Svalbard

Spitsbergen or Spitsbergen and Bjornoya

Spitsbergen and associated islands

Vestspitsbergen

Treaty 1925 West Spitsbergen?

Nordaustlandet

Nordaustlandet

North East Land

Barentsoya

Barentsoya

Barents Island*t

Edgeoya

Edgeoya

Edge Island*:~

Prins Karls Forland

Prins Karls Forland

Prins Charles Forland~w

Storoya

Storoya

Great Island

Kong Karls Land

Kong Karls Land King Charles Landw

Hopen

Hopen

Hope Island

Bjornoya

Bjornoya

Bear Island

* Originally in many languages. t Willem Barents, leader of Dutch expeditions 1594 to 1597. $ After Thomas Edge, early seventeenth century English whaler. wSeen by Barents and later named for Charles, Prince of Wales and later King of Britain and Ireland. [[Although discovered at least as early as 1617 by T. Edge this name was proposed by Petermann after Karl I (1823-91) King of Wtirttemberg.

Fig. 1.4. Map showing the principal topographic features of Svalbard, approximate locations of mountains are indicated by triangles with elevation in metres. Ice-cover in white is demarcated by dotted lines.

SVALBARD

1.1.2

7

The lands

The smaller islands need no further classification, but Spitsbergen and Nordaustlandet are now divided into lands for general descriptive purposes. These are not political units and have no precisely defined boundaries. Some names are as old as the island names in use and in many forms before the separate islands were distinguished as, for example, Ny Friesland. Other areas have been designated to complete the modern mosaic with the names of the Norwegian royalty, as for example Olav V Land which was introduced after the publication of Place Names o f Svalbard as in Fig. 1.3. The boundaries shown on Fig. 1.3 are diagrammatic and have no authority. In this work Ny Friesland will continue to describe the area which includes much of Olav V Land. Indeed for geological description Svalbard is classified in this work into sectors that are the descriptive Chapters 4 to 11 and also into terranes. These divisions are peculiar to this work. They are explained in Chapter 3.

1.1.3

Norwegian place names

Since 1942, with the publication of Place Names o f Svalbard, all official names have been Norwegianized: descriptive names being translated; proper names being preserved and usually each is combined with a geographical term. The last one or two letters of the term indicate the definite article, which in Norwegian syntax may be omitted, but in international and especially geological application the name should be indivisible. The plural form may modify the suffix. The common terms used as suffixes in place names are listed here. Mountains and hills, etc.: berget, fjellet, haugen, kammen, kollen, nuten, piggen, ryggen, tinden, toppen. Valleys, passes: dalen, passet. Plains etc.: sletta, vidda, oyra, flya, steinen (stone). Glacial: corrie, glacier, icefield: botnen, breen, fonna, jokulen, morene. Rivers and streams: elva bekken. Lakes, tarns: vatnet, laguna, tjorna, tjernet. Coastal inlets: hamna, pollen, bukta, vftgen. Coastal promontories: halvoya, huken, neset, odden, pynten, tangen, kapp. Shore: stranda. Water: sjoen (sea or lake), fjorden, sundet, flatet (sea bottom). Submarine features: banken, renna, flaket. Shoal, reef and skerry: grunnen, revet, skja~ret. Islet, island: holmen, oya. Settlement, mine, hut, cabin: byen, gruva, hytta, varden (landmark or cairn). Similarly the Norwegian geographical terms for north, northern etc. may constitute the first element in the place name thus: aust, austre; nord, nordre; sor, sore; vest, vestre. There remain a number of (descriptive) names which stand on their own e.g. Lykta, Eplet, Krokodillen. Happily these are often brief. The geological use of place names is discussed in Chapter 3. In maps and diagrams where space may be critical, contractions and abbreviations of the suffix are useful as -fjt for -fjellet, -fja for fjella, -fdn- for fjorden, -bn for -breen.

1.2

Topography and bathymetry

The northwestern margin of the European continental lithosphere comprises the Barents Shelf (Fig. 1.5). Extending northwards from Norway and northwestern Russia, the shelf is covered by the Barents sea except at the northwestern margin where the Svalbard archipelago, and further east Franz Josef Land emerge. The northern margin of the shelf is marked by the continental slope down to the Polar Ocean Basin. The western margin of the shelf similarly terminates along the oceanic Norwegian Greenland Sea.

Fig. 1.5 Bathymetry of the western Barents Shelf. Isobaths (in metres). (simplified from the map of Western Barents Sea Bathymetry, 1: 1 500 000, Norsk Polarinstitutt, Oslo, 1989).

Within the Barents Sea water depths rarely exceed 400 m. In the ocean basins they plunge rapidly from 500 m to 2000 m. On the shelf the bathymetry reflects Neogene and Quaternary history with a subdued drainage pattern. The topography of Svalbard, while reflecting the detailed geological structure which determines many contrasting land forms, shows certain general features. Sea-level changes have eroded and then exposed large tracts of nearly flat land or raised beach. A typical coastline consists of low cliffs seldom exceeding 10m and a coastal plain (strandflat) of variable width behind which steep mountains rise.

8

CHAPTER 1

The mountain peaks all fall within a general summit envelope representing an uplifted and warped peneplane almost regardless of the attitude of the strata, typically about 1000m. Land sculpture is a continuation of glacial erosion resulting in steep cliffs, valleys and glaciers. Other mountain contours typically result from a cold-desert environment with steep scree slopes and cliffs, where the rocks are resistant, giving little opportunity for vegetation to become established. Soft rocks give a more subdued landscape. The variety of land forms is typical of the Arctic as illustrated by Thor6n (1969)

1.3 1.3.1

The physical environment Latitude and daylight

The main islands lie between 76 ~ and 81~ Many distinctive features of this Arctic environment derive from the angle of incidence of solar radiation (Table 1.2; Kosak 1967 p. 99).

1.3.2

Marine influences

Svalbard is a relatively small archipelago and the climate is influenced by two sources of surface ocean water: (i) the West Spitsbergen Current, is the northern-most remnant of the Gulf Stream moving relatively warm water northwards along the west coast; (ii) the East Spitsbergen Current brings cold water and packice southwestwards east of Spitsbergen and the eastern islands. These currents meet off Sorkapp and the cold water is deflected and continues northwards between the warmer current and the coast, often carrying pack-ice with it, and causing fog (Fig. 16). On the western approaches the upper Atlantic layer of approximately 200-900 m in depth has a fairly uniform temperature of about 3~ whereas the bottom layer may be about - 1.0~ The tides range between about 2 m for spring and 1 m for neap except where restricted by land.

1.3.3

Fig. 1.6. Prevailign surface currents of the Barents Sea and North Atlantic areas, abstarcted from V. Hisdal (1985, fig. 12, p. 21) Geography of Svalbard.

is about 300-400mm (with a maximum of about 1000mm), most of which falls as fine snow or rain in summer and autumn. In summer the low humidity, cold land and warm air interact, often causing dense fog and low cloud over the glaciers and ice filled waters. In winter it is usually clear. The summer air temperature at sea level averages about 4-5~ and in winter about - 1 2 C ~ and commonly down to - 2 0 ~ in the west. Temperatures are lower towards the north and east. Summer temperature may rise to 10~ the extreme range may be - 5 0 ~ to +22 ~ There is usually some wind, which may be strong locally, especially in long fjords with direct access from inland ice. Mirages, haze, ice blink and white-out are all common.

Weather

Annual precipitation is low. In the east it is almost all snow and may be as low as 10 mm, per year. On the west coast the average

Table 1.2. Arctic summers and winters in Svalbard Latitude

80~ 79~ 70~ 66.5~

Number of days of continuous Daylight

Darkness

137 107 70 23

123 94 55 0

1.3.4

Sea ice

There is an inexhaustible supply of pack ice (often some years old) drifting from the polar basin with the East Spitsbergen Current. It depends for its subsequent distribution mainly on the marine currents but often and unpredictably on winds. It melts slowly in the warmer waters. The old, thicker, harder ice is a more serious factor in shipping especially when it drifts round the south of Spitsbergen and then northward along the west coast. On the other hand the annual freezing and thawing in the fjords provides a bay ice (never exceeding a metre in thickness) that melts rapidly, becoming rotten in early summer. A third floating hazard are the icebergs that come from calving glaciers. Larger bergs occur in many fjords and beyond,

Fig. 1.7. Principal ice cover and valleys of Svalbard. The ice-covered areas shown on the map are extremely generalized. Glaciers etc. are numbered black circles and valleys are numbered rectangles, each are listed in alphabetical order. Glaciers: (1) Aavatsmarkbreen; (2) Aust Torellbreen; (4) Balderfonna; (5) Barentsjokulen; (6) Bivrastfonna; (7) Borebreen; (8) BrSsvellbreen; (11) Chydeniusbreen; (12) Comfortlessbreen; (14) Dahlbreen; (15) Digerfonna; (16) Doktorbreen; (17) Dunerbreen; (19) Eidembreen; (20) Esmarkbreen; (21) Etonbreen; (23) Forstebreen; (24) Fridjovbreen; (26) Glitnefonna; (27) Gronfjordenbreen; (30) Hansbreen; (31) Hellefonna; (32) Hinlopenbreen; (33) Holmstrombreen; (34) Holtedahlfomla; (35) Hornbreen; (38) Isachsenfonna; (40 Kongsvegen; (41) Kronebreen; (42) Kvalbreen; (43) Kvitoyjokulen; (45) Leighbreen; (46) Lilliehookbreen; (47) Lomonosovfonna; (49) Maudbreen; (50) Mittag-Lefflerbreen; (51) Monacobreen; (53) Nansenbreen; (54) Nathorstbreen; (55) Negribreen; (56) Nordbreen; (57) Nordenski61dbreen; (58) Nordmannsfonna; (60) Olsokbreen; (61) Oslobreen; (63) Penckbreen; (64) Poulabreen; (65) Raudfjordenbreen; (66) Recherchebreen; (67) Renardbreen; (68) Rimfonna; (70) Samarinbreen; (71) Sefstrombreen; (72) Sjettebreen; (73) Smeerenburgbreen; (74) Sorbreen; (75) Sorkappfonna; (76) Storbreen; (77) Strongbreen; (78) Stubendorffbreen; (79) Sveabreen; (80) Terre Glac6e Russe; (81) Tunabreen; (83) Ulvebreen; (84) Ursafonna; (85) Uversbreen; (87) Valhallfonna; (88) Vasilievbreen; (89) Vegalfonna; (90) Venernbreen; (91) Vest Torellbreen; (92) Veteranen; (93) Veternbreen; (94) Vonbreen; (95) Von Postbreen; (98) Wahlenbergbreen; (99) Werenski61dbreen. Valleys: (1) Adventdalen; (3) Berzeliusdalen; (5) Colesdalen; (7) Dicksondalen; (8) Dyrdalen; (10) Forkdalen; (12) Gipsdalen; (13) Grondalen; (15) Kjelstr6mdalen; (17) Plurdalen; (18) Purpurdalen; (21) Reindalen; (22) Rijpdalen; (24) Sassendalen; (25) Semmeldalen; (28) Vestfjorddalen; (30) Woodfjorddalen.

SVALBARD

9

10

CHAPTER 1

long after the bay ice has melted. There is an increased supply of bergs from calving in the summer when glacier cliffs are undercut by warmer water. Their distribution is then a product mainly of tides rather than winds at least for the larger and deeper bergs. Figure 1.1 plots the extreme limits of pack ice in summer and winter (see Lunde 1965).

1.3.5

Snow and ice cover

In winter thin snow cover is general with bare patches and thick drifts. This melts throughout the summer leaving bare ice covering about 60% of the whole area above sea level. The larger islands all have ice caps from which glaciers flow, many reaching the sea (Fig. 1.7). The larger icefields are true ice caps, as in Nordaustlandet; the smaller are of 'highland ice' in which the subglacial topography is reflected in the surface contours of the ice. Most mountains also contain independent valley and corrie glaciers.

1.3.6

Frozen ground

Permafrost is defined as permanently or, more accurately, perennially frozen ground. The term is used in different senses. It is most usefully taken to mean that where seasonal melting at the surface occurs a distinctive active zone is separated from the permafrost by the permafrost table. Two terms, not in common use and of Russian origin, may be noted. Pereletok is a mass of anomalous frozen ground within the active zone, and talite is a mass of anomalous unfrozen ground within the permafrost. The formation, temperature, and depth of permafrost are the result of a complex interplay between the microclimatological conditions, the surface cover and the rock beneath, as are the movements that take place within the active zone to form many distinctive types of patterned ground (soil polygons). The sum of all these effects through many years yield a temperature curve with depth from which paleotemperatures may be inferred (section 21.8.4). Permafrost does not occur beneath large bodies of water or ice, so that the undersurface of frozen ground reflects all the above circumstances in a complex manner. In Spitsbergen it is said to have an average depth of 300 m and on Bjornoya only 60 m. Any disturbance of the equilibrium may lead to local phenomena such as pingos, and to frost heaving of man-made structures if adequate precautions have not been taken.

The contemporary (evident) biota (typically visible) Vertebrates Mammals Arctic fox, Alopex lagopus Reindeer, Rangifer tarandus platyrhychus (Musk ox, Ovibos moschatus, recently extinct in Svalbard) Polar bear, Ursus maritimus Seals: hooded, Crystophora cristata; harp, Phoca groenlandica; ringed, Phoca hispida; bearded, Erignathus barbatus Walrus, Odobenus rosmarus Whales: sperm, Physeter eatodon; killer, Orcinus orca; blue, Balaenoptera musculus; white (beluga) Delphinapterus leucas; narwal, Monodon monoceros; minke, Balaena aeutorostrata Birds Diver: red-throated, Gavia stellata Petrel: fulmar, Fulmarus glacialis Geese: barnacle, Branta leucopsis; pink-footed, Anser brachyrhynclus; brent, Branta bernicla Ducks: eider, Somatenia mollissina; king eider, S. spectabalis Waders: purple sandpiper, Calidris maritima; ringed-plover, Charadrius hiaticula; turnstone, Arenaria interpres; sanderling, Calidris alba; grey phalarope, Phalaropus fulicarius Passerine: snow bunting, Plectrophenax nivalis Skuas: arctic, Stercorarius parasiticus; long tailed, S. longicaudus; great, S. skua Gulls: kittiwake, Rissa tridactyla; glaucous, Larus hyperboreus; great black-back, L. mar&us; Sabine's, L. sabini; ivory, Pagophila eburnea Tern: arctic, Sterna paradisaea Auks: puffin, Fratercula arctica; little, Plautus alle; black guillemot, Cepphus grylle; Brtinnich's guillemot, Uria lomvia; common guillemot, Uria aalge Svalbard ptarmigan, Lagopus mutus hyperboreus Fish Arctic char, Salvelinus alphinus Bullhead, Cottus gobio Capelin, Mallotus villosus Cod, Gadus morrhua; burbot, Lota lota Halibut, Reinharditius lippoglosoides Shark: Greenland, Somniosus; basking, Cetorhinus maximus Echinoderms Echinoids, Stronglocentrotus cf. droebachiens& Asteroids Ophiuroids Crinoids

1.4

The biota

Flora and fauna reflect the above physical conditions. The land-based biota is fragile. About 160 species of flowering plants and a few other species occupy low ground and flourish as the snow cover recedes in the short summer, often with spectacular flowers. Grasses may exceed the 15 cm height of dwarf birch and willow. Vegetation directly supports a variety of insects, reindeer and ptarmigan and indirectly the arctic fox. Summerhayes & Elton (1928) made an early study. The marine biota is perhaps the more remarkable. In winter, marine life continues, evident at the surface only by seal, walrus and the predatory polar bear; females hibernate in the snow. Bears number around 5000. With melting of the bay ice in summer, upwelling currents rich in nutrients coupled with continuous daylight generate a prodigious marine food chain exploited by many millions of migrant birds as well as by seal and bear. The birds nest on land and fertilize rich vegetation locally. Ptarmigan overwinter, and occasionally snow bunting and sand piper. The land mammals belong only to three species, fox, reindeer and the polar bear which lives largely off sea ice; voles are recorded at Grumantbyen. A selective list of the more evident Svalbard species follows. Plants, birds, reindeer and bear are protected.

Arthropods Crustaceans Barnacles, Balanus balanoides Crabs and crayfish Ostracodes Arachnoids Spiders and mites Myriapods Insects Spingtails Flies: mosquito; chironomid midges; dragonfly; dameselfly; hoverfly; dipterids Beetles Annelids (oligochaets) Nematodes Molluscs Bivalves Astarte boreal&; A. montagui; A. elliptica; Thyasina flexuosa; Chinocardium ciliatum; Serripas groenlandicus; Macoma calcarea; Lyosima fluetuosa; Saxicava arctica; Mya truncata

SVALBARD

Gastropods Margarites groenlandicas; M. helicinus; Littorina saxatites; Natica clausa; Sipho togatus; Buccinum groenlandicus; B. glaciale; Lora bicanisata; black-winged pteropod, Clio Foraminifers (Nagy 1965) Inner fjords: Cassidulina reniforme; Elphidium clavatum Glaciomarine: Quinqueloculina stalkeri Cyanobacteria, Algae, Fungi and Plants Elvebakk & Prestrud (1996) catalogued 2885 Svalbard species*

Algae and cyanobacteria (1122 spp. recorded*): for example, Laminaria; Lithothamnion glaciale Lichens (593 spp. recorded*) Fungi (624 spp. recorded*) Mosses (373 spp. recorded*) Pteridophytes (7 spp.*) Equisetum arvense; Lycopodium selago Flowering plants-Angiosperms (no gymnosperms) (of 165 spp* 48 from Gaerevoll & Ronning, Flowers of Svalbard, 1980) Arenaria pseudofrigida; Arnica alpina; Braya purpurascens; Campanula uniflora; Cardamine nymani; Cassiope tetragona; Cerastium arcticum; Cochlearia officinalis; Draba corymobsa; D. lactea; Dryas octopetala; Erigeron humilis; Eriophorum scheuchzeri; Melandrium apetalum; M. augustiflorum; Mertensia maritima; Minuartia rubella; Oxyria digyna; Papaver dahlianum; Pedicularis dasyantha; P. hirsuta; Petasites frigidus; Polemonium boreale; Polygonum viviparum; Potentilla chamissonis; P. hyparctica; P. pulchella; Ranunculus hyperboreus; R. lapponicus; R. nivalis; R. pedatifidus; R. pygmaeus; R. sulphureus; Salix polaris; Saxifraga aizoides; S. cernus; S. cespitosa; S. flagellaris; S. hieracifolia; S. hirculus, S. nivalis," S. oppositifloria; S. rivularis; Silene acaulis; Stellaria crasspipes; S. humifusa; Taraxacum arcticum; T. brachyceras

1.5

Political history

In the middle ages, Norwegian kings claimed sovereignty over all land in the Arctic Ocean from Greenland to the Russian arctic islands. In the sixteenth century Spitsbergen became a whaling centre with ships from Holland, England, Denmark-Norway, France and Hamburg. The Dutch settlement, Smeerenburg, on Amsterdamoya was the largest, with peak populations estimated at 200 (or even 1200) persons in the summer. The Greenland whale (Balaena mysticetus) was nearly exterminated in the fjords by 1640 and whalers had to make their catch in the open sea. Of the many claims in the early seventeenth century King Christian IV of Denmark-Norway claimed sovereignty over Spitsbergen, in opposition to the British and Dutch. The Basques of SW France specialised in exploiting the Northcaper whale (Balaena glacialis) and in eighteenth century land-based whaling declined with the whale population, in favour of their migration routes in the open ocean until about 1800 when systematic whaling was finished. From about 1715 to 1850 Russian 'pomors' went to Spitsbergen and wintered to hunt polar bear, reindeer, fox and seal. Norwegians began sealing in Spitsbergen waters in the latter part of the eighteenth century and after c. 1850 without competition. The exploitation of coal began at the close of the 19th and beginning of the twentieth century (Gjelsvik 1968). Early claims to the sovereignty of Spitsbergen by Britain, Holland and Denmark were never followed up. However, competition for mineral wealth continued by many individuals and companies and the map of Spitsbergen was a patchwork of, often optimistic, claims. At the same time scientific exploration by British, French, German, Norwegian and Swedish bodies had heightened the interest in the sovereignty of the archipelago. Arlov (1994) described early negotiations between the Arctic nations in Oslo Conferences 1910 to 1914.

11

The Versailles Treaty makers set about clarifying competing national aspirations when they were arranging protectorates for former colonies. The result for Svalbard was the Spitsbergen Treaty. The history of exploitation in and around Svalbard is outlined more fully in the handbook by Arlov (1989, 1994) and in detail by Hoel (1966).

1.6

The Spitsbergen Treaty

The Spitsbergen Treaty was signed in Paris on 9 February 1920 and Norway assumed administrative responsibility on 14 August 1925. The original signatories were Australia, Britain, Canada, Denmark, France, India, Italy, Japan, Netherlands, New Zealand, Norway, South Africa, Sweden and USA. Other nations followed. e.g. USSR 1924, Germany 1925 later totalling more than 40 signatories. The treaty provides that citizens of these other nations shall enjoy the same rights as Norwegian citizens and as the Norwegian government with respect to access and economic activities on the islands and in the territorial waters. The 10 articles are indicated as follows: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

defines by latitude and longitude, the boundaries of the archipelago, i.e. 74 ~ to 81~ and 10~ to 35~ provides equal fishing and hunting rights; guarantees free access to all waters and to all lands to all signatories; concerns the use of radio; concerns meteorological stations; recognises pre-Treaty rights of ownership and exploration; guarantees equal treatment of all signatories in future acquisition of land and mineral rights; outlines Norwegian intentions with regard to existing mining rights guarantees the neutrality of Svalbard; provides for Russia, then without government, to enjoy the same rights as other signatories.

Procedures for establishing existing claims were laid down under the jurisdiction of a commission to be nominated by the Danish Government (Sindballe 1927). Many other consequences followed from the Spitsbergen Treaty: administrative, strategic, economic/political and environmental.

1.6.1

Administrative consequences of the Treaty

Longyearbyen is the seat of the local administration where the Governor (Sysselmannen) has office and residence supported by police, now mainly helicopter borne. The mining inspector (bergmesteren) is responsible not only for mining operations but also for granting and refusing claim applications and for inspection of claims. The Norsk Polarinstitutt, under the Ministry of the Environment, is responsible for the geological survey of the island and is the Norwegian scientific (including geoscientific) armmainly concerned with the islands. Its former responsibility for topographic and bathymetric survey has been taken over by the Norwegian Mapping Authority (Statens Kartwerk). Appropriate ministries oversee other aspects of the administration such as postal services, radio communications, meteorological stations, building standards and conservation.

1.6.2

Strategic consequences of the Treaty

The strategic situation of Spitsbergen, so evident during the war years 1939 to 1945, and then subsequently in the Cold War between the Warsaw Pact and NATO has been neutralized (Article 9) so that no military establishments nor activities have been permitted.

12

CHAPTER 1

This was monitored by the Norwegian administration and from the Soviet settlements. The exception in World War II was mainly directed to the destruction and denial of facilities to the other side and to placing meteorological stations (Elbo 1952).

The Treaty did not foresee the complications of the off-shore exploration and exploitation of petroleum--it being largely concerned with mineral rights on land. Mineral claims on land were easily regulated by the mining inspector (Bergmesteren) agreeing approximately rectangular parcels each of 10km 2 area, not exceeding about 8 km in length and needing each to be staked, witnessed and claimed with specimens of a mineral to substantiate the claim. In effect this limits the seaward extension of any claim to within 4 nautical miles from a stake at the coastline. At that time, Norwegian maps showed the treaty area delineated by the bounding lines of latitude and longitude (e.g. 1 : 2M NP map of Svalbard 1958). This area was accepted by USSR maps which thus claimed a sector boundary from the NorwayUSSR frontier north along the line of longitude. It was shown to step eastwards between latitudes 74~ and 81~ to accommodate the Treaty area. Subsequently with the advent of subsea petroleum exploration and extended fishing claims far beyond the original 3 mile territorial waters it seemed that the Barents sea (i.e. on the continental shelf) was Norwegian or Soviet. Differences then emerged. On the one

hand Norway claimed a boundary to their part of the shelf based on the equidistant mid-line principle as applied elsewhere in offshore Europe. The USSR followed their meridional sector principle. This created a large disputed zone between the mid-line of the Norwegian government and the sector line of the former Soviet Union. On the other hand the extension of Norwegian continental shelf was held in Norway to override the earlier Treaty area so that the seas 4 miles offshore of the islands within the original latitude, longitude frame were regarded by Norway as outside Treaty jurisdiction. Norwegian maps no longer show this Treaty frame. All these matters have still to be finally resolved, while in the meantime a cooperative spirit in practical economic developments is taking place between Norway and Russia. Figure 1.8 illustrates the political problem accentuated by the economic consequences. The eastern margin of the Svalbard Treaty coordinate area (Long 35~ passes midway between Kvitoya (Svalbard) and Victoria Island (Russia) so that applying the preferred Russian sector principle the sector line running due north from the Norwegian-Russian international boundary on the mainland must be deflected eastwards, as in most Russian maps, to accommodate the Treaty coordinate area. This boundary favours Russia whereas the line median between the national coasts (as applied in the North Sea) passes in a NE direction before joining the same line between the two islands. On the other hand if Svalbard be defined as the archipelago limited to 4 nautical miles offshore, and if the continental shelf, to say the 500m isobath or 200 miles offshore, be applied most of the sea area in the archipelago would be Norwegian as is currently assumed.

Fig. 1.8. Diagrammatic map to show boundaries of possible political interest.

Fig. 1.9. Map showing environmentally protected areas of Svalbard. Redrawn from leaflet issued at Longyearbyen Airport and published by Norsk Polarinstitutt.

1.6.3

Economic/political consequences of the Treaty

SVALBARD

1.6.4

Environmental consequences of the Treaty

Another unforeseen consequence of the Treaty that allows virtually free access by the world's citizens without passport control has been the arrival of many nationalities in unprecedented numbers by cruise liners supplemented by the airport opened in 1975. The pressure on a fragile environment led to the establishing of national parks, bird sanctuaries and other environmental regulations. Thus while there is theoretical freedom of access this can only be permitted within the various necessary regulations and also within the limitations of very few tourist facilities except by sea. Figure 1.9 shows the national parks and nature reserves of Svalbard. Three national parks and three nature reserves, fifteen bird sanctuaries and three plant reserves have been established in Svalbard (see map). No waste may be emptied or left behind in any of the protected areas. The flora and fauna must be protected against injury and unnecessary disturbance. The use of cross-country vehicles is prohibited in the national parks and reserves. Nor are aircraft permitted to land in these areas without the permission of the Governor. From 15 May-15 August it is not permitted to travel within a distance of 300 meters from the edge of the bird sanctuaries. In the Moffen National Reserve all treaffic is forbidden from 15 May to 15 September, both dates inclusive. The ban also includes flying over the reserve at a height of less than 500 meters. All travel on Svalbard must take place in a manner that does not damage or unnecessarily disturb the natural environment. Special care should be exercised in the vicinity of lairs, breeding grounds and nesting sites. The use of motor vehicles is forbidden on thawed ground, and on ground covered by vegetation. There are special regulations for economic or industrial activity on Svalbard. These regulations are printed in the 'Regulations concerning Conservation of the Natural Environment in Svalbard', adopted by Royal Decree of 16 December 1983.

ropeway system long used for transporting coal from mine to loading dock has been replaced by road transport. The University in Svalbard (UNIS) was established in 1995 for one-year courses in Arctic disciplines (biology, geology, geophysics and technology).

1.7.2

1.7.3

Ny-.~lesnnd

Found on the south side of Kongsfjorden, coal was first mined by the Kings Bay Kulkompani A/S (KBKC) in 1917 until 1929 and resumed in 1947. Fifteen men were lost in an accident in 1948, but work continued. In 1960 modernization and extension of the mine was planned but was terminated on 5 November 1962 after an accident in which a whole shift of 21 men were lost. The small town (never more than 300 inhabitants) was then reduced to a small (international) scientific station with a Norsk Polarinstitutt research centre. It has a winter population of 20-30, greatly expanded in the summer by 200 or more visiting scientists and participants in conferences, courses etc.

Barentsburg

Settlements

There is no indigenous population. The principal settlements are based on Norwegian and Russian coal mines with a total population of about 3300 winter inhabitants. There is a large exchange in the summer.

1.7.1

Sveagruva

Located at Braganzavfigen at the head of van Mijenfjorden (in Bellsund) was mined for coal by a Swedish company from 1917 to 1925 when it was sold to SNSK. No mining was done for some years. The installations were destroyed in the war. Mining was resumed but abandoned in 1949 and extensive development (as a satellite mine for Longyearbyen) was planned in the late 1970s. Sveagruva is now the site of the main economic coal mining prospect in Svalbard with accessible reserves estimated at 25 million tonnes and contains one remarkable 5 m thick seam.

1.7.4 1.7

13

Longyearbyen

This is the seat of government of Svalbard and is situated at the head of Adventfjorden south of middle Isfjorden. The coal mine was founded by the American, J. M. Longyear, in 1904 and was worked till 1916. It was then sold to the Store Norske Spitsbergen Kulkompani A/S (SNSK). The earlier mines were in the mountain sides in Longyeardalen and most were destroyed during the 19391945 war. Post-war mines have been developed in mountains along the south side of Adventdalen and Adventfjorden. Coal is mined throughout the winter and stored at Hotellneset for summer shipping when mining ceases giving place to maintenance work. Output has been about half a million tons or less pa. Good facilities for mining personnel have been developed with school, hospital and modern city services. The services are mostly company property. However, the c o m p a n y is increasingly providing for tourists, expeditions and shipping on a commercial basis. The Longyear airport (opened 1975) with scheduled flights to Norway is situated at Hotellneset and there is a good internal road system. Longyearbyen is the principal base in Svalbard for the Norsk Polarinstitutt. The coal reserves, easily accessible from Longyearbyen are being rapidly e x h a u s t e d - the seams being high up in a series of mountains. At the same time Longyearbyen has been developed with an infrastructure, comparable to the best in Norway for a winter population of around 1200 including families. Whereas Sveagruva has coal reserves the investment in infrastructure in Longyearbyen could hardly be duplicated at Svea. The gantry

Located on the western side of Gronfjorden south of the entrance to Isfjorden, is the principal Russian settlement based on a coal mine. It was founded in 1919 by De Russiske Kulfelter. Extensive building was carried out by a Dutch company between 1921 and 1926 who sold it to the Soviet organization Arktikugol in 1932. In the 1930s the settlement was the largest in Spitsbergen. It was destroyed in the Second World War. As the Russian 'Capital' with consul, scientific offices etc. it recently had a population of more than 1000, now 950. Its original reserves have been exploited and mining is extending, by arrangement, into the neighbouring Norwegian claim area. Its economic viability is in question.

1.7.5

Pyramiden

Located at the head of Billefjorden (from northern Isfjorden) was originally a Swedish concession and has been owned by Arktikugol since 1934 [19267]. Construction work began in 1938. The population of about 650 is largely Ukranian.

1.7.6

Older settlements

Earlier settlements based on coal mines and now discontinued include Grumantbyen (FSU, west of Adventfjorden), M u s h a m n a (Norwegian) east of Adventfjorden, Tunheim (Norwegian) on the northeast coast of Bjornoya.

1.7.7

Manned Norwegian radio and meteorological stations

These include the principal station for shipping at Kapp Linn~, at the mouth of Isfjorden, operated from Longyearbyen; also

14

CHAPTER 1 lr~

~

2Ts

/6 ~

/12"

h5 ~

118~

I

'

I

[24 ~

~27 ~

\30 ~

\33 ~

510 80*

0

z~

C>

521

80

79 ~

78 ~

77*

504

/ 76~

76 ~

3G

509

[~501 7 4 o-

0

502 12~ i10o

115o

j20o

Polarinstutt, from catalogue.

at N o r d h a m n a on the north coast of Bjerneya, and at Hopen. Telecommunication from all Norwegian settlements is integrated into the Norwegian system.

publications

Scientific literature on such a small remote area as Svalbard has multiplied not only because of its inherent interest but by virtue of the participation of groups from many nations. A selected bibliography of geoscientific publications appears in part 4 of this volume. Here the the range of official publications is outlined.

1.8.1

Bathymetric

charts

As is customary, charts are under frequent revision while detailed surveys proceed to more remote areas. 12 charts are issued by the N. P (Fig. 1.10). Most other charts are derived from this information. Hydrographic survey is now the responsibility of Statens Kartverk.

1.8.2

Topographic

k.~

1o0

115"

D20 1: 40, 000

118~

/

2G

1:500 000 Sheets

121~

124~

127~

Svalbard 1" 100 000 Sheets

j25o

Fig. 1.10. Sheet lines of charts as originally published by Norsk

Official

4G~

75*

506

1.8

,~, ~ ,

A4 A5 A6 A7 A8 B4 B5 B6 B7 B8 B9 B10 Bll B12 C4 C5 C6 C7 C8 C9 C10 Cll C12 C13 D3 D4 D5 D6 D7 D8 D9

Vasahalveya Magdalenefjorden Krossfjorden Kongsfjorden Prins Karls Forland Reinsdyrflya Woodfjorden Eidsvollfjellet Tre Kroner St. Jonsfjorden Isfjorden Van Mijenfjorden Van Keulenfjorden Torellbreen Mosselbukta Asgardsfonna Austfjorden Dicksonfjorden Billefjorden Adventdalen Braganzav~gen Kvalv&gen Markhambreen Serkapp Storsteinhalveya Gotiahalveya Lomfjordhalveya Vaigattfjorden Hinlopenbreen Negribreen Agardhfjellet

D20 E1 E2 E3 E4 E5 E6 E7 E8 E9 El0 Ell E12 E13 F2 F3 F4 F5 F6 F9 F10 Fll G2 G3 G4 G5 G7 G14 H3 H7 J3

Bjernoya (1:40 000) Sjueyane Nordenski61dbukta Rijp~orden Wahlenbergfjorden GustavAdolf Land Wilhelmoya Kapp Payer Barentsjekulen Freemansundet Guldalen Kvalpyntfonna Tuseneyane H~eya Repeyane Duvefjorden Austfonna Vibebukta Br&svellbreen Berrheia Stonebreen Deltabreen Foyneya Leighbreen Isispynten Isdomen Svenskeya Hopen Storoya Kongseya Kviteya

maps

Topographic maps of Svalbard, published by the Norsk Polarinstitutt (NP) are published on the following scales 1:2000000 1 : 1 000 000 in single sheets; 1:500 000 in four sheets, and 1 : 100 000

Fig. 1.11. Sheet lines of maps (topographical and geological) in both 1" 100 000 series and 1:500 000 series, published by the Norsk Polarinstitutt and redrawn from sales catalogue.

SVALBARD planned for 60 sheets (Fig. 1.11). 1 : 50 000 are available as working dieline prints, with and without place names, and as official maps of various claims and 1 : 2 5 000 map of Bjornoya. There are also some local maps of settlements, mines etc. Map projections are as follows: The 1:1000000 is a conical projection, whereas all other larger scale maps are based on the transverse Mercator projection which is conveniently fitted to the rectangular grid on which the surveys have been based. The grid (essentially the same as used by the British Ordnance Survey) is defined as follows: axis of projection origin of eastings origin of northings Earth's semi-diameters

meridian 15~ 100 km west of axis 8500 km north of equator 6 3 7 8 3 8 8 m and 6356912m.

The origin is therefore false, the point 100000 having the position 15~ 76 ~ 32.89rN. The 1:500 000 map shows 100 squares, but not as above in order to conform to the international U T M series of maps.

1.8.3

Geological maps

These follow the scales, sheet lines and names of the topographic maps (see Fig. 1.11). At scales of 1: 50 000, 1 : 100 000 and 1 : 1 000 000. The principal series is published to the scale of 1 : 100 000 (Fig 1.11). It is planned for sheets to have companion outline texts. In due course these will provide a systematic description of Svalbard geology. In recent years the compilation of these maps and texts from various surveys has been the principal work of the geologists of the Norsk Polarinstitutt, often with international collaboration.

1.8.4

15 Thematic maps

These are also available (on a variety of scales), especially geomorphological. A single sheet 1:400 000 map of mineral claim rectangles is available.

1.8.5

Scientific serials of the Norsk Polarinstitutt

After a number of changes of title the principal multidisciplinary serial is Skrifter of the Norsk Polarinstitutt for monographs published irregularly. Polar Research is for shorter scientific contributions, and the Arbok which continues for internal reports etc. in Norwegian. Skrifter and Polar Research are in English. Meddelelser is of more popular or general nature and has reprinted some work published elsewhere, e.g. translated from Russian. The Polarhdndboker series of small volumes are recommended as introductory companions to this volume: No. 2 (V. Hisdal, 1985, 2nd Edn, Geography of Svalbard); No. 4 (T. B. Arlov 1994, A short History of Svalbard); and No. 7 (A. Hjelle, 1993. Geology of Svalbard), is especially well illustrated with colour photographs and maps. For further superb colour photographs and a further general account see Worsley in Aga et al. (1986), which geological history of Svalbard published by Statoil is a useful introductory supplement to this work. The Norsk Polarinstitutt (NP in this volume) has its headquarters and research facilities currently at Middelthunsgate 29, Postboks 5072, Majorstua, 0301 Oslo with an office in Longyearbyen. From 1997 the institute will move to a somewhat larger organization in Tromso.

Chapter 2 Outline history of geological research W. B R I A N H A R L A N D 2.1 2.2 2.3

2.1

Early exploration, 16 1858 to 1920, 16 1920 to 1945, 18

Early exploration

Useful records of observations perhaps began in 1596 with Barents' voyage and resulting chart. The many expeditions until the middle of the eighteenth century were primarily for whaling with minor additions to the charts. In 1758 A. R. Martin led a Swedish voyage and in 1773 C. J. Phipps commanded a British naval expedition, the first of several, to seek a northeast passage to the Pacific. They penetrated no further than Spitsbergen and made useful observations. At that time and for many years the British Admiralty was concerned with extensive Arctic exploration. The elaborate nature of these expeditions was not so much designed for scientific purposes as for useful employment for enterprising officers, with ships in numbers no longer needed in the period of naval supremacy after 1805. Hydrographic survey was often the principal achievement. In terms of efficiency and Arctic know-how the early whalers such as Scoresby were superior. 1827 may be considered as the year when geological work began, with expeditions from Norway (B. M. Keilhau 1831) and Britain (Capt. Parry, e.g. Horner 1860; Salter 1860). Keilhau, a geologist, visited Edgeoya and Bjornoya. Admiral Parry, Hydrographer of the Navy, wintered on H M S Hecla in Sorgt]orden where further specimens were collected. In 1837 an early Swedish expedition was directed by Lov+n. Then, 1838 to 1840, the French voyage of La Recherche took place under the Commission Scientifique du Nord (e.g. Robert 1840). Only a selection of the many expeditions in the second half of the century are noted here. In 1858 a Swedish scientific expedition included Nordenski61d who later led exploratory voyages with several scientific objectives, including preparatory work for the major international enterprise to determine the Arc of Meridian, as first suggested by Sir Edward Sabine. The main activity was then British, Norwegian, and Swedish, with the first German Arctic expedition in 1868. Arctic scientific exploration had become the international norm. During the years 1850 to the Treaty of S~vres (Paris) in 1920 major expeditions of various kinds include: British 33, Swedish 30, Norwegian 20, German 16, French 6, Russian 4, Austro-Hungarian 2 Dutch, Swiss and American 1 each. From a scientific point of view, distinguished work was done on many of the visits and will be referred to in later chapters.

2.2

1858 to 1920

A series of Swedish investigations led by S. L. Loven (zoologist), D. M. Torell (later Director of the Swedish Geological Survey), A. E. Nordenski61d, and later by A. G. Nathorst and G. de Geer resulted in the first systematic geological knowledge of Svalbard. Thus, whereas previous surveys were essentially for coastal charts (e.g. the British Admiralty chart of 1860), the map of Spitsbergen published in 1865, from field work done in 1861 and 1864, depicted the geological structure throughout the land area, albeit in rudimentary fashion. Nordenski61d's Sketch of the Geology of Spitsbergen (1867, 1876) integrated previous known work, and introduced the name Hecla Hoek. A detailed geological survey was accomplished during Nordenski61d's over-wintering party at Mosselbukta by C. B. Blomstrand (1864) with initial attempts to unravel Hecla Hoek stratigraphy. A further general account with a geological map

2.4 2.5 2.6

1946 to 1960, 19 1960 to 1975, 20 1975 onwards, 21

is found in Suess (1888) Das Antlitz der Erde based on information given him by Nathorst, who, after many published investigations in Arctic palaeobotany by both O. Heer and himself, wrote what was for many years the definitive account of the geology of the archipelago in 1910. Thereafter Swedish work tended to palaeontological studies, e.g. by C. J. J. E. Wiman and E. H. O. A. Stensi6. Nathorst's map (in Suess 1888 reproduced here as Fig. 2.1) distinguished eight rock groups. The Archean outcrops comprise all the more intensely metamorphosed rocks in northern 'Nord-Ost Land', western Ny Friesland and northwest Spitsbergen. The Hecla Hoek System occupies the remainder of the preDevonian outcrop area of less metamorphosed rock. The Liefde Bay System approximates the Old Red Sandstone outcrop and is separated from Archean rocks to the East by a major fault from Billefjorden to Wijdefjorden. The Ursa stage, ('Mountain Limestone', and Permian) corresponds very well to the Carboniferous-Permian outcrop. It is separated from the western outcrop of the Hecla Hoek by another major fault that parallels the coast. The Trias is roughly as now mapped. Cretaceous outcrops, which are largely continental, are not distinguished from Jurassic in this map. The Tertiary outcrops are designated Miocene which was a general opinion then for plantbearing continental sandstones and shales in the North Atlantic Arctic province. A Miocene age was the opinion of O. Heer the leading Swedish paleobotanist who wrote at that time extensively on Arctic floras, which are now mainly regarded as Paleogene. Nathorst's 1910 paper has the systematic structure of a modern monograph on the geology of Svalbard (Beitrdge zur Geologie der Bdren Insel, Spitzbergens und des KO'nig Karl-Landes). The Arc of Meridian project (1899-1902) was a RussianSwedish geodetic enterprise developed from earlier Swedish work. Preliminary investigations for this had been made by Torell in 1861 and 1864. The Swedish section was based on Sorgfjorden and the Russian section on the west coast of Edgeoya. From this remarkably ambitious project flowed many studies, and northeastern Ny Friesland and northwestern Nordaustlandet long continued as Swedish centres for scientific work. Behind much endeavour was the possibility of mineral wealth and political influence in this 'no man's land'. An abortive Swedish attempt was made to mine phosphorite at Kapp Thordsen, as well as early Swedish claims for coal. In view of their outstanding earlier work with Nathorst's palaeobotanical studies up to 1920 it caused some disappointment in Sweden that she was not awarded Spitsbergen at Versailles in the Treaty of Paris. However, at the turn of the century, when the political field was still open, the economic possibility of mineral wealth on land was in many minds. This led to a new surge of interest and, after 30 years of Swedish domination, scientific research became more international and with a competitive edge. After Nordenski61d's expeditions, few had ventured far inland. Interior geology was mostly unknown. Sir Martin Conway with geologist companions, E. J. Garwood and J. W. Gregory (1896), crossed Spitsbergen from Is0orden to Stort]orden and back in 1896. Garwood accompanied Conway the following year. This work contributed to the stratigraphy of central Spitsbergen. The Prince of Monaco arranged expeditions to northwest Spitsbergen in his yacht Princess Alice. The main work, directed by Gunnar Isachsen, was topographic and bathymetric. One object was to connect this triangulation with the Arc of Meridian Survey further east. These voyages afforded excellent geological opportunities. W. S. Bruce, a Scot, joined the vessel in 1898 and 1899 and

OUTLINE HISTORY OF GEOLOGICAL RESEARCH

17

Fig. 2.1. Geological sketch map of Spitsbergen by A. E. Nordenski61d and A. G. Nathorst, E. Suess, 1988, Der Antlitz der Erde, reproduced from E. Suess, The Face of the Earth, H. B. C. Sikes translation 1905, Oxford. Vol. 2, p. 68, Figure 8. returned again in 1906, 1907 and 1909 to explore Prins Karls Forland, which had hitherto been geologically unknown partly, no doubt, because of a lack of evident fossils in rocks. A. Hoel and O. Holtedahl accompanied Isachsen on the mainland work in northwest Spitsbergen and so began a continuing Norwegian

contribution to the Geology of Svalbard. Norwegian independence in 1905 was probably a major influence in the new strength of Norwegian geoscience. Hoel became active in promoting Norwegian interests with respect to the Spitsbergen coal potential and later was responsible

18

CHAPTER 2

for systematic geological surveys. He returned in 1911, 1912 and 1915 and discovered Cretaceous coal between Adventt]orden and Bellsund in 1916. Holtedahl, after work on Carboniferous rocks further south, used this opportunity in the northwest to contribute a first understanding both of the Caledonian nature of rocks previously regarded as Archean and of the Old Red Sandstone stratigraphy and tectonics. H. G. Backlund worked on the basic volcanics and intrusions of the area. Ki~er (1916) defined Devonian strata. Swedish work continued with Wiman's Uppsala expeditions in 1912, 1913 and 1915 to 1917. They resulted in palaeozoological publications especially on Triassic vertebrates and Late Paleozoic brachiopods. Nathorst continued his palaeobotanical studies related to coal deposits of many ages. The Swedish stratigraphical and structural studies might be seen to have culminated in 1910, not only with the publication of Nathorst's monograph, but with the Swedish led excursion of the International Geological Congress from Stockholm led by G. de Geer. The opportunity so afforded led to specialist interest by a wider international community, especially palaeontological. The international exploration for mineral wealth continued with Swedish geologists. In 1916 Birger Johnson led an expedition of 30 to investigate coal in Bellsund, in Pyramiden and in Biinsowland (both beside Billefjorden in Is0orden). Thus the Swedish coal claims were amongst the first of all the claims. Similarly the Scottish Spitsbergen Syndicate (SSS) had made coal and mineral claims. Bruce revisited Spitsbergen in 1912, 1914 to establish these. In 1919 he led a major expedition under SSS auspices and in 1920 a further SSS expedition led by Mathieson was accompanied by several geologists, including G. W. Tyrrell who published various regional studies.

2.3

1920 to 1945

The award of the archipelago to Norway under the Spitsbergen Treaty led to the establishment of the Norges Svalbard og Ishavsundersokelser under the leadership of Adolf Hoel, the forerunner of the present Norsk Polarinstitutt. It had the daunting task, for a small organization, of promoting multidisciplinary studies and organizing the hydrographic, topographic, geological and biological survey of the islands. Results from annual expeditions were published mainly in the new Skrifter om Svalbard og Ishavet. As it happened Hoel was a good organizer as well as a geologist, and the first requirement was to assess the geology of the various mineral claims and especially of the coal fields. With a stable political situation studies proceeded systematically. His own papers were published in 1924 and 1925, and with a summary of earlier Norwegian work in 1929. Norwegian activities 1936 to 1944 were reported (Anon 1945). G. Horn also wrote on the coal of Svalbard (1928), Horn and A. K. Orvin on the Geology of Bear Island (1928) and Orvin in 1934 on the Geology of the Kings Bay region a study of the Ny-Alesund coal field. Bjornoya while much nearer to Norway and generally free of sea ice is hardly more accessible because of the few landing places- none are satisfactory. However, Norwegian expeditions directed by A. Hoel established the coalfield and the general outlines of the geology of the island (e.g. Holtedahl 1920; Horn & Orvin 1928). After preliminary topographic surveys Svalbard was covered by oblique aerial photography in 1936. A major scientific initiative was to record the standard stratigraphic sequence of the Central Basin where the strata at the western limit of the outcrop, between Kapp Linn~ and Gronfjorden, dip steeply at Festningen, at the south western entrance to Isfjorden. Carboniferous to Cretaceous strata are well exposed and a series of detailed descriptions began with Hoel and Orvin's measured section in 1937. This was followed by a rapid succession of about 12 biostratigraphic descriptions of this Festungsprofil from 1928 to 1931 all mainly as Skrifter monographs and mostly by H. Frebold.

Frebold's interest led to his major synthesis published in 1935 Geologie yon Spitzbergen, der Bdireninsel, des K6nig Karl- und Franz-Joseph Landes. (Frebold's geological map is reproduced as Fig. 2.2). Oslo University-based tectonostratigraphic studies were notably advanced through the work of O. Holtedahl (1925) in which the Caledonian interpretation of Svalbard was shown to have close parallels with Scotland. As it turned out later the contemporary assumption that Caledonian Orogeny deformed Early Paleozoic rocks (by analogy with Wales) proved to be misleading in both Svalbard and Scandinavia, where the thick geological successions deformed in mid-Paleozoic time were mainly Late Proterozoic rather than Paleozoic. This misconception hardly affected the tectonic significance of Holtehal's interpretation. Holtedahl also laid the foundation of Devonian stratigraphy in Spitsbergen, of the Ordovician strata in Bjornoya and the geology of the central western Spitsbergen area. Then T. Vogt, in the course of studies of mainly Devonian strata, was the first to note the importance of Late Devonian diastrophism in what he referred to as the Svalbardian folding. Thus two main tectonic episodes were clearly distinguished in Silurian and Devonian time. Swedish work, mainly palaeontological, continued for a time. J. P. J. Ravn (1922) from marine mollusca in the Tertiary coalbearing strata established their Paleocene rather than Miocene age. A. E. Stensi6 (1918-1927) continued his detailed investigation on Devonian fish as also S/ive- S6derbergh (1935-1941) and T. Nilsson (1941-1946). T. H. Hagerman (1925) reported Swedish work in southwestern Spitsbergen in 1924. There was, however, a major expedition in connection with the International Polar Year 1931 to 1932 based in northwestern Nordaustlandet. Of the many results the work of O. Kulling on the Hecla Hoek rocks (1932-1937) provided the first systematic account of Hecla Hoek stratigraphy with description of tillites. The first tillite record had been by Garwood & Gregory (1898) in southwest Spitsbergen. British work took a different turn. From the Scottish Spitsbergen Syndicate exploration for mineral wealth grew a tradition of private expeditions organised in universities, first Oxford then Cambridge. From 1921 to 1938 12 expeditions worked in the northeast sector of Svalbard. While they were mostly multidisciplinary, there was a significant geological contribution. In 1927 on a Cambridge expedition to Edgeoya, N. L. Falcon (1928) first recorded the petroleum potential of Triassic shales. In Ny Friesland, the work of Cambridge geologists on Oxford expeditions, concerned the Hecla Hoek rocks. N. E. Odell (1927) described the unmetamorphosed succession. W. L. S. Fleming and J. M. Edmonds (1941) traversed the Ny Friesland terrane from north to south in 1933 investigating older rocks. P. E. Fairbairn (1933) and Harland (1941) worked on the metamorphic rocks following Tyrrell's (1922) petrological study. The Oxford work, mainly glaciological, then came to be centred on Nordaustlandet, but with a stratigraphic component by K. Sandford (1925-1929). As Kulling had shown that both Nordaustlandet and Ny Friesland had unmetamorphosed Hecla Hoek rocks in common, the question persisted and persists as to the relationship of these strata to the metamorphic rocks that had first suggested an Archean age in the previous century and had been so described by Tyrrell (1922). The International Polar Year in 1934 introduced Polish geologists to Svalbard and they focused their investigations on the southwest sector of Spitsbergen. The work continued in 1936 and 1938, though S. Z. Rozyicki's main work in Wedel Jarlsberg Land was not published until 1959. German expeditions (from Hamburg) visited Svalbard in 1927 (Gripp 1927-1929) and 1935. The earlier one afforded H. Frebold a further opportunity to investigate Mesozoic rocks as well as to continue with glaciological work. Soviet geological work during these years was mainly concerned with their coal concessions and little beyond. From fieldwork in 1932 Ye. M. Lyutkevich published on the Pyramiden coal field geology and D. L. Stepanov (1937) on Permian brachiopods. T. Vogt (1938) wrote on the stratigraphy and tectonics of the Old Red Sandstone deposits. In 1939 a British, Norwegian, and

OUTLINE HISTORY OF GEOLOGICAL RESEARCH

19

Fig. 2.2. Geologicalmap of Spitsbergen reproduced from Hans Frebold (1935). Geologie yon Spitzbergen, de Bdreninsel, des Konig Karl und Franz Josef Landes, 195 pp, Plate 7, in Geologie der Erde, Berlin, Gebrfider Borntraeger, Berlin.

Swedish expedition set out to investigate Devonian stratigraphy and especially to collect fossil fish (Foyn & Heintz I943). From 1939 to 1945 war in Europe brought field work in Svalbard to a close (EIbo 1952). However, the Norsk Polarinstitutt in Oslo continued to function under German occupation and this enabled a synthesizing of results to proceed under Hoel's direction, Notable achievements were A. K. Orvin's (1940) Outline of the Geology and History of Spitsbergen and his monumental Place names of Svalbard (1942, Skrifter No. 80). Similarly H. Frebold continued to work in occupied Denmark and part of his work developed into his Geologie des Barentsschelfes (1951). Geologically irrelevant but of prophetic interest were the polar flights based on Spitsbergen during 1924-25 when Amundson and Ellsworth made a flying boat attempt, and in 1926 they with Nobile flew from Spitsbergen to Alaska in the dirigible Norge. In the same

year Byrd flew to the Pole; and in 1928 Wilkins flew from Alaska to Spitsbergen, the year that the ill-fated Nobile attempt by airship Italia crashed with the loss of some personnel and of Amundson on his rescue attempt. In 1938 Lauge Koch reconnoitred Greenland, from Spitsbergen, for air support for his post-war East Greenland expeditions.

2.4

1946 to 1960

The post war reconstruction of the mines destroyed in the war was a first priority along with the re-establishing of navigation beacons. The Norsk Polarinstitutt (NP) was refounded in 1948 in Olso in succession to the Norges Svalbard - og Ishavs-Undersokelser. One

20

CHAPTER 2

of the last Skrifter (No. 89) to be published under that name from war time compilations was Orvin's Bibliography of literature about

the geology, physical geography, useful minerals, and mining of Svalbard (1947). The organization of the institute and its publications continued with little change except of name and the inclusion in its remit of Antarctic research and with some expansion of staff. Harold Sverdrup (oceanographer) replaced Adolf Hoel as Director in 1940 until his death in 1951 when Anders Orvin, who had been the senior staff and principal geologist, followed as Acting Director until his retirement in 1960. In 1948 the Norsk Polarinstitutt began annual field work in Svalbard for systematic hydrographic, topographic, geodesic and geological surveys, as well as research in other disciplines. Since 1948 the Norsk Polarinstitutt has been the leading Svalbard research institution for geology, as well as for many other disciplines. Early postwar research, focused at first on Sorkapp Land where, in the enigmatic 'Hecla Hoek' rocks, Cambrian and Ordovician fossiliferous successions were reported by H. Major and T. Winsnes (1955). Operational research on the Tertiary coalfields was continued by Major, with palynological investigations by Manum (1954 and 1960). A dictionary of all named and published stratal units of Svalbard was prepared by Major et al. (1956) as part of the French inspired International Stratigraphic Lexicon. Paleontological studies continued in the University Museum, Oslo (e.g. Wangso 1952). In 1956 in connection with the third International Geophysical Year, Polish work under the leadership of S. Siedlecki resumed in Wedel Jarlsberg Land between Bellsund and Hornsund from a new base (Ibjornhamna) on the north shore of Hornsund. While the earlier work was published, new work led by Birkenmajer and his team described the complete stratigraphy along the north of Hornsund (1958-1959). This usefully complemented the work by the Norsk Polarinstitutt in Sorkapp Land just south of Hornsund. The new features of this work; in addition to confirming fossiliferous Cambrian and Ordovician strata (e.g. Kielan 1960) was to formulate a long sequence of Precambrian strata and tectonic events supported by petrological studies with suggestions of granitization (Narebski 1960, Smulikowski 1960). Almost continuous multidisciplinary Polish work since then is recorded in the works of Birkenmajer and his colleagues. The combined results of the Norwegian and Polish work were presented to the members of the excursion of the 1960 International Geological Congress. During this excursion footprints of Cretaceous Iguanodon were demonstrated (e.g. de Lapparant 1962). In the meantime private ventures from a number of British universities had been active and indeed resulted in the larger number of geological publications during these 15 years. Birmingham groups in 1948, 1951, 1954 and 1958 worked in southern Oscar II Land between Isfjorden and St Jonsfjorden where slices of Carboniferous and Permian strata with distinctive fossils are tightly compressed with Precambrian strata (Baker Forbes & Holland 1952). In addition to structural studies (Weiss 1953, 1955, 1958) Carboniferous and Permian strata were described (Dineley 1958). The problem of distinguishing deformation structures that are preCarboniferous from post-Permian became evident and persists. Devonian rocks with fish in Ekmansfjorden were also introduced (e.g. Dineley 1955, 1960; Barr 1960). Atkinson of Imperial College, London worked in Prins Karls Forland in 1950, 1951, 1953 and mapped the area in more detail than previously (1952-1963). Oxford work was largely glaciological and Sandford continued to publish results from earlier field work, and new aerial photographs (1950-1963). From the Queen's University, Belfast, work between Isfjorden and Kongsfjorden further elucidated understanding of the Precambrian strata (Bates & Schwarzacher 1958; Preston 1959). From Durham University a party investigated inner Kongsfjorden, and A. Challinor, one of its members, later joined the Cambridge group. This Cambridge group (CSE) led by W. B. Harland first arranged a small party in 1948 to investigate the Scottish Spitsbergen Syndicate properties in Btinsow Land. This was followed in 1949 by Carboniferous and Permian studies (Gee, Harland & McWhae

1953; Forbes 1960; Forbes, Harland & Hughes 1958). The structural problem of the Billefjorden Fault Zone was addressed by McWhae (1953). It then seemed to be initially a compressive thrust fault system. Most effort was devoted to the survey, topographical as well as geological, of Ny Friesland to determine the Hecla Hoek succession and its relation to the schists and gneisses occupying the western part of the Land. This was an old problem. It seemed to be solved by extensive reconnaissance mapping which showed a relatively concordant sequence of about 18km of strata in which the metamorphic rocks comprised the lower part. No major unconformity had then been demonstrated (Harland & Wilson 1956) and the Caledonian deformation and deep burial seemed to account for the tectonic contrasts (Harland 1959). The succession was first divided into Lower, Middle and Upper Hecla Hoek; the Lower being metamorphosed (Bayly 1957), the Middle only partly so (Wilson 1958 and posthumously 1961), and the Upper part in two groups a lower tillite-bearing group (Wilson & Harland 1964) and overlying Cambrian and Ordovician strata - the first fossils, Salterella rugosa, being found by Wilson in 1955 and then a richer Ordovician fauna (Gobbett 1960; Gobbett & Wilson 1960; Hallam 1958). Investigations of this rich succession had only just begun by 1960 and it already had become, perhaps prematurely, a standard for comparison and correlation of Precambrian rocks elsewhere in Svalbard (e.g. Harland 1960). In 1958 palaeomagnetic collections throughout the unmetamorphosed rocks of the area were made by D. E. T. Bidgood for comparison with Greenland (Bidgood & Harland 1961) but the samples proved to be unstable. Beginning in 1951 and 1953 the structures in the Old Red Sandstone, west of Wijdefjorden, had been noticed overlying the Billefjorden Fault Zone (as later named) and P. F. Friend began his investigations of the Old Red Sandstone rocks in 1955 and continued in 1958 and 1959. His main work and the published results followed from 1960 onwards (e.g. Friend 1961; Friend & Moody-Stuart 1972). At this time although Soviet Geologists were not active far outside the coal concessions their prominence in continental and global map compilations in Moscow inevitably led to the need to include Svalbard and so interpret its structure. An example is Klitin's (1960) paper on the tectonics of Spitsbergen with its prevailing fixist interpretation and a network of deep-seated faults dividing the terranes.

2.5

1960 to 1975

A major change in Svalbard research came about with the industrial interest in the petroleum potential in the Barents Shelf. In 1960 the Shell Oil Company addressed the possibilities and AMOSEAS (a consortium of Chevron and Texaco in the US) undertook their own systematic investigations. A new era of logistic support, previously unthinkable, with helicopters and skidoos was introduced replacing to a large extent dependence on small boats, man-hauled sledges and pack-carrying. Larger vessels continued to be essential for logistic back-up. These changes coincided with the general acceptance of standardised international conventions, especially in stratigraphic nomenclature. Previously, as with place names different groups had developed their own mainly European practices and the recently developed North American Stratigraphic Code which, for rock unit nomenclature formed the basis of the international standard, had the effect of focusing stratigraphic work on the whole rock unit rather than on the interesting beds or fossiliferous niveaux. Probably another consequence of this American petroleum influence was the decision in the USSR to match this new scientific input. From then on each year Soviet geological parties each of three or four, with heavy camps suited to the Soviet Arctic, were deposited by large helicopters according to a systematic programme throughout Svalbard. The Soviet tendency was to work

OUTLINE HISTORY OF GEOLOGICAL RESEARCH independently and produce their own confidential maps of the whole region. Many results were published, but at first detailed maps and other records were not available as was also the case with the western petroleum companies. Sokolov (1965) and Krasil'shchikov (1973) synthesized results of the older rocks. Until about 1960 practically all geological work had been of a reconnaissance nature and the different areas of interest that tended to be the province of one research group were not trespassed upon by other groups. This had the effect that any geological synthesis tended to be a compilation of different components each generated by a differing outlook. From about 1960 onwards territorial preserves ceased and there was enough geological personnel for the main groups each to extend elsewhere in whole region. This certainly applied in different ways to oil company exploration, the Norsk Polarinstitutt, the Soviet presence mainly organized through the Institute for the Geology of the Arctic in Leningrad, the Polish work mainly in the south and, with less resource, to the Cambridge group which graduated from small open boats and man-hauled sledges to enclosed motorboats. The Norsk Polarinstitutt had in 1960 a new Director, Tore Gjelsvik. His emphasis was first to ascertain whether any mineral resources had been overlooked. Geological publications during this 1960-1975 period were at a rate more than three times that of the preceding 15 years. Increased output tends to submerge significant scientific developments. Groups centred in Oslo, Leningrad and Cambridge were each comprehensive in their interests and similar in output. The Polish group on the other hand focused on the southern part of Spitsbergen. This had the advantage of more thorough connected studies but lost in some appreciation of their regional context. By 1975 all areas of Svalbard had been described in some degree, some areas by more than one group. Stratigraphically rock units had been named consistently with more or less standard descriptions of the strata, based on innumerable measured sections and so with a systematic view as to their local variation. Individual palaeontologists, especially in France and Germany as well as in the other groups, described more and more fossils from the rich horizons. Devonian fish were investigated especially in Oslo and Paris. A new Ordovician fauna was discovered in northeast Ny Friesland first by Cambridge and later investigated by the Natural History Museum in London and the University Museum in Oslo. The ubiquitous coal and plant bearing strata were the subject of palaeobotanical studies which were largely done in Germany whereas palaeontological investigations were active in Cambridge, Oslo, and St Petersburg. Mesozoic ammonites were described in detail in Hamburg, St Petersburg, and in England. CarboniferousPermian faunas were described especially in Poland, Britain and Soviet Union. Moscow palaeontologists made comparisons of stromatolites, oncolites and phytolites with Late Riphean sequences in the Soviet Arctic. Mineral occurrences and geochemical studies were especially undertaken in the Norsk Polarinstitutt, but are of genetic rather than economic interest. Petroleum prospects were explored with deep wells in Spitsbergen, Edgeoya and Hopen (Appendix). Perhaps the result of these 15 years work was to remove the early optimism about the land areas of Svalbard as good petroleum prospects. Source rocks occur; but tectonic compaction and sedimentary facies and erosion have reduced the likely petroleum content of the reservoirs. Since then the main interest of Svalbard to the petroleum industry has been as a sample of the strata already being delineated by seismic and other surveys in the Barents Sea. Coal, petroleum and mineral exploration are discussed further in the appendix. The better understanding of the local geology provided a platform for informed tectonic studies. These 15 years corresponded with the conversion of a majority of geologists to accept hypotheses of continental drift with the early development of plate tectonic interpretations. In such studies Svalbard played a key role from the very beginning. The detailed separation of Spitsbergen from north of Greenland with the complex opening of the Norwegian Greenland ocean basin, and the (simple) spreading

21

about the Nansen-Gakkel Ridge to form the Arctic Ocean Basin were amongst the first kinematic results to be established. They had indeed been anticipated by Wegener (1924), Taylor (1928), du Toit (1937) and by Carey (1958). Svalbard data yielded one of the first instances where palaeocontinental drift was argued with the closing of the Iapetus Ocean that separated Greenland with Svalbard from Norway and the Baltic Shield. Major Devonian sinistral strike-slip had already been suggested (Harland 1965) to move Svalbard from central East Greenland to the south of north Greenland and by 1971 sinistral transpression (and transtension) along the Billefjorden Fault Zone had been identified. The long history of this fundamental fault was documented in 1974. By 1975 it was suggested, not only on the basis of structures, but mainly on that of contrasting stratigraphic sequences in distinct terranes, that Svalbard now comprised at least three major allochthonous terranes with subterranes, separated by at least two fundamental strike-slip fault zones. The allochthonous terrane concept elsewhere in the world became generally accepted and was gradually applied by more scientists in Svalbard (see section 3.5). Svalbard was also noteworthy because of the ubiquitous diamictites, which contribute excellent evidence for the global Varanger (late Vendian) ice age, for long doubted but now generally accepted. The two distinct Varanger tillite horizons are recognizable in all three Svalbard provinces or terranes, thus giving a basis for wider correlation. Subsidence of the Hecla Hoek geosynclinal basin by thermal contraction of the mantle was also one of the early suggestions of a mechanism (Harland 1969) that has since become rigorously established but in this case on a far longer time scale. Whereas the deformation of strata up to early Paleocene in age along the western margin of the Central Basin had long been established (e.g. Orvin 1934, 1940) new reconnaissance demonstrated a far more elaborate fold and thrust belt than had earlier been anticipated. This investigation of the structure of PostDevonian strata was led by A. Challinor (e.g. 1967 and Fig. 20.8). The West Spitsbergen Orogen was so defined (Harland & Horsfield 1974). The immense interest of these structures has subsequently resulted in a flood of publications (e.g. Dallmann et al. 1993a). During the late 1960s and early 1970s the availability of helicopter platforms on ice-strengthened ships enabled renewed reconnaissance of the eastern islands of Svalbard by Norwegian and Cambridge parties (see especially Chapter 5).

2.6

1975 onwards

The all-weather Longyear Airport was opened in 1975 and thereafter contributed to the increasing scientific activity, not least by enabling field work to increase at the expense of travel time. The rate of publication of serious geoscientific work relevant to Svalbard continued to increase to more than 50 significant geoscientific publications a year. A notable change was the participation of many American and then Japanese scientists so that Svalbard ceased to be so conspicuously a European scientific arena. Whereas hitherto much of the stratigraphic endeavour had been unsophisticated, a new onslaught with sedimentological expertise and palaeogeological interpretations now becomes the rule. Similarly a more rigorous discipline in structural geology was applied so that far more information was obtainable from a local study than previously. Thus the intensive structural studies within and beyond the West Spitsbergen Orogen mushroomed with investigations dominated by Norwegian and American geologists as summarized by Dallmann, Andresen et al. (1993). New palaeontological techniques were brought to bear so that, for example, the immense mass of Hecla Hoek rock of the Ny Friesland geosyncline, hitherto thought to be mostly barren, yielded fabulous detail of microbial remains preserved in chert going back hundreds of millions of years into Precambrian time (e.g. Knoll 1982, 1985).

22

CHAPTER 2

Submarine and aerial surveys by industry were becoming available. Seafloor spreading sequences for the Norwegian Greenland seas in particular for Cenozoic configurations were worked out in detail with adequate control especially in the University of Bergen with its strong geophysical divisions. Microseismic cooperation between American and Norwegian seismologists began to map out the contemporary stress-strain adjustments in Svalbard with perhaps unexpected results (e.g. Mitchell et al. 1990). A local matter, but significant from the author's point of view, was that while hitherto the Cambridge group had enjoyed active cooperation for Svalbard research with the petroleum industry in Norway, it became understandable Government policy to recommend companies seeking concessions to commission work from Norwegian institutions and this acted positively to encourage the Cambridge group to extend their comparisons with the Soviet, Canadian Arctic and Greenland (the author having worked a little with Lauge Koch). So in 1975 the Cambridge Arctic Shelf Programme (CASP) was formed and Cambridge Svalbard Exploration (CSE) was slowly merged with it. The scientific consequence was to focus on the whole Arctic in which Svalbard would always be a key element. From being a personal charitable enterprise, CASP became a company limited by guarantee with charitable

status in 1988. As such, its prime object continues namely research, publication and education. The Norsk Polarinstitutt under its new government umbrella, the Ministry of the Environment, led by the Chief Geologist, W. K. Dallman pursued a vigorous policy, giving priority to the systematic completion of the 1 : 100 000 geological map series, each with an accompanying explanatory text. In this programme foreign geologists were invited to participate both in comment and criticism and as joint authors. For many years the Norsk Polarinstitutt had arranged logistic support for groups engaged in local mapping projects, but the new policy gave the international community an opportunity to engage in cooperative research. It had long been policy that mapping, both topographic and geological, should be organized by the Norsk Polarinstitutt. This volume may be seen to mark the fulfilment of the reconnaissance phase of Svalbard geology as recounted above. The future is exploding with detailed and systematic investigation of the archipelago according to new and more rigorous standards and certainly with participation of scientists from many countries increasingly coordinated by and cooperating with the Norsk Polarinstitutt. One example is the publication in English of Russian work, some previously unpublished (e.g. Krasil'shchikov 1996).

Chapter 3 Svalbard's geological frame W. B R I A N 3.1 3.1.1 3.1.2 3.1.3 3.1.4 3.1.5 3.2 3.2.1 3.2.2 3.2.3 3.3

The space frame: Svalbard's structural frame, 23 Solid outcrops, 23 Regional descriptive sectors, 23 Discontinuities as convenient boundaries, 23 Structure of Svalbard, 25 Kinematic interpretation of Svalbard's history, 25 The time frame, 25 International time frames, 25 A provisional time scale, 28 Svalbard's chronometric record, 29 The rock frame, 29

This chapter gives an outline of the geology of Svalbard, an introduction to the principles applied in this work and a preview of the interpretations and conclusions that have come out of these studies. The key position of Svalbard in relation to other Arctic lands is shown in a Polar projection (Fig. 3.1).

3.1 3.1.1

T h e s p a c e frame: S v a l b a r d ' s structural f l a m e Solid outcrops

The conventional geological map of Svalbard shows in outline the outcrop areas according to age. (Fig. 3.2). Although rock ages are matters of interpretation, the diagrammatic map is at least consistent with the conclusions in this work. It differs from most maps in the larger outcrop of Vendian rocks within the basement. The outcrop pattern ignores Quaternary deposits, i.e. it is a solid geology map. It is diagrammatic because detail is impossible to show on this scale. The larger ice masses which obscure the exposure are also diagrammatic.

Fig. 3.1. Svalbard in the Arctic (polar projection), based on various sources. Greenland has been officially divided as indicated by the dashed boundaries and initials, EI is Ellesmere Island; NS is Nares Strait.

HARLAND 3.3.1 3.3.2 3.4 3.4.1 3.4.2 3.4.3 3.5 3.5.1 3.5.2 3.5.3 3.5.4

3.1.2

A lithic code, 29 Some practical stratigraphic conventions in this work, 31 Teetonostratigraphie terranes and their sequences, 31 The terranes and their sequences, 32 Combined sequence for Svalbard, 36 Sequence stratigraphy, 37 Geotectonic interpretations, 37 Provinces and allochthonous terranes, 37 Differential horizontal lithosphere motions, 38 Polar and lithosphere wander, palaeoclimates, 40 Differential vertical lithosphere motions, 43

Regional descriptive sectors

Because the intention in this work is generally to describe rocks before interpreting their history and so not to begin with too many assumptions, the rocks are described in Part 2 of this work in the eight sectors or regions (Chapters 4 to 11) as shown in Fig. 3.3. Their boundaries are not fixed because it is convenient to treat some geological matters together in one chapter, even when they might overlap onto another. They are not terranes. Where strata are described the succession is presented as observed with the youngest at the top (as in Part 2). When the sequence is interpreted later (as in Part 3) the earliest events precede the later.

3.1.3

D i s c o n t i n u i t i e s as c o n v e n i e n t b o u n d a r i e s

Some boundaries on the geological outcrop map are important discontinuities. These are mainly fault zones or lineaments and some are fundamental in the sense that they dip steeply and persist through long spans of geological time. Other boundaries are perhaps equally significant as unconformities which, generally dipping gently, do not appear as fixed lineaments on a map.

24

CHAPTER 3

SVALBARD'S GEOLOGICAL FRAME Figure 3.4 depicts important named fault zones or lineaments as continuous lines. Dashed lines indicate the major unconformity between the older (pre-Carboniferous rocks) and the younger postDevonian strata. The fault abbreviations listed in the caption to the figure may be used throughout this work. These boundaries separate descriptive terranes or subterranes as listed in Section 3.4.4 with their distinct tectono-stratigraphic sequences.

3.1.4

25

/

I/

/

1/2 ~

I

16 ~

/

2 0 c"

28 ~

24 ~

Structure of Svalbard

32 ~

/

I

.%

l

Figure 3.5 shows Svalbard in relation to the structural elements of the Barents shelf and especially the position of Bjornoya in that context. Figure 3.6 shows diagrammatically the structure of the rest of Svalbard according to the interpretation of Russian geologists (Krasil'shchikov, Abakumov et al. 1996). It is a useful summary of one viewpoint which assumes that the structural elements of Svalbard as seen now have persisted in that relationship through geological time. It is therefore a basis from which kinematic interpretations of Svalbard's history that led to the present configuration may be explored.

5

~

3.1.5

!i

Kinematic interpretation of Svalbard's history

Postulated successive spatial arrangements in a palinspastic sequence depend on interpretation of similarities and contrasts between terranes, not only in Svalbard. These may be speculative or controversial postulates and are reserved for Section 3.5 in this chapter. However, it is one of the objectives in Earth history to elucidate past movements between lithospheric plates. The description of Svalbard tectono-stratigraphic sequences is therefore arranged here in the terranes selected for convenience in discussing palinspastic possibilities without prejudice as to their prior configuration. Should Svalbard, as concluded later, be the result of juxtaposition of far-travelled terranes deriving from distinct provinces the exercise may be worthwhile even if it be contradicted by new evidence. But this discussion is for Section 3.5 and is touched on especially in Chapters 12-15 in Part 2.

KEY

"i

I

11

0 I

krn I

I O0 I

Fig. 3.3. Regions of Svalbard as used in this book for Chapters 4-11, with the general extent of coverage for particular chapters in Part 2. The numbers refer to the numbered chapters as follows: (4) Central Basin; (5) Eastern Platform; (6) Northern Nordaustlandet; (7) Northeastern Spitsbergen; (8) North central and northwestern Spitsbergen; (9) Central western Svalbard; (10) Southwestern Spitsbergen; (11) Bjornoya and related submarine shelf.

Neogene plateau lavas

Silurian-Devonian plutons

Paleogene

Cambrian-Ordovician

3.2

Early Cretaceousbasites

Vendian

3.2.1

EarlyCretaceous

Late Neoproterozoic

There are two elements in the standardization of international geological time: chronostratic and chronometric (Harland et al. 1990).

Jurassic-Cretaceous dolerites

Early Neoproterozoic granites

~

Jurassic

~

Triassic

Early Neoproterozoic volcanics ?Early Neoproterozoic granites and migmatites

Carboniferous-Permian /

Late Paleoproterozoic basement

~

[~

Devonian Fig. 3.2. Generalized geological map of Svalbard, from various sources and this work.

The time frame International time frames

Chronostratic scale. This scale, commonly referred to as the stratigraphic scale, began nearly 200 years ago as a sequence of geological events, even catastrophes, which divided Earth history into natural chapters. These packages of strata, developed step by step, into the geological systems with their series and stages. When it was assumed that there was a definite identifiable body of rock constituting a system it was logical to divide it into upper, middle and lower etc. It was inherent in this thinking that rocks existing today (i.e. in Holocene time) could be interpreted by superposition processes as formed in successive earlier times. 100 years later it became evident that the stratal record did not divide globally in an easily identifiable way and the problem became

26

CHAPTER 3

Fig. 3.4. Principal discontinuities in Svalbard. Fault lineaments: (BBF) Breibogen Fault Zone: (BFZ) Billejorden Fault Zone; (HBF) Hannabreen Fault; (KHFZ) Kongsfjorden-Hansbreen postulated fault zone; (KVL) Knipovich Lineament; (LFZ) Lomfjorden Fault Zone; (RFF) Raudfjorden Fault Zone; (VL) Veteranen Line; (WSTF) West Spitsbergen (orogenic) Thrust Front. Major unconfomities with relevant age indicated by dashed lines and a dotted line.

one of the correlation of essentially diachronous boundaries. Then after another 50 years it was realized that for international agreement to use the same boundaries it was necessary to standardise each b o u n d a r y at only one point (the GSSP = Global Stratotype Section and Point) or 'golden spike' (Cowie 1986; Cowie et al. 1986; R e m a n e et al. 1997). Moreover, this point was to be defined geometrically in strata and was to be interpreted as a point in time (e.g. the m o m e n t of deposition o f that sand grain). Elsewhere any rock age should be expressed as earlier or later than this point event. The age o f rock elsewhere is thus never certain, but rather for estimation and judgment. This changes with changing technology. As far as possible the traditional stratigraphic divisional names were applied and are being standardized in this way. Perhaps one consequence of this procedure, not yet c o m m o n l y applied, is that ages o f most rocks are estimated by time correlation from the standard and the time scale is expressed as time, i.e. early and l a t e - no longer lower and upper. The practice was applied (e.g. t h r o u g h o u t in H a r l a n d et al. 1990) without dissent and should be applied t h r o u g h o u t this work. The concept o f a geological system as a chronostratic division is operationally o u t m o d e d . It exists, but its exact boundaries c a n n o t be k n o w n and therefore c a n n o t be a standard. The international c o m m u n i t y is working towards the standardization of such a chronostratic scale and its current state is

Fig. 3.5. Major structural features of the western Barents Shelf, based on fig. 3.1 of Vorren et al. (1991), Marote Petroleum Geology, 8.

tabulated broadly in Fig. 3.7. The details, where relevant, will be discussed period by period in Chapters 12-21 in Part 3. We observe rocks that can properly be divided as needed into lithic units: lower, middle and upper. The code for their use, as far as this work is concerned, is outlined in Section 3.3. below.

The chronometric scale. This, c o m m o n l y referred to as t h e numerical scale, is the generally used scale in years. It is far from absolute in its application to rock. Only two elements are required for international agreement (i) the standard for the unit of time and (ii) any classification of spans of such units and their names. (i) A year no longer depends on the standard year of the International Astronomical Union, but on its calibration in seconds as defined by the International Union of Weights and Measures in terms of perturbations of the cesium atom. These refinements are irrelevant for geological estimates of age. All ages may be expressed numerically, commonly for pre-Pleistocene stratigraphy in millions of years. The convention in this work is that Ma stands for an age, i.e. so many million years before the present. (ii) However, the second requirement is optional, i.e. to name specified intervals of time defined, not by GSSP but by an exact number of years. For the rock record in Precambrian time this has been agreed by the International Union of Geological Sciences. These names are appended here. There are numerous technical reasons why numerical estimates of age can hardly be true ages but rather apparent ages, which is only one reason for not regarding them as absolute. Even the errors properly quoted merely measure the limitation of the laboratory results and ignore the many other uncertainties arising from the geological history and relationships of the sample. The

SVALBARD'S GEOLOGICAL FRAME )MM & LM.t

27 !

!

12 ~

\ 30 ~

21 ~

_80 ~

ilia+

+ + +1|

++++++ +++++ ++++++

+++++) NORDAUSTLANDET

~79 ~

79 ~ ~O~ G ~

~

78 ~-

-78 ~ SPITSBERGEN

EDGEC)YA Folded b a s e m e n t

~

Devonian molasse

complex

~

Platform cover Major f a u l t zones

-77 ~ ~IU.

77 ~-

~ A x e s of a n t i c l i n e s (a) and s y n i c l i n e s (b)

Hopen

I North-East uplift II Nordenski6ldbukta anticlinorium:

1 PrinsOscars Land horst-anticline 2 Lovdn syncline 3 Nordkapp anticline III Hinlopenstretet synclinorium Ilia Eastern limb IIIb Western limb

Fig. 3.6. Major structural elements of Svalbard, a Russian interpretation. Redrawn with permission from Krasi'shchikov et al. (1966). Main features of the Geology of Svalbard in Krasil'shchikov (ed.) Soviet geological research in Svalbard 1962-1992, extended abstracts of unpublished reports, Meddelelser, 139, Norsk Polarinstitutt, Oslo, pp. 14-15.

4 Floraberget anticline 5 L~goya synciine 6 Kinnvika syncline 7 Sveanor syncline 8 Sparreneset syncline 9 Heclahuken anticline 10 Kluftdalen syncline 11 Gulfaksbreen anticline 12 Veteranen syncline 13 Kvitbreen syncline IV Wester Ny Friesland anticlinorium:

14 Atomfjella anticline 15 Bangenhuken anticline V North-West uplift:

16 Richardvatnet anticline 17 Sn~fjella syncline

following scale though endorsed by the IUGS, confuses latinized event names with precise numerical definitions and may gradually be superceded by the chronostratic scale as it extends backwards into Precambrian history except for the names and divisions in bold letters and numbers. Other ages are given by number.

I

!

I

Major basement structures:

30 ~

21 ~

12 ~

18 Krossfjorden anticline 19 Blomstrandhalvoya graben-syncline 20 Mitrahalvoya syncline Vl West coast horst-anticlinoriun: 21-26 minor synclines:

21 Bulltinden 22 Alkhomet 23 Kapp Lyell 24 Sofiekammen 25 Luciakammen 26 Hornsundtind

Major structures of Devonian complex and platform cover: vii Devonian graben of Andrde Land:

27 Inner horst 28 Andree Land anticline VIII West coast horst-like uplift: 29-33 superimposed graben-troughs:

29 Kongsfjorden 30 Forlandsundet 31 Renardodden 32 Hornsundneset 33 Oyrlandet 34 Olsokbreen swell

IX West-Spitsbergen graben-like trough:

35 Iradalen depression 36 Holmsenfjellet swell 37 Skiferdalen depression 38 Reindalen swell 39 Tverrdalen depression 40 Bettybukta depression 41 Isbukta swell X Sassendalen monocline XI East-Svalbard horst-like uplift:

42 East-Spitsbergen depression 43 Barentsoya-Edgeeya swell

Major fault zones: 1-4 fault zones:

1 Western marginal zone 2 Eastern marginal zone 3 Pretender zone 4 Erdmannflya-Bohemanflya zone 5-9 faults:

5 Raudfjorden-Kronebreen 6 Bockfjorden-Ekmanfjorden 7 Lomfjorden-Agardhbukta 8 Hinlopenstretet 9 Duve~orden

Precambrian Chronometric Scale as defined internationally (Table 3.1). P h a n e r o z o i c is n o t classified chronometrically. The initial C a m b r i a n b o u n d a r y is defined in G S S P in N e w f o u n d l a n d , therefore the age (here at 545 Ma) is a current estimate a n d n o t a definition (Tucker & M c K e r r o w 1995).

28

CHAPTER 3

Table 3.1. Precambrian chronometric scale Neo-Proterozoic III

Eon

Neoproterozoic

Pedod

Era

650 Ma

O

Cryogenian

N 0 r-

Tonian 1000 Ma

(J

Epoch

Quatemary

Q

Neogene

Ng

Paleogene

Pg

Stenian K2

Ectasian Cretaceous

1400 Ma

K1

Calymmian 1600 Ma Statherian

J3

1800 Ma o

2050 Ma

N 0 O0 (I)

Rhyacian 2300 Ma

Jurassic

J2

2800 Ma Tr 3

Mesoarchean

3.2.2

Triassic

3200 Ma

O

3600 Ma

O N O n,' uJ Z < "T" EL

A provisional time scale

The above international conventions simply inform us how to use names and numbers. However, the calibration of the chronometric by the chronostratic is always a scientific problem that is never finally soluble. A time scale is thus one of many attempted calibrations (in years) of the chronostratic scale. Ages of events are often quoted in years without calibration as though the calibration is an established fact. With so many time scales in use it was decided to make a single justified scale so that Svalbard history could be discussed within one group (CASP) at least on a common basis. This was first completed in 1982 and a more thorough revision attempted in 1989 (Harland et al. 1990). The attempt was made to apply the latest or most likely international, rather than regional, nomenclature and classification. The Cambrian and consequently parts of the Ordovician scale were especially weak at that time owing to lack of good determinations. A new crop of U - P b zircon ages has since greatly strengthened this part of the scale as reviewed by Tucker & McKerrow (1995). The accompanying Fig. 3.7 combines the two scales referred to above so that the later values replace the earlier ones wheresoever they can be applied throughout Cambrian, Ordovician and Silurian time. Otherwise the scale is as published in 1990. In making this composite scale without the many other improvements an important principle is at stake: a published calibration is of little use if the reasoning behind it is not clear. In this case the data and arguments are available in Harland et al. (1990) and in Tucker & McKerrow (1995). It is the intention that this scale be used throughout this work for comparison and consistency; but not with any suggestion that it is correct or even the best. In any case these new data from Newfoundland and Britain are reasonably consistent with somewhat earlier determinations from Russia (Bowring et al. 1993; Knoll et al. 1995)9 Figure 3.7 is simplified for use in Svalbard where asterisks mark ages which have some biostratigraphic basis. Rocks thought to be more than 1000Ma old have not yet yielded fossils and age estimates depend entirely on isotopic determinations. Figure 3.8 tabulates some of these critical data. Improvements will continue indefinitely. One chronostratic change referred to in Chapter 14 is that the Llandeilo division may well be subsumed as Llanvirn

8.5 32 15

"k

13 7 14

132 146

Kimmeridgian W Oxfordian -k

11 157

"k W

Bajocian

21 178

30

Hettangian

4000Ma

12.0 21.0

97 "k * -k

Tr 2 Tr 1

Permian

P1

=~ Pannsylvanian C 2 s -2 Mississippian

C1 D3

o

N 0

D2 Devonian

(0 EL

D1

Silurian

Ordovician

Rhaetian

W

Norian Camian Ladinian

-k -k ~k

Anisian Scythian Lopingian

W -k ?9

27 235 241 245

13 9 5 8 8 12 10 17 13

Pragian Lochkovian

25

03

Ashgill Caradoc

02

(Llandeilo) Llanvim

"k -k

Merioneth

"C2

St David's Toyonian Botomian

Sinian

Sturtian Karatau Riphean

2 11

428 443

15 6 9

458 ~t

6 6

47O 495

15 ~

10

~,

23 518 "k

Atdabanian Tommotian Nemakit Daldyn k9 Ediacaran

4 3

525

L 534

,

9

545 21 590

Varangian

o* [ -610 -800

, ^

I 1050

Yurmatin Burzyan

[ ~

i

Neoproterozoic

10 190 --

1000 Mesoptz

1650 2200

~

2450

~

2800

-?- - -

,

1350

Animikean Huronian Randian Swazian Isuan

14

?--k--

Arenig

-C~

14

417

Tremadoc

Vendian

5

.k I "k 290 "k .k 303 Moscovian -k Bashkidan -k 323 Serpukhovian "k Visean "k Tournaisian -k 363 Famennian -k Frasnian "k 377 Givetian Eifelian ~, 391 Emsian -k

Wenlock Llandovery

s

6 4

Sakmadan Asselian Gzelian Kasimovian

S2 S1

Cambrian

1 t

6 13

Pridoli Ludlow

O1

2O8

Guadelupian -k , Kungurian W L! 256

S4 S3

Ma

3.5 18.3

J1 i Sinemurian

2500 Ma Neoarchean

Paleoarchean

0.01 1.63

35.5 t 56.5 65

Aalenian Toarcian -k Pliensbachian

Siderian

Eoarchean ...?...

Aptian Barremian Neocomian "rithonian

-Myr

23.5

Oligocene Eocene Gulf Albian

-Ma 0.01 1.64 5.2

Pliocene Miocene

Callovian Bathonian

(J

Orosirian Paleoproterozoie

Ct

Paleocene

1200 Ma Mesoproterozoie

Holocene Pleistocene

o

850Ma

Chronometric standard

Estimated calibration

Chronostratic standard

545 Ma

1600 Paleoptz 2500

Archean

3500 oonn

Fig. 3.7. Provisional time scale used in this book, the asterisks mark Svalbard strata with fossil record. Compiled from Harland, Armstrong, Cox, Craig, A. G. & D. G. Smith (1990) and modified from Tucker & McKerrow (1995) for Cambrian through Devonian numerical values.

SVALBARD'S GEOLOGICAL F R A M E ( F o r t e y e t al. 1995, b u t c o u n t e r e d by Basset & O w e n s 1996). A n o t h e r p r o b l e m is the status o f the latest P e r m i a n L o p i n g i a n division ( C h a p t e r s 17 a n d 18). N e w scales a p p e a r frequently, b u t are n o t i n t e g r a t e d into this w o r k (Shell 1995; G r a d s t e i n & O g g 1996).

3.2.3

Svalbard's chronometric record

A p p a r e n t n u m e r i c a l ages f r o m isotopic d e t e r m i n a t i o n s o f S v a l b a r d rocks are i n d i c a t e d against a c h r o n o m e t r i c scale (Fig. 3.8). Particular d e t e r m i n a t i o n s will be discussed in their historical c o n t e x t in P a r t 3 w h e r e they are critical (with their sources referenced). This p l o t s h o w s the range o f m o s t p u b l i s h e d results. Analytical a n d o t h e r critical d a t a are n o t r e c o r d e d here because in this general w o r k precise values are n o t relevant for the s t r a t i g r a p h y . T h e p i c t u r e that e m e r g e s reflects n o t only the available rocks a m e n a b l e to such analysis, b u t also the interest o f the investigators a n d the field a n d l a b o r a t o r y costs o f each d e t e r m i n a t i o n .

3.3

The rock frame

N e a r l y all k n o w l e d g e o f geological history, d e p e n d s o n the evidence p r o v i d e d by existing rock. I n d e e d (possibly differing) interpretations by m a n y w o r k e r s as to age, c o n t e m p o r a r y e n v i r o n m e n t a n d processes, p r e v i o u s l o c a t i o n a n d a t t i t u d e etc. m a y be referred to the s a m e r o c k s as p r i m a r y reference. It is t h e r e f o r e p a r a m o u n t to agree o n h o w all scientists m a y refer to p a r t i c u l a r r o c k in c o n v e n i e n t n a m e d r o c k units. F r o m the n a m e d units as listed, for e x a m p l e in section 3.4 a n d in t h e glossary a n d index in P a r t 4 it is e v i d e n t t h a t in even a small area such as S v a l b a r d the geologic c o m p l e x i t y is such t h a t s o m e h u n d r e d s o f units n e e d n a m e s . For many years, especially in the Old World, rocks were described as though their ages were known, or should be known, and this often depended on their contained fossils. The earlier descriptions in Svalbard focused on the fossil horizons, or niveaux, selected from the body of rock in which they occur. Nowadays the whole rock bodies are described. Hence a lithic (approximately, lithostratigraphic) code has developed, largely based on the early American codes. The trend is towards international standardization even for national surveys. This process is not yet complete. For example what is often taken as an international standard (Hedberg 1976) claims only to be a guide in which all contrary opinions expressed on controversial matters by the Subcommission were not referred (Harland 1977). So there is still some way to go. Having been party to other attempts at an international code (e.g. George et al. 1969; Harland et al. 1972) the principles adopted here and throughout this volume interpret the international consensus on matters which have hardly proved to be controversial. T h e r e l a t i o n s h i p b e t w e e n the r o c k (a) a n d the t w o time scales (b) a n d (c) is d e p i c t e d as follows. T h e r e is n o w a y t h a t (b) a n d (c) c a n be related except t h r o u g h (a). A n y o t h e r i n t e r p r e t a t i o n (x) m u s t also derive f r o m (a). Thus: (b)+-+(a)~(c) a n d ( a ) ~ ( x )

3.3.1

A lithic code

This section discusses a lithic c o d e - t o w a r d s an i n t e r n a t i o n a l c o d e for defining, n a m i n g a n d classifying local r o c k bodies or units. T h e c o n s i d e r a t i o n s are r e c o u n t e d n o t as a legal f i ' a m e w o r k c o m p e t i t i v e w i t h o t h e r codes, b u t r a t h e r to indicate t h o s e m a t t e r s w h e r e differences o f o p i n i o n or practice h a v e persisted a n d hence w h e r e this w o r k has m a d e choices a n d i n d e e d r e c o m m e n d a t i o n s . T o this e n d s o m e principles b e h i n d these choices are listed below. (a) The term litbic is used advisedly in preference to lithostratigraphic because in many minds the category 'lithostratigraphic' implies perhaps indefinite parallel systems of other units (biostratigraphic, magnetostratigraphic, chronostratigraphic etc.). The case here is that one neutral scheme only of rock units is necessary, indeed obligatory, and that all other geoscientific disciplines with their terminologies serve to qualify these lithic units in many different ways as in the above formula.

29

(b) The units should be capable of location in the field as mappable units and therefore recognisable to other workers. (c) The rock so classified should not be genetically based. Thus interpretation as to environment of formation (e.g. sedimentary, metamorphic, igneous) must not preclude any rock unit from the lithic code. (d) The units should be conterminous as in a map or section so that there is no overlap or gap between them. Consequently any observation could be related in space to a position in one unit itself identifiable geographically and in relation to other units. (e) Formal definition of a unit begins in some locality, large or small, with thickness and description of the boundary with adjacent units. Features that are convenient may be used to define and characterise a unit and distinguish it from adjacent units. Typically these are lithological (sandstone, limestone, basalt etc.) colour, resistance to denudation, obvious macrofossils, minerals, or geophysical parameters especially if the unit is not exposed or sampled. (f) The time-honoured principle of naming the unit from a local place name is appropriate. Once this has been done, unless there has been a radical weakness in the description, that name should remain attached to the package of rock originally intended whether or not it changes rank up or down from the primary formation. To allow the lithic system to be comprehensive, additional terms such as complex, suite, pluton, sheet may be useful and further division may be necessary by qualifiers (supergroup, subgroup). (g) In naming units or selecting named units some sympathy with those having used a name might well take some precedence over the absolute correctness of application of the geographical name. Brevity and ease of use in other languages are considerations. Nor should the temptation to 'correct' an established name be entertained. Thus the name should also be fixed from its first use and not changed with subsequent political, linguistic, genetic, chronostratic arguments or superior scientific knowledge. The name should thus not be translated or modified in another language other than by transliteration to a different alphabet. Thus once the name of a unit has been published with sufficient description to identify it that name shall have priority. Subsequent fuller descriptions, genetic interpretations, and minor modifications do not qualify to rename the unit. (h) Unpublished names in reports, dissertations etc. when significant work has been done should be used by later workers when publishing the work with formal names and then attached to the originally intended unit of rock as far as practicable, but the date of the unpublished work gives no priority. (i) The formation is the primary unit. A group can only be established from a combination of two or more formations from which it is defined. A member can only be a division of a formation. But greater knowledge may require more divisions which will probably enter at a lower rank and thus the rank of the superior units may be raised. The reverse process is also possible. (j) Hierarchy of named units is a convenient convention. Formations may be grouped in groups, supergroups or subgroups or divided into members or beds in which the division need not be exhaustive. One advantage of hierarchies of names is that each scientist may choose or discover at what level memory serves for the task in hand. (k) Formational boundaries may be expected to be diachronous, whether or not this can be demonstrated, and thus attempts to revise a lithic system to fit time intervals should be resisted not least because time correlation is a matter of changeable opinion. (1) On the other hand if two parts of a formation are shown to have widely discrepant ages it may be suspected that the body could not once have been contiguous so that an additional named unit may be necessary for that part not in the primary definition. In this case the original name should remain with the rock originally or significantly applied. (m) Multiplication of names in any discipline is unpopular and the limitations of memory are often quoted in favour of fewer items. There is a scientific principle in favour of splitting rather than lumping, at least in the first stages of description. That is because if later the splitting proves to have been mistaken then combination of entities is easily applied retrospectively. The other way round, at a later stage to split a lump, may require that the lump then needs redescription by characters not evident in the earlier literature. (n) Disuse of names may be recommended in favour of some better scheme. But names cannot be suppressed except within an organization. Falling into disuse is a more equitable fate. (o) Conversely the use of new names or schemes cannot be obligatory except within an organization. They are essentially recommendations whose use may depend on their perceived scientific merit.

30

CHAPTER

Ma

WJST

WJNT

NDKT

O2LT

BHFT Richarddalen

WNWT I (4) 325 ( ~

NFWT

NFET

NAET t

CHRONOSTRAT 332

I

Vis

-- 350 -- 360

(11)347

(3) 346 I ~ (3) 351 ~ - - 349

(11)358

(2) 358

-- 370 (1) 375 (1) 379 [1) 380(9) 38( (3) 380 (3) 390 (4) 389 (1) 390 (3) 394

(3) 382

-- 390

(3) 385

i (1) 392 ( ~ (1) 395 ( ~

(1) 397

-- 400 (16) 402

(31) 404

(11) 407 (6) 410

4 1 0

-- 420 -- 430

(6)431 15)433 22)436

-- 440

(3) 409.5 (33)413 ~ (16)413 (10) 414 ~_) (15) 420 (33) 4 2 3 (15)425 }16{ 428 (3) 429 429 (9) 430 (15)433 (~) (16)437 (1) 439 (4) 438.5 (3) 443

(16) 410 ' (16) 418 (16) 420 (16) 423 (16) 430 (1)433 (16) 443

(32) ?

- - 377 (2) 381 Giv (3) 385 (~) Eif (2) 387 - -

(2) 396

Ems

(1)413 ( ~

Pra

(27) 4 2 4 (4) 427 (4) 430 (4)434

4) 422 1)425 (1)426 ( ~ (4) 428.4 (32) 432 (~)

(2) 411 (2) 415 (4) 419.3

Lok

417pr i Lud Wen -

(4) 442.6

(34) 442

4 4 3 - Ash

- -

Crd 458 LIo

(16) 455

- -

(33) 461

(11)462 (17) 4 6 6

-- 470

(11) 481

02

Tin

- - 470

(11) 472

-- 480

S Lly

-- 450 -- 460

D2

3 9 1

_

(25) 410 (28)

141442444

(4) 390 (3) 395 (4) 398 (3) 4O0 (3) 405

(24) 4 7 6 (6) 479 (6) 484

Arg

(16) 481

O1

- -

Tre

-- 490

-- 495 -- 500 --

D3

Frs

(5) 376

!

O1

Tou

(3)361 ( ~ - - 3 6 2 . 5 ~ - - - (3)366 ( ~ - - 3 6 7 ram

(3) 370.5

-- 380

- -

NAWT

"]'ADLT 1 1(4) 3151

(11)337

-- 340

3

(16)500 (16)504

(29) 500

-

Mer

-'~3

5 1 0

StD -- 520

-'~2

--518 -

(12)520

-

- - 525 -- 530

Atd

-- 534 (1) 538 (16) 542

- - 540

Tom Man

-- 545 (4) 549

--550 i (33).56.1

555.55-'(4)565 --600 (4)594 -

(2) 556 (14)620 (14)661

(6) 631

"~ 1

(13)600

(23) 624

-

Edi

V2

-- 580 ~ 610

V,

-

(34)677

--700 ~

Stu (8) 766

(4) 789.5 (4) 822.5

--800

- -

8 0 0 -

z

--900

(33) 952 - - 1 0 0 0 - - - -(34) o (22) "~ (22) - - 1 2 0 0 ~ (34)

1100 1130 1135 1200

Kar

(25) 939 14) 955 14) 965

(33) 1050 (36) 1190"

/",11399 1435

-- 1400 i

(35) 1317"

- - 1 0 5 0 ~ Yur

(35) 1735 (28) 1737 ( ~ (18)

--1800 o

(4) 1937

R2

(7) 1275 - - 1 3 5 0 Bur

-- 1600--

R 3

970

R1

--1650--

1750

(31) 1766 (19) 1800

--2000

Animikean

(24) 2121 - - 2 2 0 0 ~ (34) 2200 - - 2400

--2200-Huronian

(20) 2400 -

(23) 2415

(20) 25o0

--2600

Randian

- - 2800

- -

3000~
1.2 km, carbonate: (Arenig to Early Llanvirn) Valhallfonna Fm, 220 (?Late & Mid-Canadian) Kirtonryggen Fm, 750 m (Early Cambrian) Tokammane Fm, 192m (Vendian) Polarisbreen Gp, 0.7 km (Ediacara) Dracoisen Fm, 245 m (Late Varanger) Wilsonbreen Fm, 160 m (Early Varanger) Elbobreen Fm, 362m Lomfjorden Supergp, 6 km, Akademikerbreen Gp, 2.0 km, all carbonates Backlundtoppen Fm, 360-700 m carbonates Draken Fm, 25-300 m carbonate conglomerate Svanbergfjellet Fm, 100-625 m (Sturtian) Grusdievbreen Fm, 865 m (700-800 Ma) Veteranen Gp, 3.8 km, mainly siliciclastic Oxfordbreen Fro, 550m Glasgowbreen Fm, 540m Kingbreen Fm, 1500m quartzites with limestones (800-900 Ma) Kortbreen Fm, 1200m conformable on Vildadalen Fm NY FRIESLAND, WESTERN TERRANE (NFWT) (Tournaisian unconformable cover) Ny Friesland (Caledonian) Orogeny Stubendorffbreen Supergp, 11 km+ Planetfjella Gp, 4.7 km Vildadalen Fm, 3250m Flgten Fm, 1500m unconformity Harkerbreen Gp, 3.5-4.0 km Sorbreen Fm, 250+ m, psam, qi & amph Vassfaret Fm, 600 m quartzites and amphibolites Bangenhuk Fm, 200 m granitoid Rittervatnet Fm, 350m semipelites, amphs, feldspathites Polhem Fm, 900+ m psammites unconformity Instrumentberget-Fl~ttan granitoid Finnlandveggen Gp, 2.7+ km Smutsbreen Fm, 1200+ m, peliles & marbles Eskolabreen Fm, 1500+ m gneissose feldspathites & amphibolites ?AustJjorden tectonothermal event

(1750 Ma) (

-Kortbr. ~

~1000m (CB6). Poorly sorted sandstones, siltstones, calcareous shales, clay ironstones, thin coals and plant beds, altogether exhibiting soft sediment deformation, occur mainly in hill tops in the centre of the Paleogene basin. (5) Battfjellet Fm (Major & Nagy), 60-300 m (CB5). Well-laminated fissile and cross-bedded alternating grey-green to whitish sandstones interbedded with siltstones and minor black shales, some with marine bivalves. (4) Frysjaodden Fm (Livshits 1967), 200-400m (CB4a). This formation between CB5 the Battfjellet (sandstone) Formation and (CB3) the Grumantbyen (sandstone) Fm exhibits different successions between the NE and SW developments which has caused some confusion between Russian workers in the west and Norwegian in the east. The complex interdigitation of the strata reflects a changing pattern of sedimentation and provenance and the nomenclature has been resolved accordingly by SKS (1995) as follows.

In the NE the original Gilsonryggen Fm (of Major & Nagy 1964) is typically a black silty-shale succession with some chert pebbles and marine bivalves and it should be referred to as the Frysjaodden Fm (SKS 1995). In the SE the Hollendardalen (sandstone) Fm (Livshits 1967), (CB4), is a wedge of sandstone thickening to the SW and dividing the lower part of the Frysjaodden Fm. It was given formation rank because of the history of its name and its significance as indicating the first major sedimentation source in the west. A new name, Marstranderbreen Mbr (SKS 1995), was proposed for the shales of the Frysjaodden Fm beneath the Hollendardalen Fro. The shales above it being referred to as the Gilsonryggen Mbr up to another sandstone wedge from the west: the Bjornsonfjellet Mbr (Steel et al. 1981). The shale between this member and the Battfjellet Fm has no separate name and is presumably a digitation of the Gilsonryggen Mbr. The Sarkofagen Fm (Major & Nagy 1972) corresponding to part of the Hollenderdalen and probably the Morstanderbreen units is relegated to disuse. Hollendardalen Mbr, in the lower part which corresponds to the upper part of the green sandstone of the earlier Sarkofagen Fm. (3) Grumantbyen Fm (Livshits 1964), 200 45 m (CB3). Replaces the lower part of the earlier Sarkofagen Fm as defined further east (Major & Nagy 1964). It is a greenish (glauconitic) bioturbated sandstone.

52

CHAPTER 4

(2) Basilika Fm (Major & Nagy 1964, 1972), 10-350m (CB2). Mainly black and dark grey shales with occasional well-rounded pebbles of quartzite and chert and interbedded siltstones and sandstones near the base. (1) Firkanten Fin (Major & Nagy 1964), 100-170m. A coal-bearing sandstone unit interbedded with marine and non-marine siltstones and shales with a basal conglomerate resting with sub-parallel unconformity on Carolinefjellet Formation members. It has been divided into four members. Endalen Mbr (Steel et al. 1981, SKS), 40-100m (CBI.d) of stacked 4-5m bioturbated sandstone, cliff-forming strata with interbedded thin conglomerates, clay ironstones and minor shales, interfinger with underlying member. Kolthoffberget Mbr (Steel et al., SKS), up to 120 m (CBI.c) is a fine-grained lateral equivalent of the above member comprising organic-rich shales and fine bioturbated sandstones. Todalen Mbr (Steel et al., SKS), 60 m comprises three to five sequences of shale-siltstone-sandstone-coal. Gronfjorden Mbr (SKS), 4.5m is the irregular basal conglomerate with conglomeratic sandstones.

4.2.4

Isolated outliers

Southwest Sorkapp Land Oyrlandet Formation.

This is a poorly exposed sandstone, with some fault contacts, occurring at the southwestern tip of Sorkapp Land. It was regarded by Atkinson as part of the Central Basin succession and was correlated by Livshits (1992) with the Firkanten Formation and so mapped by SKS (fig. l a) and therefore part of the Van Mijenfjorden Group. The above name may be useful unless or until it is established as Firkanten Formation. It occurs well to the west of the main foldbelt which normally defines the western margin of the main Paleogene outcrop, yet it is still within the orogenic zone.

Eastern Outliers.

Whereas the Van Mijenfjorden Group main outcrop is bounded in the west north of Sorkapp Land by the eastern margin of the orogenic fold and thrust belt so forming a sharp, often vertical, limb to the Central Basin, its eastern boundary merges eastwards into the relatively flatlying platform mainly of Mesozoic strata. Consequently the Paleogene strata pass eastwards from the main outcrop into many outliers in the tops of the higher mountains and there is no knowing how far the Paleogene strata extended.

The Ny-,~lesund coalfield.

The outlier of undoubted Paleocene strata (Chapter 9) probably correlates with the one or two of its lower formations. Its Ny-Alesund Subgroup is classed within the Van Mijenfjorden Group of the Central Basin (SKS).

4.3

The Adventdalen Group ( C r e t a c e o u s - J u r a s s i c )

The Adventdalen Group of the Central Basin of Spitsbergen is up to 1800 m thick. Early, Mid- and Late Jurassic, and Early Cretaceous deposits are present. It rests on the Kapp Toscana Group with varying degrees of minor unconformity. In contrast the overlying Firkanten Formation of the Van Mijenfjorden Group, of Paleogene age, rests with increasing unconformity northwards on different members of the Carolinefjellet Formation; parts of the Mid-Albian and the whole of the Late Albian and Late Cretaceous deposits are missing (Nagy 1970). The Adventdalen Group forms a NNW-SSE-striking asymmetric syncline, which plunges gently to the SSE. Dips in the eastern outcrops are at a low angle and in the western outcrops are variable to steep. The main outcrop lies south of Isfjorden,

Sassendalen and Agardhdalen and runs south to Sorkapp Land, with outliers between Agardhbukta and Wichebukta. For convenience the minor outcrops on the north side of Isfjorden, southern Oscar II Land, are also included here.

4.3.1

Lithic units

Jurassic and Cretaceous strata of Svalbard are treated as a whole in Chapter 19. The following outlines the lithic units of the Adventdalen Group of the Central Basin which for this chapter is extended to the west and south to the outcrop limits.

Adventdalen Gp: Bathonian-Mid-Albian (Parker 1967). Carolinefjellet Fm, 1200+m marine shales to sandstones; Aptian to Albian (Parker 1967). Schiinrockfjellet Mbr, 70+ m, sandstones with minor shales and siltstones; Middle Albian (Nagy 1970). Zillerberget Mbr, 375+ m (Nagy 1970), shales and siltstones often with clayironstones and with minor sandstones; Early to Mid-Albian. Langstakken Mbr, 208m (Parker 1967), sandstones with minor siltstones and shales; Early Albian. Innkjegla Mbr (Parker 1967), 430 m mainly shales and siltstones in the upper part with shales and clay-ironstones in the lower part; Aptian-Early Albian. Dalkjegla Mbr (Parker 1967), 131 m laminated to thin bedded sandstones with alternating shales and siltstones; Aptian. HelvetiafjeHet Fm (Parker 1967), 53 m continental sandstones with coals and minor shales; erosive base; Barremian. Glitrefjellet Mbr, 69 m cross-bedded and rippled sandstones, carbonaceous shales, clay-ironstones and thin coals; Barremian (Parker 1967). Festningen Mbr, 30 m massive sandstones, often conglomeratic, with minor shales; Barremian (Parker 1967). Janusfjellet Subgroup, (Parker 1967): marine, predominantly argillaceous; ?Bajocian-Barremian Rurikfjellet Fm (Parker 1967), 176m shales to siltstones; BerriasianBarremian. Ullaberget Mbr (Rozycki 1959), sandy shales and siltstones with clayironstones and local calcareous sandstone; Valanginian?-Hauterivian. Wimanfjellet Mbr (Dypvik et al. 1991), silty shales with sideritic and calcareous concretions; Berriasian-Barremian. At the base in eastern Nordenskioid Land is the Myklegardfjellet Bed (Birkenmajer 1980), a glauconitic plastic clay with erosive base; Berriasian. Disturbed sedimentation has been related to the effects of an impact (Chapter 19.5.2) At the base in western Torell Land is the Polakkfjellet Bed (Birkenmajer 1975), conglomeratic sandstone; Volgian. Agardhfjellet Fm (Parker 1967), 243 m at type locality to 115m to west but > 49 m locally sandy-conglomeratic base. Revidalen, (Lindstromdalen), thickening but otherwise mainly shales to siltstones and fine sandstones; Bathonian Volgian. Slottsmoya Mbr (Dypvik et al. 1991), grey organic-rich shales with dolostone concretions; Kimmeridgian-Volgian. Oppdalshta Mbr (Dypvik et al. 1991), silts to fine sandstones; Oxfordian. Lardyfjellet Mbr (Dypvik et al. 1991), grey organic-rich shales with dolostone concretions; Bathonian-Callovian. Oppdalen Mbr (Dypvik et al. 1991). This basal unit of the Agardhfjellet Fm is generally calcareous and contains coarse clastics with conglomerates, sandstones, and siltstones, and locally phosphoritic and glauconitic, oolites; Bathonian-Callovian. It includes three beds. Dronbreen Bed (Dypvik et al. 1991), fine sands to silts; BathonianCallovian; Marhogda Bed (B/ickstr6m & Nagy 1985), with a maximum thickness of 1.5 m at the type locality near Diabasodden, south of Sassenfjorden. It is a microsparitic limestone, partially dolomitised and seriticized with quartz grains, chert ooids and glauconite. Brentskardhaugen Bed (Parker 1967), is at the very base of the member, with type locality on the south side of Sassendalen. It contains rounded fossiliferous phosphoritic, chert and quartz pebbles in a microsparitic ferruginous dolomitic cement. It reaches a maximum thickness of 1.35m east of Konusdalen, just west of Marhogda (B/ickstr6m & Nagy 1985). The base is erosional but without angular discordance on the Wilhelmoya Fm. The age is Bathonian. The nodules contain a diverse assemblage of bivalves, ammonites, belemnites and vertebrate bones of Toarcian-Aalenian age (B/ickstr6m & Nagy 1985). The erosive base.rests on the Kapp Toscana Group, whose youngest age is Toarcian (see below, 4.4).

THE CENTRAL BASIN The above units are described briefly from eastern Nordenski61d Land through the main outcrop clockwise along the east coast, where the sequence is only mildly deformed, south to Sorkapp Land, and then northwards through more disturbed strata of the western outcrops within, and in the vicinity of, the western deformation zone.

4.3.2

Eastern Nordenski61d Land and southwestern Sabine Land

In eastern Nordenski61d Land, the Adventdalen region and the mountains to its east, including Helvetiafjellet and Janusfjellet, are characterized by subhorizontal strata, with gentle westerly inclination. The original mapping by Major & Nagy (1964) of the area has been substantially revised and reinterpreted (Sheet C9G, Major et al. 1992). The readily weathered Janusfjellet Subgroup occupies the lower gound with a more intact outcrop pattern and the higher ground is characterized by the Helvetiafjellet Formation with Carolinefjellet Formation above, frequently isolated as outliers (Fig. 4.4). Cliff-forming sandstones crop out clearly in the Festningen Member of the lower part of the Helvetiafjellet Formation, and less prominently in the Sch6nrockfjellet, Langstakken and Dalkjegla members of the Carolinefjellet Formation. This pattern of outcrop continues southeastwards through Lardyfjellet in southwest Sabine Land to Rurikfjellet and Kapp Dufferin in northern Heer Land. The higher members of the Carolinefjellet Formation are progressively cut out northwards under the base of the Paleogene Firkanten Formation, which rests on the Langstakken and Zillerberget members; the latter is only represented in the very southeast of Nordenski61d Land. Thrusting from the west penetrates the Adventdalen Group, particularly at Arktowskyfjellet and Juvdalskampen where it affects the shales of the Agardfjellet Formation. The continuation of the Billefjorden and Lomforden lineaments affect especially the Janusfjellet Formation, causing thinning of sediment, and giving anomalous NNW-SSE striking anticlinal axes running under Bergmannhatten and just to the east of Tronfjellet. East of the Billefjorden lineament, the Agardhfjellet Formation is locally absent. Parker (1967) interpreted this as erosional, but it is at least in part due to decollment/thrusting (Parker 1966; Andresen, Haremo & Bergh 1988; Andresen e t al. 1992). A dolerite sill complex penetrates Triassic sediments around Diabasodden.

Carolinefjellet Fm at Langstakken, the type locality, is 768.5m (Nagy 1975), only the Dalkjegla, Innkjegla and part of the Langstakken members are represented and share the same type locality. Immediately under the Firkanten Formation is the: Langstakken Mbr, 208 m with eroded top; Dalkjegla Mbr, 131 m; Innkjegla Mbr, 429.5 m. Heivetiafjellet Fro. At Helvetiafjellet 54m of non-marine sediments (Parker 1967) comprise: Glitrefjellet Mbr, 49m sandstones to shales, thickening to 66m at Carolinefjellet; Festningen Mbr, 4m massive coarse grained to conglomeratic sandstones. Thickens to 14m on Carolinefjellet. Janusfjellet Subgp. The type section on Janusfjellet, 502 m comprises principally shales and siltstones (Parker 1967). It is marine throughout: Rurikfjellet Fro, 342m at Wimanfjellet is mainly argillaceous; contains two members: Ullaberget Mbr, sandstones with shales are thickest and more sandy in the northwest at Janusfjellet, 160m and generally thin to the south west, e.g. Lardyfjellet, 60m although are even thinnner in association with the Billefjorden and Lomfjorden faults (Dypvik et al. 1991). Between one and five coarsening upwards cycles are recognized. Bioturbation is characteristic, with some ammonites and belemnites; bivalves include mainly Buchia. Wimanfjdlet Mbr, grey shales with sideritic and calcite concretions, 182 m thick at the type locality; relatively poor in fossils; the base is formed by the: Myklegardfjellet Bed, thin plastic glauconitic clay crops out in eastern Nordenski61d Land including Lardyfjellet (40cm) and Glitrefjellet (50 cm) (Dypvik, Nagy & Krinsley 1992) and contains rare belemnites and Berriasian foraminifera (Nagy et al. 1990). The base is erosive. Possibly coeval with Mjolnir impact.

53

Agardhfjellet Fm (Parker 1967) is predominatly argillaceous, but two of the four members are sandy. Generally just over 200 m thick at Janusfjellet and Glitrefjellet, but thins to 100 m on the Billefjorden Fault lineament. Slottsmoya Mbr, grey organic-rich shales with siderite concretions (Dypvik et al. 1991), 90 m thick at the type section, siltier units in the upper part are characterized by ammonites, including Dorsoplanites and benthos. Oppdals~ta Mbr, silts to fine sandstones in three coarsening-upward cycles (Dypvik et al. 1991), 28 m thick at the type locality. Lardyfjellet Mbr, 35 m grey particularly organic-rich shales with dolostone concretions (Dypvik et al. 1991) at the type locality, macrofauna occasional. Oppdalen Mbr, 60m is the basal unit of the Agardhfjellet Formation, generally calcareous and containing coarse clastics, but locally oolitic (Dypvik et al. 1991), it includes three beds. Dronbreen Bed of fining upward sandy to silty clay with sideritic horizons, up to 60m thick (Dypvik et al.1991). Marhogda Bed with a maximum thickness of 1.5 m at the type locality near Diabasodden, south of the mouth of Sassenfjorden, a microsparitic calcarous sandstone, partially dolomitized and sideritized, with quartz grains, chert, ooids and glauconite (B~ickstr6m & Nagy 1985). Brentskardhaugen Bed (Parker 1967) forms the base of the member. At the type locality it is 130cm thick. It contains richly fossiliferous reworked phosphoritic concretions with cherts and quartz in a microsparitc ferruginous dolomitic cement (B/~ckstr6m & Nagy 1985). The base is erosional but without angular discordance on the Wilhelmoya Fro.

4.3.3

Sabine Land

The near horizontally bedded outliers northeast of Agardhbukta include the principal exposures on Agardhfjellet, Myklegardfjellet and Holmgardfjellet (Miloslavskiy 1993, D9G), where there is a complete sequence through the Janusfjellet Subgroup, capped with minor sandstone outliers of the Helvetiafjellet and Carolinefjellet formations. Agardhfjellet lies on the axis of a N N E - S S W minor syncline and Holmgardfjellet on a gentle anticline. The easternmost outcrop just east of Eistraryggen shows an overturned N N E - S S W striking syncline adjacent to a normal fault. There are extensive dolerite sills in the lower part of the Janusfjellet Subgroup in the west, north and east (Birkenmajer 1979). The lower part of the Janusfjellet Subgroup is similarly exposed to the north at D o m e n and Krogfjellet (Miloslavskiy e t al. 1993) and also Teistberget (Miloslavskiy 1992, D8G). At the last locality, N - S monoclinal flexuring and W S W - E N E normal faulting occur. The complete sequence from Glitrefjellet Member to Brentskardhaugen Bed (502 m) has been described from Myklegardfjellet (Birkenmajer 1980). His figure is comparable to a value of 555 m by Pchelina (1967) and of 473 m (based on Parker 1967 and additional data) from the same area.

Section at Myklegardfjellet (Birkenmajer 1980) Carolinefjellet Fm basal unit is present only on Agardhfjellet where carbonate-rich Dalkjegla Member crops out (Bjoroy & Vigran 1979). Helvetiafjellet Fm was formerly over 5 5 m thick and represents an overall fining-upward sequence on Myklegardfjdlet (Birkenmajer 1984) comprising: Glitrefjellet Mbr, 32 m comprizes sandstone shale alternations with minor conglomerates, coal shales, thin coal seams, rootlet horizons representing minor distributaries, channel lags, and interdistributary deposits, with a current direction from the northeast; Festningen Mbr, (c. 23 m) containing large-scale cross-bedded quartz sandstones and lag conglomerates with a sharp erosive base. The cross bedding is mainly planar, with planar and occasionally concave erosional surfaces with megaripples and some slumping. Together with current orientations these features indicate a fluvial system with source from the west. Janusfjellet Subgp, 417.5m is well exposed in Myklegardfjellet and contains eight macrofaunal horizons (Birkenmajer, Pugaczewska & Wierzbowski 1982). Rurikfjellet Fm, with type section on Agardhfjellet, 176m (Parker 1967), also on Myklegardfjellet, 203 m (Birkenmajer 1980), is predominatly shales with common sideritic and dolomitic concretions. It has not been subdivided north of Agardbukta. At the base is: Myklegardfjellet Bed plastic clay, 0.5-1.0 m with erosive base.

54

CHAPTER 4

Fig. 4.4. Geological map and cross-section of eastern Nordenski61d Land and Sabine Land, drawn by S. R. A. Kelly, based on Dallmann (1993) Geological Map of Svalbard 1.'500000, Sheet 1G. This legend serves also for Figs 4.5, 4.6, 4.7 & 4.8.

THE CENTRAL BASIN

55

AgardhfjeHet Fm is 245m on Myklegardfjellet (Birkenmajer 1980) and 241.5 m on Agardhfjellet (Parker 1967)). The section of Birkenmajer (1980) can be subdivided according to Dypvik et al.'s (1991) scheme: Slottsmoya Mbr, 110 m grey organic-rich shales with dolostone concretions; contains Fauna 8 including bivalves and the ammonite Pectinatites of Early Volgian age; Oppdalsfita Mbr, 61 m silts to fine sandstones with faunas 4, 6, 7, mainly of bivalves and 5 of belemnites; LardyfjeHet Mbr, 72.5 m return to grey organic-rich shales with Faunas 1 and 2 mainly of ammonites; Oppdalen Mbr shows a fining-up sequence; Dronbreen Bed, 40 m sands and silts overlying Brentskardhaugen Bed, 0.5m containing fossiliferous phosphoritic and quartzitic pebbles in a dark clayey matrix, resting with erosion on the Wilhelm6ya Formation.

4.3.4

Heer Land

A l t h o u g h m u c h o f the inner part of H e e r L a n d is ice covered, Helvetiafjellet a n d Carolinefjellet f o r m a t i o n s crop out extensively and almost horizontally f r o m the coast westwards, just reaching V a n Mijenfjorden, with only a small a m o u n t of Tertiary cover in the west (Salvigsen & W i s n e s 1989, C10G; Steel, Winsnes & Salvigsen 1989, C10G) (Fig. 4.5). The Janusfjellet F o r m a t i o n has a n a r r o w coastal o u t c r o p reaching s o u t h w a r d s to Kv~lv~gen ( D a l l m a n n 1991, C 11G), forming the base of the cliffs w h i c h are c a p p e d by Cretaceous strata. Extensive dolerite sills occur f r o m K a p p Dufferin n o r t h w a r d s , and affect the Janusfjellet Subgroup. Pavlov & P a n o v (1980) s u m m a r i z e d the geology of H e e r L a n d , recognizing some 971 m o f Cretaceous a n d 240 m of Jurassic strata. The V a l a n g i n i a n / H a u t e r i v i a n - A l b i a n sequences of K j e l s t r 6 m d a l e n , originally described by H a g e r m a n n (1925), and Kvalv{tgen and have been described within a biostratigraphic f r a m e w o r k by Pchelina (1967). The s o u t h e r n m o s t effects of the Billefjorden and L o m f j o r d e n F a u l t Z o n e s are seen in K j e l l s t r 6 m d a l e n a n d on Rurikfjellet respectively.

Carolinefjellet Fm reaches its maximum differentiation in southern Heer Land and northern Torell Land and all five members are recognized; the highest, the Sh6nrockfjellet Formation is restricted to this area and is of Mid-Albian age (Nagy 1970). Helvetiafjellet Fm (100 140m) fluvial sandstones of Kvalvfigen are characterized by quartzose lithic arenites with the quartz derived from the west and volcanics showing affinity with those of Kong Karls Land (Edwards 1978). At least four coals exist up to l m thick, of fusainsemifusainous durain (Pavlov & Panov 1980). Dinosaur footprints, attributed to a carnosaur, occur at Boltodden (Edwards, Edwards & Colbert 1978) in emergent point bar sandstones. Festningen Mbr sandstone forms a 20 m thick channel complex of planar to trough cross-bedded sandstones. The junction deposits of the HelvetiafjeHet Fm and the Janusfjellet Subgroup shows the existence of an unstable delta front which is affected by gravitational movement of slide blocks and is spectacularly exposed at Kv~lvagen (Nemec et al. 1988a). Whole blocks up to 80 m across and including both units have broken away from an arcuate scarp and rotated during down-slope movement from a delta-front. Janusfjellet Gp outcrops. Ullaberget Mbr a generally coarsening upwards sequence of shaley mudstones with thin massive, cross and plane bedded sandstones.

4.3.5

Eastern Torell Land

L o w westerly dips in the Helvetiafjellat and Carolinefjellet f o r m a t i o n s continue in eastern Torell L a n d . Janusfjellet S u b g r o u p no longer crops out on the coastal cliffs, whose base is n o w Cretaceous from Kvalvftgen south to H a m b e r g b u k t a . The higher parts of the coast a n d m o s t of the inland o u t c r o p is Paleogene (Birkenmajer, N a g y & D a l l m a n n 1991, C12G) (Fig. 4.6).

Carolinefjellet Fm is fully developed as in southern Heer Land and reaches 810m at Sch6nrockfjellet a near maximum recorded thickness of 840m at Kostinskifjellet and thickens further southwards beneath the Firkanten Formation unconformity (Nagy 1970).

Fig. 4.5. Geological map of the east coast of Spitsbergen from Agardhbukta to Hambergfjellet, drawn by S. R .A. Kelly, based on Dallmann (1993) Geological Map o f Svalbard 1:500 000, Sheet 1G (see Fig. 4.4 for key).

Schiinrockfjellet Mbr, 83m at the type locality on Sch6nrockfjellet, predominantly cliff-forming fine grained sandstones, with rare bivalves and crinoids. Becomes muddier southwards and passes laterally into the Zillerberget Mbr (c. 350 m). Langstakken Mbr, up to c. 50m but passes laterally into Innkjegla or Zillerberget Mbr southwards. Innkjegla Mbr, c. 120 m. Dalkjegla Mbr, c. 50 m. Helvetiaqellet Fro. 4.3.6

Sorkapp Land

The o u t c r o p p a t t e r n in S o r k a p p L a n d increases in complexity s o u t h w a r d s and westwards, whose interpretation is h a m p e r e d by considerable ice cover e.g. in the central S o r k a p p f o n n a (Winsnes et. al. 1993, C 13G). In the northeast, b r o a d N N W - S S E fold axes are

56

CHAPTER 4

Fig. 4.7. Geological map and cross sections of the Adventdalen Group in Sorkapp Land, drawn by S. R. A. Kelly, based on Dallmann (1993) Geological Map o f Svalbard 1: 500000, Sheet IG and Winsnes et al. (1993) Geological Map of Svalbard 1 ."100 000, Sheet C13G.

Fig. 4.6. Geological map and cross sections of the Adventdalen Group in Wedel Jarlsbert Land and western Torell Land, drawn by S. R. A. Kelly, based on Dallmann (1993) Geological Map of Svalbard 1-500 000, Sheet 1G.

seen in Cretaceous rocks, but dips remain low and there is a small a m o u n t of n o r m a l faulting. In the south of Sorkapp L a n d N W - S E normal faulting and associated folding cause disjunct outcrop pattern. At K i k u t o d d e n on the coast and inland on Keilhaufjellet, E-dipping (20-45 ~) Jurassic and Cretaceous rocks are exposed. The top of the Cretaceous rocks crops out on the west and n o r t h flanks of D u m s k o l t e n , where a small synclinal fold again brings the Tertiary to sea level and Cretacous outcrop is interrupted on the coast. The Cretaceous-Jurassic sequence next appears in a comparable situation, although steep and overturned in proximity to a N N E - S S W - s t r i k i n g thrust, from Gideanoyfjellet and Smalegga to the south coast of inner H o r n s u n d at Brepollen (Fig. 4.7).

A series of small outliers is largely controlled by normal faulting in south and central western Sorkapp Land. Janusfjellet F o r m a t i o n outliers resting on K a p p Toscana G r o u p occur on the summit of Kistefjellet, Oyrlandssleira (with Helvetiafjellet Formation), and Stormbukta. In northeast Sorkapp Land, a Cretaceous-Jurassic sequence resting on Triassic, crops out in a series of thrust slices on Lidfjellet. In a largely biostratigraphical account, Pchelina (1967) described the whole Jurassic and Cretaceous sequence, based on a generalized section t h r o u g h eastern Keilhaufjellet, eastern foot of Kistefjellet and shore cliffs at Austerbogen. Only in parts can this be related to m o r e recent lithic schemes.

Carolinefjellet Fm reaches its greatest measured thickness under the Firkanten Formation erosion at Tromsobreen where 850m have been recorded (Nagy 1970). Here the the Zillerberget Member is the highest unit recognized. The sandy Sch6nrockfjellet and Langstakken Members do not reach this far south. Zillerberget-Innkjegla Mbr undifferentiated shales and siltstones, c. 850 m at Havkollen and thins to 630 m at Keilhaufjellet. Dalkjegla Mbr sandy siltstones and argillite alternations thin southwards from c. 40 m to 60 m. Late Aptian heteromorph ammonites occur (Pchelina 1967).

THE CENTRAL BASIN

Helvetiafjellet Fm, 58 m comprises fining-upward cycles at Kikutodden (Edwards 1976). Pchelina (1967) identified macrofloras of Barremian to probable Aptian age. Glitrefjellet Mbr, 33 m two principal sand-mudstone cycles occur representing channel to floodplain deposits. Festningen Mbr, 25 m two alluvial channel sandstone cycles with conglomeratic bases occur, with transport direction principally from the NW and SW-W. Janusfjellet Subgp Rurikfjellet Fm is not clearly divided. Pchelina (1967) recognized three lithofacies in the Hauterivian part: at the top sandy siltstones (c. 45 m), in the middle a carbonate siltstone (c. 15 m) and at the base mudstones (30 m). The middle calcareous unit may well be related to calcareous units at comparable levels in Kong Karls Land and offshore. Clayey siltstone with carbonate concretions occupy c. 175m of Valanginian to Volgian strata. There is possibly a sandy mid-Volgian interval (c. 15 m). Agardhfjellet Fm, c. 170m mudstones to muddy siltstones with early Volgian to Callovian (probably also Bathonian) fossils. It may be possible to recognize a slightly coarser median. Oppdalsfita Mbr, with Oxfordian fossils, of c. 60 m thickness. Brentskardhaugen Bed, 0.2-0.3m (Pchelina 1967) overlies c. 10m of arenacous and conglomeratic Kapp Toscana Group sediments.

4.3.7

Wedei Jarlsberg Land and western Torell Land

J u r a s s i c - C r e t a c e o u s strata strike N N E - S S W f r o m inner H o r n s u n d in western Torell L a n d , to V a n K e u l e n f j o r d e n n o r t h e r n Wedel Jarlsberg L a n d , with o u t c r o p interrupted by ice cover and m a d e complex by N N W - S S E thrust-faulting ( D a l l m a n n et al. 1990a, b B l l G ) . M u c h of the central to n o r t h e r n part o f the area was m a p p e d originally at 1:50000 by Rozycki (1959). The broadest outcrops are of Cretaceous strata at the west flank o f the Central Basin and include Zillerberget at the north. H e r e easterly dips are m o d e r a t e to low. Except in the north, Jurassic outcrops are n a r r o w a n d dips are steep to overturned. A r o u n d P e n k b r e e n and R e i n o d d e n in the north, Jurassic strata are repeated twice because of faulting. The f o r m e r wider distribution of Jurassic outcrops is shown by the outliers west o f P e n k b r e e n and Finsterwalderbreen. The outcrops of n o r t h e r n W e d e l Jarlsberg L a n d are all influenced by thrusting. T h e wide Janusfjellet o u t c r o p is related to the m a i n o u t c r o p of H u m p v a r d e n a n d is caused by a series of folds. The outcrops of Tilaberget a n d Leinbreen are outliers directly affected by thrusting, while the R e i n o d d e n o u t c r o p is a n o r m a l faulted outlier with an o v e r t u r n e d Janusfjellet a n d Helvetiafjellet sequence. Elsewhere dips are n o r m a l l y low a n d only locally are steep to overturned. Small Janusfjellet S u b g r o u p inliers occur west o f Storbreen (Birkenmajer, N a g y & D a l l m a n n 1991) at south Grimfjellet and west M e z e n r y g g e n in gently folded strata c o m p a r a b l e to that o f Cretaceous strata in n o r t h e a s t S o r k a p p Land. Intrusive dolerite dykes occur on the south o f Bellsund (Hauser 1982). General descriptions of the J u r a s s i c - C r e t a c e o u s sequence in southwest Torell L a n d have been given by R o z y c k i (1959) a n d Birkenmaj er (1975).

Carolinef]ellet Fm totals about 700m thickness in northern Wedel Jarlsberg Land (Nagy 1970), with the four lower members represented on Zillerberget. Major sections have not been measured in the south, although the base is recognized at Polakkfjellet where dark arenaceous shales of the Dalkjegla Member occur, and equivalent strata crop out on Blfikettane and Isskiltoppane (Birkenmajer 1975). Zillerberget Mbr, 210 m at the type locality comprizes distal shelf shales and siltstones with minor sandstones and clay-ironstone concretions. The top of the member contains Middle Albian ammonites and is eroded under the Firkanten Formation unconformity. Langstakken Mbr, 40 m but passes laterally into Innkjegla or Zillerberget Member southwards. Innkjegla Mbr, 321m shales to shales with siltstones containing Early Albian ammonites, including Arcthoplites and Freboldiceras faunas. Dalkjegla Member, c. 130m sandy siltstones. Helvetiafjellet Fm comprizes three principal coarsening-upward cycles in western Torell Land (Birkenmajer 1975, 1984).Typical Glitrefjellet and Festningen member lithologies are present in some localities, not so clearly

57

demarcated at Cholmfjellet where thick alluvial channel facies in the upper part of the Formation (as opposed to the base), indicate the proximity of an easterly source for clastics from the Hornsun&Sorkapp High. The base of the Helvetiafjellet Formation is generally marked by erosion and at Bendefjellet the top of the Janusfjellet Subgroup is penetrated by rootlets from above, suggesting subaerial conditions. The basal Helvetiafjellet Formation unit in the area is usually a non-marine shale-sandstone unit. Festningen Mbr where it can be recognized, varies in thickness at Hyrnefjellet (50-60 m), Bendefjellet (45 m) and Polakkfjellet (20 m).

Janusfjellet Subgp Rurikfjellet Fm thickens northwards. There is marked thinning to less than 100m centering on southern Wedel Jarlsberg Land, and forming the Serkapp Hornsund-High. In northern Wedel Jarlsberg Land thicknesses increase to over 200 and over 400 m respectively in these formations. Ullaberget Mbr comprizes regressive sandstones of the Formation. In the southwest at Bendefjellet the member is only 6 m thick, comprising a single unit of bituminous and glauconitic sandstone with plant detritus; at Hyrnfjellet it is 10-20m and 65m at Polakkfjellet. Northwards it reaches c. 150m at Reinodden and 119.5m at Jurakammen. At Bendefjellet it is penetrated by rootlets originating in the Helvetiafjellet Fm. Wimanfjellet Mbr was originally recognized in this area as the Tirolarpasset Mbr (Rozycki 1959), with type section at Jurakammen where it is 187.5m thick. It comprizes uniform siltstones and shales with clay-ironstones. The base of the Member is the: PolakkfjeHet Bed, which is only recognized in Wedel Jarlsberg Land, a conglomerate of clasts of ferruginous sandstones and quartz pebbles, which rests on a significant erosional base. The break probably lies within the Volgian stage or at its base on an eroded Kimmeridgian surface (Birkenmajer 1975; Birkenmajer & Pugaczewska 1975). The bed is 5m thick at Polakkfjellet and stated to be 46.34m in the Jurakammen section (Birkenmajer 1975). Dypvik et al. (1991) correlate this bed with comparable sandstones in the formation below. Agardhfjellet Fm corresponds in this area to the Ingebrigtsenbukta Mbr of Rozycki (1959) with type section at Ingebrigtsenbukta on the south coast of Van Kuelenfjorden. At Jurakammen the unit is 285 m thick comprising shales and siltstones with clay ironstone concretions. It is widely exposed, but thins southwards to Polakkfjellet (150m), Hyrnefjellet (110 m), south Fonnryggen (60 m), Somovfjella and Somovaksla (both 40 m) (Birkenmajer 1975). Although the upper members of the formation have not been identified in the area, the Oppdalen Mbr is recognized at the base. Forming the base of the Agardhfjellet Fm is the Brentskardhaugen Bed which varies locally in lithology: at south Fonnryggen it is a poorly cemented fossiliferous phosphorite pebble concentrate (0.1-0.2 m); at Hyrnefjellet it contains black phosphorite pebbles in black shale matrix or is a wellcemented conglomerate of quartz, fossiliferous phosphorite and ferruginous ooids with siderite, grading up into sandstone (0.2-0.5 m). The latter may indicate existence of the Marhogda bed. At Skiferkammen the Brentskardhaugen Bed shows reverse grading and at Tilasberget in the lower part it is normally graded and in the upper part reverse graded (Maher 1989) with no angular discordance at its base. No positively Jurassic fossils have been reported from this area, (Krajewski 1992).

4.3.8

Western Nathorst Land

In M i d t e r h u k e n , west N a t h o r s t L a n d ( D a l l m a n n et al. 1990, B11G; Hjelle et al. 1985, B10G), a simple, m a i n l y easterly dipping o u t c r o p of A d v e n t d a l e n G r o u p lies between the K a p p T o s c a n a a n d V a n M i j e n f j o r d e n groups with several m i n o r Helvetiafjellet F o r m a t i o n outliers resting on the Janusfjellet Subgroup. The o u t c r o p is u n i n t e r u p t e d between V a n K e u l e n f j o r d e n and V a n Mijenfjorden. The b r o a d JanusfjeUet S u b g r o u p o u t c r o p is caused by strikeparallel N - S fold axes, a syncline o f w h i c h passes t h r o u g h the Helvetiafjellet o u t c r o p on A n n a b e r g e t . M u r o s k o has described dolerite intrusions into b a s e m e n t rocks on the M i d t e r h u k e n peninsula (Fig. 4.8).

Carolinefjellet Fro, although a relatively full sequence of the Dalkjegla to Zillerberget members is represented in western Nathorst Land, the youngest date is Early Albian (Nagy 1970). Helvetiafjellet Fm Festningen Mbr coarse massive sandstones rest sharply on the Janusfjellet Subgroup.

58

CHAPTER 4 ,,,,,,,,,,,,,,,,,,,,

,

Kvaevefjellet III~._~_oldiabukta

t!l!!

// ////

/,, OSCAR I I / / LAND

~ fjellei:ll'~r )

~

Ullaberget Mbr is 151.5m thick at the type locality on Ullaberget, and is at its maximum development. It comprizes regressive sandy shales and siltstones with minor micaceous sandstones. Janusfjellet Subgp Oppdalen Mbr is represented on Midterhuken by over 7m of calcareous sediments with ooliths and is comparable to the Marhogda Bed (Maher 1989) but in the middle of which there is the Brentskardhaugen Bed (1 m), immediately above a stromatolite rich layer. (Krajewski 1990, 1992).

o.e'aof, yal Bohemannesset

yf

~ //

Is fj o r d e n

Sylodden

Van

kk ~

Bellsund

Midterhuken ~ s

%

Western Nordenski61d Land

In western Nordenskiold Land, the Adventdalen Group crops out from between Berzeliusdalen on the north shore of Van Mijenfjorden, where it is largely obscured by drift, northwards to Gronfjorden, with the classic Festningen sequence on the south shore of Isfjorden. To the east the Cretaceous sequence dips at low angle, eastwards under the Tertiary unconformity. To the west the Janusfjellet Subgroup and the Helvetiafjellet Formation dip at moderate to high angle, and include the near vertical sandstones at Festningen itself. The Festningen section is one of the most accessable Jurassic-Cretaceous sections on Svalbard with an almost completely exposed sequence of Adventdalen Group strata exposed in low level coastal cliffs (Frebold 1928; Frebold & Stoll 1937; see Fig. 4.1).

k

A

4.3.9

Erdmanflya

Ramfjellet

Mijenfjorden ~

~ : : . j . . i.~LAN r

A' Erdmannflya 1000

~~l,,fr,1,

....

0m -1000 -2000

Gronfjorden

Carolinefjellet Fm is at its thinnest at Festningsodden, where only 180 m including only the lowermost two members occur under the basal Tertiary erosion surface. Steel, Gjelberg & Haar (1978) interpreted coarsening upwards cycles as of lower delta front facies. Inkjegla Mbr Dalkjegla Mbr Helvetiafjellet Fm non-marine sequence includes: Glitrefjellet Mbr, sands and silts are recessive. Steel, Gjelberg & Haar (1978) demonstrated distributary channel sandstones; Festningen Mbr, crevasse channel sandstones, levees, crevasse splays and interdistributary bays massive sandstones are well exposed in the, 29.5 m at Festningen itself. Frequent conglomerates indicate reworked earlier Jurassic, Permian, Carboniferous and possible Early Paleozoic deposits represented elsewhere on Spitsbergen (Parker 1967). Fossil footprints indicate the presence of a dinosaur, Iguanodon (de Lapparent 1962). Janusfjellet Subgp Agardhfjellet Fm Rurikfjellet Fm Marhogda Bed, 40 cm Brentskardhaugen Bed is only 5 cm thick although it thickens southwards to 45 cm at Vardebreen (B/ickstr6m & Nagy 1985) and crops out on the south coast at Flathaugen (Maher 1989). It occurs above transgressive sandstones of the Wilhelmoya Formation.

g w

1000 Om -1000 -2000

Fig. 4.8. Geological map and cross sections of the Adventdalen Group in Oscar II Land, Nordenski61d Land and Nathorst Land, drawn by S. R. A. Kelly, based on Dallmann (1993) Geological Map of Svalbard 1: 500000, Sheet 1G and for the Ramfjellet section, based on Ohta et al. (1991) Geological Map of Svalbard 1:100 000, Sheet B9G.

4.3.10

Central Nordenski61d Land

The relatively few published records of the sequence from the centre of the Central Basin beneath the Paleogene cover include the sequence of the Grumant borehole which was made on the north side of Colesbukta. Cretaceous to Jurassic rocks were encountered at depths from 4 5 0 m to 2620m and were described from a biostratigraphical basis by Shkola et al. (1980):

Early Cretaceous, 1000 m: Aptian-Albian, 120 m upward-fining sands to argillites. Barremian, 115 m sandstones with coals. Hauterivian, 115 m silts becoming sandier upwards. Valanginian, 220 m argillites. Berriasian, 160 m argillites with siderite. Jurassic, 350 m: Volgian, 165 m argillites Kimmeridgian, 110 m argillites Oxfordian, 45 m Callovian, 30 m sandy silts. Burial palaeotemperatures of the Early Cretaceous and Late Jurassic rocks were of 160-190~

THE CENTRAL BASIN

4.3.11

Oscar II Land

The outliers of Oscar II L a n d represent the relics of the n o r t h e r n closure o f the o u t c r o p o f the A d v e n t d a l e n G r o u p of the Central Basin. Jurassic strata rest on Triassic intermittently exposed from the west side of Y m e r b u k t a , t h r o u g h Ramfjellet and Syltoppen to Y o l d i a b u k t a , a n d is disrupted by faulting. Cretaceous rocks occur at a n d near the coast n o r t h of E r d m a n n f l y a and B o h e m a n n e s s e t a n d on Ramfjellet a n d Syltoppen (faulted) (Ohta et al. 1991, B9G). At B o h e m a n n e s e t coal was m i n e d in the early 1920s. The o u t c r o p p a t t e r n at Sylodden matches that at Festningen, on the south side o f Isfjorden, but is offset by thrust faulting in Isfjorden w h i c h strikes N N E - S S W . Here a complete Janusfjellet S u b g r o u p sequence, capped by Helvetiafjellet sandstones, occupies a syncline striking N N W - S S E , parallel to the b e d d i n g strike. The JurassicCretaceous sequence is repeated in the outliers by several thrust fault slices in the higher part of Ramfjellet, but separated by a thrust fault f r o m S - S E (5-20 ~ dipping Cretaceous, including Helvetiafjellet, sandstones. The most northerly outcrops are B o h e m a n n e s s e t a n d Kv~evefjellet where a low-dipping sequence of Janusfjellet a n d Helvetiafjellet is cut by a series of thrusts exposed on the higher ground.

Helvetiafjellet Fm Glitrefjellet Mbr, at Bohemanesset macroflora is abundant including Elatides, (Sveshnikova & Budantsev 1969) Ginkgo, Podozamites, Pseudotorellia and 'Sciadopitys-like' leaves (Bose & Manum 1990).

Festningen Mbr RurikfjeUet Fm Ullaberget Mbr, 100 m is predominantly sandstone, comprises two coarsening upwards cycles showing hummocky cross-stratification, followed by parallel lamination and intense bioturbation (Dypvik et al. 1991; Hvoslef, Dypvik & Solli 1986; Oxnevad 1985).

Wimanffjellet Mbr Mycklegardfjellet Bed is present (Dypvik et al. 1991). Agardhfjellet Fm is well exposed at Bohemanflya where it is particularly thick (260 m), Dypvik et al. (1991) gave the following sequence: Slottsmoya Mbr, 75 m upward-fining sands shales; Oppdalshta Mbr, 95 m paper shales and a 30 m thick organic-rich muddy sandstone; the latter generally macrofossil-rich, including bivalves, ammonites and belemnites; Lardyfjellet Mbr, 20 m paper shales; Oppdalen Mbr, 60m reaches its maximum thickness at Syltoppen, mainly Dronbreen Bed, sandy shales, becoming sandier upwards; and at the base, the Brentskardhaugen Bed, rests with erosion on the Wilhelmoya Formation.

4.4

The Kapp Toscana and Sassendalen Groups (Liassic, mainly Triassic)

Strata of the K a p p T o s c a n a a n d Sassendalen groups crop out extensively in S v a l b a r d - the larger area being in the east where they are described in C h a p t e r 5. H o w e v e r , the Central Basin contains the type sections for all except the u p p e r m o s t (Wilhelm o y a ) formations. W i t h the exception o f part of this f o r m a t i o n , w h i c h ranges up to T o a r c i a n age, the two groups are wholly Triassic in age. T h e n o m e n c l a t u r e a n d classification o f lithic units are discussed m o r e fully in C h a p t e r 18 a n d the f a v o u r e d scheme is a d o p t e d here. Place names are s h o w n on Fig. 18.1.

4.4.1

Lithic scheme for Kapp Toscana and Sassendalen Groups in the Central Basin

The distribution of rock units is s h o w n in the fence d i a g r a m (Fig. 4.9).

Kapp Toseana Group. This unit was originally defined as a formation with two members (Buchan et al. 1965) and they were raised in rank to

59

group (Harland et al. 1974) so that the Group was constituted by the two formations: De Geerdalen and Tschermakfjellet from which a third formation (Wilhelmoya) was distinguished at the top (Worsley 1973). The fence diagram (Fig. 4.9) shows the uniform strata throughout. Plant remains are common everywhere. Ammonites, bivalves and some gastropods occur in marine beds where also fish and reptile remains and trace fossils (Rhizocorallium and Diplocraterion) are found. Ages from Late Ladinian for the Tschermakfjellet Formation through Norian and Rhaetian for the Wilhelmoya Formation are indicated. Wilhelmnya Formation (Worsley 1973). Worsley included the Brentskardhaugen Bed at the top of his formation. It is not, however, described in the type section nor is it evident in the main development of the formation in the Eastern Platform (Chapter 5). Moreover that 'Lias conglomerate' was originally included in the Janusfjellet Formation (Parker 1966) and although subsequently taken within the De Geerdalen Formation (e.g. Buchan et al. 1965), it has latterly resumed its position as a basal conglomerate of the Janusfjellet Subgroup (e.g. Dypvik et al. 1991) and that is adopted here. The consequence is that whereas the restricted Wilhehnoya Formation is well developed in the Eastern platform and the Brentskardhaugen Bed is traceable through the Central Basin, the beds below it in the Central basin are not so easily distinguished lithologically in the Central Basin from the body of the de Geerdalen Formation as originally described. The age range of the Wilhelmoya Formation is probably Norian-Toarcian (Worsley 1973; Bjaerke & Dypvik 1977; B~ickstr6m & Nagy 1985). The Wilhelmoya Formation differs in its terriginous fraction from the rocks below being more mature in its sandstone content. It it much thicker in the Eastern Platform (Chapter 5). In the Central Basin its maximum thicknesses is in the south. It is much thicker in the Eastern Platform (Chapter 5). In the Central Basin its maximum thickness is in the south. De Geerdalen Formation (Buchan et al. 1965). Originally defined as a member this unit is largely a non-marine sequence of fine- to mediumgrained grey-green plant-bearing sandstones, weathering greenish and brown, laminated to massive, interbedded with varying amounts of grey silty shales, shaly siltstones and harder calcareous siltstones. It includes the Plateau flags of Gregory (1921) and possibly the Fosse Sandstone of Hoel & Orvin (1937). It was named from the valley (De Geerdalen) to the west of Botneheia. The composition is generally of immature sandstones with 50% or less quartz, 33% feldspar and up to 30% of rock fragments (Pchelina 1965a; Lock et al. 1978). Mork, Knarud & Worsley (1982) reported that the predominantly sandy De Geerdalen Formation consists of recurrent small and large scale sequences, upward coarsening from grey shale to very coarse grained sandstone, where at the top they were reworked by waves and bioturbated. They show channelling, hummocky and herringbone cross-bedding with many erosive contacts. Most types of ripples occur as well as lenticular, wavy and flazer bedding. A high energy environment is indicated by protective burrows and mud clasts. In the lower sandstones, cementing is by interstitial clay minerals. Tschermakfjeilet Formation (Buchan et al. 1965). Similarly, at first a Member of the Kapp Toscana Formation, this unit is distinctive but not uniformly extensive. It included the Oozy Mound Beds and Upper Nodule Bed of Gregory (1921), the Upper Daonella layers of Wiman (1910a). The upper part included the Halobia shales of Stolley (1911), his Nathorstites Niveau and his Lingula Sandstone. It is the upper Saurian Niveau of Wiman (1910b) and the Lindstroemi Sandstone of Frebold (1930b). This formation is indeed a richly fossiliferous unit with an age range from Late Ladinian to (Late) Carnian. This unit is recognized in the eastern and southern outcrops of the Central Basin and further east in the Eastern Platform. The dark shales, siltstones and fine sandstones are distinguished by their small red-weathering clay ironstone concretions which contain a rich ammonite and bivalve fauna. The unit is overlain by the lowest hard sandstone of the De Geerdalen Formation. It is underlain by the siliceous siltstone marker at the top of the Botneheia Formation. The unit also appears in southern Spitsbergen (shown as such in sections by Mork & Worsley 1979) and was then named the Austjokelen Formation by Mork et al. 1982). These southern facies differ in having fewer siderite nodules and occasionally none. It is noteably absent in the western fold belt where the thicker and sandier facies dominate. Sassendalen Group (Buchan et al. 1965). The Sassendalen Group was defined as comprising three formations: Botneheia, Sticky Keep and Vardebukta all from the Central Basin. The two upper formations comprised the Kongressfjellet Subgroup; but this is not often used. It is a clearly defined unit between the Kapp Toscana Group above and the

60

CHAPTER 4

Fig. 4.9. Fence diagram showing the distribution and thickness variation of the Sassendalen and Kapp Toscana groups, based on Buchan et al. (1965) except for section south of Kapp Lee. Tempelfjorden Group below except where there is a lithological gradation upwards into the Tschermakfjellet Formation. The three formations have been recognized satisfactorily throughout the Central Basin as was demonstrated by Mork & Worsley (1979). However, Mork, Knarud & Worsley (1982), in the course of a systematic sedimentological analysis, while adopting the same threefold classification, changed the nomenclature significantly, some aspects of which are not followed here. For example, because in Barentsoya and Edgeoya, where the three formations are not readily distinguishable and where Lock et al. (1978) for this reason introduced a single Barentsoya Formation (Section 5.7) Mork et al. (1982) reduced the three original formations to members within

the Barentsoya Formation which then became in effect the Sassendalen Group. The seven new names that were introduced for the other outcrops of the Sassendalen Group will be mentioned in the description of the three original Formations which defined the Group. Kongressfjellet Subgroup. The Subgroup comprises the Botneheia and Sticky Keep formations. Botneheia Formation, 157m (Buchan et al. 1965). The type section was measured at Vikinghogda and is well exposed to the west on Botneheia. The formation is traceable throughout Spitsbergen except that it is not so distinctive in the northeast (Section 5) and in Sorkapp Land. It is a dark grey shale sequence weathering blue black and dark grey.

THE CENTRAL BASIN The upper part is of papery, laminated, bituminous (2-11% TOC) shales or occasionally concretions of grey silty limestone (Daonellenkalk of Mojsisovics 1886). They form a distinctive escarpment (Escarpment Shales of Gregory 1921). They are equivalent to the Oil Shale Series in Edgeoya (Falcon 1928), and the Ptychites beds of Spath (1921). The lower part is of softer shales with siltstone interbeds and small phosphatic concretions, generally less than 2 cm diameter, weathering blue black, these increase to 50% of the rock at the base. Mork et al. refer to the upper part as Blanknuten Beds i.e Blanknuten Member of the formation. On the west coast they refer to the formation as the Bravaisberget Formation with an upper Somovbreen Member and a lower Passhatten Member. Their Bravaisberget Formation appears to be mainly represented by their Karentoppen Member. Bivalves are especially common and the age range would be Anisian to Early Ladinian. Sticky Keep Formation, 121 m (Buchan et al. 1965). In the type section on Vikinghogda and to the east in Sticky Keep this formation is distinguished from the softer Botneheia beds above by a cliff-forming yellow-weathering topographical ledge of siltstone. Septarian concretions (10cm to l m diameter) are common in the lower part. Ammonoids, bivalves and bone fragments occur throughout. A Smithian-Spathian age is thereby indicated. The formation includes the Posidonomya layers of Nathorst (1910) the same as the Posidonomya limestone of Mojsisovics (1886), the Fish Niveau of Wiman (1910, Arctoceras layers of Stolley (1911), the lower Posidonomya shales of Spath (1921), the Arctoceras horizon of Frebold (1930a) The upper part contains the lower Saurian Niveau and Grippia Niveau ofWiman (1910a) and (1928), and the Saurian Bed and the lower part of the Upper Posidonomya Shales of Spath (1921). The lower part contains the lowest Nodule Bed of Gregory (1921), the Anasibirites horizon of Spath (1921) and the Goniodiscus nodosus horizon of Frebold (1930a). There are thickness variations over the Billefjorden Fault zone. In the west coastal sections Buchan et al. (1965) distinguished two members at Iskletten in Oscar II Land. However two such members can be traced through most of the Central Basin though not into the Eastern Platform. Kaosfjellet Member, 76 m is named from the chevron folding at lskletten and fi'om Kaosfjellet. It is of laminated shaly siltstones alternating between softer yellow-weathering and harder grey-weathering. Iskletten Member, 154 m is the lower uniform shaly part of the Sticky Keep Formation and is characterized i.a. by grey septarian limestone concretions especially in the upper part. Fossils are not common except in the concretions. The Sticky Keep Formation is readily distinguished in the Festningen section at the south western entrance to Isfjorden, however, Mork et al. (1982) have used a local name for it (the Tvillingodden Formation). Above the Hornsun&Sorkapp High they gave a further name: the Kistefjellet Formation. The extra nomenclature was introduced to match their sedimentological interpretations of the sequence. Vardebukta Formation, 253.5m (Buchan et al. 1965). The lowest formation of the Sassendalen Group (and below the Kongressfjellet Subgroup) is best exposed at Vardebukta in the Festningen section to the west of the basin where the type section was described. It is characterised by sandstones with interbedded siltstones and shales. Similar lithologies are evident in Sassendalen and Dickson Land but the sections are often obscured by scree and float, from which a similar stratigraphy can be deduced. The best exposure in the east may be at Deltadalen which name Mork et al. introduced for a parastratotype section and named it there as a unit (member) in place of the original Vardebukta Formation as mapped there. The Vardebukta Formation has been divided into two members: Siksaken and Selmaneset. Siksaken Member, 104 m (Buchan et al. 1965) is named from Siksaken with its sharp folds in Oscar II Land and described from Iskletten composite section. The member consists of alternating grey calcareous, silty limestone, calcarenite, light grey and white sandstone, hard siltstones and calcareous shales. Fossils are common. It is distinguished by its contrasting hardness from the more shaly member below. The member includes the Pseudomonotis shale and Retzia limestone of Lundgren (1887) and the synonymous Hustedia limestone of Nathorst (1910). Selmaneset Member, 136m (Buchan et al. 1965) is named from the eastern promontory at the entrance to Trygghamna in Oscar II Land. It is of dark grey often calcareous silty shales and distinguished from the overlying member by its lesser resistance to weathering. Fossils are not common, however, the member was thought by Buchan et al. to include the Myalina Shale of Lundgren (1883) and the Claraia zone of Frebold (1936).

61

The Vardebukta Formation if present on the Hornsundet-Sorkapp High is very thin (28 m Worsley & Mork 1978) and may be represented by the Brevassfjellet Bed of Mork et al. (1982). In the following regional outline the lithologies as described above are sufficiently c o n s t a n t for the principal f o r m a t i o n s as described above to be recognized t h r o u g h o u t m o s t of Spitsbergen as d e m o n s t r a t e d by B u c h a n et al. (1965) a n d M o r k & Worsley (1979). C o n s e q u e n t l y to s u m m a r i z e the lithologies in each of the following areas w o u l d involve m i n o r variations on basic characteristics so similar as to confuse rather t h a n to clarify. There is, of course, far m o r e i n f o r m a t i o n in the original description of each section. B u c h a n et al. (1965) described the lithologies and the positions of fossil collected. M o r k & Worsley (1979) and M o r k et al. 1982 logged detailed sedimentary characters for sedimentological interpretations. The thickness estimates of each unit are derived from the published s e c t i o n s - the B u c h a n et al. values as recorded are in italics. The other values have generally been estimated f r o m the published sections.

4.4.2

Sassendalen to Storfjorden (southern Sabine Land)

F r o m Sassenfjorden along the cliffs and slopes of the m o u n t a i n s south of Sassendalen and t h r o u g h to A g a r d h b u k t a in S t o r f j o r d e n is the belt of outcrops w h e r i n the strata between the P e r m i a n K a p p Starostin a n d the Jurasssic A g a r d b u k t a f o r m a t i o n s are well displayed. T h e y are nearly fiat-lying and tectonically have suffered relatively m i n o r disturbances. M o r e o v e r their fossiliferous facies has c o n t r i b u t e d to this being a classic area of Triassic studies. In these circumstances it was n a t u r a l to establish the lithic scheme of rock units here as described above. In the stratigraphic history of Svalbard the Mesozoic interval was a time of relative tectonic stability with the result that the same lithic units can be m a p p e d t h r o u g h o u t Svalbard with only m i n o r variations. The Sassendalen G r o u p strata rest with slight disc o r d a n c e on the T e m p e l f j o r d e n G r o u p b e n e a t h a n d the K a p p T o s c a n a G r o u p strata are c o n c o r d a n t with the overlying Adventdalen G r o u p albeit with a distinctive n o n s e q u e n c e between them. These rocks crop out in a wide b a n d t o w a r d s the n o r t h e a s t (see Fig. 18.1). T h e y are less well k n o w n there except at W i l h e l m o y a and Hellwaldfjellet where the u p p e r part of the K a p p T o s c a n a G r o u p is especially well represented with the type section of the W i l h e m o y a F o r m a t i o n . But this is treated in the following chapter (5) as part o f the Eastern Platform. In addition to earlier investigations as by G a r w o o d & G r e g o r y (1896) and G r e g o r y (1921) there have been m a n y biostratigraphical and palaeontological studies, for example: the saurian w o r k s o f W i m a n (1910-1933), the a m m o n o i d studies o f L e h m a n n a n d colleagues (Weitschat 1986; Weitschat & L e h m a n n 1978, 1983; Weitschat & D a g y s 1989), and the bivalve studies of C a m p b e l l (1994) (see C h a p t e r 18). The following notes especially the thicknesses are based largely on the w o r k o f B u c h a n et al. (1965), M o r k & W o r s l e y (1979) a n d M o r k et al. (1982). F r o m these sources the succession in this Sassendalen to S t o r f j o r d e n sector is a p p r o x i m a t e l y as follows: Adventdalen Gp Kapp Toscana Gp Wilhelmoya Fm, in area c. 120 Tumlingodden Mbr, 60 m Transitional Mbr, 33 m Bjornbogen Mbr, 19 m Basal Mbr, 7 m De Geerdalen Fm, c. 380 m (at Wilhelmoya) 190m (at Botneheia) Tschermakfjellet Fro, c. 93 m at Vikinghoda, c. 63 m at Botneheia Sassendalen Group Botneheia Fm, 170-146 m at Sticky Keep, 157 m at Vikinghogda, 129 m at Botneheia Sticky Keep Fin, 120m to ?150m at Sticky Keep, 121 m at Vikinghogda, 70 m at Stensi6fjellet

62

CHAPTER 4

Vardebukta Fro, (Deltadalen Mbr of Mork et al.), 130m at Deltadalen, 115 m at Vikinghogda, 125 m at Stensi6fjellet, 129 m at Sticky Keep (102+m at Botneheia) Tempelfjorden Group. Kapp Starostin Formation

4.4.3

Nordfjorden (S Dickson Land and E Oscar II Land)

Successions thin over the old Nordfjorden Block as compared with both east and west. They are seen best to the east in the extensive and accessible outcrops of southern Dickson Land as at the classic Kongressfjellet section Tschermakfjellet and Rotundafjella but also to the west in eastern Oscar II Land at Bertilryggen and Sveaneset. In each case the regional southerly dip has the effect that the De Geerdalen strata have been mostly removed where they dipped into Isfjorden. Kapp Toseana Gp De Geerdalen Fm Tschermakfjellet Fm, 50 m at Tschermakfjellet, 70 m at Kongsressfjellet Sassendalen Group Botneheia Fro, 129 m at Tschermakfjellet, 126 m at Kongressfjellet Sticky Keep Fro, 133m at Rotundafjellet, 120 m at Tschermakfjellet, 112m at Kongressfjellet Vardebukta Fro, 61 m at Tschermakfjellet, 101m at Rotundafjellet, ?70m at Kongressfjellet Tempelfjorden Gp Kapp Starosfin Fro.

4.4.4

Western lsfjorden (SW Oscar II Land and N W Nordenskiiild Land)

West of the Nordfjorden area is the West Spitsbergen orogenic foldbelt which runs parallel to the coast from Kongsfjorden to Hornsund. In this the whole Late Paleozoic-Mesozoic successions are steeply dipping and so of narrow linear/',IS outcrop. Whereas this gives the opportunity in E - W coastal section often to traverse near-vertical strata there are also likely to be structural complications. Of these the section at the southern entrance to Isfjorden, the Festningen section (Hoel & Orvin 1937), is perhaps the best known stratigraphic profile in Svalbard with near-vertical mid-Carboniferous to Paleocene strata. The Triassic rocks being less competent than those below and to the west have therefore been somewhat thrust so that precise correlation and thickness are in question. A further consideration is the fact that the Paleogene orogen coincides approximately with a significant thickening and coarsening of the Triassic strata to the west so that the western margin of the basin has been uplifted and eroded. The fence diagram (Fig. 4.9) demonstrates this thickening with resumption of the Kapp Toscana succession at the top. It could be argued that the postulated Kongsfjorden-Hansbreen Fault which bounds the Nordfjorden High on its west has something to do with this thickening.That fault would have a long pre-Carboniferous history and possibly locate the eastern margin of the Paleogene Orogen. M o r k e t al., on the other hand, postulated an extension southwards of the Pretender Fault which extension seems to have no other supporting evidence. Indeed, there is no need for a fault to mark the thickening. The distance between the two contrasting stratal thicknesses used by M o r k e t al. is 40 or 50 km which, with a thickness difference of up to 500 m represents a maximum cumulative gradient of 1% (less than one degree). The slope could be increased by aligning the fault more closely to the two isopach points but then it would not align with the proposed faults. Moreover, M o r k e t al. did not use the southern Oscar II Land data of Buchan e t al. These gave intermediate thicknesses, i.e. not so thick values as at Festningen. Adventdalen Gp Kapp Toscana Gp. Formations are not distinguished. The group thickness at the northern entrance to Isfjorden is 207m (i.e in southern Oscar II Land) and at the southern entrance (Festningen section) is 327.5 m.

Sassendalen Gp Botnieheia Fm (= Bravaisberget Fm at Festningen of Mork et al.) Somovbreen Mbr is 262m at northern entrance and 243.5m at southern entrance to Isfjorden. Sticky Keep Fm (= Tvillingodden Formation at Festningen of Mork et al.) with a Skilisen Bed near the middle): 130 to 230m at northern entrance, 300.5 m at southern entrance to Isjforden. At the northern entrance two members were defined by Buchan et al. Kaosfjellet Mbr, 76m in N 122m in S Iskletten Mbr, 154m in N 178.5m in S Vardebukta Fin (Buchan et al. and Mork et al.), 233 m in the N 253.5 m in S. Two members were distiguished by Buchan et al. in southern Oscar II Land. Siksaken Mbr, 104m at Iskletten in N; 95.5m in S Selmaneset Mbr, 129m at Selmaneset in N; 158m in S.

4.4.5

Van Keulenfjorden (W Nathorst Land and N Wedel Jarlsberg Land)

The outcrops at the entrance to the two fjords branching eastwards from Bellsund similarly show thick successions within the foldbelt. In Western Nathorst Land at Bravaisberget north of Van Keulenfjorden is a key section measured by both Buchan e t al. and M o r k e t al. as follows and Buchan e t al. combined it with the section south of the fjord at Kapp Toscana. Adventdalen Gp Kapp Toscana Gp, 200 m Wilhelmoya Fm, c. 7 m De Geerdalen Fro, 193 m (Tschermakfjellet Fm not distinguished) Sassendalen Gp Botneheia Fm (= Bravaisberget Fm, Mork et al.), 215 m. Sticky Keep Fm 312m (Tvillingodden Fm of Mork et al. c. 280m). Kaosfjollet Mbr, 92 m Iskletten Mbr, 220 m Vardebukta Fro, 142-160m Siksaken Mbr, 62 m Selmaneset Mbr, 80 m

Tempelfjorden Gp. In northern Wedel Jarlsberg Land the cliff sections at Reinodden and at Ahlstrandodden were described in lithic and biostratigraphic terms by Nakazawa e t al. (1990). They followed and amplified in detail the Sassendalen units of Buchan et al. (1965). In broad outline the succession was given thus: Kapp Toscana Gp Sassendalen Gp Botneheia Fro, 175 m Sticky Keep Fm Kaosfjellet Mbr, 268 m Iskletten Mbr, 85 m Vardebukta Fm Siksaken Mbr, 68 m Selmaneset Mbr, 35 m Tempelfjorden Gp.

4.4.6

Wedel Jarlsberg Land, mid and southeast

The same strip of deformed Triassic strata continues parallel to the orogen. Sections were logged by Rozyicki (1959) at Passhatten and by M o r k & Worsley at Somovfjella and Tvittopane, both in mid Wedel Jarlsberg Land. Treskelen sections, north of inner Hornsund, have been available to many scientists in the Treskelodden promontory to the north of inner Hornsund. In mid Wedel Jarlsberg Land, the sequence from Rozycki (in Buchan e t al. 1965) follows. Kapp Toscana Gp, Rozicki c. 204 m Wilhelmoya Fm, c. 40 m (estimated) De Geerdalen Fro, c. 100 m

THE CENTRAL BASIN

Sassendalen Gp Botneheia Fm, 220m Sticky Keep Fm, ?83 m Vardebukta Fm, 65 m At Treskelen Kapp Toscana Gp, 150-160 m Wilhelmoya Fin, c. 23 m De Geerdalen Fro, c. 103 m Tschermakfjellet Fro, c. 34 Sassendalen Gp Botneheia Fro, 111 m or 105 m Sticky Keep Fin (85 m or 110 m) Vardebukta Fin (101 m or 80 m) Sticky Keep and Vardebukta Fms combined, 190 m

4.4.7

Sorkapp Land

Sorkapp Land contains interesting contrasts which may be summarised in four zones in all of which Sassendalen Group strata appear, it not being easy to ascertain whether or where Kapp Toscana rocks may occur. (i) In the eastern zone the Sassendalen Group rests on Tempelfjorden Group strata within the foldbelt as to the north. That is continuing the Treskelodden relationship to the SSE within the foldbelt. (ii) In the central zone relatively flatlying Sassendalen Group strata rest with sharp angular unconformity on deformed Precambrian to Early Paleozoic rocks. This zone has been referred to as the Hornsund High. (iii) In the west similarly flatlying strata rest with only minor discordance on similarly flatlying Billefjorden Group rocks. However this western zone did not escape Paleogene deformation because there are Klippen of relatively horizontal Mesozoic strata as illustrated in the Sorkapp Land map C13G (Winsnes et al. 1992). (iv) In Sorkappoya, the island south of Sorkapp Land Sassendalen Group strata are infolded in a steep syncline with Tempelfjorden Group rocks trending N W to N N W . If extended this fold belt would pass offshore west of Sorkapp Land as it parallels the West Spitsbergen Orogen. Zone (i) continues with that at Treskelen to the north with sections at Smalegga just south of Hornsund and at Austjokeltinden about 13 km south of Hornsund. Wilhelmoya Fm, c. 25 m at both localities De Geerdalen Fro, c. 40 m at Smelegga and 55 m at Ausjokeltinden Tschermakfjellet Fm( = Austjokelen Formation of Mork et al.) Sticky Keep Fm Vardebukta Fro. In zone (ii) two sections are available from Karentoppen and Kistefjellet

Kapp Toscana Gp, c. 60 m Wilhelmoya Fm at Kistefjellet, c. 35 m De Geerdalen Fin at Kistefjellet, c. 31 m Tschermakfjellet Fm at Kistefjellet, c. 16m Sassendalen Gp c. 100 m Botneheia Fm at Karentoppen, 65 m Kistefjellet 75 m Kistefjellet Fm (=Sticky Keep and part of Vardebukta) 50m at Karentoppen, 35 m at Kistefjellet. In zone (iii) No measured sections are recorded here. In zone (iv) in Sorkappoya the succession is upper strata lost to erosion Botneheia Fm, c. 60 m Sticky Keep Fro, c. 90 m Vardebukta Fro, c. 60 m Tempelfjorden Gp Kapp Starostin Fro.

4.4.8

Kongsfjorden

The coalfield at Ny-Alesund is described in Chapter 9. The Bottom Shale of Orvin (1934), beneath the coal-bearing Paleogene strata,

63

was correlated by Challinor (1967) with the Vardebukta Formation. This unit thins from 50 m at the SE of the coalfield to zero at the southwest which demonstrates the limit of Mesozoic strata of the Central Basin in that direction.

4.5

Biinsow Land Supergroup

Comprising Tempelfjorden, Gipsdalen and Billefjorden groups: Permian, Carboniferous, and latest Devonian. The cliff sections from Billefjorden through to Tempelfjorden provide excellent exposures of the whole Carboniferous through Permian succession (Fig. 4.10), and have become the type sections for central Spitsbergen, hence the Biinsow Land Supergroup. The sequence was deposited in the Billefjorden Trough, mainly situated to the east of the Billefjorden Fault zone, and an active basin from Tournaisian through Moscovian time. To the west of the fault zone lay the Nordfjorden Block/High, where sedimentary rocks of those ages are absent. Following Moscovian time, subsidence was regional and most formations are represented across both sides of the fault zone and throughout the central area. Early investigations on the succession focussed on the Billefjorden-Tempelfjorden region (Nathorst 1910). The first systematic description resulted from a measured study at the now classic Festningen section, located at the southern entrance to Isfjorden (Hoel & Orvin 1937, Fig. 4.1). Brief contemporary surveys were carried out and described by Frebold (1935) and Orvin (1940). In 1938 and from 1948 onwards many groups from Cambridge studied the exposures (for example: Gee, Harland & McWhae 1953; Forbes, Harland & Hughes 1958). Exploration by Amoseas (an industrial consortium, jointly with Cambridge University geologists in the 1960s and in consultation with Norsk Polarinstitutt, resulted in reclassification of the strata throughout Svalbard (Cutbill & Challinor 1965), using nomenclature in accordance with the N o r t h American Stratigraphic Code which was being widely adopted at that time. Several changes have been suggested since then, primarily to the Svenbreen and Nordenski61dbreen formations (Dallmann et al., SKS 1996). These and the scheme used here are shown in Fig. 4.11.

4.6

Tempelfjorden Group (Permian)

The Tempelfjorden Group in Spitsbergen comprises the Kapp Starostin Formation. It was defined by this and the Miseryfjellet Formation of Bjornoya.

4.6.1

Kapp Starostin Formation

The Kapp Starostin Formation is the main unit of the Tempelfjorden Group in central and western Spitsbergen. It consists of a thick siliceous sequence which is resistant to weathering, and hence is well exposed and a distinctive marker horizon throughout Spitsbergen, having softer Gipsdalen Group dolostones below and Triassic shales above. The type section is at Kapp Starostin (Festningen), Nordenski61d Land, where the formation is 380 m thick (Fig. 4.1). The formation mainly contains limestones, lutites, arenites and cherts, generally with sponge spicules. Sandstones are commonly cross-bedded, bioturbated and glauconite-bearing. The sequence is transgressive overall, with deposition occurring in a shallow shelf environment where shoals and reefs were present. An abundant fauna of brachiopods, bivalves, corals and others indicate a Kungurian-Ufimian age.

64

CHAPTER 4

Fig. 4.10. Geological map of Bansow Land showing the distribution of Permo-Carboniferous formations (Bfinsow Land Supergroup), adapted with permission from SKS proposals for Lithostratigraphical Nomenclature of the Upper Paleozoic rocks of SvaIbard, Part I (Dallmann et al. 1996, fig. 3d). White areas indicate fjords or (on land) supergroups younger (? Nordenski61d Land - mainly Mesozoic) or older Devonian (Liefdebay Supergroup) to the NW or pre-Devonian Hecla Hoek Complex to the NE. Place names are selected for their relevance to stratigraphic nomenclature in this classic area of north-central Spitsbergen. Those given by numbers are as follows: (1) Birger Johnsonfjellet; (2) Brucebyen; (3) Cadellfjellet; (4) Campbellryggen; (5) Carronelva; (6) Citadellet; (7) Ebbadalen; (8) Finlayfjellet; (9) Fortet; (10) Gerritbreen; (11) Gerritelva; (12) Gipshuken; (13) Hoelbreen; (14) H ultberget; (15) Minkinbreen; (16) M umien; (17) Odellfjellet; (18) Pyefjellet; (19) Pyramiden; (20) Sporehogda; (21) Svenbreen; (22) Templet; (23) Terrierfjellet; (24) Trikolorfjellet; (25) Triungen; (26) Tyrrellfjellet; (27) Wordiekammen. Definition: The formation was defined by Cutbill & Challinor (1965) and is the exact equivalent of the Brachiopod Cherts of Gee et al. (1953; Fig. 4.11). It is exposed along the west coast and extensively across northern Spitsbergen to Nordaustlandet. Small outcrops have been described from Barentsoya (Klubov 1965) and Edgeoya (Pchelina 1977). lsopachs for the formation (Cutbill & Challinor 1965) show that deposition was in the large Central Basin with thickest sedimentation in western Nordenski61d Land where up to 450 m are preserved. There appears to be a secondary centre of deposition in the Tempelfjorden area, which may, however, be due to differential pre-Triassic erosion. The formation thins rapidly onto the Hornsund High in the south. This was a positive feature during deposition and a site of pre-Triassic erosion. Southwest of the Hornsund High, Late Permian sediments are preserved in a somewhat separate basin. The top of the formation is a distinctive marker horizon, with the resistant siliceous deposits of the Hovtinden Member lying below soft shales of Early Triassic age. The base is also distinct, defined as a disconformity, overlying the less resistant gypsums, dolostones and calcretes of the Gipshuken Formation. Through many areas of Svalbard, the base is marked by a sandy bioclastic limestone, the Voringen Member, which rests with a sharp and erosive contact on the underlying Gipshuken Formation. A distinctive fauna of large thick-shelled spiriferid brachiopods gave this unit the name 'Spirifer Limestone'. It represents the transgression of a barrier sequence over the restricted marine platform and sabkha facies of the underlying group (Aga et al. 1986) and marks a clear change in environment (see below). Lithologies: The formation shows a variable development of tithofacies but in general four main lithologies are recognized: limestones, lutites,

arenites and cherts. Silicification of the limestones, shales and siltstones is characteristic and there is a continuous gradation into pure cherts, which are estimated to constitute about 50% of the rock. Indeed a distinctive feature of later Permian sediments is their high silica content and cherty rocks are the dominant lithology of the Tempelfjorden Group. About 50% of the cherts are of a massive type interbedded with shales. These consist of massive layers of dark grey or black, very hard rock, composed of sponge spicules, quartz grains and fossil fragments in a brown groundmass of authigenic silica. The sponge spicules may be calcified on diagenesis, and their axial canals are commonly filled with glauconite or silica. The brown colour of the chalcedony cement is probably due to the presence of carbonaceous matter. Finely divided hydromicas are also present. Finely crystalline cherts, consisting mainly of brown chalcedony with minor terrigenous quartz 'dust' ( ~ ~=

Tyrretl~ellet Mbr

Mbr

Ebbaelva I Gerritelva Mbr

~" L~ ~ ~ ~ 3; ~

Minkinfjellet Mbr

Minkinf]ellet Mbr

LOWER GYPSIFEROUS SERIES

Tyrrell~ellet Mbr

z

7~

Passage Beds

(=Pyramiden Conglomerate)

TyrerrelfJellet Mbr

Hultberget Mbr

Sporhogda Mbr

Cl wZ 8 ~ m~ ~J ~>m

u~ z >" w

Hoelbreen Mbr

"~' ~'

~ ~ LL

Triungen Mbr

Sporhogda Mbr

HORBYEBREEN FM

w w ..~

Sporhegda Mbr

~ O ~ ~,

Hultberget Mbr

~ z ~.~.m un~- tu nm~

Hoetbreen Mbr Triungen Mbr

HULTBERGET FM

~

MUMIEN FM

O

u~z

~

>'ILl mwmu_

~

~ =

Birger Johnsont]ellet Mbr Sporhegda Mbr Heelbreen Mbr

z O

~_ Triungen Mbr

,

Fig. 4.11. Summary of the stratigraphic schemes for Central Spitsbergen since 1950. For earlier schemes see review in Cutbill & Challinor (1965).

process has resulted in the formation of massive calcareous cherts. These are bituminous on Edgeoya (Pchelina 1977) Fine- to coarse-grained quartz sandstones are less important (about 18% of the formation). They occur in a widespread littoral facies in the Hovtinden Member and also in the Svenskeega Member. They contain cross-bedding and are commonly calcareous and bioclastic, with calcite or silica cement and are usually greenish coloured owing to the presence of appreciable quantities of glauconite (up to 3%). Porosity is generally low. These bioclastic sands, common in the middle of the group over eastern areas of Spitsbergen, can be distinguished from the major 60 m thick clastic wedge which is only seen in northwestern areas uppermost in this formation. These latter sandstones are immature and commonly contain 10-30% glauconite. Heavy bioturbation has destroyed primary bedding features. Shales and siltstones showing little or no silicification make up only 7% of the formation, occurring as thin interbeds between the limestones on the margins of the basin. They are commonly calcareous and pass laterally into limestones or arenites in the upper part of the formation. Silicification generally increases towards the centre of the basin with a gradation into cherts. Division: Cutbill & Challinor (1965) defined three members within the formation in the main Triassic outcrop of the Central Basin (Fig. 4.11): the Hovtinden Member; the Svenskeega Member; and the Voringen Member. Russian workers distinguished a separate, arenaceous 'Selander Suite' (Selanderneset Mbr), lying unconfomably above the 'Starostin Suite' in the northern sections (Burov et el. 1965). The Selander Suite is probably equivalent to the sandstone-limestone facies of the Hovtinden Member (see below), which pass laterally into shales, siltstones and cherts in Oscar II Land.

Hovtinden Mbr. This member, 203m thick in the Festningen section is present from Hornsund to Nordaustlandet though it is made up of a variety of complexly interdigitating facies. In northeastern and southern outcrops of Spitsbergen, this member lies directly on the Gipshuken Formation, the Voringen Member facies being absent. It is transgressive in southern Spitsbergen, overlapping progressively older rocks southwards towards the Hornsund High. In general, it consists of a central basinal facies of finely crystalline cherts, shales and siltstones, with arenaceous rocks and carbonates to north and south at the basin margins. The shale-chert facies in some sections is split by a limestone horizon and in north and central Spitsbergen, cross-bedded sandstones and arenaceous cherts also appear.

Svenskeegga Mbr. This member, 156m thick in the Festningen section, shows a similar facies pattern. The top is marked by the Jemtlandryggen Beds, made up of a yellow-weathering silicified limestone containing a prolific brachiopod-bryozoan fauna which is a distinctive marker horizon. Silicification locally results in true chert. There is also a sandstone or lutite interbed. Below are the Tornefjellet Beds, cherts with rare lutites, occurring in the central part of the Isfjorden Basin and Nordaustlandet. They pass both laterally and vertically into a more or less silicified limestone facies known as the Garwoodtoppen Beds which are widely developed in northern and southern Spitsbergen. The limestones are dark grey, weathering yellow, and commonly cyclically interbedded with lutites. A 10m thick breccia is present 20 m above the top of the Voringen Member of Bjorndalen (Sassenfjorden). It consists of nodular orange cherts which are commonly bioturbated and form lenticular blocks a few metres across. Bedding varies from horizontal to contorted and overturned. The basal contact of the breccia is erosive and marked by a shaly band. Voringen Mbr. This consists of 22-39 m of distinctive, light-coloured, coarse fragmental limestone with silicified brachiopods and bryozoans. It occurs at the base of the Kapp Starostin Formation from Bellsund to St Jonsfjorden and Nordaustlandet but is absent south of Bellsund and from most of Oscar II Land and is replaced by calcareous sandstones in Ny Friesland and southwest Nordaustlandet. It is the Spirifer Limestone and Brachiopod Limestone of previous authors and 'Limestone A ' of Gee et el. (1953) and is a useful marker horizon. Coal fragments are present in the lower part south of Sassenfjorden and in Nordaustlandet (Lauritzen 1981); this is probably an indication of erosion of the top of the Gipshuken Formation, as coaly shales are present in the topmost Gipshuken Formation in Nordaustlandet. The basal contact is erosive in Bellsund also, with clasts of micrite from the underlying Gipshuken Formation, which is extensively bored. Elsewhere on Svalbard, the contact is poorly exposed, owing to the susceptibility of the Gipshuken Formation to erosion, but there is further evidence for a disconlbrmity in the phosphatic nodule beds found at the base of the formation on the south side of Sassenfjorden. These may have been eroded from the underlying strata. Some were associated with glauconitic sands, a combination characteristic of episodes of slow sedimentation/non-deposition.

PNaeontology and age: The formation contains an abundant fauna, predominantly of silicified brachiopods, but also of bryozoans, bivalves, corals, sponge spicules, echinoderms, gastropods and foraminifers. Trace fossils abound, with Zoophycos, Teichichnus and Chondrites.

66

CHAPTER 4

Szaniawski & Malkowski (1979) distinguished two time-equivalent fossil associations which represent different depths: the bioclastic limestone facies of near-shore, shallow water, high energy thicker-shelled species and an offshore, low-energy, deeper water fauna dominated by sponges, with more fragile brachiopods and bryozoans, which occurs in the siliceous rocks associated with in-situ glauconite and pyrite. The brachiopod fauna is broadly comparable with the later Early Permian and Late Permian assemblages of Russia (Tschernyschew 1898, 1902). However, many of the species have long time ranges and show considerable intraspecific variation which has caused confusion over correlation. Biernat & Birkenmajer (1981) found that at the base of the Kapp Starostin Formation in Torell Land, two brachiopod species were the same as those in SakmarianEarly Kungurian rocks of Inner Isfjorden. Many species are closely related to the Artinskian or Kungurian species of the Soviet Union, but several genera characteristic of Late Permian also occur (Gobbett 1963). Ustritskiy (1962) and Burov et al. (1965) distinguished two separate faunas, both belonging to the Ufimian stage, in the 'Starostin Suite' (= Svenskeega/Voringen Members) and 'Selander Suite' (= Hovtinden Member), the latter being distinguishedby the presence of Cancrinelloides and Sowerbyna. These assemblages have not yet been recognized throughout Spitsbergen. A Kungurian age has been confirmed for the lowerpart of the formation (Nysaether 1977; Ustritskiy 1979) and a Ufimian age is indicated by the foraminifera for the small Permian inliers of Edgeoya, which are of the glauconitic chert facies (Pchelina 1977). The upper part contains brachiopods which extend into the Kazanian stage (Ustritskiy 1979) and Ustritskiy assigned the 'Starostin' (= the Voringen and Svenskeegga Members) and 'Selander' (= the Hovtinden Member) 'Formations' to Boreal stages (Paykhoyian and Early Novozeml'ian) which correlate with the Kungurian-Ufimian and Kazanian-?basal Tatarian respectively. Conodont assemblages also confirm a Kungurian-Ufimian age as they correspond stratigraphically to the Late Leonardian/Early Roadian of the USA (Szaniawskij & Malkowski 1979). As the formation is transgressive, lithological boundaries must be diachronous until open-sea cherty facies occur everywhere, i.e. at the top of the formation (Malkowski 1982). There is a stratigraphic gap in the Hornsund region, where the Voringen and Svenskeegga Members of the Isfjorden area are absent.

4.7

Gipsdalen Group (Permian-Carboniferous)

Cutbill & Challinor (1965) originally defined the Gipsdalen Group within the Billefjorden area to contain the Gipshuken, Nordenski61dbreen and Ebbadalen formations. However, the Nordenski61dbreen F m has been replaced by the Wordiekammen and Minkinfjellet formations. Hence now the group comprises the Gipshuken, Wordiekammen, Minkinfjellet and Ebbadalen formations. These four formations are (Dallmann 1996 SKS) combined in two subgroups thus: Gipsdalen Group (Cutbill & Challinor, 1965) Dickson Land Subgroup (SKS) Gipshuken Formation (Cutbill & Challinor, 1965) Wordiekammen Formation (Gee et al. 1952, SKS) Campbellryggen Subgroup (Forbes, Harland & Hughes 1958, SKS) Minkinfjellet Formation (Cutbill & Challinor 1965) Ebbadalen Formation (Cutbill & Challinor 1965) The upper subgroup extends from Btinsow Land to the west across Dickson Land. The lower one is confined approximately to the Billefjorden Trough. As elsewhere in Svalbard, the base of the group is marked by the appearance of red-beds; these pass upwards through terrestrial and marine restricted-basin deposits into platform carbonate sequences with increasing quantities of evaporites. Deposition of the group and the underlying Billefjorden Group occurred initially within distinct, small basins defined by faults (Fig. 4.12). Later deposits, however, blanketed the entire region. Each formation is described below.

4.7.1 Gipshuken Formation (Dickson Land Subgroup) Present across much of western and central Spitsbergen, the Gipshuken Formation is 150-250m thick, consisting mainly of carbonates and evaporites with minor quantities of sandstone.

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Fig. 4.12. Schematic west-east stratigraphic profile showing lateral variations and structural controls on Carboniferous stratigraphy. Simplified, and modified with later SKS nomenclature, from Cutbill & Challinor (1965) with permission of Cambridge University Press.

THE CENTRAL BASIN R h y t h m i c d e p o s i t i o n a l sequences o f l i m e s t o n e / d o l o m i t e a n d g y p s u m / a n h y d r i t e are c o m m o n , especially in central exposures. T h e f o r m a t i o n was d e p o s i t e d in w a r m , shallow seas a n d tidal flats w i t h restricted c i r c u l a t i o n t h a t allowed high salinity to develop. In general, the evaporites, w h i c h represent arid l a g o o n a l , tidal flat a n d s u p r a - t i d a l s a b k h a deposits, are m a i n l y f o u n d in central Spitsbergen. E a s t w a r d s they are replaced by limestones a n d d o l o m i t e s . Fossils are scarce, b u t those t h a t are p r e s e n t indicate an A r t i n s k i a n age. Definition: These strata were included in the Cyathophyllum Limestone of early authors (Nathorst 1910), but were distinguished as a separate unit in the Billefjorden region by Gee et al. (1953), whose upper Gypsiferous Series is an exact equivalent. The formation was defined by Cutbill & Challinor (1965) in Billefjorden, where the formation is 210 m thick. Lauritzen (1981) proposed a hypostratotype for the formation at Trollfuglfjella on Dicksonfjorden, where the formation is exceptionally well exposed. It is thickest in western Isfjorden (up to 350 m), but over much of the outcrop, it is between 150 and 2 5 1 m . It thins northwards, nearer the Northern Block and southwards towards the Hornsund High (about 70 m at Drevbreen in Torell Land). in the Hornsund area it is absent, where the Kapp Starostin Formation lies disconformably on the Carboniferous Treskelodden Beds, which were formerly correlated with the Gipshuken Formation (Cutbill & Challinor 1965). The present outcrop of the formation is largely confined to two belts. Along the west coast of Spitsbergen, outcrop is sporadic and largely controlled by the structure of the West Spitsbergen Orogen. The strata in central Spitsbergen are mainly flat-lying and relatively well exposed. The formation also crops out in eastern Ny Friesland and Nordaustlandet, bordering Hinlopenstretet, and to the south on Bjornoya. It is present beneath the younger strata of central Spitsbergen. The upper boundary of the Gipshuken Formation is mapped at the base of the distinctive siliceous deposits of the Kapp Starostin Formation. Some erosion of the top of the Gipshuken Formation took place before deposition of the Kapp Starostin Formation in marginal areas, hence its absence in the south. The base of the Kapp Starostin Formation is a marker recognized throughout Spitsbergen. The lower boundary is transitional with the underlying Wordiekammen Formation, where the formation is preserved from pre-Kungurian erosion. The base is therefore defined by the appearance of gypsum, where present, or by the widespread and distinctive Kloten Breccia Member. Where both are absent, the top of the underlying Tyrrellfjellet Member is marked by the distinctive cliff-forming 'Limestone B' (Finlayfjellet Beds). Lithologies: The formation is a major regressive sequence characterised by highly variable lithologies, dominated by carbonates and evaporites, of which approximately 60% are carbonates, 30% gypsum and 10% arenites. In the central part of the Isfjorden Basin, rhythmic deposition of dolostone/limestone and gypsum/anhydrite continued throughout the formation. The central zone of sulphate deposition is surrounded by a broad zone in which only the dolomite/limestone part of the evaporite cycle was deposited. These rocks consist predominantly of algal-laminated, locally gypsiferous, silt-textured dolostone (about 35% of the formation) formed by the trapping of lime-mud by mucilagenous green algae. Thin interbeds of silt-textured limestone occur locally. Some of the dolostones within the anhydrite zones of the lower part of the sequence in Torell Land are rich in quartz sand. Dolomitised ooids and pelloids occur with micritic dolomites in Dickson Land and Torell Land, where anhydrite nodules and cement are common in the anhydritic zones of the lower part. The gypsum/anhydrite horizons are locally massive and form relatively thick, continuous beds parallel or sub-parallel to the bedding. Elsewhere, the sulphate is laminated or finely interbanded with dolostone or rare limestone. It may also occur as nodules up to 1 m in diameter, separate crystals or infillings of cracks, fissures and stylolites (Lauritzen 1977). The gypsiferous deposits pass laterally into continuous dolostone. Laminated shales occur in units up to 2 m thick between the anhydrite beds. About 30 rhythms with anhydrite have been recognised in the Dicksonfjorden area by Lauritzen (1981), varying in thickness from 0.6 to about 9.5m. Each rhythm starts with a carbonate unit, which may contain ripples and cross-bedding or oolitic beds, followed by carbonates with anhydrite nodules, ending with chicken-wire anhydrite and commonly terminated upwards by a sharp, erosive contact with the base of the next cycle. Karstic surfaces have been observed in the anhydrite (Lauritzen 1983). Dolomitization is almost complete in this cyclic succession and is thought to be early diagenetic. Locally, in west Spitsbergen, dedolomitisa-

67

tion is well developed, with corroded clasts of yellow-weathering dolomicrite in a grey calcite matrix passing into uniformly grey calcitised rock. In the lower part of the formation, is a widespread group of carbonate breccias up to 30 m thick which make up about 13% of the formation. Two distinct types can be recognized- a hard, massive variety and a soft, porous, cellular type. The massive breccia is of rather limited occurrence in the northwest of the outcrop area, where it forms a resistant marker horizon. It consists of a complex of grey, laminated, silt-textured dolostone or limestone blocks, up to several metres in diameter, in a dolostone or limestone matrix. The dolostone weathers yellow and the limestone grey, but the unit is very hard and individual fragments are difficult to identify on unweathered surfaces. The fragments commonly show contorted lamination, indicating slumping prior to brecciation. In some cases dolomite is seen replacing calcite across fragment boundaries, whilst others show a sharp contact. Patches of dolomite crystals give a mottled effect in places. The cellular breccia has a wider distribution, and consists of brecciated silttextured limestone and dolostone. The interstices between the individual fragments may be filled by dolomite or calcite cement and calcite veining commonly gives a honeycomb structure. In places cement may be completely or partially absent, giving the rock a high porosity and permeability. Its cellular appearance is due to the variable weathering properties of calcite and dolomite. The breccias appear to pass laterally by way of sandy limestones and dolomites into arenites. In Bellsund, minor breccias are present in the upper parts of the Gipshuken Formation, where laminated dolomicrites occur with thin sandy interbeds, the relationships of which suggest that brecciation occurred prior to full lithification of the sand. Fossiliferous limestones, consisting of calcilutite and calcarenite, interdigitate with the dolostones in the upper part of the formation, making up about 8% of the sequence. In Torell Land they form the upper third of the formation and show a general increase in coarseness towards the top from dark grey micrites to grey-black biosparites. The darkening in the biosparites probably reflects increasing contents of organic matter. Fine laminations and small-scale ripple-marks and convolute bedding have been recorded (Nysaether 1977). Fossils are not common, but brachiopods do occur. Division: Gipshuken Formation deposits show a variation in facies, but only the distinctive breccias have been defined as members where they appear (see below). In Spitsbergen, in a general way, the sequence can be divided into: (5) The upper dolostone-limestone zone consisting of interdigitating dolostones and limestones. In Torell Land there is only limestone. (4) The upper gypsum zone comprising the evaporite deposits occurring in the centre of the basin, particularly on the west coast. North of Isfjorden, there are only nodules and thin beds of evaporites in a predominantly dolomicrite sequence. (3) The Kloten Breccia Mbr (Cutbill & Challinor 1965) containing the various types of limestone/dolostone breccia described above. It forms a conspicuous marker horizon 88 m thick in the type section at Scheteligfjellet in the northeast of Spitsbergen and similar breccias occur eastwards to Tempelfjorden and also in Ny Friesland and Nordaustlandet. The latter outcrop was named the Zeipelodden Mbr by Lauritzen (1981). (2) The lower dolostone zone consisting of dolostones transitional between the Kloten Breccia Member and the lower gypsum zone below. It is only recognisable in the area of northwest Spitsbergen (Colletthogda) where true brecciation has not taken place, but contortion and slumping has occurred. (1) The lower gypsum zone consisting of the evaporites occurring in the lower part of the formation, mainly in the Billefjorden and Nordfjorden regions. The zone is rather restricted in western Spitsbergen. The Zeipelodden Mbr is 8 m thick and contains a mixture of lithologies, limestone breccias occurring together with finely laminated algal limestones, one passing into the other. Irregularly bedded horizons are weathered into distinctive caverns up to I m high. Hemispheroids of algal build-ups 2-3 m across, algal mats and crusts have been identified. A mixture of white chert and calcite is found within some of the hollows of the rock. The rocks are highly porous and dominantly calcitic, with clear evidence of dedolomitisation. This unit is, however, best considered in Chapter 5. Palaeontology and age: The bulk of the Gipshuken Formation appears to be unfossiliferous. Dolomitization has destroyed much of the evidence of fauna but algal lamination is extremely common in the micrites, caused by mucilaginous blue-green algae (Lauritzen 1981). Another prominent feature observed in thin-sections from the upper part of the succession (Lauritzen 1981) is Microeodium which has been described from palaeosols (Klappa 1978).

68

CHAPTER 4

Fossiliferous beds do occur in various places. Gastropods, especially bellerophontids, and bivalves have been recorded by Lauritzen in the Dicksonfjorden area as well as a little bioturbation. In addition, CSE 1985 found echinoids, crinoids and bryozoa in Nordaustlandet. A few productid brachiopods have been found in the upper part of the formation in Nordaustlandet, Kopernikusfjellet and at Trygghamna which indicate a correlation with the Hambergfjellet Formation of Bjornoya; (the latter contains Artinskian fusulinids). Cancrinella koninkiana which was found in the Gipshuken Formation by Ustritskiy (Burov et al. 1965) is typical of the Artinskian stage and Sossipatrova (1967) discovered the Frondieularia multicamerata assemblage in the middle of the formation in Bunsow Land and correlated it with the Artinskian deposits of the Urals and north Timan.

4.7.2

Wordiekammen Formation (Diekson Land Subgroup)

T h e W o r d i e k a m m e n L i m e s t o n e o f G e e et al. (1953) was redefined (SKS, D a l l m a n n et al. 1996) to take in the u p p e r t w o m e m b e r s (Tyrrellfjellet a n d Cadellfjellet) o f the N o r d e n s k i t l d b r e e n F o r m a tion o f Cutbill & C h a l l i n o r (1965). W i t h the G i p s h u k e n F o r m a t i o n it c o m p r i s e s the D i c k s o n L a n d S u b g r o u p , the characteristic o f w h i c h is a relatively u n i f o r m s p r e a d o f facies t h r o u g h o u t m o s t o f Spitsbergen. In this respect the D i c k s o n L a n d S u b g r o u p contrasts w i t h the u n d e r l y i n g C a m p b e l l r y g g e n S u b g r o u p w h i c h is s e p a r a t e d into distinct basins.

Tyrrellfjellet Member is a widely d e v e l o p e d c a r b o n a t e sequence o f Early P e r m i a n ( A s s e l i a n - S a k m a r i a n ) age, o c c u r r i n g at the t o p o f the o t h e r w i s e C a r b o n i f e r o u s W o r d i e k a m m e n F o r m a t i o n . T h e type section is at Tyrrellfjellet, Billefjorden, w h e r e it is 1 6 0 m thick; elsewhere its thickness is variable f r o m 1 0 0 - 1 6 0 m . It c o n t a i n s limestone, d o l o s t o n e a n d arenites, with local gypsiferous units, widely d e v e l o p e d cherts, a n d P a l e o a p l y s i n a b i o h e r m a l m o u n d s . T h e f o r m a t i o n was d e p o s i t e d in l a g o o n a l a n d o p e n m a r i n e basin e n v i r o n m e n t s . It is highly fossiliferous with a varied fauna.

Definition: The member was defined by Cutbill & Challinor (1965). These limestones form the middle part of the Cyathophyllum Limestone of early workers (Nathorst, 1910); they are equivalent to the Mid- and Upper Wordiekammen Limestones described by Gee, Harland & McWhae (1953) in the Billefjorden area. It is thickest in the west (243 m at Orustdalen); over most of Spitsbergen it is 100 150m thick. The formation thickens slightly across the Billefjorden Trough, and thins slowly to the east across Ny Friesland. In Nordaustlandet it is replaced by the similar Idunfjellet Member and in southern Spitsbergen by the Treskelodden and Reinodden formations. The formation lies conformably beneath the dolostones and evaporites of the Gipshuken Formation. The highest beds of the Tyrrellfjellet Formation are transitional, containing dolostones, but the boundary can be mapped by the distinctive facies attributed to the Gipshuken Formation (see above) and by the occurrence of the distinctive cliff-forming 'Limestone B' at the top in the Billefjorden area (see below). The lower boundary of the formation represents a widespread marine transgression in Spitsbergen, which approximates the initial Permian boundary. In the west and south, the formation rests on various Carboniferous horizons, but throughout the northern outcrop it overlies Late Carboniferous shelf carbonates. However, near the base, the Brucebyen Beds form a marker horizon which can be recognised over much of the area. A thin sandy horizon, locally conglomeratic, occurs a few metres below the Brucebyen Beds which marks the basal disconformity or non-sequence in this area and can be recognized when outcrop is sufficiently good. Lithologies: The Tyrrellfjellet Member is made up of limestones (c. 85%), dolomites (c. 5%) and arenites (c. 10%). Fossiliferous relatively shallow-water shelf limestones, consisting of calc-lutite and calcarenite with subordinate dolostone occur over large areas of Spitsbergen in the lower part of the formation. They contain abundant corals, brachiopods and fusulinids. Similar shelf carbonates occur in the upper part of the formation, but are more commonly dolomitic, much less fossiliferous and pass laterally into dolostones. Close examination of the sequence has revealed the presence in the lower part of the sequence of biohermal structures (Skaug et al. 1982). The bioherm horizons are separated by fusulinid-rich wackestones and packstones which are dolomitized or bituminous as in the Brucebyen Beds (see below), which is a bituminous fusuline coquina.

Intraformational conglomerates occur locally above the bioherms, as do desiccation cracks. The bioherms are up to 2500 m 2 in area and their original calcite mudstone is dolomitized to some extent. Examination of thin sections (CSE 1985) revealed two types of dolostones, fine and coarse. The finer dolomicrite variety suggests early 'penecontemporaneous' replacement, possibly by evaporitively modified brines, since these solutions tend to have a considerable potential to dolomitize and hence are likely to alter calcium carbonate very rapidly, producing fine-grained dolomite; the presence of nodular gypsum locally provides evidence of an evaporative environment. The coarse dolostone is probably late-diagenetic as high-magnesium calcite crinoid and echinoid fragments, which should have been preferentially altered have not been dolomitized, suggesting that they were stabilized to low-magnesium calcite prior to replacement. All bioherms show good primary growth-framework porosity which is enhanced by secondary porosity associated with the dissolution of skeletal grains during dolomitization. In places porosity has been reduced by the crystallization of gypsum in pore spaces. Dolostones occur mainly in the upper part of the formation and largely in the northwestern outcrop area. They consist of very thinly bedded or laminated silt-textured dolostones with rare limestones, locally gypsiferous, and pass laterally into shelf carbonates. In the dolostone interbeds of the lower part, pseudomorphs after ?evaporite crystals have been noted, in places filled by length-slow chalcedony, calcite or dolomite; others are darkstained with a high kerogen and pyrite concentration (Skaug et al. 1982). Chert, generally occurring as nodules or rarely as bands, is locally widely developed, though not on the scale of the Tempelfjorden Group. The nodules, preserving bioclastic remains, are found within secondary dolostones in which sedimentary fabric has otherwise been destroyed. Sedimentary laminae are commonly deformed around the chert nodules, pointing to early diagenetic silicification, prior to complete compaction. Stylolites, which skirt around the nodules, support the latter observation. Calcareous sandstones, locally silty, are found as thin layers or lenses in the shelf limestones. They occur in the north, and in Ny Friesland where they are fine to medium-grained and interbedded with limestones. Crossbedding indicates currents from the southeast. On the Hornsund High, the limestones pass laterally into the commonly calcareous sandstones of the Hyrnefjellet Formation (Chapter 10). At the base of the formation is a thin sandstone horizon with a locally developed basal conglomerate. Division: The upper part consists of carbonates, commonly dolomitic, occurring throughout much of northern and eastern Spitsbergen. To the east and north they pass laterally into calcareous sandstones, and in the northwest into the dolomitic Ki~rfjellet Beds. Defined by Cutbill & Challinor (1965), the Kiaerfjellet Beds are thinly-bedded soft dolostones 96m thick developed at the top of the Tyrrellfjellet Member in the northwest of Spitsbergen. In eastern Svalbard and in the type section on Tyrrellfjellet, there is a cliff-forming calc-lutite forming the upper part of the member named 'Limestone B' by Gee et al. (1953, fig. 4.7) and Finlayfjellet Bed (SKS, Dallmann et al. 1996). The limestone is a 38 m thick cliff-forming micrite which makes a useful marker at the top of the Tyrrellfjellet Member in Btinsow Land. The lower part of the Tyrrellfjellet Member on Spitsbergen consists of fusuline limestones, locally biohermal, underlain by the bituminous micrudite Brncebyen Beds which are themselves underlain by up to 10m of dolostone, again locally biohermal, then a thin basal sandstone horizon with a locally developed conglomerate. The Brucebyen Beds, (Cutbill & Challinor 1965), consist of 2-20 m of distinct dark grey bituminous fusuline limestone coquina or biomicrite with a gradational top and base, 5-10m above the base of the Tyrrellfjellet Member. The fusulinids lack wall structures and their body chambers are infilled with dolomite. This is an excellent marker horizon over large areas of Spitsbergen. These beds occur within or below the palaeoaplysinid biohermal structures. In some areas eg. Gerardfjella, the carbonates are completely replaced by dolomicrite; nodular gypsum is also present here. Palaeontology and age: The formation is highly fossiliferous, with brachiopods, corals, bryozoans, echinoderms, bivalves, gastropods, sponges and foraminifera, of which fusulinids are particularly important as zone fossils where they occur, which is in the lower part only. Plant remains including algae, Microcodium and rootlets are also found. Skaug et al. (1982) described localised bioherms with Palaeoaplysina which are developed over the Billefjorden Fault Zone and elsewhere. There may be an algal contribution to the development of these structures. They are generally discoid and made up of subparallel to undulating plates up to 40 cm across which

THE CENTRAL BASIN may be closely packed or may enclose and bind pockets of bioclastic mudstone or wackestone containing all the above-mentioned fossils. They consist of small isolated dome structures up to 6 m high, tabular units up to 15m high, or offlapping sequences with one bioherm draping over the adjacent one to form structures up to 2500 m 2 in area. Their basal surfaces are sharp and usually planar to slightly undulating; most tops are sharply defined but some are gradational to overlying bedded carbonates. Studies of the abundant faunas found in the Tyrrellfjellet Member limestones by Forbes et al. (1958), Forbes (1960), Gobbett (1964), Cutbill & Challinor (1965) and Cutbill (1968) indicate an Early Permian age for these rocks. Gobbett distinguished two distinct brachiopod faunas in the Gipsdalen Group. The younger fauna, found in both the Tyrrellfjellet Member and also the Hambergfjellet Member on Bjornoya indicates a correlation with the Early Permian (Asselian/Sakmarian) faunas of Russia. Studies of fusulinids (Ross 1965; Cutbill & Challinor 1965) are in agreement with these ages. The lower part of the Tyrrellfjellet Member contains Asselian species of the Schwagerina anderssoni zone which compares with the Lower Wolfcampian fauna of Ross (1963) in North America. A poorly known assemblage from the middle of the formation belongs to the Monodiexodina zone which compares with the Early Sakmarian faunas of the Urals and Upper Wolfcampian faunas of North America (Ross 1963). The small foraminifers have received less study and stratigraphic conclusions based on them are less certain. Sosipatrova (1967) described a foraminiferal assemblage from the Tyrrellfjellet Member which helps to confirm the Asselia~Sakmarian age since Protonodosaria rauserae and Nodosaria parva are foraminifers diagnostic of the Boreal Sezymian stage (Asselian-Sakmarian). The Brucebyen Beds have a nearly identical fauna to the lower fusulinid-rich limestone within the palaeoaplysinid biohermal dolomites of the Kapp Dun6r Formation of Bjornoya.

Cadellfjellet, Kapitol and Morebreen Members.

The Cadellfjellet

M e m b e r , with equivalent Kapitol and Morebreen m e m b e r s to the west, consists o f a sequence o f late C a r b o n i f e r o u s limestones (locally dolomitic), occurring widely across Oscar II L a n d , James I Land, D i c k s o n L a n d and Btinsow Land. It reaches 200 m thickness in the Billefjorden area. The c a r b o n a t e s locally c o n t a i n gypsiferous layers and chert nodules. C a l c a r e o u s sandstones a n d s a n d y limestones f o r m a m i n o r p a r t o f the sequence. T h e f o r m a t i o n represents a stable m a r i n e shelf e n v i r o n m e n t , with sabkas present locally in coastal areas. F a u n a are sparse, but fusulinids suggest a late C a r b o n i f e r o u s ( K a s i m o v i a n - G z e l i a n ) age, possibly extending back to M o s c o v i a n .

Definition: Below the Tyrrellfjellet Member in central and western Spitsbergen lies a sequence of mainly limestones and dolostones. They are thickest in the Billefjorden Trough, where the type section lies; and thin westwards onto the Nordfjorden Block (the Kapitol Member), and then thicken again slightly into the St Jonsfjorden Trough in Oscar II Land (the Morebreen Member). The third is described in Chapter 9; the first two are described below. To the east in Ny Friesland, it is much thinner (40 m) and more arenaceous (see Chapter 7). The Cadellfjellet Formation is the lowest unit that can be identified across the Nordfjorden Block; below it deposits are restricted to the isolated basins of the St. Jonsfjorden and Billefjorden troughs. The Cadellfjellet strata were included in the Cyathophyllum Limestone of early workers and are equivalent to all but the uppermost part of the Lower Wordiekammen Limestones of Forbes, Harland & Hughes (1958). The unit was defined as a member within the Billefjorden area only, by Cutbill & Challinor (1965), equivalent to and laterally continuous with the Kapitol Member. (Nordfjorden area) and Morebreen Member. The top of the Cadellfjellet Member is marked by the widespread disconformity at the base of the Permian Tyrretlfjellet Member, which can be difficult to recognise in the carbonate sequence of this region. However, there is a thin, sandy, locally conglomeratic horizon at the bottom of the Tyrrellfjellet Member, and a few metres below, the distinctive bituminous fusulinid limestone coquina of the Brucebyen Beds In the Billefjorden Trough, the lower boundary is taken at the base of a black limestone horizon known as the 'Black Crag' (see below). Everywhere, the base is also defined by the appearance of Waeringella usvae zone fusulinids. The Kapitol Member is only about 50m thick thinning westwards across the East Dickson Land Axis from the 200m Cadellfjellet Member east of the Billefjorden Fault Zone.

69

Over the Nordfjorden Block, the Kapitol Member replaces the Cadellfjellet Member. The lower boundary is a strongly developed unconformity, below which Devonian sandstones occur. To the west of the Billefjorden Fault zone at Kapitol (type section of the member), the Cadellfjellet Member passes almost entirely into carbonates with very little horizontal or vertical variation. Limestones, mainly biomicrites and biosparites, form 70% of the sequence there. They are rather pure, grey and buff-weathering, with a high biogenic constituent. They commonly have a siliceous cement and horizons with abundant chert nodules occur. The remainder of the sequence is formed by primary dolomite as in the Mathewbreen Beds, which are largely uninterrupted in the east of the area but are interbedded with the limestones in the west. The Morebreen Mbr further west in the St Johnsfjorden Trough is thicker but not so easy to distinguish from the rest of the Wordiekammen Formation. It is described in Chapter 9.

Litbologies: The type section of the member is on Cadellfjellet, where it is thickest. There it consists predominantly (95%) of limestones, locally dolomitic, and rare gypsiferous layers. The limestones are grey, mainly massive micrites, becoming coarser-grained to the east. Calcareous sandstones and sandy limestones constitute the remaining 5% of the sequence. In the northeast (Ny Friesland), they occur in the upper part of the formation, commonly interbedded with gypsum layers and sedimentary breccias. In places, the lower 10-20 m of the basal limestones are brecciated. This was originally thought to be a result of collapse, following solution of evaporites in the underlying Minkinfjellet Formation (McWhae 1953). However, small-scale thrusts have also been observed forming an imbricated structure in the underlying beds, and suggesting at least a tectonic component. In southeast James I Land there is a thin conglomerate at the basal unconformity (Bates & Schwarzacher 1958). The clasts are generally small (5-10mm) and consist mainly of Devonian quartz sandstones and older quartzites in a reddish sandy matrix. In exposure east of Billefjorden, a distinctive, dark-grey micritic bed over 50 m thick occurs at the base (the 'Black Crag'; see below). Division: The Cadellfjellet Member is subdivided regionally into three as described above, with the type section in the Billefjorden area in the east, becoming the Kapitol Member in the central region and the Morebreen Member in the west. However, the main lithological subdivisions are the 'Beds' originally defined by Cutbill & Challinor (1965) - the Mathewbreen, Gerritbreen and Jotunfonna beds. The Mathewbreen Beds comprise the dolomitic limestones and dolomites of the formation. They are 34 m thick on Cadellfjeltet, but pass eastwards into arenites. In eastern Dickson Land they are up to 39 m thick, and occur as a thin outlier further west. They contain the Rugofusulina arctica zone fusulinid assemblage. They are not known west of Dickson Land. The distribution of these beds indicates some slight erosion at their top (prior to the Permian transgression) and in the west, the base is slightly unconformable on the underlying Gerritbreen Beds which have undergone some erosion (see below). The Gerritbreen Beds are limestones, mainly massive micrites and sparites, with a Waeringella usvae zone fusulinid assemblage. The beds occur right across the Nordfjorden Block where they are 30-50 m thick, with a marked thinning over the East Dickson Land Axis. A slight unconformity occurs at the top where the upper part of the W. usvae zone is locally absent and at the base where the underlying Jotunfonna Beds are also locally missing. In the east at Cadellfjellet they are 67 m thick. The Jotnnfonna Beds are grey bedded limestones and interbedded buff dolomites, with a Wedekindellina zone fusulinid fauna. A thin basal conglomerate occurs locally. On Kolosseum, the bottom 5-10m contain a Profusulinella zone fauna and are the oldest Middle Carboniferous beds so far found on the Nordfjorden Block. The beds are 50 m thick on the west side of Billefjorden, 30-50 m thick across the Nordfjorden Block, but are locally absent along the East Dickson Land Axis. They are not recognised on the east side of Billefjorden. The 'Black Crag' is a distinctive bed of massive dark grey micrite, over 50 m thick, found in the Adolfbukta region of Billefjorden. The lower 10-20m are commonly brecciated and it forms an excellent marker horizon in that area (Gee et al. 1953), but elsewhere it is much coarser-grained and cannot be distinguished from the rest of the formation. The Pyefjellet Beds occur to the east and in part replace the Black Crag (Pickard et al. 1996). Palaeontology and age: The formation contains a rather sparse fauna, of which brachiopods, molluscs, corals, trilobites, bryozoans and fusulines have

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been described (Gobbett 1964; Forbes et al. 1958; Cutbill 1968). No macrofauna was recorded across the Nordfjorden Block except for a few brachiopods reported by Gobbett (1964): Krotovia? sp.; ?Chaoiella cf. taiyuanfuensis (Chao); Choristites sp.; and Spiriferina sp. These may, however, come from the overlying formation, although fossils do undoubtedly occur in the Cadellfjellet Formation there. The coral, bryozoan and brachiopod faunas in eastern areas imply a Late Carboniferous age, and the strata were first assigned to the Triticites zone (Forbes et al. 1958). The fusulinids are abundant, Cutbill's work on them defined two zones. The upper Rugofusulina arctica zone correlates with the latest Carboniferous (Gzelian) of the Russian Platform, and is found in the Mathewbreen Beds. The lower Waeringella usvae zone correlates with the Gzelian and Kasimovian stages and occurs in the Gerritbreen Beds. At Kolosseum, the basal 5-10 m contain a Profusulinella zone (Early Moscovian) fauna, and the 'Black Crag' contains Wedekindellina sp. and the coral Bothrophyllum conicum, both of which indicate a latest Moscovian age (Wedekindellina zone). Thus the formation has a Kasimovian-Gzelian age, except for these local Moscovian units.

4.7.3

Minkinfjellet Formation (Campbellryggen Subgroup)

T h e Minkinfjellet Formation is p r e s e n t in the Billefjorden area only. It is a u n i t with steep lateral a n d vertical facies variations. It has a thickness o f 3 0 0 - 4 0 0 m with its m a x i m u m a d j a c e n t to the Billef j o r d e n F a u l t zone (Fig. 4.12) w h i c h c o n t r o l l e d d e p o s i t i o n . It consists m a i n l y o f c a r b o n a t e s , s a n d s t o n e s a n d evaporites, with red c o n g l o m e r a t e s in places. D e p o s i t i o n o c c u r r e d d u r i n g M o s c o v i a n time, p r o b a b l y in fluvial fans b u i l d i n g o u t into a m a r i n e basin. S a b k h a s a n d l a g o o n s d e v e l o p e d o n the fan b u t were subject to r a p i d base-level changes.

Definition: The Minkinfjellet Fm consists of a variable sequence of carbonates, sandstones and evaporites which occur mainly within the Billefjorden Trough, below the massive limestones of the Cadellfjellet Member. The sequence was first described by Scottish Spitsbergen Syndicate geologists, who introduced the term 'Passage Beds' in unpublished reports (Tyrrell 1919; Wordie 1919). Gee, Harland & McWhae (1953) gave further stratigraphic details, including the strata in the Campbellryggen Group. The unit was defined as a member within the Nordenski61dbreen Fm by Cutbill & Challinor (1965) and raised in rank by Dallmann (1993). It is thickest (300-400m) within the Billefjorden Trough adjacent to the Billefjorden Fault Zone, becoming thinner to the southeast. The Jotunfonna Beds at the base of the Cadellfjellet Formation (see above) occur on the west side of Billefjorden interleaved with the formation, but have not been identified to the east. The upper boundary is conformable and is marked in the Adolfbukta area by the overlying 'Black Crag' of the Cadellfjellet Mbr (see above). Elsewhere the top is marked only by the appearance of W. usvae zone fusulinids in the overlying strata. The base is apparently conformable within the trough, at the base of the Carronelva Beds, although this contact is probably disconformable (Dallmann 1993), as in the eastern area those beds overlap the Ebbadalen Formation and rest unconformably on pre-Devonian basement. On the western edge of the Billefjorden Trough, the formation overlaps the Billefjorden Fault zone and lies with distinct unconformity on various horizons of the Billefjorden Group. The formation is variable in thickness from 50m to 350m (Dallmann 1993). Lithologies: The type section is at Minkinfjellet. The formation is characterized by facies variation. It is dominated by carbonates, with dolostone, limestone, sandy limestone, marly limestone, limestone conglomerate and limestone breccias present. Coarse clastic rocks, generally yellowish or greenish in colour, are interbedded with the carbonates in places, as are thin beds of gypsum which also lines vugs in limestones. Limestone/dolostone breccias occur in the middle of the formation. Lateral variability is common within the formation. In places, grey, fossiliferous limestones (biomicrites and biosparites) are commonly interbedded with dolostones. In eastern Ny Friesland, the limestones become arenaceous and pass laterally into calcareous sandstones. Buff-coloured, micritic dolostones occur associated with evaporites and pass eastwards into limestones. A laterally restricted gypsum-anhydrite facies occurs in the central part of the trough. The evaporites are interbedded with dolostones which they pass into eastwards. To the west, towards the Billefjorden Fault Zone, they pass into clastic rocks.

Immediately adjacent to the fault zone, thick red and variegated conglomerates and sandstones occur in considerable thicknesses, comprising the whole formation. The red colouration may in part be secondary as the conglomerates are commonly derived from Devonian red-beds to the west. Division: In view of the lateral facies variation, widespread lithostratigraphic subdivision and correlation of the formation is difficult. Cutbill & Challinor (1965) originally recognized four u n i t s - the Carronelva, Elsabreen, Pyramiden and Anservika beds. However, Dallmann (1993), after Norsk Polarinstitutt remapping of the area, thought that the Pyramiden Beds and Elsabreen Beds were in fact the same unit. Furthermore, he thought that they are the lateral continuation of the Ebbadalen Formation to the south. He retained the Carronelva and Anservika beds but upgraded them to member status, and introduced a new unit, the Fortet Mbr, to the formation. The Anservika beds were indeed the equivalent of the Terrierfjellet beds (SKS). The Carronelva Mbr forms the lower part of the formation in central and northern areas. It is 41 m thick at its type locality, increasing to over 100 m in Ebbadalen and Ragnardalen. The base of the member is normally coarsegrained, either in the form of red conglomerates and other clastic lithologies or yellowish polymict conglomerates and sandstones. Yellowish sandstones continue through the middle of the member and are sulphurous in places. The upper strata consist of shales, marls, limestones and sandy limestones with some gypsum vugs. The member interfingers with the Anservika Mbr in its upper levels, and is overlain by either carbonates of that member or by breccias of the Fortet Member. The Terrierfjellet Mbr: The member is mainly exposed in eastern and southern parts of the Billefjorden Trough, but it is also present in the upper levels of the formation in central and northern areas. It consists of limestones and dolostones, interbedded with minor marls and marly limestones. Flint concretions and layers occur in the west of the outcrop, as also do rare gypsum layers. The thickness of the member varies from 33 m thick at the type section to 250-300 m in the central part of the outcrop. The Fortet Mbr: This member was defned by Dallmann (1993) for the intraformational carbonate breccias and conglomerates that are abundant in the upper part of the formation around the head of Billefjorden. The rocks overlie or replace (in the north) the carbonates of the Anservika Member. The breccias are probably of both in-situ brecciation and transported origin; grain- and matrix-supported varieties occur, with unsorted angular clasts up to 10cm in diameter. Dallmann estimated the member to be thickest at its type locality (approx. 240m).

Palaeontology and age: Limestones from the formation contain a marine fauna of which brachiopods, bivalves, corals and foraminifera have been described. The brachiopod assemblage compares with that of the Middle Carboniferous of the Moscow Basin (Gobbett 1964) and Cutbill's (CSE) Wedekindellina and Profusulinella zones are represented which correlate with the Moscovian stage. Crinoids were reported by Dallmann (1993).

4.7.4

Ebbadalen Formation (Campbellryggen Subgroup)

T h e E b b a d a l e n F o r m a t i o n is o n e o f the best k n o w n lithostratig r a p h i c units o f Svalbard. Like overlying units its d e p o s i t i o n was c o n t r o l l e d by its p r o x i m i t y to the Billefjorden F a u l t zone; it is t h e r e f o r e also laterally variable with wedges t h i n n i n g a w a y f r o m the fault in a h a l f graben. It is c h a r a c t e r i s e d by alluvial fan red-beds at the base a n d a d j a c e n t to the fault, which die o u t a w a y f r o m it a n d pass into two m e m b e r s . In the u p p e r p a r t o f the m a i n basin sequence are c a r b o n a t e s a n d evaporites; in the lower p a r t fluvial s a n d s t o n e s a n d shales. T h e total t h i c k n e s s o f the f o r m a t i o n is in the o r d e r o f 750 m b u t this decreases to the east a w a y f r o m the fault to zero. T h e f o r m a t i o n c o n t a i n s a variety o f f a u n a that indicate a B a s h k i r i a n age.

Definition: The Ebbadalen Formation is equivalent to the Lower Gypsiferous Series of Gee, Harland & McWhae (1953) but excludes the lateral equivalents of the Minkinfjellet Formation. The formation occurs only in the BiUefjorden Trough, and like the overlying Minkinfjellet and Cadellfjellet units is thickest adjacent to the fault zone on the western margin of the trough, where up to 750m are preserved. It thins rapidly to the east and pinches out about 25kin east of Billefjorden. The type section is at Ebbadalen with reference sections at Cadellfjellet, Odellfjellet and elsewhere. The formation was defined by Cutbill & Challinor (1965) and has been described by Holliday & Cutbill (1972) and Johannessen & Steel (1992).

THE CENTRAL BASIN The upper boundary of the formation is marked by the appearance of the sandstones of the overlying Carronelva Beds, above which cherty carbonates occur and evaporites are rare. The lower boundary is above the red beds of the Hultberget Formation which overlies the coal-bearing sequences of the Billefjorden Group. Lithologies: Facies are extremely variable as Gypsum-anhydrite rocks are an important constituent of the upper part of the formation especially, and are widely developed in the central part of the Billefjorden Trough. They are of the nodular type and formed during early diagenesis in soft sediments (Holliday 1967, 1968). Gypsum was the primary sulphate mineral deposit, while anhydrite formed by solution and reprecipitation. Sandstones form a major constituent of the lower part of the formation. They are light coloured, white, red and green, generally fine-medium grained with horizontal and both large and small-scale cross-stratification. In the central part of the basin they are commonly interbedded with carbonates and shales. Black shales occur with the sandstones in the lower part of the formation; in Ebbadalen, the shales form a thick, clearly defined horizon (the Ebbadalen Shale Beds). Red sandstones, conglomerates and shales occur interbedded in the upper part of the formation adjacent to the fault belt. Conglomerates and sandstones also occur in the east of the basin, e.g. at Cadellfjellet, where they form the Margaretbreen Conglomerate facies. Red beds also occur across the area at the base of the formation. Skeletal calcarenites, commonly oolitic, with sparry calcite cement and little or no lime mud, occur in the east and as thin horizons elsewhere. Locally, a limestone breccia (the Ragnarbreen Breccia of McWhae 1953) is developed at the top of the Ebbadalen Formation. As there is no evidence of tectonism and it occurs in abnormally thin sections lacking sulphates, it is thought to be a solution breccia, resulting from the removal of sulphates. Division: Holliday & Cutbill (1972) examined the complex lateral facies variations within the formation and defined a number of local members, beds and 'facies'. Detailed mapping of key limestone horizons allowed correlation of the different facies. Johannessen & Steel (1992) defined a further member within the formation, and redefined the base to include the red beds of the Hultberget Member, which had previously been assigned to the underlying Svenbreen Formation. The Odellfjellet Mbr: Johannessen & Steel (1992) introduced the member for alluvial fan and related deposits that occur adjacent to the Billefjorden Fault zone. These deposits were originally referred to as the Lower and Upper Red Bed Facies of the Trikolorfjellet Member by Holliday & Cutbill (1972). They consist of red, grey and yellow conglomerates and sandstones, red shales (with gypsum nodules in places) and yellow dolostones. In the lower red beds, conglomerate clasts are mainly quartzose, sorting is poor, stratification irregular and there is rapid lateral variation. The member is up to 400 m thick adjacent to the fault, but to the east it thins considerably and interdigitates with the Trikolorfjellet Member. On the west side of Billefjorden, the 'Pyramiden Conglomerate' (= Pyramiden Beds and equivalent to Elsabreen Beds of Cutbill & Challinor 1965; Dallmann 1993) consists of a group of rudites adjacent to the Billefjorden Fault zone, where they comprise the entire formation and are 300-400m thick. Originally placed in the Minkinfjellet Fm they are now considered to be equivalent to the Odellfjellet Mbr and are placed within it (Dallmann 1993). The Trikolorfjellet Mbr: The type section of the member is in Ebbadalen where it is 186 m thick, although it is thickest (326 m) at Trikolorfjellet from where it is named (Holliday & Cutbill 1972). The member is laterally variable in facies and lithologies; it mainly contains gypsum-anhydrite rocks with interbedded carbonates, but the evaporites are replaced to the west by red shales and then by sandstones and conglomerates of the Odellfjellet Mbr, with which it is equivalent. Thin black limestones and dolostone interbeds are common throughout. A basal sandy fossiliferous limestone is incised as much as 40 m into the underlying strata. Elsewhere, the base is conformable and defined at the bottom of the red beds. In some areas (e.g. at Trikolorfjellet), the Odellfjellet and Trikolorfjellet members interdigitate to the extent that red and white coloured lithologies appear to be cyclic (each cycle typically 15-30m thick), consisting of upward-coarsening red sandstones and conglomerates capped by a white quartzitic sandstone, which is in turn overlain by dolostone (fossiliferous at some levels). Holliday & Cutbill (1972) introduced the term Teltfjellet Mbr for the eastern lateral equivalent of the Trikolorfjellet Mbr. However, this term has fallen into disuse, as the two members may be difficult to distinguish, and therefore the strata are included within the Trikolorfjellet Mbr. The type section of the Teltfjellet Mbr was on Cadellfjellet, where evaporites occur with the same widespread limestone beds as to the west. The carbonates thicken to the east in the upper part of the member in north Biinsow Land and finally form the continuous Urmstonfjellet Limestone Bed. The base of the

71

member is unconformable in the east, where it oversteps onto the Ebbaelva Mbr (Gerritelva Sandstone Mbr of Holliday & Cutbill; see below), the Llulberget and Mumlen fms and the Hecla Hoek basement. The Ebbaelva Mbr: This member comprises grey and yellow sandstones interbedded with grey-green shales. They occur in discontinuous upwardfining cycles in the central and northern parts of the area. Thin black dolomites and white nodular gypsum and anhydrite are interbedded towards the top of the member. In the Ebbadalen area, Holliday & Cutbill identified two sub-units- the upper Ebbabreen Shale Beds and lower Ebbabreen Sandstone Beds, although it is unclear whether they can be traced further than the local area and the names have not been used in later literature. Holliday & Cutbill also introduced the Gerritelva Member. As with the Teltfjellet Member, the name has fallen into disuse, with the strata included in the Ebbaelva Mbr (e.g. Johannessen & Steel 1992) as they are probably the lateral equivalent of the Ebbabreen Sandstone Beds. The Gerritelva Mbr was defined to include 0-70 m of sandstones occurring east of Adolfbukta, containing both horizontal and large-scale cross-bedding and some pebble horizons. The beds are flaggy to massive and commonly gypsum-cemented. Palaeontology and age: Once thought to be unfossiliferous, the Ebbadalen Formation is now known to contain a wide variety of fossils including crinoids, corals, brachiopods and fusulinids. Only the latter two groups have been described to date. These occur mainly in dolostones and shales of the Ebbaelva Member. The brachiopods described by Gobbett (1964) and Holliday (pers. comm.) are on the whole too wide-ranging for an accurate age correlation. However, the occurrence of Striatifera sp. in dolostones high in the Ebbaelva Member and in the basal limestones of the Trikolorfjellet Member may be significant as this genus has previously been regarded as restricted to the Early Carboniferous epoch (Muir-Wood & Cooper, 1960). Fusulinids from the upper part of the formation belong to the P. antiqua zone of Cutbill and correlate with the Bashkirian stage of Russia. No Moscovian species occur below the Minkinfjellet Member, and the top of the Ebbadalen Formation probably corresponds to the Bashkirian/Moscovian boundary. The formation is therefore of Bashkirian age.

4.7.5

Hultberget Formation (CampbeHryggen Subgroup)

This u n i t was originally the (upper) H u l t b e r g e t M e m b e r o f the S v e n b r e e n F o r m a t i o n o f the Billefjorden G r o u p (Cutbill & C h a l l i n o r 1965), the lower S v e n b r e e n U n i t being the S p o r e h o g d a M e m b e r . H o w e v e r the N o r s k P o l a r i n s t i t u t t m a p p e d a b r e a k b e t w e e n the t w o m e m b e r s a n d t h e H u l t b e r g e t u n i t h a d m o r e affinity with the overlying strata because o f its red beds. T h e S v e n b r e e n F o r m a t i o n was t h u s d i s c o n t i n u e d as a useful m a p p i n g u n i t a n d divided b e t w e e n C a m p b e l l r y g g e n S u b g r o u p a n d the Billefjorden G r o u p . T h e H u l t b e r g e t M e m b e r o f Cutbill & C h a l l i n o r was described as 7 9 m thick w i t h a coal s e a m at the base a n d overlain by grey to red shales a n d s a n d s t o n e s . T h e coal s e a m has m o r e affinity w i t h the newly defined M u m i e n F o r m a t i o n below. T h e f o r m a t i o n consists o f red a n d p u r p l e shales, m u d s t o n e s , siltstones, s a n d s t o n e s a n d thin i r o n s t o n e b a n d s w h i c h m a y be recystallized l i m o n i t i c m u d s . L i m e s t o n e n o d u l e s m a y also o c c u r in s o m e o f the shale beds. M o s t beds are parallel l a m i n a t e d or crossb e d d e d ; s a n d s t o n e s are fine to m e d i u m grained. N o r t h w e s t o f Elsabreen, c o n g l o m e r a t e layers are present. T h e strata p r o b a b l y r e p r e s e n t s t r e a m a n d o v e r b a n k d e p o s i t s w i t h i n a n d a d j a c e n t to alluvial fans at the base o f the fault.

4.8

BiHefjorden Group (Early Carboniferous)

I n the c u r r e n t s c h e m e the Billefjorden G r o u p in the type area is n o w defined by the t w o c o n s t i t u e n t f o r m a t i o n s : M u m i e n a n d H o r b y e b r e e n (SKS, D a l l m a n n et al. 1996). This r e a r r a n g e m e n t resulted f r o m the division o f the S v e n b r e e n F o r m a t i o n o f Cutbill & C h a l l i n o r (1965) into its u p p e r H u l t b e r g e t M e m b e r , d i s t i n g u i s h e d by red beds, to b e c o m e the lowest f o r m a t i o n o f the G i p s d a l e n G r o u p a n d the lower S p o r e h o g d a M e m b e r to be redefined as the newly n a m e d M u m i e n F o r m a t i o n .

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CHAPTER 4 unconformably on the Hecla Hoek metamorphic basement with a thin basal conglomerate of locally-derived pebbles. Lithologies: Two lithofacies can be distinguished in the formation constituting the two members. The upper member consists of dark grey or black carbonaceous shales, associated with thin coals and some sandstones. The lower member in Dickson Land is characterized by massive, lightcoloured, thick-bedded, coarse sandstones (Johannessen & Steel 1992).

Since the C a m b r i d g e w o r k , m o s t s e d i m e n t o l o g y a n d stratigrap h y has been carried o u t either by g r o u p s f r o m the University o f Bergen (Gjelberg & Steel 1981; Gjelberg 1987; J o h a n n e s s e n & Steel 1992) or the N o r s k P o l a r i n s t i t u t t , w h o have recently r e - m a p p e d the area ( L a u r i t z e n et al. 1989, C 8 G ; D a l l m a n n 1993; D a l l m a n n et al. 1994, C7G). B o r e h o l e a n d seismic d a t a have also been collected by oil c o m p a n i e s interested in the area, s o m e o f w h i c h have been p u b l i s h e d ( Y e v d o k i m o v a , V o r o k h o v s k a y a & B i r y u k o v 1986).

4.8.1

The Birger JohnsonqeUet Mbr: This is the coal-bearing part of the formation, made up of small cycles of shale and siltstone which are locally carbonaceous and pass into coaly shale and coal. Plant remains are common. Up to 18 coal seams are present, from 0.1-1.45 m in thickness. Underlying root horizons or soil profiles are absent, although root horizons do occur elsewhere in the member (Abdullah et al. 1988). There is considerable lateral facies variation and also thickness variation (7-57 m) within the member. The base is defined as the first thick sequence of coal seams. The Sporeh~gda Mbr: This member consists mainly of massive white, thickbedded, coarse sandstones 20-76m thick. The whole unit shows crossbedding, wash-outs and rapid lateral changes in thickness of individual beds. Allochthonous plant debris and coaly clasts are common. Sandstones in the lower part contain large carbonaceous fragments and moulds of Lepidodendron stems. Towards the east, shales occur between the sandstone units. In the Ebbadalen area, the facies is fine-grained and contains several thin coals, which are usually associated with carbonaceous black shales containing plant remains, into which they pass laterally and vertically. Only rarely, e.g. at Hultberget, north of Ebbadalen, do the coals lie on a rootlet horizon. Although the individual seams have little lateral continuity, the coals fall into three recognisable horizons, two of which can be traced over quite a wide area. In places the shales contain ironstone concretions, but they are not as abundant as in the overlying Birger Johnsonfjellet Mbr. There is a thin basal conglomerate of locally-derived pebbles where the sandstones rest directly on basement rocks, which is absent elsewhere. Otherwise, medium and coarse conglomerates are rare. Yevdokimova et al. (1986) correlated the upper part of this coal-bearing facies in their section, only a small distance to the south, with that of the Birger Johnsonfjellet Mbr west of Billefjorden.

Mumien Formation

This f o r m a t i o n is the lower p a r t o f the original S v e n b r e e n F o r m a t i o n , its u p p e r b o u n d a r y being below the lowest red beds o f the H u l t b e r g e t F o r m a t i o n . It is a t e r r i g e n o u s u n i t p r e s e n t in the Billefjorden area, with a thickness o f u p to 230 m. It c o n t a i n s two m e m b e r s - Birger J o h n s o n f j e l l e t a n d S p o r e h o g d a . T h e S p o r e h o g d a M e m b e r c o n t a i n s massive coarse s a n d s t o n e s w i t h m i n o r shales a n d a l l o c h t h o n o u s coal, w h e r e a s the Birger J o h n s o n f j e l l e t M e m b e r c o n t a i n s n u m e r o u s coal seams w i t h i n a p r e d o m i n a n t l y shale a n d siltstone sequence (Fig. 4.13). T h e f o r m a t i o n is i n t e r p r e t a t e d as a terrestrial unit, with dep o s i t i o n w i t h i n a large fluvial system for the S p o r e h o g d a M e m b e r b u t c h a n g i n g to lacustrine a n d v e g e t a t e d f l o o d p l a i n e n v i r o n m e n t s for the Birger J o h n s o n f j e l l e t M e m b e r . D e p o s i t i o n o c c u r r e d d u r i n g Visean a n d possibly into S e r p u k h o v i a n time.

Definition: The Svenbreen Fm was defined by Cutbill & Challinor (1965) as 'the upper coarse sandstone series' of the Billefjorden Gp which crops out only in the East Spitsbergen Basin. The Mumien Fm was introduced (SKS, Dallmann et al. 1996) for the lower member of the Svenbreen Fm. The type section is on Birger Johnsonfjellet. Thicknesses are greatest to the east of the Billefjorden Fault Zone, with a maximum of 230m at the northern end of Billefjorden. The formation thins rapidly to the west and east and is absent west of the East Dickson Land Axis and in central and eastern Olav V Land. The upper boundary is here redefined as the base of the alluvial red bed sequence of the Hultberget Fm (Campbellryggen Subgroup), which locally rests on the coal-bearing strata below (Cutbill & Challinor 1965). In most of Dickson Land the Cambpellryggen Subgp is absent and the Mumien clastic rocks are overlain by limestones of the Dickson Land Subgp. The basal sandstones of the Mumien Fm in the west are concordant on the upper shales of the Horbyebreen Fm below, though there may be a disconformity, as in the east the lower formation is absent and the Mumien Formation rests

Rock units 13_

Thin-bedded sandstones and shales, commonly red

Red-beds, sandstones and conglomerates

Gjelberg & S t e e l (1981)

O n(3 Z I.U -J < a (f) 13_

Gjelberg (1987)

Abdullah et al. (1988); Michelsen & Khorasani (1991)

Johannessen & Steel (1992)

Dallmann (1993); McCann & Dallmann SKS and this work (1995)

EBBADALEN FORMATION

Hultberget Mbr

Hultberget Mbr

SVENBREEN FM

HULTBERGET FM

13_ O n~ (_9 Z LU J < a co

13. m (~

Hultberget Mbr

Coal-bearing siltstone / shale sequence

s :~ O r~ (.9

Massive thick-bedded sandstones

Z Ill r'~ I:::E O ii UJ "J ._]

Siltstones, shales and coal

Cutbill & Challinor (1965)

Palaeontology and age The formation contains a plentiful Early Carboniferous macro-flora (Forbes et al. 1958) and micro-flora (Playford 1962/1963), described in Chapter 17. In general it is difficult to separate the Mumien and Horbyebreen formations on palaeontological grounds, as no stratigraphically separate assemblages are apparent in the macro-flora. However, Playford (1962/1963) recognized his Aurita microspore assemblage in the Mumien Formation and upper Horbyebreen Fm, concluding that these strata have a Visean age, possibly extending to earliest Serpukhovian. There is some statistical evidence that this assemblage can

SVENBREEN FORMATION

Birger Johnsonfjellet Mbr

Birger Johnsonfjellet Mbr Sporehegda Mbr (Herbyebreen Fm)

Sporeh~gda Mbr

Fig. 4.13. Stratigraphic schemes for the Billefjorden Group.

MUMIEN FM

Z

Sporehegda Mbr

HORBYEBREEN FORMATION Hoelbreen Mbr Triungen Mbr

13_ O r~ (3 UJ a n," O ii Ill ._A .,,A m

THE CENTRAL BASIN be subdivided at the junction betweenthe Mumien and Herbyebreen fms (Cutbill & Challinor, 1965) and that this may approximate the ViseanSerpukhovian boundary. Retiolites radforthii Staplin, is found only in the Mumien Fm. In this case, the Mumien Fm would be entirely Serpukhovian.

4.8.2

Harbyebreen Formation

The H e r b y e b r e e n F o r m a t i o n lies u n c o n f o r m a b l y on Proterozoic basement rocks in D i c k s o n L a n d and s o u t h e r n N y Friesland. It is variable in thickness f r o m 57 to 2 0 0 m thinning to the west. It contains sandstone, conglomerate, shale a n d coal, c o m m o n l y occurring in cyclic sequences. The lower part of the f o r m a t i o n is d o m i n a t e d by the coarser-grained lithologies a n d assigned m e m b e r status (Triungen Member); the u p p e r part contains most o f the shales and coals and forms the H o e l b r e e n M e m b e r . Deposition is t h o u g h t to have been in a continental setting within a small and restricted basin. It was p r o b a b l y f a u l t - b o u n d e d to the east, a n d the sediment source was also probably in that direction. Facies show large lateral variations. The T r i u n g e n M e m b e r was mainly deposited by westward-flowing braided streams with o v e r b a n k deposits; the H o e l b r e e n M e m b e r by n o r t h w a r d - f l o w i n g m e a n d e r i n g streams in a s w a m p y floodplain environment. The f o r m a t i o n is o f T o u r n a i s i a n and possibly of Late F a m e n n i a n a n d / o r Visean ages on the basis o f microflora.

Definition: The unit was defined by Cutbill & Challinor (1965) as the lower formation of the Billefjorden Gp. It is restricted in outcrop to central Dickson Land and southern Ny Friesland. The upper boundary may be a disconformity in view of the basal Mumien Fm overstep to the east, but sandstones of the Mumien Fm concordantly overlie the shales at the top of the Herbyebreen Fm. The base is unconformable on preCarboniferous rocks. Lithologies and division: The formation consists of a cyclic sequence of shales, coals, sandstones and conglomerates from 57-200m thick. Fine sediments and coals predominate in the upper part, while the lower part consists entirely of sandstones and conglomerates. This has led to a division into two members: the Hoelbreen and Triungen Mbrs. Hoelbreen Mbr: The type section for the Hoelbreen Member is on Birger Johnsonfjellet where it is 146m thick. The member thins markedly to the west, e.g. at Gonvillebreen it is only 54 m thick. Within this upper member, thinly bedded, cyclic and laterally persistent coal-bearing carbonaceous shales and siltstones predominate. The siltstones show occasional low-angle cross-bedding, though it is usually flat or wavy. Dark grey, shaly, micaceous argillites, 0.5m thick usually occur above the coal seams. Fine-grained sandstone interbeds up to 2 m thick and showing some cross-bedding occur, especially in the east, in the lower part of the sequence, but they are locally developed and laterally impersistent. 10-15 cycles of sand-silt-clay-coal have been recognised. 10% of the member is sandstone; 50% is dark grey siltstone containing plant remains; 20% is made up of argillites and 20% of coal. The coals are generally quite thin and die out laterally, but they are more extensively developed in two well-defined horizons in the south-east of the outcrop, seams varying in thickness from 0.66-7.4 m. In the region of Pyramiden, the coals are sufficiently thick (up to 9m) to be mined. Transported plant remains are common in all lithologies, but are generally poorly preserved. In-situ plant fossils are rare and there is generally a lack of seat-earths, indicating that the coals are mainly allochthonous. However, seat-earths and rootlet beds are present locally. Triungen Mbr: The type section of this lower member is beside Gonvillebreen where it is 99 m on Odellfjellet. There is a general reduction in coal and carbonaceous material towards the west. Thicknesses are irregular, from 5-100m due to lateral facies variations. The dominant lithologies are thick-bedded sandstones and almost uncemented heterogeneous conglomerates. The latter show coarse cross-bedding and contain a variety of pebbles, including white, pink and purple quartzites, black and grey chert and rare mica-schist. The upper 20m are less conglomeratic, and there is a transition into the carbonaceous sandstones and shales of the Hoelbreen Mbr. The upper boundary is at the top of the highest thickbedded sandstone. The conglomerates around the Billefjorden Fault Zone, e.g. at Birger Johnsonfjellet, are noticeably coarser than further west, e.g. at Gonvillebreen.

73

Palaeontology and age: There is an abundant macroflora in the Mumien and Horbyebreen Formations, though no stratigraphically separate assemblages have been recognized. However, the microflora has proved more useful. Playford (1962/63) recognized his two distinct assemblages in these strata, defining the Aurita and Rarituberculatus zones, which indicate a Visean and Tournaisian age. The lower Rarituberculatus (Tournaisian) assemblage is restricted to the Horbyebreen Fm. However, the lower member does not yield a microflora, except in its uppermost part. The upper Hoelbreen Mbr contains the Rarituberculatus assemblage for more than half its thickness. There is then a break, and the overlying strata contain the Aurita assemblage. This break is not marked by any lithological change. The Aurita assemblage is also present in the overlying Mumien Formation but there is some evidence that the Aurita assemblage can be subdivided at the disconformity between the Mumien and Horbyebreen fms which may mark the Visean/Serpukhovian boundary (Cutbill & Challinor 1965).The assemblage, according to Playford, could possibly extend to Early Serpukhovian time. The Horbyebreen Fm is thus of Tournaisian and Visean age. However, given the rarity of preserved palynomorphs from most of the Triungen Member, it is possible that the lowest part may have a Famennian age, and this appears to have been confirmed (van Veen, pers. comm.).

4.9

The structure and development of the Central Basin

The Basin is d o m i n a t e d by three kinds of Paleogene structure. (i) The eastern front o f the thrust a n d fold belt of the West Spitsbergen O r o g e n m a r k s a distinct b o u n d a r y w h e t h e r a steep m o n o c l i n e or an eastward verging thrust front. (ii) In line of the fault, the Billefjorden a n d L o m f j o r d e n fault zones, thrust structures have c o n c e n t r a t e d also with easterly vergence resulting in some thickening. These structures a p p e a r to have been generated t h r o u g h the Paleogene strata or to the n o r t h t h r o u g h decollement zones in Mesozoic and Paleozoic strata. The G i p s h u k e n F o r m a t i o n contains examples o f such bedding-shear as m o n i t o r e d in the ellipsoidal a n h y d r i t e - g y p s u m concretions. Similar facies in the lower gypsiferous strata in the Billefjorden t r o u g h were protected by the N o r d f j o r d e n H i g h ( H a r l a n d , M a n n & T o w n s e n d 1988). The result was d e f o r m a t i o n c o n c e n t r a t e d in the older fault zones (Fig. 4.14; Andresen, H a r e m o & Bergh 1988). (iii) T h e m o s t obvious feature of the Central Basin is the oval shaped o u t c r o p o f the Paleogene strata in which the d e p o c e n t r e shifted s o u t h w e s t w a r d s so that at places, w h e r e the strata are

WEST

EAST

I Tp --'~ f-I (a)FLOWERDALEN-MARMIERFJELLET

Sea level 1000 metres

i

5OO

1'.0

2.0

kilometres of Festningen sandstone

__f••.base ~

f- I

~

-

-

-

-

~

T#r_- - _ ..-,,/.,-I KT ....

~

~

~_._..---..~ KT

s

~'Sea level

(b) A D V E N T D A L E N - ESKERDALEN (north side)

base of C r e t a c e o u s shale

~ f-I (c) REINDALEN (south side)

~ ~t'"-base of Festningen sandstone

Abbreviations: T - Tertiary Ju - Upper part of the Janusfjellet Subgroup JI - Lower part of the Janusfjellet Subgroup

Sea level

KT - Kapp Toscana Formation S - Sassendalen group TP - Tempelfjorden group f-I - fault line

Fig. 4.14. Simplified structural cross-sections of the Central Basin (from Parker, 1966) to show deformation and tectonic thickening above the southern extension of the Billefjorden Fault Zone, f-1 in sections (a), (b) and (e), and the anticline thrust structure diverging to the east, south of the fault in Nordenski61d Land.

74

CHAPTER 4

thickest, they are truncated by faulting (probably transpressive) along the west Spitsbergen orogenic front (e.g. Steel et al. 1981). The structure has been further delineated by seismic studies of the Polish group (Guterch et al. 1978; Guterch, Pajchal & Perchuc 1982; Guterch & Perchuc 1990). It is not so obvious to what extent a Mesozoic basin structure coincided with the Central Basin. Because the basal Paleogene Firkanten Formation unconformably oversteps northwards successive members of Early Cretaceous Carolinefjellet Formation in a seemingly plane erosion surface which itself was followed by southward tilting of Spitsbergen. Late Triassic strata thicken eastwards and Early Triassic strata possibly westwards away from a delta source, so that there is an incipient differential Sassendalen Group subsidence in the west along the orogen. Late Paleozoic structures are best seen emerging northwards, and Early Carboniferous strata reflect the Devonian fault pattern. West of the Billefjorden Fault Zone (BFZ) was the Nordfjorden High bounded on the West by the West Spitsbergen Fault Zone beyond which the St Jonsfjorden Trough is considered in Chapter 9. The Billefjorden Trough east of the BFZ and a similar less pronounced trough further east related to the Lomfjorden Fault Zone accumulated sediments in isolated basins before Wordiekammen Limestone times. It is suggested here that three successive groups of factors operated.

(1) During Carboniferous time especially, but right through Jurassic time at least, the three mentioned fault zones were intermittently reactivated but not in a strike-slip sense. (Chapters 17 and 18). (2) Upward tilting to the north was demonstrably active in late Cretaceous time with the elimination of Mesozoic strata beneath the Paleogene strata at around the latitude of Kongsfjorden so giving the characteristic outcrop pattern with the older rocks in the north. Just prior to this differential uplift was a marked Albian differential subsidence to develop a rapidly increasing thickening of the Carolinefjellet Formation. These two evidences may point to a single tilting operation in which differential mantle heating in the north replaced the long period of slow cooling platform subsidence. (3) The marked localisation of the Central Basin into the Central Tertiary Basin could well have a Paleogene strike-slip component as a partial pull-apart (transtensile) basin in its initial stages. When, by Late Palaeocene and Eocene time transpression, dominated the West Spitsbergen Orogeny compressive stresses were effective throughout the basin area as seen in structures localised especially near the old fault zones. Such compression could have contributed to a final downward buckling to depress the basin further in which sedimentation from the uprising welt filled the space available (Chapter 20).

Chapter 5 Eastern Svalbard Platform W . B. H A R L A N D 5.1 5.2 5.3 5.4 5.4.1 5.4.2 5.4.3 5.4.4 5.4.5 5.5 5.5.1 5.5.2 5.6

with a contribution by SIMON

Platform strata, 75 Igneous rocks, 76 Submarine outcrops, 76 Northeastern Spitsbergen, Wilhelmuya and Hinlopenstretet, 77 Northeastern Spitsbergen: Permo-Carboniferous terrane, 77 Northeastern Spitsbergen: Triassic terrane, 77 Wilhelmoya and Hellwaldfjellet, 77 Islands of Hinlopenstretet, 79 The structure, 79 Southwestern Nordaustlandet, 80 Earlier work, 80 Stratal succession, 81 Kong Karls Land (W.B.H. & S.R.A.K.), 83

The Platform sequence (of younger rocks) i.e. latest Devonian, Carboniferous/Tournasian through Albian (and excluding Tertiary strata on land at least) appears once to have extended east of Spitsbergen in one sheet of which little now remains above sea level. It comprises two supergroups: Bfinsow Land and Nordenski61d Land. The map (Fig. 5.1) illustrates that each of the islands rests on a much larger shelf, no deeper than 100 m and that with the exception

o~

5.6.1 5.6.2 5.7 5.7.1 5.7.2 5.7.3 5.7.4 5.7.5 5.8 5.8.1 5.8.2 5.8.3 5.9

Fig. 5.1. Map of the eastern platform area of Svalbard showing the main place names and principal bathymetric features (adapted from 1:2 000 000 bathymetry chart of the Western Barents Sea, Norsk Polarinstitutt, Oslo 1989; compiled by Kristoffersen, Sand, Beskow & Ohta).

Earlier work, 83 Stratal succession, 83 Barentsoya, Edgeoya and Tusenoyane, 86 Earlier work, 86 Stratal succession, 87 Sub-surface stratigraphy, 89 Biostratigraphy/age estimates, 89 Structure and igneous bodies, 91 Hopeu, 91 Earlier work, 92 Succession from outcrop, 93 Subsurface succession, 93 Correlation of four exploratory wells: Edgeoya and Hopeu, 93

of the outlying islands of Kong Karls Land and Hopen the 100m isobath contains them within the Spitsbergen shallows. In these circumstances, it would appear to be somewhat fortuitous as to what strata are preserved above sea level and it is perhaps remarkable that, if relatively thin strata with a maximum combined and exposed thickness in the area from (Tournaisian) through ?Barremian of c. 2 km, some representatives occur on each island with neither younger nor older rocks. If we plot the TriassicJurassic boundary, say the Rhaetian stage, it occurs at the top of the east Spitsbergen, south Nordaustlandet and south Edgeoya outcrops at heights respectively of about 550, 350 and 500 m a.s.l., at about 0-100 m at Kong Karls Land and at 370-300 m in Hopen. Thus departures from sea level over distances of 350 km N to S and 200 km E to W hardly exceed 500m with average gradients of perhaps 300m in 300 k m - about half a degree. It is therefore reasonable on present evidence exposed above sea level to refer to this as a platform. On the other hand local dips may be very much steeper. One might speculate that the highly resistant Kapp Starostin Formation may be in part responsible for the wide extent of the shallow water around the islands. One striking feature which distinguishes eastern from western Svalbard is the greater degree of Late Jurassic Early Cretaceous basic igneous activity, mainly evident in sills. They are often thick enough to form major topographical features and with evidence of volcanism in the east. Indeed in Kong Karls Land not only do lavas occur but the stratigraphic successions there appear to show more Mesozoic disturbance than elsewhere in Svalbard for this interval.

5.1

H~ y

R. A. K E L L Y

P l a t f o r m strata

In each area discussed the rock units named and employed are explained. The sedimentary (and volcanic) successions as recorded in the separate areas considered here are described in this chapter as follows. Northeast Spitsbergen and Wilhelmoya (Section 5.4) is, for convenience, taken as the area east of the Lomfjorden Fault in which mainly Permian and Triassic strata crop out. Latest Triassic and Jurassic strata are recorded in the tops of the mountains of Hellwaldfjellet and Wilhelmoya. The islands in Hinlopenstretet are mainly basic igneous rocks, presumably late Mesozoic sills and dykes. Southwestern Nordaustlandet (Section 5.5) is in effect an extension of the above mainland area with Permian-Triassic successions but no record of latest Triassic or Jurassic strata. The Paleozoic strata are seen to rest unconformably on Precambrian (Caledonian) basement.

76

CHAPTER 5

Kong Karls Land (Section 5.6) is a small isolated archipelago ranging Late Triassic through Early Cretaceous strata (with lava flows). Jurassic faunas are especially rich. Barentsoya, Edgeoya and Tusenoyane (Section 5.7) is a large, almost exclusively Triassic terrane with three minor Permian inliers but no Rhaetian or younger strata recorded. The two islands are penetrated by late Mesozoic basic sills and such rocks form the thousand islands to the south (Tusenoyane). Two deep wells, Plurdalen-1 and Raddedalen-1 penetrate strata at least well into Early Carboniferous and possibly earlier units. Hopen (Section 5.8) is a singularly linear island again probably exclusively of Late Triassic strata. Two wells (Hopen-1 and Hopen-2) penetrate Early Triassic and Permian to Carboniferous strata. The four wells are compared in Section 5.9.

5.3

Data from the area roughly east of Nordaustlandet, Edgeoya and Hopen and west of longitude 35~ were recorded by Elverhoi & Lauritzen (1984) and yielded a map with predominant Quaternary rock fragments classified mainly as Hecla Hoek in the north around Kvitoya, as chert and silicified limestone (typical of the Tempelfjorden Group) south and east of southern Nordaustlandet and east of Edgeoya, with the remaining larger area yielding mostly sandstones probably Mesozoic. Elverhoi et al. (1989) divided the northwest Barents Sea into six structurally defined elements: 1. 2. 3.

5.2

Igneous rocks

The mainland of Spitsbergen, Nordaustlandet, Kong Karls Land, Barentsoya and Edgeoya are all characterized by basic intrusions. In addition Kong Karls Land exhibits volcanic lavas. The igneous activity spanned ?Kimmeridgian to Barremian time. Evidence also suggests that the rocks belong to one main igneous suite. Some of the characteristics will be mentioned here and not necessarily repeated under subsequent headings. One obvious feature is that the rocks are generally more resistant than their host strata which they protect. They thus crop out in a disproportionally large area for their bulk and often have a significant control of topography. Nearer to sea level the sedimentary rocks have often been removed and many small islands expose only basic rocks. This is typical of the islands in Hinlopenstretet, in Tusenoyane and around Kong Karls Land. It may well be that this is only part of a larger province well exemplified in the less accessible archipelago of Franz Josef Land. The petrology of these basalts, dolerites and occasional gabbros has been studied by relatively few workers because of their relative uniformity and the thorough nature of the early investigations. Historically the rocks were noticed by Nordenski61d with their peculiar 'hyperite' facies. This is softer rock and is not often encountered. Backlund was the first to make a systematic study of these rocks (1907a, b, 1908, 1911, 1920) from the Arc of Meridian Surveys of 1899-1901. The 1907 publication is a monograph on the 'diabases' of eastern Svalbard beginning with a thorough review of previous work, then outlining knowledge of the rocks in Spitsbergen. The principal work is on the Storfjorden rocks and especially those of Edgeoya and Barentsoya with a detailed description of their many occurrences. The main body of the work is petrographic with optical studies of the principal minerals, plagioclase, pyroxene, titano-magnetic, olivine and with notes on apatite and quartz and then with chemical analysis of the rocks including marginal facies. This laboratory work in St Petersburg can hardly be surpassed. The second fascicle (1908) described similar rocks observed in the course of a traverse from Johnstonbukta in Storfjorden to Billefjorden (via the high mountains including Backlundtoppen). Backlund (1907b) had already made a study of the Kong Karls Land and Franz Josef Land material collected on earlier expeditions. A more accessible and convenient study of the dolerite and basalts of Svalbard, and with further chemical analysis (Tyrrell & Sandford 1933) confirms the view of a variety of facies but still with a remarkably uniform character and chemical composition. Analyses compare closely with those from British quartz dolerites and tholeiitic rocks of the British Tertiary Province, with Karoo basalt lavas, Deccan traps and South American Gondwana dolerites. An average composition of four Spitsbergen dolerites was shown as follows: SiO2, 49.2; A1203, 14.4; Fe203, 3.4; FeO, 10.1; MgO, 5.4; CaO, 9.4; Na20, 2.0; K20, 1.0; H20, 1.6; TiO2, 2.9; P20, 0.2; MnO, 0.4; = 100%.

Submarine outcrops

4. 5.

north of Kong Karls Land, gently southward (1-3 ~ dipping strata with main fold south of Kvitoya; Kong Karls Land Structural High with intrusives; south and southeast of Kong Karls Land, structurally disturbed; around Storbanken sediments are flat lying; south of the Olga Basin is a major synform.

The distribution of Jurassic and Cretaceous deposits offshore on the northwest Barents Shelf was initially analysed from grab samples (Dibner 1968; Bjorlykke, Bue & Elverhoi 1978). Much of the shallow bedrock geology has been deduced from the analysis of Mesozoic clasts which occur in Late Quaternary sediments and which are believed to have been locally derived. Subsequently much seismic data has become available as well as information from shallow cores (e.g. Elverhoi & Lauritzen 1984; Gramberg & Pogrebitskiy 1984). The data were reviewed by Elverhoi et al. (1989) and Dowdeswell (1988). Nagy (1973) identified Oxfordian to Hauterivian macrofaunas including buchiid bivalves, belemnites and onychitids in dredged blocks from Svalbardbanken. Edwards (1975) recognized Helvetiafjellet-Carolinefjellet lithologies from blocks from central Svalbardbanken and Janusfjellet Subgroup lithologies on the northeast central part and more widely on the flanks. Bjaerke & Thusu (1976) listed Cretaceous and possible Jurassic palynomorphs from blocks on the south side of Spitsbergenbanken, suggesting the presence of Rurikfjellet and Carolinefjellet formations or their equivalents. Elverhoi et al. (1989) recognized widespread Rurikfjellet Formation especially in fine grained lithologies, although Jurassic and Cretaceous sandstones were more difficult to separate from those of the Wilhelmoya Formation. Early Cretaceous trace- and body fossilrich sandy limestones occurred more distally from the clastic sources, but indicated shallow marine conditions and showed affinities with the Tordenskjoldberget Member of Kong Karls Land. Sideritic cements in the limestones suggested a meteoric water origin of undetermined date. Feldspathic sandstones are comparable to those of the Kong Karls Land Formation and with the Helvetiafjellet Formation of Kvalvgtgen on the east coast of Spitsbergen and are related to the Kong Karls Land volcanics. Dolerites are particularly common northeast of Hopen. ,~rhus et al. (1990) described cored sections from the Bjornoya Basin/east Bjarneland Platform. Here a condensed marine sequence of latest Jurassic to Early Cretaceous (Volgian-Barremian) age was penetrated. Dating of the sequence was by buchiid bivalves which gave latest Volgian to Hauterivian ages (Buchia cf. unschensis, B. cf. volgensis, B. okensis, B. keyserlingi and B. cf. sublaevis) and 47 dinoflagellate taxa which gave Volgian to Barremian ages. Other bivalves, brachiopods, cirripedes and foraminifers were also recognised. Although Late Cretaceous sediments are not recognized in the northwest Barents Shelf, they are present under Cenozoic cover in the Nordkapp Basin, the Tromso Basin/Senja Ridge area, Bjornoy Basin and Hammerfest Basin in the southwest Barents Sea (Faleide, Gudlaugsson & Jacquart 1984). Late Cretaceous sediments are also known from Franz Joseph Land where a Cenomanian transgressive sandstone occurs, and in the northeast Barents Sea (Dibner 1970, 1978). Erratics containing inoceramid bivalves have been brought onshore in southern Novaya Zemlya (Cherkesov & Burdykina 1981).

EASTERN SVALBARD PLATFORM

5.4

Northeastern Spitsbergen, Wilhelmoya and Hinlopenstretet

The Lomfjorden Fault Zone is a convenient western boundary to this area which is considered in three parts (1) the Permian-Carboniferous outcrops east of that fault zone from Lomfjordenhalvoya, through Olav V Land to Akademikerbreen. (2) The Triassic strata of eastern Olav V Land and Wilhelmoya (3) the islands of Hinlopenstretet (and southeast of Wilhelmoya). Much of the mainland is ice-covered and the islands are separated by water. The result is that the three contrasting rock types: Mesozoic dolerites; Mesozoic strata (mostly Triassic); Permo-Carboniferous strata while easy to identify, even from a distance, are hardly anywhere exposed in contact. Moreover, the area is relatively remote and while the rocks were long known in the broad outline indicated above it was only since about 1953 that more detailed studies became available. From the above distribution of three rock types the early maps of this area were constructed e.g. by Nathorst (1910), Frebold (1935), Orvin (1940). The western limit treated in this section approximates the eastern limit of the early Cambridge exploration of Ny Friesland (e.g. Harland & Wilson 1956 and Harland 1959). Indeed the complex fault pattern in Lomfjordenhalvoya with inliers of Hecla Hoek surrounded by Permian and Carboniferous outcrops is separated in this treatment according to age. Hence there are two distinct terranes, Permo-Carboniferous and Triassic separated by wide expanses of ice except west of Hinlopenbreen and at the southwestern head of Negribreen.

5.4.1

Northeastern Spitsbergen: Permo-Carboniferous terrane

The earliest detailed succession is due to Cutbill (1968). His maps of this terrane, largely followed on a smaller scale by Lauritzen & Worsley (1975), are redrawn in Fig. 5.2, based on earlier C.S.E fieldwork and the later work in conjunction with Amoseas. Cutbill's stratigraphic scheme, modified only according to rank of units to be consistent in this volume with SKS recommendations, is as follows. It is based on his measured sections at Polarisbreen, Komarovfjellet and Malte Brunfjellet. Lauritzen & Worsley from work in the Lomfjorden area added further sections at Mjolnerfjellet and Eremitten and revised some of Cutbill's conclusions. The following account is intended to combine and summarise those data from different sections and interests: Cutbill giving biostratigraphic data and Lauritzen & Worsley lithological.

Tempelfjorden Group. As in most of Spitsbergen, the sole representative of the Tempelfjorden Group is the Kapp Starostin Formation. Kapp Starostin Formation, 140+ m (mid to Late Permian). Complete exposure was nowhere recorded; but at Eremitten more intermittent resistant beds comprise about 50% of the succession where a highly siliceous biomicrite bed is overlain by silty shales of presumed Triassic age. Typical lithologies reported are sandy biosparites in which the bioclastic fraction is dominated by brachiopod debris. Glauconite was seen in most specimens suggesting correlation with the Hovtinden Member.

Gipsdalen Group Gipshuken Formation. 140-179 m (Artinskian). Similarly perhaps less than half of the succession is exposed with the harder beds only being described, the most distinctive rock being a brecciated, cavernous dolostone suggestive of evaporites and dolomitic micrites. Wordiekammen Formation. This carbonate unit extends from the Central Basin with similar facies but is somewhat thinner. Tyrrellfjellet Member. 100 to c. 130m. (Asselian & Sakmarian). The upper part is poorly exposed and may be calcareous flaggy sandstone and the main and lower part is of elastic dolostones. Rugofusulina arctica, and Schwagerina anderssoni were recorded at the base. Cadellfjellet Member. c. 40 m (Gzhelian) More of this unit is exposed and largely sandy limestone and biomicrite, the latter containing Quasifusulina longissina and Montiparus montiparus. Malte Brunfjellet Formation. 60-70m (Late Moscovian). Complete sections are exposed and comprise biomicrites in the main upper part with fusiline faunas and calcareous sandstones in the lower part Beedeina

77

rockymontana, Wedekindellina dutkevichi, Pseudostaffella sphaeroidea are characteristic. Cutbill suggested that this, his Minkinfjellet Formation, represents a marine transgression because there appears to be no equivalent to the Ebbadalen Formation here. It does, however, occupy a basin related to the Lomfjorden Fault Zone and is so distinguished from the Minkinfjellet Formation of the Central Basin.

Billefjorden Group Mumien Formation. A basin equivalent of the Mumien Formation is present, but no representative of the lower (Horbyebreen) formation of the Billefjorden Group is recorded so that the succession is not only thinner but less complete than in the Billefjorden trough. Cutbill recorded only about 40 or 50 m of sandstone beneath his Minkinfjellet Formation resting on Hecla Hoek strata and none at Malte Brunfjellet. Lauritzen & Worsley argued for a greater thickness, partly on the basis of observations in the Lomfjorden area and partly by reinterpreting as Mumien Formation the lower part of Cutbill's Minkinfjellet Formation. The argument seems reasonable so that about 100 m is suggested. The formation contains spores of the Aurita zone assemblage (Playford 1962/63) suggesting a Visean (and possibly Serpukhovian) age.

5.4.2

Northeastern Spitsbergen: Triassic terrane

This terrane was originally almost u n k n o w n territory, and previously referred to as Terre Glac6e Russe (see Fig. 1.7), has been included in the relatively newly named Olav V Land. It is largely dominated by an ice sheet with glaciers draining into the sea through Triassic hills at its margins. Its western boundary is the range of high mountains of Hecla Hoek rocks and the strip of Permo-Carboniferous rocks. It so happens that the two highest mountains to the east are at Hellwaldfjellet and Wilhelmoya. These preserve Rhaetian and Jurassic strata in their tops and so have received more attention. Accordingly these two areas are reported in the Section 5.4.3. The southern boundary is at Negribreen, the largest glacier reaching the sea in Spitsbergen. Backlund (1908) traversed the ice from north of Negribreen westwards to Nordenski61dbreen (Storfjorden to Billefjorden) and Holland (1961) reconnoitred the southern margin of Negribreen southwestwards through to Tempelfjorden similarly traversing central Spitsbergen at its narrowest. At northern Hahnfjella, south of the Negribreen outlet, Holland recorded a Triassic succession which, although outside the terrane as defined, may be the only measured section in the general area. Abbreviating somewhat, the succession was recorded thus: 9 m (at summit) thin bedded blue shales with brittle fossiliferous limestone nodules with Arctoceras (cf. A. O'bergi or Flemmingites; Halobia cf. zitteli, Daonella cf. lindstomi etc.; 12m alternating blue shales with concretionary limestones; 12 m paper thin blue shales with occasional iron-stained limestone nodules; 19m blue shale down to limestone shales interbedded with limestone and limestone concretions; 16m thin grey shales; 68 m grey and grey and black shales with Arctoceras sp. and Keyserlingites sp; 46 m thin bedded, grey fawn and grey baked shales to dolerite intrusion about 120m a.s.1. The lithologies and fossil indentifications by L.F. Spath would correlate with the Botneheia and Sticky Keep formations (Sassendalen Group).

5.4.3

Wilhelmoya and Hellwaldfjellet

The importance of Wilhelmoya was perhaps first realised by de Geer (1923) who reported a succession through Early Kimmeridgian, late Lias, latest Triassic and Carnian strata. This was used and discussed by Frebold in his 1935 synthesis and notably Arkell (1956). From a visit by an Oxford party in 1951 Holland (1961) described a sequence of 13 beds. The rocks were described in detail but the fossils identified, mostly bivalves, left the ages indeterminate. The relation between this work, that of De Geer and the opinion of

78

CHAPTER 5

Fig. 5.2. Geological map of eastern Ny Friesland, with representative cross-sections, showing the distribution of Carboniferous and Permian deposits (rearranged after Cutbill 1968).

EASTERN SVALBARD PLATFORM Frebold were discussed. The undoubted Jurassic above Triassic strata here led Sandford to postulate Jurassic rocks at the top of the Triassic succession in Nordaustlandet. In 1961 the section was reconnoitred by a party commissioned by American Overseas Petroleum Limited (Amoseas) and was noted in Buchan et al. (1965, Section JDL21). Klubov (1965) first reported Rhaetian (beds 23-27) in his succession ranging from Carnian to Kimmeridgian rocks from the top of Wilhelmoya. However, his measured succession for the island is not supported by later work possibly because he did not take account of land slips. Worsley (1973), from visits in 1970 and/or 1971, described the uppermost strata and made a case for a new Wilhelm~ya Formation to include similar strata in Hopen and the Brentskardhaugen Bed of Spitsbergen. Smith (1975) described the whole in situ section on the island from a survey with CSE in 1969. He incorporated Worsley's new unit name but as a member within the De Geerdalen Formation which had already been defined to include the Brentskardhaugen Bed at the top. Accordingly in Wilhelmoya and Hellwaldfjellet he named the rest of the De Geerdalen Formation, i.e. above the Tschermakfjellet Formation, as another member (Uleneset) 254 m thick. However, the case is argued by Worsley & Heintz (1977) that the De Geerdalen Formation should be redefined and reduced so as to allow this new formation above it. A consequence is that the reduced De Geerdalen Formation is indeed Smith's Ulaneset Member which no longer needs that name, the Kapp Toscana group thus comprising the rocks as originally defined but in three rather than two formations. Both Worsley and Smith visited similar successions from Wilhelmoya and Hellwaldfjellet on the mainland to the southwest. Smith described the whole sections and Worsley the proposed Wilhelmoya Formation. The following description combines the two.

Wilhelmeya and Hellwaldfjeilet. The Hellwaldfjellet section on the mainland is similar, Hellwaldfjellet being only 35 km to the south, so the description is combined, where there are differences the symbols W and H respectively identify which section is referred to. Smith (1975, pp. 486-487) plotted both sections in full.

Agardhfjellet Fm. Black shales with ammonites of Oxfordian to Kimmeridgian age are separated (W) or capped (H) by a dolerite sill. Ammonites from these (W) include tenuilobatus zone of Arkell (1956, p. 505) and would correlate with middle Agardhfjellet Member to the east (Parker 1967). Klubov (1965a, 1970) reported a bed of clay with belemnites and two foraminiferal assemblages: Bajocian-Bathonian and Callovian. His exposure probably represents a slipped mass amongst others from the Agardhfjellet Formation. The total thickness of sediments above is about 10 m (W) and 35 m (H). Wilhelmoya Fm Turalingodden Mbr, 60m (W) 54m (H), named from the slopes above Tumlingodden, mainly comprises friable fine-grained yellowish grey sandstones. The boundary between the Wilhelmoya and Janusfjellet formation is marked by a thin conglomerate of fine quartz pebbles (H). The top 10 m has pockets of phosphorite nodules including Toarcian fossils similar to those found in the fauna of the Brentskardhaugen Bed. 28m sandstones with a basal pebble bed and winnowed fossils (including belemnites) but absence of plant fossils contrasts with the lower sandstone. A 4 m bed of clay 30 m from the base. Thin black coal lenses and black shales occur within the lower 28 m with tree trunks up to 20cm thick in a metre section are preserved within sandstone concretions. Thin sandstone layers and pockets of quartz and chert pebbles. About 10m from the base is a cliff of well-consolidated sandstone with tabular cross-bedding which indicates westwards sediment transport. Transitional Mbr, 33 m (W) 5 m (H). Dark yellow friable flaggy siltstones with intercalated beds of more resistant cliff-forming olive flags (which weather purple) dominate the upper part and decrease downwards. Harder beds contain mud flake conglomerates, mica and plant debris. The upper boundary is obscured because of the soft overlying beds. Bjornbogen Mbr, 19m (W) 33m (H), named for the bay on the south of Wilhelmoya, is formed of thick dark grey shale which contains winnowed

79

interbeds of plesiosaur bones. Clay ironstones occur with a rich bivalve fauna. Basal Mbr, 7 m (w), is of sandstone. The base of the formation (W only) is marked by a bed with pebbles, sandy limestones, phosphorites and quartzites in a ferruginous silty limestone matrix (W & H). For reference purposes it would have been more convenient to include the Transitional Member as a division in the Tumlingodden Member and the Basal Member as basal beds of the Bjarnbogen Member and this was done later. De Geerflalen Fro, 384 m (W), 401 (H). The thickness includes a 10 to 30 m dolerite sill. The rocks were described by Klubov (1965). They consist predominantly of siltstone and fine-grained sandstone with occasional beds of better-cemented, sometimes calcareous, coarser sandstone. The upper 154 m contains several horizons of shell fragment limestone. Carbonaceous plant material and thin coal seams occur in the lower 200 m. At the base of the Formation is a prominent sandstone bed above the siltstones and shales of the Tschermakfjellet Formation. Invertebrate fossils are rare. Klubov recorded bivalves Lima, Megalodon, Ostrea and Mytilus of shallow marine or non-marine conditions and suggested a Norian-Carnian boundary 221 m from the base of the formation. However, Smith's palynological evidence suggests that the strata are largely Norian. The formation at Hellwaldfjellet is generally sandier, less consolidated and without shell fragments and so less distinct from the Wilhelmoya Fm, (Smith 1975). Of 20 or more samples through the whole succession investigated palynologically in 1961 and 1969 only three gave significant results and these came from the De Geerdalen Formation roughly 337m 166m and 73m from the base of the formation. They were all concluded to be of Norian age (Smith 1975) and to compare with the lower part of the Iversenfjellet Formation of Hopen. Tsehermakfjellet Fm 34+ m to SL (W), ?70 m (H). Siltstones with siderite concretions and Halobia bivalves occur in a disconnected outcrop (H) and from near the base (W) Klubov reported Nathorstites spp. and Halobia zitteli, and higher up Sirenites cf. nanseni, all of which confirm a similar age for the strata. A discussion of these and other finds with conflicting assessments conclude with an Early Carnian estimated age for the formation in Withelmoya (Smith 1975). Botneheia Fro. An exposure of a few metres at the shore by Hellwaldfjellet of silty shale yielded ammonites in 1969: ?Gymnotoceras and ?Hollandites with bivalves indicating an Anisian age (Smith 1975).

5.4.4

Islands of Hinlopenstretet

Whereas Wilhelmoya preserves a Mesozoic succession with incidental dolerite sills, all the other (much smaller) islands, except one between Spitsbergen and Nordaustlandet, have been eroded to the extent that only their igneous rocks are seen. The exception is the largest of the islands, Wahlbergoya where two Permo-Carboniferous outcrops appear on the 1:500 000 map of Hjelle & Lauritzen 3G (1982). Moreover, Korchinskaya (1972a) identified the Arctoceras blomstrandi zone of Spathian age on the island. Tyrrell & Sandford (1933) described many of the known dolerite occurrences and noted that opposite the largest sill in the coast south of Kapp Fanshawe are islands which may well be an extension of it. They suggested that these are fragments of a huge laccolith, possibly of cedar tree type. On and off the Nordaustlandet coast are the massive intrusions at Diabastangen (Hyperite Point) and the Gylden islands. Some dolerite islands further south are surrounded by deep water and form an irregular incomplete ring. This and other arrangements suggest that the islands may be relics of vertically sided intrusions and not irregularly sunken sills (Tyrrell & Sandford 1933, p. 292).

5.4.5

The structure

The dominant feature of this area is the western boundary which is the Lomfjorden (Agardhbukta) Fault Zone and the Hecla Hock

80

CHAPTER 5

synclinorium which is occupied by the strait separating Spitsbergen and Nordaustlandet. Otherwise the platform strata are generally flat-lying.

5.5

Southwestern Nordaustlandet

Nordaustlandet is mostly covered by ice and the exposures are mainly coastal. The platform succession is exposed only in the southwest sector of the island, almost all south of Wahlenbergfjorden. The same three rock types are distinctive from the air namely the black dolerite intrusions, the less resistant dark coloured Triassic strata and the paler harder Permian and Carboniferous strata. Figure 5.3 summarizes the outcrops from a number of independent investigations.

5.5.1

Earlier work

Because it was relatively easy to distinguish Triassic and Permian and/or Carboniferous strata the approximate occurrences were

already plotted as on the maps of Nathorst (1910), Kulling (1934), Frebold (1935) and Orvin (1940). However little was published of the stratigraphy till later. Triassic material from the earliest known outcrops at Torellneset collected in 1931 comprised Saurian remains, bivalves and ammonites (Kulling 1932, 1934). The molluscs were identified by E. T. Tozer and reported briefly by Tozer & Parker (1968) and more fully later (Tozer 1973). These identified late Scythian and Anisian ages. Oxford parties on expeditions to Nordaustlandet in 1923 (Sandford 1926), 1949, 1951 and 1953 described both Hecla Hoek and younger rocks (Thompson 1953; Holland 1961). Of the latter the reports of observations by glaciologists interpreted by Sandford (1963) establish a clear unconformity at Idunfjellet where Late Carboniferous and Permian strata rest on Hecla Hoek rocks. This together with a small outcrop of ?Carboniferous sandstones at Brageneset to the west is the only occurrence of the younger rocks north of Wahlenbergfjorden. South of that fjord and at its mouth De Geer (1923) had reported 200m of Productus Limestone overlying 42 m of Spirifer Limestone. Holland, in a posthumous work edited by Sandford (1961), described Mesozoic and Late Paleozoic rocks in both northeastern Spitsbergen and Nordaustlandet. These Permo-Carboniferous strata

Fig. 5.3. Geological map of southwestern Nordaustlandet showing the known extent of Phanerozoic outcrops. Key to numbered localities: (1) Bodleybukta; (2) Eltonbreen; (3) Ericabreen; (4) Mariebreen; (5) Palanderbreen; (6) Rosenthalbreen; (7) Svartberget; (8) Torellnesfjellet; (9) Winsnesbreen. Compiled from Geological Map of Svalbard 1:500 000 sheets 3G (Hjelle & Lauritzen 1982) and 4G (Lauritzen & Ohta 1984) and from SKS Upper Carboniferous Report Map 3a (Dallman et al. 1996).

EASTERN SVALBARD PLATFORM

Kapp Toscana Grp (?) Wilhelmoya Fro. It is not impossible that this formation is represented at the highest part of the succession at Torrellnesfjellet which was inaccessible to Lowell (1968) owing to ice cover. Sandford in Thompson (1953) and in Holland (1961) suggested the possibility that the highest strata might be Jurassic, on the basis of the presence of black shales at Torellnesfjellet and lithological comparison with samples from Wilhelmoya. If this were so, however, the De Geerdalen Formation might be exceptionally thin. De Geerdalen Fm. 40?+50m. Lowell 1968 described the top of his succession as largely sandstone scree: grey brown, some slightly greenish, faintly limonitic calcareous, finely laminated and platy. Sassendalen Gp Barentsoya Fro. 118 m Lowell 1968 described a uniform sequence of grey shale with thin platy beds of siltstone weathering brown to yellow which are calcareous with 'occasional fontainbleau' structure (i.e. with matrix of larger enveloping calcite crystals). He reported the presence of brachiopods. Cutbill (CSE) had already identified these rocks as belonging to the Sassendalen Group. The name Barentsoya Formation is applied here because, with the exception of some interbedded limestone with chert in the lower 20m the whole was described as undifferentiated. In so far as the three formations, which define the Sassendalen Group in Central Spitsbergen, are not distinctive here, the Barentsoya Formation is applied from Barentsoya and Edgeoya where the three formations also are not readily distinguished. Kulling's collection was from two levels and he suggested that the upper level was the Upper Saurian Niveau. The underlying level 'Daonella Niveau' was exclusively of bivalves (Posidonia arenea Tozer) which is restricted to the later Spathian Zone (Keyserlingites subrobustus zone). This correlates with the Sticky Keep Formation of Spitsbergen. Fossils from Kulling's upper horizon of typical Botneheia facies include nine ammonite species and the ichthyosaur Phalardon nordenskioldi was identified by Stensi6 (Kulling 1932). These give a certain middle Anisian age and possibly an Early Anisian age also. In any case they confirm correlation with the Botneheia Formation in Spitsbergen. Tempelfjorden Gp Kapp Starostin Fm. Lauritzen (1981) distinguished two limestone members in the otherwise siliceous sequence, the basal Voringen Mbr (recognised elsewhere), and the Palanderbukta Mbr (Fig. 5.4). This led to the naming of the remainder of the alternating normal siliceous sequence with the names from central Spitsbergen thus: Hovtinden Mbr: 27 m of yellow and grey cherts at the top with subordinate sandstones; glauconitic. Then predominantly sparitic limestones, in places dolomitized, with chert bands and nodules. Palanderbukta Mbr: 17.5m characterized by glauconitic and fossiliferous limestones, with pure chert beds. Svenskeega Mbr: 37.5m of chert-dominated sequence with relicts of calcareous beds or nodules. Intraformational conglomerates and erosion horizons at the top.

in N o r d a u s t l a n d e t were described f r o m m a n y localities and m a p p e d as such with a large o u t c r o p occupying m o s t of Gustav A d o l f L a n d (south of W a h l e n b e r g f j o r d e n ) and excepting the Triassic o u t c r o p extending eastwards a n d inland f r o m Torellneset. There the succession was described generally as (4)

Upper chert, Marble and Limestone Series with Stenopora ramosa 30+ m (3) The Rough Limestones, with S. ramosa, Spiriferella cf. lita etc. 40 m. (2) The Cliff Limestones, with Spiriferella cf. polaris, etc. 55 m (1) The Calciferous Sandstone Series with Productus (Horridonia) timanicus, 45 m. Base not seen. Fuller descriptions of each of these units was given with fossil lists for each but lacking detailed maps or sections this pioneer reconnaissance is difficult to follow. The Mesozoic results were largely published in T h o m p s o n (1953) with a postscript by Sandford. The next field w o r k was in the early 1960s w h e n CSE c o o p e r a t e d with A m o s e a s using helicopter support. Cutbill extended his study of P e r m i a n and C a r b o n i f e r o u s stratigraphy. H e n o t e d Triassic successions comprising u p p e r m o s t strata which he regarded as K a p p T o s c a n a and a lower 150m of shales as Sassendalen G r o u p above K a p p Starostin (especially Voringen M e m b e r ) overlying the G i p s h u k e n F o r m a t i o n , with basal Hftrb a r d b r e e n M e m b e r (Cutbill & Challinor 1965). Lowell (1968) of A m o s c a s filled in m o r e detail a n d m e a s u r e d two Triassic and P e r m i a n sections as well as giving a m o r e detailed o u t c r o p map. Lauritzen (1981), w o r k i n g f r o m Wahlenbergfj orden, addressed only the Late Paleozoic succession a n d with m o r e m e a s u r e d sections. This resulted i.a. in extending the age of the lower p a r t of the succession back to M o s c o v i a n time. His w o r k was also incorporated in the 1:500 000 geological m a p 4 G (Lauritzen & O h t a 1984). M a n g e r u d & K o n i e c k i (1991), investigating the P e r m i a n rocks of N o r d a u s t l a n d e t palynologically, r e c o r d e d sixty forms ranging mostly in the ?Gipsdalen G r o u p . H o w e v e r , little was a d d e d to previous k n o w l e d g e as to their age. Nevertheless a useful synthesis o f m e a s u r e d sections by M. B. E d w a r d s with those of Lowell & Lauritzen (already m e n t i o n e d ) shows the position of their samples. A t the same time an i m p r o v e d sketch m a p of W a h l e n b e r g e t and P a l a n d e r b u k t a distinguished clearly the T e m p l e f j o r d e n a n d Gipsdalen G r o u p outcrops.

5.5.2

81

Stratal succession

K n o w l e d g e has c o m e s o m e w h a t piecemeal. The succession is s u m m a r i z e d in Fig. 5.4.

Nordaustlandet Cutbill & Challinor (1965) KAPPTOSCANA (?~chermakqtFm)

This work (following SKS 1996)

Lauritzen 1981

Lowell1968

De Geerdalen Fm

KappToscana Fm

Barentsoya Fm

SASSENDALEN GROUP (undifferentiated)

Kapp

Kapp

Starostin

Starostin

Svenskeegga Mbr

Fm

Voringen Mbr

Palanderbukta Mbr

Kapp Starostin

Svenskeegga Mbr

Fm

Gipshuken Fm Zeipelodden Mbr

Carbonate Unit

DICKSON LAND

Idunfjellet Mbr Nordenski61dbreen

H&rbardbreen Mbr

TEMPELFJORDEN GP

Voringen Mbr

Gipshuken Fm Gipshuken Fm

SASSENDALEN GP

Hovtinden Mbr

Hovtinden Mbr

Fm

KAPP TOSCANA GP

Fm

Idunfjellet Fm ]

Wordiekammen Fm

H&rbardbreen H&rbardbreen Mbr L Fm

SUBGP

CAMPBELLRYGGEN SUBGP J

Fig. 5.4. Stratigraphical schemes for Permian and Triassic units of Nordaustlandet.

82

CHAPTER 5

Voringen Mbr: 9 m of sandy biosparite with conglomerate layers. Erosion surfaces, cross-bedding and bioturbation are common. Coal fragments occur at the base, and fossils are abundant. It rests on a clearly eroded surface of Gipshuken Fm. Lauritzen interpreted the Voringen Mbr as a transgressive shallow marine unit, probably near-shore as indicated by erosion surfaces. The change to cherts indicates a switch to an open shelf environment and hence subsidence, but this reverses at the top and into the Palanderbukta Member which is once again a shallow marine unit with periods of erosion. Basin deepening occurred at the transition to the Hovtinden Member with biosparite deposition and then further cherts, which are commonly spiculitic.

Gipsdalen Gp Gipshnken Fro. Cutbill & Challinor (1965) described the Gipshuken Fm with the H~trbardbreen Mbr (Formation) at its base. Lowell (1968) followed this section referring to the rocks between that member and the Kapp Starostin Fm as the Carbonate Unit. This might have merited a separate name had not Lauritzen (1981) shown that biostratigraphically the lower part of the Carbonate Unit belonged to the Nordenski61dbreen Fm (Wordiekammen + Minkinfjellet fms) and named it the Idunfjellet Mbr (see below). Thus the Gipshuken Fm is equivalent only to the upper part of Lowell's Carbonate Unit. Lauritzen (1981) described the formation from Zeipelfjella (Fig. 5.5.2) and Zeipelodden in the Wahlenbergfjorden area. The formation reaches a maximum thickness of 121 m there, with a clearly identifiable member (the Zeipelodden Mbr) at the base. The member is a 8 m thick unit of limestone breccias and laminated algal limestones with algal mats, crusts and chert nodules. The remainder of the formation consists of well-bedded limestones and dolomites with chert nodules. He interpreted the formation as a lagoonal deposits with some tidal influence, especially the basal member which was probably intertidal. Mangerud & Konieczny (1991) investigated the palynology of the formation in the area. Although the middle and upper parts did not yield age diagnostic forms, the lower part was given a Sakmarian to Artinskian age along with the underlying Idunfjellet Fm. Idunfjellet Fm (Lauritzen 1981) Up to 150m thick, the Idunfjellet Fm consists of limestones and dolostones with minor sandstones (Fig. 5.4). It is the northeastern equivalent of the Wordiekammen Fm. The carbonates contain chert nodules; the sandstones cross-bedding and intra-formational conglomerates. The formation was deposited on an open marine shelf, some parts in the inter-tidal zone, with a terrigenous input from a nearby land mass. Periods of non-deposition were common, as the formation represents the entire late Carboniferous to early Permian time-span. Fossils have mostly been destroyed by dolomitization; however some from the base indicate a Moscovian age for that level and palynomorphs indicate a Sakmarian-Artinskian age. The 135.4 m thick type section consists of limestones and dolomites with a quartz content varying from 6 to 21%, especially in the lower l0 m, which are well-bedded sandy dolostones. The sand is the same grain size as in the Hftrbardbreen Fm below. Chert nodules are abundant in some beds, which preserve bioclastic remains. Silicification tends to follow certain horizons and the cherts are sometimes associated with crusts of hematite and thin layers of goethite. Erosive sandstones occur, containing thin intraformational conglomerates and cross-bedded units. Dolomitization has destroyed most fossil fragments, except in some horizons where they are abundant, especially 10m above the base in a distinctive partly dolomitized and silicified biosparite which contains a variety of fossils. Brachiopods, gastropods, echinoderms, cephalopods, foraminifers and ostracodes occur. The biosparite horizon ! 0 m above the base has been dated as Moscovian on the basis of the foraminifera Palaeojusulina trianguliformis and several Bradyina species (Lauritzen 1981). Palynological investigations of the formation indicate a Sakmarian to Artinskian age (Mangerud & Konieczny 1991), and hence it would appear to have a long time span. This is consistent with the common erosion surfaces and intraformational conglomerates, which imply reworking and periods of non-deposition. Also, the overlying Gipshuken and Kapp Starostin fms have been correlated with the same formations in the rest of Svalbard on the basis of lithology. Thus, the Idunfjellet Fm and the basal Hftrbardbreen Fm together appear to represent the Wordiekammen and Minkinfjellet fms respectively. Lowell (1968) described his Carboniferous unit (Idunfjellet and Gipshuken Fro, i.e. above the Dickson Land Subgroup) as being a condensed sequence compared with the much thicker equivalent succession in Central Spitsbergen. This argument is strengthened by the large age span for these rocks as indicated above. However, Lowell followed Cutbill when including these rocks within the Gipsdalen Formation.

Fig. 5.5. Sketch map of Svenskoya, Kongsoya and Abeloya (redrawn with permission of Cambridge University Press from Smith et al. 1976).

H~rbardbreen Fm. This unit at the base of the Permo-Carboniferous sequence in the Nordaustlandet area, was, in the absence of datable fossils, assigned to the base of the Gipshuken Fm by Cutbill & Challinor (1965). Lauritzen (1981) redefined it, after detailed studies, in the section at Idunfjellet on the opposite side of Wahlenbergfjorden from H~rbardbreen. It lies conformably below the Idunfjellet Mbr and its base is a strong angular unconformity with pre-Devonian (Hecla Hoek) rocks. There is evidence that the basal conglomerates are laterally replaced westwards and on the south side of Wahlenbergfjorden by sandstones (e.g. at Hftrbardbreen). The formation is a 15.5 m thick unit, consisting of light, yellowish-grey, fine-medium quartzitic sandstones with some conglomeratic horizons. Crossbedding is locally present and the whole unit becomes finer upwards. There is a basal conglomerate 8m thick which unconformably overlies the preDevonian peneplain surface. The clasts are mostly of dolomitic mudstones,

Fig. 5.6. Sketch map of Svenskoya showing principal topographic features and geology (redrawn with permission of Cambridge University Press from Smith et al. 1976).

EASTERN SVALBARD PLATFORM but also clasts of the underlying red mudstone commonly occur. The conglomerates appear to be locally developed, with lateral replacement by sandstone. The formation has no fossil record, but a Moscovian transgression has been described in Ny Friesland and central Spitsbergen (Cutbill & Challinor 1965) and this unit may therefore be the lateral equivalent of the base of the Campbellryggen Subgroup there.

5.6

Kong Karls Land

Kong Karls Land is a group of three main islands (Fig. 5.5) and many smaller ones and is the easternmost substantial land in the Svalbard archipelago. It is generally surrounded by sea ice even through the summer so that visits have been limited either by ship in favourable seasons or more recently by helicopters from icestrengthened ships. Apart from the ubiquitous Quaternary cover the rocks are entirely Mesozoic. Svenskoya is the westernmost island, 20 km by 6 km (Fig. 5.6). Most of the island is of beach deposits but there is an axial N-S ridge the length of the island rising from Kukenthalfjellet, 180 m in the south to Dun~rfjellet, 250 m in the north. The main island Kongsoya (Fig. 5.7) is central and about 40 by 8 km, but of irregular outline. It divides naturally into five terrains from west to east (1) a western complex of fiat topped hills, (2) a neck of low ground, raised beaches and blown sand, (3) a low lying plain of basalt, (4) a low hilly area of basalt with a small ice cap, Rundisen, and (5) one main hill (Johnsenberget) sloping down from 240 m to low cliffs at the east coast. The eastern irregular island, Abeloya is not more than 4 k m across, mostly less than 5 m above sea level and formed of basalt.

5.6.1

Apart from occasional visits the first, and for many years the only, proper geological investigation was by the Swedish expedition of 1898 led by Nathorst (1901, 1910; Pompeckj 1899; Bliithgen 1936) (Fig. 5.8). This gave a topographic base and a geologic outline. The uppermost strata are basalts and plant beds. These were shown to truncate and overlie three blocks, normally faulted, from west to

KONGSE

east: (1) Eastern Svenskoya of Volgian, Kimmeridgian, Oxfordian strata; (2) A central block (eastern Svenskoya and western Kongsoya) of Callovian over Bathonian strata and (3) the main body of Kongseya of Valanginian, Late and Early Volgian, Kimmeridgian strata. In 1930 the Norwegian expedition to Franz Josef Land in passing confirmed that Abeloya was entirely igneous. A new era in geological exploration of these often ice-bounded islands began with the use of helicopters. In 1969 a Cambridge reconnaissance of the islands of eastern Svalbard was supported by Norske Fina. Sections were recorded at most cliff exposures of Kongs Karls Land and the structure and stratigraphy were described (Smith et al. 1976). Norsk Polarinstitutt geologists visited the islands in 1973 and they found an exposure lower than previously recorded in northwest Kongsoya (Worsley & Heintz 1977). This was supplemented by palynostratigraphy (Bjaerke 1977, Bjaerke & Dypvik 1977). The material collected in 1969 continued to yield results (e.g. Rawson 1982; Doyle 1986, 1987; Doyle & Kelly 1988; Ditchfield, 1997). The rock units of Kong Karls Land were defined by Smith et al. (1976) and related to those of Pompeckj (1899), Nathorst (1901) and Bliithgen (1936), with one addition and one modification proposed by Worsley & Heintz (1977) as shown in Fig. 5.8. Their distribution is shown on the maps of Svenskeya (Fig. 5.6) and Kongseya (Fig. 5.7). The strata were described and measured in 15 or more sections (Smith et al. 1976) Because of the variety of facies including lavas even within one island the units were named independently as members within three distinct units. The Kong Karls Land, Kongseya and Svenskoya formations. However the Wilhelmoya Formation (Worsley 1973) has priority over the name Svenskoya and is applied here.

5.6.2

Earlier work

83

Stratal succession

Adventdalen Group. The correlation of the principal stratigraphic sections of Svenskoya are given in Fig. 5.9 and of Kongsoya in Fig. 5.10. Kong Karls Land Fm. This is the uppermost unit comprising plant bearing sandstones interbedded with lavas. It approximates stratigraphically to the Helvetiafjellet Formation in Spitsbergen which also contains evidence of vulcanicity and has been taken to be of Barremian age (Parker 1967).

A ~

Ose~

Notcl~s~ynlim

Kaoo Otnva

..

0 I

~

5 =

i

10 k m I

, - -

Fig. 5.7. Sketch map of Kongsoya showing principal topographic features and geology (redrawn with permission of Cambridge University Press from Smith et al. 1976).

84

CHAPTER 5

Schemes of rock units Early age estimates

Pompeckj & Nathorst Smith, Harland, Hughes & Picton 1976 with proposals* by Worsley & Heintz 1977 1899 1901 KONG KARLS LAND

SVENSKOYA

Current age estimates

KONGSOYA ~ X,BELWESTERN EASTERN OYA

13 basalt Kong

Member

H&rfagrehaugen Member

Johnsenberget Member

Karls

sandstone

sandstone

sandstone

Land Formation

65.5 m (Beds 10 & 12)

14 m (Beds 10 & 12)

30 m (Bed 10)

K0kenthalfjellet

12 plant bearing layer with Phoenocopsis Neocomian

11 basalt

c0 Barremian

10 plant bearing layer

Late

Volgian I=nrly Early Kimmeridgian

g Bed with Aucella keyserlingi 8 Bed withAucelta fischeriana and A. volg,,ensis eto 7 Bed withA, pallasi 6 Bed with Cardioceras. andAucella sp.

s./.

Tordenskjoldberget Member limestone 30 m (Bed 9)

~" ~ c

Kongs~ya Formation

5 Bed with A. bronni vat. lata Oxfordian Middle & Late 4 Bed with Cadoceras and belemnites Callovian - 3 Bed with Macrocephalites (=Arcticoceras Early arcticus) & belemnite~ Late

Fig. 5.8. Stratigraphic schemes of rock units with age estimates. In this work the units are described as by Smith et al. (1976) and accepted as shown, but with the later proposals by Worsley & Heintz 0977) for the Wilhelmeya Formation (rather than the Svenskoya Fm) and the Kapp Koberg Member.

Bathonian

Bed with Pseudomonotis etc.

sand and sandstone

no fossils

Dunerfjellet Member

upr

shale

Iwr

(upper & lower) 6O m (Beds 3-7)

~ ~

~ ~

~ = "~ ~

~

~

~

Nordaustpynten Member

Kimmeridgian Oxfordian Callovian Bathonian

?50 _m_(_Be_d_ 9_L _ shale

?150 m (Bed 8)

s.I.

Bajocian

Member clay 75 m (Bed 4) Sjergrenfjellet Member

sandstone (Beds 1 & 2)

sandstone

Arnesodden Bed

*Kapp Koberg Member

shale

Hauterivian Valanginian Berriasian Tithonian

Passet

Mohnhegda Member

_

~

Retziusfjellet Member shale 75+ m (Beds 6-7)

Upper part of Kongseya Formation

Aalenian Toarcian Ptiensbachian ?Sinemurian ?Hettangian

Rhaetian

MOHNH~GDA k'0KEI,fI'HALFJELLET

DUNI~RFJELLET

bQsatt

T

?-"v

i

7t i

200 m

-r T

i

u

x

!":" ," ;

:...i/..:.1 K O W - n t ~

9 , -~ oi

Fig. 5.9. Correlation of the principal stratigraphic sections on Svenskaya (redrawn with permission of Cambridge University Press from Smith et al. 1976).

Lend Fm

~

Fm

Member

Fm

;.4

\1

100

KongKor~

Member

5o 0

i

2

3

4

I

I

I

I

I

5kin I

ArnesenoddenBed

It includes units 10 to 13 of Nathorst but there are more lavas than he listed. The three members each represent the entire formation in a particular area. The reference section at Mohnhogda in Svenskoya may be taken as the type for the Formation. Kiikentbalfjellet (sandstone and basalt) Mbr, 65 m at Ktikenthalfjellet the southernmost mountain of Svenskoya comprises a variable sequence of mainly arenaceous sediment with basalt layers which are units 10 and 12 of Nathorst (1910, p. 362). 5.1 m basalt, lava flow, vesicular in the basal 2 m; 6.1 m sandstone with some shale and compressed plant remains; 2 m coal seam with brown clay; 2 m sandstone, fine, weathering brown, with calcareous streaks; 19.6m sandstone, soft and white, with irregular clay laminae; 99 m basalt, massive, probably a sill; 1.4 m brown sandstone; 10.8m sandstone, soft white, with a thick discontinuous body of massive brown weathering medium sandstone probably a channel fill; The sill meets the lava in the west (as was noted by Nathorst). Each of the six intermediate sections measured is different (Smith et al. p. 205). At the northernmost mountain Mohnhogda (20 km to the north) two basaltic

;RA

lava flows, 17.4 and 44m respectively, cap the mountain with 10.3m sandstone between and 7.3 m in sandstone beneath. They are not separated by sandstone to the south at Dun6rfjellet. In each case the topmost lava forms a protective covering to the softer sandstones beneath and only a narrow ridge remains9 Nathorst recorded Cladophlebis sp. Taeniopteris or Anamozamites, Podozamites laneeolatus pichwaldi and Pinus sp. H~rfagrehaugen (sandstone and basalt) Mbr of western Kongsoya. The type section is at Tordenskjoldberget and is confused by several slipped masses, referred to as Belemnitkullarna (belemnite mounds) by Nathorst, with mixed origins. This member comprises 14m mainly of sandstone beneath a thinner basalt lava. Loose to unconsolidated sandstone, (medium to coarse) siltstone and shale make up the sedimentary part. Coal and carbonaceous beds are characteristic and two lava flows (generally in contact) cap the mountain. Compressed plant remains have well preserved cuticles. Petrified wood occurs, several trunks being up to 1 m long just beneath the basalt, and some fragments were found in the basalt shot through with siliceous veins. Such material, probably from here, was described by Gothan (1907) who commented that the excellent preservation could be attributed to the

EASTERN SVALBARD P L A T F O R M PASSEr

SJIZ~.-,RENFJELLET

TORDENSKJOLDBERGET

W

E

..

..

7-" v I basalt

-

Vv

"-,'1 -

v

basal1

I

100

.. Kong Karls Lend Fm

200 m SJcrgrenllellet M e m b e r

-

85

v

_ --__

x ? dolerite X X

Rotzlu,~ot _

blombor

Kono~o Fm

svom~qo Fm

?

/o

0

1

2

3

4

I

I

I

I

I

5 km

I

overriding lava. He identified the following species which included new taxa suggesting at first a Late Jurassic age but later (1910) changed to early Cretaceous: Phyllocladoxylon sp; Xenoxylon phyllocladoides Gothan; Cupressinoxylon cf. mcgeei Knowlton; Cedroxylon cedroides Gothan; Cedroxylon transiens n.sp; Protopiceoxylon exstinctum Gothan. From evidence in Kong Karls Land, a Valanginian or later age is deduced. By lithological analogy with Spitsbergen the age may be Barremian. Johansenberget (sandstone and basalt) Mbr of eastern Kongsoya. At the top of the hill are 30 m of sediment underlying 20 m of basalt. The sediments include Nathorst's bed 10. Sandstones with plant remains are conglomeratic in part. In conclusion, throughout the islands the basalts are better exposed than the sediments and generally at least two lava flows can be traced either in contact with each other or separated by sediment. Reconnaissance investigation of the Kong Karls Land Fm palynomorphs gave three significant results. (i) Rhaeto-Liassic spore and pollen types occur and suggest that erosion of the earlier strata contributed to the sediments. (ii) Lack of angiosperm pollen indicated an age earlier then Albian. (iii) The main flora is of long range species, not older than latest Jurassic, and entirely consistent with Early Cretaceous. All characteristics indicate a non-marine environment for the Kong Karls Land Formation. Kongsoya Fro. This unit is of typically marine facies dominated by shales rather than sandstones. It would thus appear to correspond stratigraphically to the Janusfjellet Subgroup of Spitsbergen. The particularly well-preserved Arcticoceras fauna in the lower part of the formation is of mid-Bathonian age (Rawson 1982). The early record of Arctocephalites arcticus (Newton) in Kong Karls Land was of Early Bathonian age (Pompeckj 1899; Arkell 1956) but has not been collected recently. These Bathonian faunas may be compared with the fuller East Greenland sequence (Callomon 1994). Dnn~rfjeUet (shale) Mbr, 6 3 + m (in Svenskoya). A shale unit, with distinctive upper and lower divisions, but the base is not seen. Upper division, 19m tough shale with bivalves Buchia, ammonites Amoeboceras (Amoebites) of early Kimmeridgian age and fish fragments probably including the new species Leptolepis nathorsti (Woodward 1900). Lower division, 42+ m (bottom not seen) is of weathered dark grey shales with small belemnites and ammonites preserved in pyrite: Cardioceras cf. cordatum (Late Oxfordian) and Arcticoceras and Cadoceras (Late Bathonian or initial Callovian). Facies are variable, even in the small outcrop on Svenskoya, and include northeast of Kiikenthalfjellet a unit 47 m with horizons of clay ironstone, similar to Janusfjellet, where fish fragments characterize the upper part and belemmites and pyritized ammonites the lower part. At Mohnhogda the member is represented by 20 m of dark shale. No macrofossils were recorded there but organic microplankton indicate a marine environment. The thickness was probably reduced here by preKtikenthalfjellet Member erosion. Tordenskjoldberget (limestone) Mbr, 30 m in southwestern Kongsoya. This is of limited extent known only from near the type locality 1.5kin east of Passet and was estimated by Bltithgen (1936, p. 59) to be of Early and Mid-Valanginian age. To the east it is rich in belemnites which weather

;RAI

Fig. 5.10. Correlation of the principal stratigraphic sections on Kongsoya (redrawn with permission of Cambridge University Press from Smith et al. 1976).

out of mounds formed by landslips. To the west it is overstepped by the Kong Karls Land Formation. One of the few occurrences of extrusive igneous rocks below the Kong Karls Land Formation is seen within this member as bright red weathering pumice including fragments of baked sediment. This Valanginian eruption is the earliest evidence of igneous activity in western Kongsoya. Upper division (15m) shales, siltstones with dark brown weathering ironstone nodules and a calcareous horizon, 4 m above the base with bivalves. Lower division (15 m) of white and light yellow loosely cemented calcareous sandstone consisting of inoceramid type fragments. Complete Buchia keyserlingi (Lahusen) are common together with abundant belemnite guards. The solitary coral ?Theococyathus nathorsti (Lindstr6m 1900) was recorded. Retziusfjellet (shale) Mbr, 7 5 + m in western Kongsoya. This member correlates with the upper division of the Dun~rfjellet Member of Svenskoya. At the type section it rests on the thin orange-weathering hardground at the top of the Passet Member. It consists of grey and black shales with occasional horizons of nodules weathering red or yellow. At Retziusfjellet in particular some concretions are large, some septarian, and many with ammonites, belemnites (with phragmocones) and bivalves in full relief. The youngest ammonite fauna consists of Amoeboceras (Amoebites) kitchini and Aulacostephanus (Xenostephanus), probably of Early Kimmeridgian mutabilis zone, and Amoeboceras with Rasenia probably cymadoce zone and flattened Amoeboceras (Hoplocardioceras). Mid- or Late Callovian ages are implied by Longaeviceras? and Quenstedtoceras s.1. (e.g. Eboraciceras) The oldest confirmed fauna is the Arcticoceras fauna dated as early ishmae zone (mid-Bathonian) by Rawson (1982). The Member is overstepped at Passet by the Kong Karls Land Formation. Passet (clay) Member 65+ m in western Kongsoya, is predominantly of clayey beds, generally unconsolidated and including occasional ironstone nodules and beds of sand or sandstone. It is cut out to the west by the Kong Karls Land Fm (Hgtrfagrehaugen Mbr) and is approximately equivalent to the lower divisions of the Dun~rfjellet Mbr of Svenskoya. It includes occasional ironstone nodules and beds of sand or sandstone and a fauna of small belemnites. Nathorst's estimate of this bed 4 was Mid- to Late Callovian. There is a Sinemurian-Toarcian foraminiferal date (Lofaldli & Nagy 1980); Doyle & Kelly (1988) gave an Aalenian (possibly Toarcian) Bajocian age based on belemnites alone. Eastern Kongsoya In the upper slopes of Johnsenberget clays, siltstones, yellow and green sandstones are exposed with belemnites and bivalves and a calcareous sandstone near the top. These belong to the upper part of the Kongsoya Fm. Nathorst's equivalent (Beds 8 & 9) would suggest an early to Middle Valanginian age for the bivalves. Nordaustpynten (shale) Mbr (?150-200 m), is a black shale also placed in the Kongsoya Fm. It occupies the lower slopes and the extreme eastern sea cliffs of Kongsoya where between two basalt layers, probably extrusive, is a horizon with flattened ammonites and bivalves ?Rasenia/Aulacostephanus with cardioceratids indicate an Early Kimmeridgian age. In the southeastern exposures bright red baked shales mark eruptions, probably volcanic.

86

CHAPTER 5

Wilhelmoya (Svenskoya) Fm. This formation comprises an upper continental sandstone division and the upper part of a lower shale division and occurs the length of Svenskoya, but only in western Kongsoya, being in each case the lowest formation above sea level. The sands are unconsolidated (without cemen0 and of high porosity, a facies not reported in Spitsbergen. Nevertheless there is some similarity in facies and position with the original De Geerdalen Fm, particularly its upper unit, Worsley's Wilhelmoya Fm. However, Worsley & Heintz (1977) acknowledged that the De Geerdalen Formation had been defined to include all rocks up to the "Lias conglomerate'. They reported a lower unit, the Kapp Koberg Member, which usefully extends the Kongsoya sequence downwards. They also recommended to drop the name Svenskoya Formation in favour of Wilbelmoya Formation (Worsley I973) accepted here. Mohnhogda (sandstone) Mbr, 197m in northern Svenskoya is thickest at Mohnhogda where the lowest 50m is largely obscured by loose talus from the sands above. It consists mainly of sandstone or loose sand coloured grey, yellow or brown with occasional interbeds of sandstone bearing fragments of fossil wood. Further south thin pebble horizons occur and at the far south a thin gravel conglomerate. Arnesodden (shale) Bed, 5 m to sea level. This Mack shale and siltstone occurs at the base of the steep sandstone slope and represents the lowest beds exposed in Svenskoya. Sjogrent-jellet(sandstone) Mbr, 130+ m possibly 235 m in western Kongsoya corresponds to the Mohnhogda Member in having poorly consolidated fine sandstone with stringers and interbeds of grey and brown clay, and thin coal seams. Beds of harder sandstone, some weathering orange, and pebbly horizons occur. Plant fragments, wood and lignite were noted at Passet where slump structures were seen in the sands. Kapp Koberg Mbr, 36 m in western Kongsoya. Whereas the above units were all described by Smith et aL (I976). This member was newly defined by Worsley & Heintz (1977) and extends the Kong Karls Land sequence downwards. It is a conspicuous in the cliffexposure near sea level, at the base of a cliff and may have been obscured by ice foot in 1969. The member is a shale, coarsening upwards to sandstones of which the lower 13 m consists of poorly consolidated mudstones with silty interbeds. The friable sandstones with cross-bedding indicate N NW to W directed flow, with similar orientation of the plant fragments. The lower 25 m of the whole section contains occasional vertebrate remains in sideritic beds or in small erosive washout structures. One sandy bed contained a large sideritic concretion with a nearly articulated plesiosaur skeleton. It was partially eroded in the cliff section. Parts of which were collected together with the palynomorphs so providing a marine assemblage. WBhehnmya Fm palynomorphs. The palynomorphs from upper and lower horizons in the higher sandstone units of the Svenskoya Formation were investigated by Smith (Smith et al. 1976) from samples from north and south Svenskoya. Preservation is good. The assemblages almost entirely without marine influence except for occasional microplanton but no dinoflagellates. All the taxa have Rhaeto-Liassic ranges. The assemblages from the upper part of the formation in each locality were similar and correlation was suggested tentatively with Orbells" (1973) two zones (based on sections in England, Sweden and Greenland). The lower samples collected near sea level, approximate to his Rhetopollis zone and the remaining preparations to his Heliosporites zone. With several qualifications enumerated by Smith this could indicate a Triassic-Jurassic boundary somewhere within these sandstone members. A late limit of Sinemurian was suggested and the earliest part is probably Rhaetian. This conclusion is consistent with palynological work by Bjaerke (1977), Bjaerke & Dypvik (1977), and Bjaerke & Manum (1977) and makes it almost certain that the Kapp Koberg Mbr is Rhaetian. Smith made comparisons with Hopen (Smith et ai. 1976), confirmed by Bjaerke & Manum (1977), that the lowest shale unit in Kong Kads Land and the overlying sandstone represent a marine followed by a non-marine sequence very similar to the sequences in Hopen and Wilhelmoya and could thus all be coeval. The age of the Arnesodden shale bed remains uncertain. It could be an extension of the Kapp Koberg Member, but it has not been investigated.

5.7

Barentsoya, E d g e o y a and T u s e n e y a n e

Edgeoya, t00 km from north to south, is the third largest island in the Svalbard archipelago after Spitsbergen and Nordaustlandet. It is nearly half covered by ice which tends to occupy the higher ground rather than concentrate in valley glaciers. Barentsoya at perhaps a quarter of the area is the fourth largest.

Pre-Quaternary strata are remarkably uniform throughout both islands on which Triassic outcrops exceed in area the combined Triassic outcrops of the rest of Svalbard. Exceptional Permian inliers give a base to the Triassic succession and the highest mountains in southern Edgeoya are capped by the youngest s t r a t a - probably Rhaetian, possibly Hettangian. Dolerite sills occur extensively and form the 'thousand islands' (Tusenoyane) scattered throughout an area (the size of Barentsoya) to the south o f Edgeoya. It is convenient to treat the two main islands together.

5.7.1

Earlier work

The southern coast of Edgeeya protected by the dangerous Tuseneyane was probably known from the early expeditions o f Barents from 1959 and shown on a map by Plancius in 1612. The name is for Thomas Edge an English whaler whose visit in 1616 may be the first recorded. Barentsoya was not known to be an island separate from Spitsbergen until the middle of the nineteenth century. It had been k n o w n as Barents Land. Fuller details of this early history entailing the (mainly British and Dutch whaling fleets are given in Place Names o f Svalbard (Norsk Polarinstitutt Skrifter N o 80, 1942). The first geological record is by Keilhau in 1827 and the second by Lamont in 1859 with fossils identified by Salter (Lamont 1860). From Nordenskirld's 1864 expedition material was shown to be Triassic (Lindstrrm 1865). The Russo-Swedish Arc of Meridian Expedition 1899-1901 was the first systematic survey of the western parts of the islands from which Wittenburg (1910) described Triassic faunas and Baeklund (1907) described and interpreted (1921) the dolerite intrusions. Arising from the same Swedish work was De Geer's contribution including these islands in his general account of Svalbard (1910). The Scottish Spitsbergen Syndicate was geologically active after the First World War in several parts of Svalbard in support o f mineral claims, giving rise to several useful publications. In the course of work in Storfjorden, Tyrrell (1933) described sections from the west coasts o f Barents~ya and Edgeoya. This interwar period saw the beginnings of Oxford and Cambridge expeditions including one to Edgeeya led by G. Watkins on which Falcon (1928, later Chief Geologist in British Petroleum) proposed a three-fold division of Triassic strata which has continued to this day. He noted the importance o f the lower unit (the oil shales group). Little was done in these islands geologically until the new stimulus of the search for hydrocarbons beginning about 1960 (e.g. Nagy 1965). At this time also there was renewed interest in describing lithic units in which to relate paleontological records so leading to new systematic schemes o f nomenclature. A distinct Soviet contribution in this episode was the description of the three Permian exposures beneath the Triassic strata, one quite easily seen on the north cast coast of Barentsoya and two minute inliers in the interior of Edgeoya (Klubov 1964, 1965a, b, c). The next significant geological exploration of the islands was in 1969 by two independent groups, one from the Norsk Polarinstitutt, Oslo, (Hood, Nagy & Winsnes 1971) and the other from Cambridge Svalbard Exploration (CSE) in cooperation with Norskefina (throughout eastern Svaibard). Both had the benefit of helicopter support from ice-strengthened ships. In each case research continued from that 1969 basis. Flood, Nagy & Winsnes (197I) published their first results on these islands and Hopen. Their paper included a map of the islands to a scale of 1: 500 000. Edwards (1976) noted growth faults in the Late Triassic unit seen from the air in cliffs at Kvalpynten. Much other Norsk Polarinstitutt work has been concerned with topographic survey and Quaternary studies. Two deep wells were drilled in Edgeoya which CSE investigated (Section 5.7.3 below) one interpretation of which has been published (Shvarts 1985).

EASTERN SVALBARD PLATFORM

No overlying unit remains in these islands. The base of the formation is taken at the first prominent sandstone (thicker than 1 cm) above the underlying shales of the Tschermakfjellet Formation. On this basis the boundary is transgressive and presumably correspondingly diachronous. The formation is at least 400 m in Edgeoya and 240 m in Barentsoya. It is of, generally flaggy, sandstones with subordinate siltstones, sandy and silty buff shales with rarer black and grey shales, thin coal seams ironstone and oolitic, micritic and shelly limestone beds. Flood et al. (1971) reported that the sand grains rarely exceed 0.5 mm with an average composition of quartz 40%, rock fragments 30%, cherts 15%, alkali feldspar 10%, other grains (including muscovite and plagioclase) 5%. They regarded euhedral quartz grains as suggesting derivation from the Precambrian quartz-porphyries of Nordaustlandet, but Lock et al. considered the crystal shapes as authigenic. Cement is generally of calcite, often sparry with carbonate mud. Organic remains include fossil plants and some bivalves (including oysters in some beds). Klubov (1965a) recorded a specimen of Nathorstites at the base of the formation at Negerpynten. Echinoderm fragments have also been reported. Falcon recorded a reptilian jaw bone with teeth in the same general locality. The sedimentological model (D.J.A. Piper in Lock et al. 1978) is of a delta complex supplied by rivers from the northeast entering a marine basin. This interpretation is based on seven lithofacies (i) Turbidites (0.01 to 1.Sm thick) with sole marks especially groove casts and Bouma C and BC sequences. (ii) Thick sandstones filling slide scars up to 30 m deep. The sliding units are mostly of turbidite facies. Channel structures and mudstone intraclasts are also observed. (iii) Shallow marine sequences occur as coarsening-upward cycles of silty shales followed by sandstones with bioturbation. The sandstones may be cross-bedded in sets up to 10m thick followed by massive sandstone (Edwards 1976b). They are sometimes capped by a coquina or oyster bed. Marine sequences are more abundant in the lower part of the formation and a shallowing marine or marine environment was suggested. (iv) Mouth bar sequences in the form of sandstones up to 3 m with largescale high angle cross-bedding. Load structures occur in the underlying thinner sandstones. These characters suggest prograding mouth bar facies. (v) Fluvial channel sequences with upward-fining sequences are cha~teristic of the upper part of the formation may be associated with (vi) Fluvial overbank facies of thick dark siltstones and mi'nor silty coals, mudstone intraclasts and plant fossils. (vii) Marginal marine facies of ironstones (some oolitic), sandy stromatolites, thin algal limestones and beds with high concentrations of bivalves,

The CSE work on the surface outcrops was published after an agreed interval (Lock e t al. 1978) in parallel with work on other islands: Wilhelmoya (Smith 1975), Hopen (Smith, Harland & Hughes 1975) and K o n g Karls Land (Smith e t al. 1976). Lock e t al. took previous work into account and made the basis for the present summary. However it could not have noticed the work of Pchelina (1977), who gave more biostratigraphic detail from molluscan faunas which was not in conflict with CSE conclusions. The Norsk Polarinstitutt map: 1:500 000, sheet 2G, Edgeoya (Winsnes 1981) accompanied by a commentary (Winsnes & Worsley 1981) follows almost exactly that in Flood e t al. (1971). The commentary remarks 'The lithostratigraphic units concern with those of Flood e t al. (1971) [see Fig. 5.11], and adopt neither the proposals of Lock e t al. (1978) for Barentsoya and Edgeoya nor those of Smith e t al. (1975) for Hopen are adopted here. It is noted, however, that a revised stratigraphic scheme for Triassic strata of the entire Svalbard will be proposed in the near future' (A. M o r k pers. comm.). This book attempts to assess and synthesize all points of view and so far as Triassic classification and nomenclature is concerned the matter is discussed in the Triassic chapter Section 18.1 and 18.3. The conclusions arrived at there are applied here without further discussion.

5.7.2

Stratal succession

Figure 5.11 shows the relation between the scheme adopted here (and justified in section 18.1.3) and earlier schemes. A generalized geological map of Barentoya and Edgeoya is shown in Fig. 5.12 showing the distribution of the principal formations. Kapp Toscana Gp De Geerdalen Fin (Buchan et al. 1965)= Negerfjellet Fm (Lock et al. 1978) >400m. This is the 'Sandstone Group' of Falcon (1928). It corresponds to the De Geerdalen Formation and perhaps the uppermost part of the Tschermakfjellet Formation of Flood et al. (1971) - units that were defined by Buchan et al. (1965) in Spitsbergen and approximately equivalent in these islands. Lock et al. (1978) based it on a measured type section at Negerfjellet in southwest Edgeoya (op. cit. p. 29) supported by five other sections extending to northwest Barentsoya.

Falcon 1928

Klubov 1965

Sandstone Group

"Sandstone formation" (Upper unit of T3)

Purple (Blue & Purple) shales group or series

"Passage Beds ! (lower formation" | two

Flood etal. 1971 Winsnes & Worsley 1981

s (.9

8 P-

units

"Argillite formation"

/ of ,A T3)

De Geerdalen Formation

v

Tschermakfjjellet Formation

Lock et aL 1978

o (.9

80~ ~2 o. Q. (~

Oil Shales group or series

T 1 and T 2

~) Sticky Keep Member

-~

(/)

(~

(Permian rocks not recognised)

"Selander suite"

~--~~) EE ~ $ eLL vo

Vardebukta Formation

Kapp Starostin

Formation

Mork et al. 1982

This work

Nege~ellet Formation

De Geerdalen Formation

De Geerdalen Formation

s (.9

Edgeoya Formation

Tschermakfjellet Formation

Tschermakfjellet Formation

~r

I

Botneheia Member

87

P3~ Oil shales I Member I ---~) ~ Barentsoya Formation

I

Blauknuten Beds ?

I I

.

.

.

Barentsoya Formation

.

.

Oil shales Member . . . .

I

I I

s

(.9

g

Barentsoya Formation o~ CO

Kapp Ziehen formation

Kapp Starostin Formation

Kapp Starostin Formation with Kapp Ziehen, Raddodalen and Veidebreen units (members?)

Fig. 5.11. Proposed nomenclature for local rock-units on Barentsoya and Edgeoya as used in this work, compared with previous authors' schemes.

.~ =~ (.9 __

88

CHAPTER 5 ironstones. But formal members were not proposed because the boundary is ill-defined (Lock et al. 1978). The lowest beds of the formation are generally characterised by abundant ironstones. But locally by grey shale. The variable thickness appears to result in part from facies variations within the unit and partly from the vagaries of the succeeding deltaic front. The formation is characterised by marine fossils- ammonites and bivalves with a bed rich in N a t h o r s t i t e s 20 to 30m above the base. This Nathorstites band forms a useful marker horizon. Silicified wood also occurs.

Sassendalen Gp Barentsoya Fm, c. 300 m (Lock et al. 1978). This formation, as defined above

Fig. 5.12. Geological map of Barentsoya (to the north) and Edgeoya, combining figs 4 and 5(B) of Lock et al. (1978). generally of a single species. Marine facies may coarsen upwards into dark siltstones or coals. These facies indicate shallow open marine, lagoonal, tidal flat swampy terrestrial environments. In addition, conspicuous rotational faults developed with sedimentation seen in the Negerpynten cliffs. The strata dip up to 20 ~ northwards as a result of the southward slipping rotation. They were noticed by De Geer (1919), Falcon (1928), CSE 1969 and described by Edwards (1976a, b). Abnormally high fluid pore pressure may have facilitated this faulting. It is not unexpected in the above complex that no satisfactory marker horizons have been identified in the formation. Tsehermakfjellet Fm (Buchan et al. 1965)= Edgeoya Fm, (Lock et al. 1978), 125m. This is the purple shale, or blue and purple shale unit of Falcon (1928) and the argillite plus Passage Beds of Klubov (1965a, b). In stratigraphic position it corresponds to the Tschermakfjellet Formation of Spitsbergen. The type section was taken at Veidemannen in southwest Edgeoya (Lock et al. 1928, p. 4). It is clearly distinguishable from the Negerfjellet sandstones above and the cliff forming bituminous shales of the Barentsoya Formation below. The type section is supported by six further measured sections, four in Edgeoya and two in Barentsoya. Thicknesses were plotted at 26 localities in the islands and range from 51 to c. 130 m. The formation is entirely missing at Mistakodden in northwest Barentsoya. The formation consists of shales with subsidiary fine siltstones becoming more abundant towards the top. There are thin red to purple-weathering clay-ironstone beds and thin argillaceous and arenaceous micritic limestones some with cone-in-cone structure. The lowest bed is of yellow-weathering calcareous silts and small nodules. The upper part of the Edgeoya Formation is, as Klubov reported, somewhat transitional to the succeeding deltaic facies and two divisions are thus discernible, the lower one being of shales and red weathering clay

and as followed by Mork et al. (1982), completely represents the Sassendalen Group in these islands, it not being practicable to map divisions within it, whereas the Group is defined by three distinct formations in Spitsbergen. It corresponds to the 'Oil Shales Group' of Falcon 1928, T I + T 2 of Klubov (1965a, b), and the Kongressfjellet and Vardebukta formations of Flood et al. (1971b) which were extended from the mainland of Spitsbergen but without detailed sections. The type section is a composite one near Kapp Ziehen in northeast Barentsoya where it rests directly on the Permian sandstones and limestones of the Tempelfjorden Group. This lower boundary at Kapp Ziehen, not well exposed, was described by Burov et al. (1965) as a pitted erosion surface. The boundaries at the two Permian inliers in Edgeoya are still less visible. The upper boundary is easily observed throughout the outcrops being marked by a sharp change from compact paper shales, often bituminous, to the overlying purple or grey shales with red-weathering concretions. The main and upper part of the formation crops out from northern Barentsoya to southern Edgeoya and was depicted in six representative measured sections (Lock et al. 1978). It is a unit of shales, often bituminous and papery towards the top and with subordinate beds of limestone, septarian nodules, calcareous siltstones and argillaceous sandstones. Septarian concretions often contain liquid bitumen, and phosphatic nodules occur lower down in the succession. At the top a distinctive bed of yellow-weathering argillaceous limestones or calcareous siltstones commonly occurs with ichthyosaur bones. This represents a widespread non-sequence and disconformity with the overlying strata. The cliff forming bituminous shales may be taken as an informal 'Oil Shale Member' in the upper part of the formation. It thins from 100m in the west to 50 m in the east. The lower part of the formation is of limited exposure near the Permian outcrops. Its relationship to the upper-part is not seen. It consists of grey shales and siltstones with a few prominent beds of yellow weathering carbonate-cemented siltstones and silty, clayey limestones. The formation is richly fossiliferous. Abundant ammonoids, often impressions, Daonella, ichthyosaur and plesiosaur bones, and fish remains are characteristic. The fauna is consistent with the euxinic interpretation of the bituminous shales forming in stagnant conditions on the sea bed. Tempelfjorden Gp. Permian strata are known from three localities: (i) at Kapp Ziehen in northeast Barentsoya reported by Burov et al. (1964); (ii) in central Edgeoya and (iii) in central south Edgeoya. Localities (ii)+ (iii) are tiny inliers (each less than 1 km 2) discovered by an Amoseas exploration party in 1963 (King 1964) and mentioned in the synthesis of Cutbill & Challinor (1965) who implied that all three exposures would correlate with the Kapp Starostin Formation of Spitsbergen. Flood et al. (1971) reported Klubov's discovery of Kapp Starostin Formation but no data were provided. Lock et al. (1978) reported on some fieldwork in 1969 at the three localities referring to all the rocks informally as Kapp Ziehen formation, but except for a general similarity with Kapp Starostin strata these occurrences could not be correlated within the two islands. The 1:500 000 geological map and text 2G (Winsnes & Worsley 1981) refers to all three localities as Kapp Starostin Formation. Therefore although correlation between Spitsbergen and these islands is not so good as with the more distant Miseryfjellet Formation of Bjornoya we adopt this nomenclature. Because of the distinct nature of the three occurrences and the convenience to label them for discussion it is proposed here to name them informally as follows: (i) The Kapp Ziehen occurrence to be the Kapp Ziehen member for that outcrop and not for (ii) and (iii) below. (ii) The central Edgeoya occurrence to be the Raddedalen member from the name of the well near that locality and which penetrated the Tempelfjorden Group.

EASTERN SVALBARD PLATFORM (iii) The Central South Edgeoya rocks to be the Veidebreen member from the neighbouring glacier. Kapp Starostin Fm (i) Kapp Ziehen member. The largest outcrop, extending for about 10kin along the northeast coast of Barentsoya described by Klubov (1965c). It is poorly exposed with only intermittent beds recorded dipping gently SSE. The outcrop suggests a thickness of at least 250 m but only the top 28 m are exposed as cherty limestones, dense, dark grey to black, in places transitional organogenic cherty rock. 60-70 m are covered. 1 m light grey shelly limestone with 10 brachiopod species. 10 m covered; 3.5m yellow organogenic cherty ferruginous rock (2 brachiopod species recorded); 10-15 m covered; 1.5 m light cherty, organogenic limestone. (7 species recorded); 10-15 m covered; 1.5 m light grey cherty, organogenic limestone (7 species recorded); 20 m covered; 1 m light grey shelly limestone (11 species recorded) 20 to 30 m covered; 5 m cherty limestone, dense dark grey with light calcite veining, echinoid spines and sponge spicules (10 species recorded); 100 m covered; 0.5 m Calcareous sandstone, green/grey, medium grained, thin-bedded, with glauconite and sponge spicules (2 species); Lower beds obsured. (ii) Raddedalen member. In central Edgeoya is a small outcrop with blocks of richly fossiliferous Permian strata but hardly exposed in situ. In the float the relationships with the overlying rocks cannot be seen. Its position is shown on the map, but it is not easy to locate on the ground. It occurs at the northern end of the pass between Storskavlen and Edgeoyjukelen. About 15 species of brachiopods, pectinid bivalves and bryozoans were collected (Lock et al. 1978). The unit is so named here because it was later the site of the well 'Raddedalen-l' drilled by the Companie Frangaise du Petrole (Total, CFP). The only previously published record was by Schwarts (1985) who, from mud samples exchanged, recorded 202m of Tempelfjorden Group above upper Gipsdalen Group etc. (see below). (iii) Veidebreen member. In Central South Edgeoya is a small outcrop in a complex exposure amongst meltstreams just north of the terminal moraine of Veidebreen. This is about 7 km NNE of the northernmost coastline of Tjuvefjorden. This exposure is of light grey chert with sponge spicules and bryozoa, but no brachiopods were collected. Fossil species were not easily identified. Palynological investigation yielded only one long ranging acritarch genus Micrhystridium.

5.7.3

Sub-surface stratigraphy

Two deep wells were drilled in Edgeoya. One in southwest Edgeoya by Norske Fina: Plurdalen-1, the second already mentioned was: Raddedalen-1 drilled by Compagnie Franqaise du Petrole (CFP). See also Section 5.9.

Raddedalen-1, 22~ 77~ The already published record (Shvarts 1985) concerns Raddedalen-1. The mud samples from this well were obtained from C F P in exchange for material from the Soviet well Grumantskaya-1. It was drilled to a depth below surface of 2823 m. The Cambridge samples were obtained through Norske Fina by exchange for Plurdalen-1 material. Below the 202m of Tempelfjorden Group, Shwarts recorded 205 m of Upper Gipsdalen Group and a Moscovian-Bashkirian boundary just below a depth of 407 m and down a further 306 m through lower Gipsdalen Group rock. Then 161 m of Culm was reported down to an unconformity at 874m. Of the remaining 1949m the upper 945m was interpreted as Early Silurian or Ordovician and the lower 1004m as Ordovician. Independently, and recently released information (courtesy Dragon Oil, was reported to Norske Fina in 1974 and 1975 on material by Cambridge Svalbard Exploration (CSE). The CSE work was primarily a palynological investigation by J. F. Laing,

89

advised by N. F. Hughes and the samples were cuttings etc. The conclusions were that below the more easily identified Permian and Pennsylvanian strata was a succession of about 2000 m of Early Carboniferous (Mississippian) and possibly late Devonian age. The Devonian palynomorphs all had ranges well into Carboniferous time if not younger. The two investigations are plotted side by side in Fig. 5.13. They were of course entirely independent, CSE results transmitted to Fina with little information other than depth in well from CFP. Obviously the C F P conclusions would be more useful. Shvarts with apparently more information on the well from C F P quoted 'foreign geologists' N. Couleau, I. Per6, A. Fedyayesky and D. Somm~ as giving the age of the lowest strata as Silurian?-Devonian. The critical evidence for Ordovician age is the conodont Drepanodus, which, if properly located in the well and properly identified and not a conglomerate clast, might well be conclusive. However, the general account of Shvarts would make this a quite remarkable result for Svalbard geology. He was able to report that the strata were a conformable sequence with dips ranging from 0 to 3 ~ and neither indicating tectonic nor magmatic activity. He suggested that Svalbard east of the Billefjorden Fault Zone was a stable platform escaping Caledonian tectonism. Apart from this conundrum the Russian report gives too much petrographic detail to recount here and generally not related to identified sample depths. The conclusions preferred here are put into context at the end of this Chapter (Section 5.9). Plurdalen-1, 21~ 77~ in southwest Edgeoya, just west of the snout Philippbreen, was drilled by Norske Fina. Cambridge Svalbard Exploration (CSE, mainly C. Croxton) reported palynologically on cuttings and selected cores which it is now possible to publish, courtesy Dragon Oil. The data here merely summarize results from six progress reports in 1973. The actual drilling occasioned widespread comment because of the conspicuous floods of red sediment emanating from the well. Because of this the first CSE study was to identify all red beds in Svalbard from the CSE collection. A summary of the results is plotted in Fig. 5.14. The whole-rock R b - S r determinations by Pringle were invited because the lithology of the red sediments appeared to be similar to the Vendian Nyborg Formation in Finnmarken from which he had obtained a result (1973). As we now know the Nyborg value (668 4-23 Ma) was significantly older than is currently thought likely (c. 600 Ma) and probably because of inherited clay minerals. On this basis the value of 410 M a (Early Devonian) could similarly be too high which could bring it to late Devonian or Early Carboniferous. Samples determined from different depths yielded no significant age differences.

5.7.4

Biostratigraphy[age estimates

?Jurassic strata. The possibility has been considered that the highest strata in the hill tops above Kvalpynten in south west Edgeoya may be earliest Jurassic, but no positive evidence has been forthcoming.

Triassic strata. Barentsoya and Edgeoya have provided rich collections of fossils (Fig. 5.15; from Lock et al. 1978, table 2). In comparison with an earlier similar plot, Flood et al. (1971b) did not emphasise the potential mid-Ladinian nonsequence separating the Barentsoya Formation from the Edgeoya Formation. No positive evidence for Rhaetian strata has been identified and the oldest strata, of which exposures are few, yielded Late (but not yet early) Griesbachian fossils. The recorded fossils, (ammonoids, stage by stage) were discussed by Lock et al. (1978, pp. 36-50).

Permian strata. Of the total of about 27 forms recorded from the Kapp Ziehen rocks by Klubov, most are brachiopods and there

90

CHAPTER 5

EDGEOYA

RADDEDALEN-1

Shvarts 1985 based on samples at 4, 8 and 10 m intervals Biostratigraphic age

W e l l d r i l l e d b y C o m p a g n i e Fran(~aise du P e t r o l e ( T O T A L ) Cambridge Svalbard Exploration (CSE) based on 56 evenly distributed samples or chippings in 4 reports from 1974-1975

Well depth (m) Lithic description

Lithic divisions based partly on recovered well log

Palynology by A.F. Dibner algae by G.P. Sosipatrova and M.F. Solov'eva Conodonts by N,N. Sobolevy 0

Late Permian 202 m

--100--

III

Palynological age, assessment by J.F. Laing advised by N.F. Hughes

Kapp Starostin Fm

Grey mottled chert with spicules

- - Sea level

b

202---200-Early Permian 205 m

-500-Middle Carboniferous 306 m

NO RESULTS

Gipshuken Fm

Approx. Wolfcampian EARLY PERMIAN

--300-- 407----400--

CSE corerlation optirnised by W.B.Harland, J.L. Cutbill and D.J. Gobbett, with unit names updated

NO RESULTS

White, light, medium and dark grey crystalline limestone II with shelly fossils, crnoids, corals, bryozoans and forams

Tyrellt]ellet Mbr Cadellt]ellet Mbr

Wordie Kammen Fm !

BASAL PERMIAN

~-6oo--

NO RESULTS

Minkinflellet Fm Ebbadalen Fm

.

.

.

.

.

Early Carboniferous 161 m

713_ ~ - - - 7 0 0 - ~

NO RESULTS

:T" : i

i: :

~800--

enlc imestones, algae, 674- ~_ 9 0 0 - / )otis, ostracods, echinoderms brachiopods, osl and foram fragments --1000Coral at 1049 m Nuia sibidca at 1054 m - 1092- ~_ 1100 - -

NAMURIAN (=EARLY BASHKIRIAN AND SERPUKHOVIAN)

(Hultberget Fm)

--1200

Early Silurian and Ordovician 945 m

Zoophytogenic limestone with scaps of algae and Giztare#a and fragments of brachiopods, crinoids, ostracods and conodonts

~ 1300-

/

-- 1400---1500--

Id White and light grey crystalline limestone with many beds of coral, pale green often pyritic fine sandstone, red fine sandstone and medium grey mediumgrained sandstone

(Mumien Fm) i

PROBABLY VISe:AN

--1600 -1649M~rophylithiclirnestone with brachiopods, crinoids andcale~rus

--1700

1819,--1800-Zoophytogenic limestone in uniform units with fine-grained limestone with numerous remains of algae in lumps and clots and fragments of brachiopods, crinoids, ostracods, and sponge spicules.

- - 1900 --2000 --2100---2200--

Ordovician 1004 m (on basis of Drepanodus)

Biogenic formations are evenly distributed as calcitic, often dolomitized cracks in limestones with black organic matter. The algae Nuia sibirica and the conodont Drepanodus was recorded

Ir Similar to Id, but mrdium grey mediumgrained sandstone is a more important constituent

H6rbyebreen Fm

--2300---2400 --2500--

Ib Similartolc butgrey sandstone of minor importance

--2600---2700--

Base of well 2823

VISE~AN OR TOURNAISIAN

--2800--

VISI~AN TO LATE DEVONIAN

la Similar to Ib but with appearance of dark grey fine sandstone as a major lithology

Fig. 5.13. Interpretations of Raddedalen-1 well (Edgeoya) by Shvarts (1985) and CSE, first published here, based on reports by J. F. Laing for Norske Fina, courtesy of Dragon Oil plc.

EASTERN SVALBARD PLATFORM

PLURDALEN-1

EDGEOYA

Well drilled by Norske Fina

Epoch

91

Stage

Zone

Well depth (m)

Equivalent Spitsbergen units ( 9 core sample)

_3

Approximate age

Norian Al~v~rrT --

-- 0 1

Barents~ya Fm (Sassendalen Gp)

Early Tdassic

Kapp Starostin Fm

Late Permian

I 3CSilicified

2 Camian 1

2 Asselian

Dolostone 538 Brucebyen Beds Wordie and . . . . . . . . 7 limestnne 555 , i Kamen i - - 602,5 - - 600 -- Cadellfjellet Mbr / Fm Oolitic and bioclastic 3A limestone - 7 0 0 . . . . . . . . . _ __Minkin_fje/letFro_ i --760.5 Quartzmc - 800 - sandston~ - 811 9

J

1

Orenburgian Gzelian

3

Moscovian

Anisian

"Early Carboniferous"

1

,~

--839-

Spathian

Slratigraphic break 9

-

Red beds almost entirely barren

-1100-

~_ I-

Z

Smithian

,~,

~

Dienedan

-1200Red beds

-1400-

_1600_ ~-1586 9 --1640- 9 1645 -1700-

Ii

i Ic. 410 al

Dark purple and red brick siltstones

8

Green beds

"1940 9 -2000spores found ~ No ? Pre-Devonian

-2200 - -2180 9

- 2300 -2344 9 "~Ann

Fig. 5.14. Interpretation of Plurdalen-1 well (Edgeoya), by CSE, first published here, based on reports for Norske Fina by C. A. Croxton, I. Pringle, J. L. Cutbill, D. J. Gobbett & A. B. Reynolds, courtesy of Dragon Oil plc. seems little chance that the faunas recorded would enable independently dating the seven fossiliferous beds so the fauna must be taken as a whole. A CSE collection of bivalves brachiopods and bryozoans from the Radeddalen outcrop was identified by D. J. Gobbett (who had monographed Svalbard Carboniferous and Permian brachiopods, 1963) and 15 brachiopod forms were listed (Lock et al. 1978, p. 18). Of these only four are named in common and another four might be the same with different names. A Ufimian age was in the end favoured (Lock et al., p. 16).

5.7.5

Madeami

wO .1-.LL

,,] I--

Possible

sequence I I[

Daonella trami, Panapopanoceras vemeuili, Ptychites trechlaeformis

Subaspedum Chischa

Gymnotoceras ?laqueatum

Deleeni Varium

? Hollandites Koptoceras

Caurus

Keyserlingffes subrobustus, Posidonia aranea, Svalbardiceras cf. spitzbergense

Subrebustus

"Pseudomonotis" occidentalis, Xenoceltites Arctopdonites nodosus

Tardus Romundefi Sverdrupi

Euflemingites, Posidonia mimer "Pseudomonotis" cf. multiforrnis

Candidus Strioatus Commune Boreale Concavum

Ophiceras (?) sp Claraia stachei

NOnL I I ?

Bivalves, bryozoans and brachiopods: more KAPPTOSCANA than 40 forms recorded by Klubov (1965) and rKappZiehenMbr) 17 brachiopods by Lock et al. (1978)

Fig. 5.15. Edgeoya and Barentsoya Triassic biostratigxaphy, after Flood, Nagy & Winsnes (1991) and Lock et al. (1978).

-1900 -

-2100 -

Guadelupian Kungurian

Rb-Sr 9 age of red beds

- 1 8 0 0 - ~1810 9

7

Halobia zitteli Nathorsites mcconnefli, N. tenuis, N. gibbous, Precladiscites cf. martini

Lopingian

LATE =ERMIAN

-1500-

Green siltstone and red brick argillite

Griesbachian

Unit 5 ? Bashkidan to Late Silurian spores

-1300-

,,'dz ,,?o

Nanseni

Pilaticus

r -1000

~L~

_i

Sirenites sp., Nathorsites gibbous

Meginae Poseidon

Ladinian

3B

- 900 - -

Macrolobatus Welled

Obesum

Tyrellt]ellet Mbr

m~ w~ O0

Dawsoni Kerri

Su~eflandi

- 400 -484.5 - _ 500 --

Meleagdnella antiqua, Lingula cK polads, Pentacrinus (?) sp., Estheria cf. minuta

Dilleri

Eady Permian

Gipshuken Fm 3 Carbonate section --

Palynomorphs and Pterophyllum sp., Macrotaeniopteris sp., Taeniopteris sp., Podozamites sp., Tod/tes sp.,

Magnus 1

- 300 --

Suess Columbianus Rutheffo~i

2

"Shaly Lower Triassic." --100 ---128.5- 2 0 0 --

Formations

Marshi

Rhaetian Descriptive units

Key Fossils (after Flood et al. 1971 & Lock et al. 1978)

Structure and igneous bodies

The large area of the two islands, a distance of > 150 km N-S and 75 km E - W is occupied almost entirely by Triassic outcrops representing a maximum thickness of between 800 and 900 m with a

typical relief of between 400 and 450 m. The strata thus seem to be flat lying. However interest is attached to the detailed structure from the point of view of hydrocarbon exploration. Figure 5.16 shows contours at the top of the Barentsoya Formation from data obtained in 1969 (Lock et al. 1978). There is insufficient control to have confidence in the exact structure but it is clear that there are significant minor basins and swells with a closure of 50-100m and two of the Edgeoya swells were drilled. Sills in the main islands and the basic bodies that constitute the 'thousand islands' (Tusenoyane) were described in considerable petrographic detail by Backlund (1907 et seq.). The distribution of the typical sills in Svalbard was summarized by Tyrrell & Sandford (1933). It is noteworthy that in the two main islands and especially in their western coastal areas. This seems to be part of a zone running the length of Storfjorden and Hinlopenstretet. Their age (?latest Jurassic through to Barremian) is discussed in Chapter 19. They affect the structure locally as might be expected.

5.8

Hopen

Hopen (70~ I'N, 25~ is a straight narrow island trending between N N E - S S W and NE-SW, about 35 km long and 0.5-2.5 km wide, with a mountain plateau around 300m rising to 370 m at Iversenfjellet in the south. The plateau slopes gently to the SE and is bounded by cliffs that fall directly into the sea or to a low raised beach. Shallow waters (largely uncharted shoals) offshore for more than 1 km prevent access by all but small boats and then only at a few favourable landings. At one of these is the radio station on the east coast about 8 km north of Kapp Thor at the southern tip of the island below Iversenfjellet. The plateau is punctuated by about five saddles each corresponding to the narrow necks in the islands plan. These are probably the remains of valleys in a much larger island.

92

CHAPTER 5

Fig. 5.16. Generalized structural map of Barentsoya (to the north) and Edgeoya, with structure contours in metres for the top of the Barentsoya Formation, combining figs 4 and 5(B) of Lock et al. (1978).

The regular elongate shape of the island implies a N E - S W structural control confirmed by lines of offshore submerged rocks; but there is no apparent dip across the island - the sloping plateaux being the result of differential erosion between east and west coasts of the island with stronger seas and currents on the west. Transverse structures cut across the island. Some are anticlinal and correspond with the saddles, some are the result of faulting which let down higher strata in the north; but the dips in the step-faulted blocks are southwesterly. They strike W N W - E S E . The net effect is to displace the marker horizon at the top of the lower formation from 325 m asl in the southwest systematically to 150-160 m at Lyngefjellet and up to 180 m at the northeast tip.

5.8.1

Earlier work

This account is as summarized by Smith, Harland & Hughes (1975) who reviewed earlier researches and gave the most complete account of Hopen geology to date based on 1969 and later fieldwork (Fig. 5.17). The history of geological exploration is brief because of the remoteness and difficulty of landing on the island protected by inshore shallows. Access for drilling in 1972 and 1973 was by means of hovercraft from a ship anchored some distance off-shore. The rocks were taken to be Mesozoic because the dominant sandstone lithology favoured correlation with the Spitsbergen

Fig. 5.17. Geological map of Hopen and a longitudinal section along the island, redrawn with permission of Cambridge University Press from figs 2 and 3 in Smith et al. (1975).

EASTERN SVALBARD PLATFORM succession, but opinion as to their age wavered between Triassic and Cretaceous from the lack of decisive diagnostic fossils afforded by the cursory visits. Nathorst's (1884) study of Paleozoic Arctic floras maps Hopen as Triassic but his 1910 m o n o g r a p h leaves it blank. He failed to land on Hopen in 1889. He later suggested a Jurassic age on the basis of plant fossils collected by the Prince of Monaco's expedition in 1898. Hoeg (1926), from the presence of coal, argued a Cretaceous age. Norwegian expeditions in 1924 & 1926 (Iversen 1926) resulted in some geological observations as well as a topographic map, e.g. Werenski61d (1926) on general geology, Hoel (1925) on fossil plants and Bodylewski (1926). F r o m these Hoeg proposed a late Triassic and the others an early Cretaceous age. Another Norwegian expedition to Franz Josef Land (Horn 1932) collected pieces of coal in passing and a Cretaceous age was suggested. These data were perhaps the only basis for later published estimates, e.g. Frebold (1935, 1951) and Orvin 1940 assumed Cretaceous ages in their review syntheses of the Barents shelf and Spitsbergen respectively. However, Selling (1944, 1945 and 1951) from three studies of Hopen concluded only Late Triassic to Early Cretaceous possible ages. Buchan et al. (1965), with no further evidence, suggested a Triassic correlation, and a Swedish-Finnish expedition in 1965 from observation at sea also suggested a Triassic age. These questions were settled from field work in 1969. Flood, Nagy & Winsnes (1971) who found not only that the lithologies matched those of the De Geerdalen Formation of Barentsoya and Edgeoya, but confirmed this correlation by collecting Pteridophyllum common to both. They also reported Halobia zitteli, a gryphaea, and one ammonoid, probably Arctosirenites. These ruled out a Cretaceous age but were not so specific as to a likely Late Triassic age. However the published report is brief with no section. Russian work in 1966 and 1971 (Pchelina 1972) resulted in a composite stratigraphic succession for the southern part of the island divided into Carnian and Norian stages partly on lithological grounds but with reference to fossil plants, bivalves and phyllopods. She suggested that the north of the island might preserve Jurassic strata. Similarly Worsley (1973) suggested that his proposed Wilhelmoya Formation might occupy the hill tops in the north where there was some evidence of down faulting. Exploratory wells were drilled by Norske Fina and associates in 1971 and 1973. These followed a preliminary study of samples by W B H in 1967 and field work in 1969 by a CSE party. The resulting paper (Smith, Harland & Hughes 1975) summarized available knowledge and reported permissible results from these investigations.Their conclusions are summarized below.

weathering bright red-brown to purplish which tend to follow the coarser horizons. At the bottom is a horizon of brown bioturbated siltstone. Rare ammonoids and abundant bivalves are found in the clay ironstone beds. The member is marine throughout with ammonoids, bivalves, ichthyosaurs, acritarchs and dinoflagellates. The scarcity of ammonoids and the good spore and pollen content suggest a near shore environment. Worsley suggested an Early Jurassic age but the palynological evidence makes a Rhaetian age more likely. Iversenfjeilet (= De Geerdalen) Formation, 325 m down to sea level at type section. This unit forms the greater part, and always the lower part, of Hopen. It consists of alternating sandstones, siltstones and shales in cyclothems of metres or decimetres. Shales or siltstones grade upwards into fine-, medium- or coarse-grained sandstones. The uppermost part is of calcareous, yellow-weathering sandstones with bivalves. The prominent ledge at the top may be Worsley's Basal Member. Lower down, siltstone and shale are the dominant lithologies, nodular ironstones, weathering red-brown are common at the base of the shale beds. Associated shales may be green or red. Siltstones are often bioturbated. The lower 100 150m in the south are often coarse-grained with large channel structures tens of metres across with cross bedding. The sandstones are often calcareous with beds of dolomitic mudstone. The age of the Iversenfjellet unit is probably latest Carnian to Norian and possibly earliest Rhaetian. Stratigraphic section at northeast Lyngefjellet from 290 m down to sea level from Smith et al. (1975).

Wilheimoya Fm Lyngefjellet (sandstone) mbr, 80+ m top of exposure; 15 m medium-bedded white sandstone with dark silty shale interbeds 35m massive quartz sandstones weathering white, thin bedded in part, occasionally pebbly; cross-bedded and ripple marked. 29 m Interbedded fine to medium sandstone and grey siltstone

Flatsalen (shale) mbr, 55 m; 55 m grey silty shales with red-weathering nodular ironstones especially near base. Three prominent beds of interbedded fine sandstone and siltstone. Bioturbated brown-weathering siltstone at base; 1 m prominent bed of yellow-weathering calc siltstone to fine sandstone with thin layers of coarse sand near top.

Iversenfjellet Fm 155 m; 95 m alternating fine to medium sandstone, silty shale and clay ironstone. about 13 cycles in this interval. Sandstones have ripple marks and small scale cross-bedding. Sandstone and siltstone often finely interlaminated. Shaly beds generally thicker (3-4 m) than sandstones (2 m); 60 m alternating sandstones and siltstones; sandstones medium-grained, thin to thick bedded, relatively little shale or siltstone.

5.8.3 5.8.2

Succession from outcrop

F r o m sections measured and collected from north to south three stratigraphic formations were proposed. However, Worsley (1973) proposed the Wilhelmoya Formation which has priority and to which he related the two upper units on lithological grounds. Smith et al. (1975) units are therefore taken as members of the Wilhelmoya Formation.

Wilhelmoya Formation Lyngefjellet (sandstone) Member, 80 m to top of hill is limited to Lyngefjellet and north in the hill tops. It is a white-weathering medium to coarse-grained sandstone mostly of quartz with occasional pebbles, cross bedding and ripple structures in the middle. Carbonized plant fragments are abundant and are often current oriented. The facies suggest fluvial deposition. The age of the member was estimated biostratigraphically as latest Triassic to earliest Jurassic (Rhaetian to Hettangian). It correlates with the Transitional and Tumlingodden Members of the type section of the Wilhelmoya Formation (Worsley 1973). Flatsalen (shale) Member, 55 m. The appearance is similar to the 'Aucella Shales' of the Janusfjellet Formation of Spitsbergen. It crops out as a less resistant unit between the sandstones above and below. Its main outcrop is in the north but three other outcrops cap the hills including Iversenfjellet. The dominant lithology is dark grey silty shale with prominent siltstone and fine sandstone horizons. The shales have beds of nodular clay-ironstone

93

Subsurface succession

The two wells, Hopen-1 and Hopen-2, drilled by Norsk Fina 19711973, were investigated by Cambridge Svalbard Exploration and summarized in Fig. 5.18. Hopen-1, 25~ 76~ near the southern tip of the island was drilled at near sea level to a depth of 908m and penetrated Norian into Anisian strata as estimated palynologically by M. G. Mortimer. Hopen-2, 25~ 76~ was sited on a hill top at the north of the island higher in the succession. J.F. Laing reported on the Triassic palynology. The Kapp Starostin Formation was met at about 1360m and drilling continued to c. 2870 still probably in lower Gipsdalen Group strata. There was little difficulty in correlating the strata with the Spitsbergen succession. Correlation between the two wells and those on Edgeoya as discussed in the Section 5.9.

5.9

Correlation of four exploratory wells: Edgeoya and Hopen

The four exploratory wells noted above (Sections 5.7.3 & 5.8.3) were drilled in the early 1970s namely: Plurdalen-1 and Raddedalen-1 in Edgeoya and Hopen-1 and Hopen-2. Cores and cuttings were made

94

CHAPTER 5

available to Cambridge Svalbard Exploration by Norsk Fina for independent opinions on the ages of the samples. The materials are now part of the Svalbard collection of the University of Cambridge by courtesy of Dragon Oil plc. The 25 biostratigraphic progress reports remained confidential until recently. In due course it would

be sensible to publish the mainly palynological results, and better still to combine all investigations in a comprehensive assessment. Only the broad conclusions of the Cambridge investigations directed by W.B.H. are reported here. The only other known publication was by Shvarts (1985) on Raddedalen-1 drilled by CFP. Some of this

EASTERN SVALBARD PLATFORM

95 Correlation with surface geology of Hopen

HOPEN-2 Approximate correlation with

-

BiUefjorden Trough RADDEDALEN-1

Early Triassic

Tatadan, Kazanian& Kungurian Artinskian Sakmadan& Asselian Kasimovian& Gzelian

- Mcmr Bashkilian

Namurian

•LUO

..........

....

Kapp Starostin Fm Gipshuken Fm

~Q(.

:111:

Svenbreen Fm

2

?__~,~

Lynge~ellet Sandstone Fm Flatsalen Shale Fm

1

i

I

$4.=a

HOPEN-1

: - - ~ ?9- ~ .~. . . . . . . . . . . . . . . I~' 3C

~

3b

, ~

3a

~

Iversenfjellet Fm

i a. o

Rhaetian

'< Norian and Camian

o VI-~ I I /

H

.....

II

.--9--

Cadelff]elletMbr Min~t Mbr~ Ebbadalen Fm

PLURDALEN-1 --lz

?--

Ladinian

t .9"

I

Anisian an( Scythian

Id

IV

Late Permian

Ill

Ic

Ib la

Fig. 5.19. Suggested correlation of the Edgeoya wells (Raddedalen-1 and Plurdalen-1) and Hopen-1 and Hopen-2 wells, based on CSE reports to Norske Fina and especially the final report by J. F. Laing, courtesy of Dragon Oil plc. material was exchanged by Norsk Fina and was added to the Cambridge investigation. The material Shvarts investigated was obtained by exchange for a Russian well, Grumantskaya-1. The preliminary conclusions are reported above: two Edgeoya wells in Section 5.7.3 and two Hopen wells in Section 5.8.2. An attempted correlation is shown in Fig. 5.19. The major problem was the age of the relatively barren red beds low in the Edgeoya wells. It was unexpected that the two Edgeoya wells should appear to be so different; still more unexpected that the two

reports on Raddedalen-1 should differ so much. There is probably a significant geological difference between the two Edgeoya wells suggesting separation by a minor fault. Both Edgeoya successions, according to the CSE interpretation, fit the idea of Svalbardian tectonics, possibly strike slip faulting accompanied by transtension with local subsidence in the typical Billefjorden continental environment. Triassic and possibly late Paleozoic strata appear to thicken systematically towards the southeast.

Chapter 6 Northern Nordaustlandet (and associated Islands Storoya, Kvitoya) W. B R I A N

HARLAND

6.1 6.2 6.2.1 6.2.2 6.2.3 6.2.4 6.3 6.3.1 6.3.2 6.3.3

Early work, 96 Stratal succession, 96

6.4.1 Laponiahalvoya granites, 105 6.4.2 The Rijpfjorden, Rijpdalen and Duvefjorden granites, 106

Hinlopenstretet Supergroup, 99 Murchison Bay Supergroup, 100 Kapp Hansteen Group, 103 Brennevinsfjorden Group, 103

6.5

Subjacent metamorphic complex, 104

6.6 6.7

6.4

Late tectonic plutons, 105

Evolution of ideas, 104 Migmatic and magmatic components, 104 Supracrustal inclusions, 105

Nordaustlandet is the second largest island in the Svalbard archipelago. It has been generally inaccessible by ship because of polar pack ice except for the west coast, or in exceptional summers. Exploration has therefore been limited. The major part of the interior is covered by two large ice caps: Vestfonna and (the large) Austfonna which forms all of the southern coastline in the eastern part of the island. Pre-Devonian, mostly Precambrian outcrops of solid rock extend along the northern and northwestern seaboard. Wahlenbergfjorden divides the west coast with post-Devonian rocks cropping out to the south of it. These have already been referred to in Chapter 5 so that the main object in this chapter is to outline what is known of the older rocks. Because of the ice caps covering the major part of the island, exposures, especially in the north and east, are often isolated on promontories along the highly indented coastline (Fig. 6.1).

6.1

Early work

After the early visit by Parry in 1828 research was largely by Swedish geologists with A.E. Nordenski61d's sledge journeys in 1861, 1866, 1869 and 1873. A Swedish initiative led to the Russo-Swedish Arc of Meridian Survey along both sides of Hinlopenstretet. During the period 1899 to 1902 (De Geer 1923; Nathorst 1910) and later the SwedishNorwegian expedition based at Sveanor in Murchisonfjorden (Kulling 1932) resulted in a thorough study of the Hecla Hock rocks (Kulling 1934). Alongside this were a series ofmultidisciplinary expeditions from Oxford University in 1924, 1935-36 and 1951. Sandford accompanied the 1924 expedition (1926) and since then he interpreted the many careful observations made by non-geologists aided latterly by the use of oblique air-photographs (1950, 1954, 1956, 1963). From their extensive surveys these expeditions for long provided the most reliable maps of Nordaustlandet (e.g. Glen 1937). The above work had depended on ship and sledge; then after sundry visits in 1965 the Norsk Polarinstitutt surveyed the large area of older rocks with helicopter transport. The resulting accounts are the principal sources for this chapter (Flood et al. 1969; Hjelle 1966, 1978a, b; Hjelle, Ohta & Winsnes 1978; Ohta 1978, 1982a, 1985). However, later isotopic studies have further elucidated the tectonostratigraphic history (e.g. Gee et al. 1995) and consolidated the evidence for a major unconformity to divide and so practically eliminate the Botniahalvoya Supergroup. Isotopic ages for all Svalbard included earlier data for Nordaustlandet (e.g. Hamilton & Sandford 1964; Gayer et al. 1966; Edwards 1976; Edwards & Taylor 1976).

Minor igneous bodies, 106

6.5.1 Acid intrusions, 106 6.5.2 Basic layers to northeast, 106 6.5.3 Dolerite sills and dykes, 106 Summary of isotopic ages, 106 Structure of Nordaustlandet, 107

6.7.1 A Barents craton, 108 6.8

The Lomonosov Ridge in relation to Nordaustlandet, 108

Quaternary studies were undertaken but are discussed in Chapter 21 (e.g. Salvigsen 1978). Various geological maps and accompanying descriptions consolidated the information as follows: 1:500 000.3G (Hjelle & Lauritzen 1982) and 4G (Lauritzen & Ohta 1984, and I:IM Bedrock Map (Winsnes 1988). Russian work was included by Krasil'shchikov (1967) and in his Precambrian synthesis (1973). Sundry visits in western Nordaustlandet added miscellaneous observations by Cambridge parties (Knoll 1982a, 1984; Hambrey 1982; Hambrey, Harland & Waddams 1981; Harland, Hambrey & Waddams 1993).

6.2

Stratal succession

Confining the study area in this chapter to the land north of about 79~ t, with few exceptions all the exposures to the north are of preCarboniferous and all to the south are of post-Devonian rocks. The exceptions include dolerite intrusions of probable Cretaceous age and one outcrop of Carboniferous/Permian strata at Idunfjellet, north of Wahlenbergfjorden. It has been convenient to include consideration of these exceptions in (the preceding) Chapter 5. The sequence of strata as worked out by Kulling (1932/4) and by Norsk Polarinstitutt geologists (e.g. Flood et al. 1969; & Ohta 1982), modified by Gee et al. (1995) is compiled in Fig. 6.2. The origin of the names in the evolving scheme is discussed here and adopted for descriptive purposes. (1) On the names. From Kulling's classic work the names Kap Sparre, Murchison Bay, and Kap Hansteen were introduced in 1932 in the first Swedish report using Swedish place name spellings. His full report with definitions was in English (1934) with Cape Sparre, Murchison Bay and Cape Hansteen. The original Swedish names have been generally followed but often mistakenly edited into the Norwegian spelling of Kapp for Kap, whereas the Norwegian place name is Sparreneset. In this work Sparreneset formation is introduced for what is only a part of the original Kap (Cape) Sparre Formation to avoid ambiguity which, unfortunately, was not done by Harland, Hambrey & Waddams (1993). Similarly the revision e.g. by Lauritzen & Ohta (1984) limits radically the meaning of the original Kap Hansteen Formation to a part of it, namely their Kapp Hansteen Formation. The new spelling is intended for the units as they have been revised; but the English form is used in discussion when referring to Kulling's units as he described them. Krasil'shchikov (1967) described the tillite-like rocks of Nordaustlandet with a radical redivision of Kulling's scheme. This was accepted by Harland (1985) and Harland et al. (1993) but with mistaken application of two names that are corrected here. However the major Norsk Polarinstitutt geological exploration of Nordaustlandet carried out in 1965 when published did not take account of Krasil'shchikov's work (Flood et al. 1969). The following notes attempt to clarify a confusing nomenclature in a rapidly developing geological understanding as shown in Fig. 6.2.

N O R T H E R N NORDAUSTLANDET

97

Fig. 6.1. Map of northern Nordaustlandet showing principal topographic features, ice-rock boundaries and major place names. (1) Adlersparrefjoren; (2) Bodleybukta; (3) Botnvika; (4) Bragerbreen; (5) Bragneset; (6) Depotodden; (7) Ekstremhuken; (8) Gimterbreen; (9) Gylde~n6yane; (10) Holmboeodden; (11) ldunneset; (12) Isrundingen; (13) Kapp Fanshawe; (14) Kapp Lady; (15) Kapp Laura; (16) Kapp Lindhagen; (17) Kapp Lord; (18) Krossoya; (19) Langgrunodden; (20) Lindhagenbukta; (21) Maudbreen; (22) Nilsenbreen; (23) Nordporten; (24) Nordre Franklinbreen; (25) Normanbreen; (26) Oxfordhalvoya; (27) Pentavika; (28) Rijpbreen; (29) Ringertz6ya; (30) Schweigardbreen; (31) Selanderneset; (32) Sore Franklinbreen; (33) Svartneset, (34) Zeipelodden.

(i) Kulling's (1932, p. 142) preliminary scheme:

His full scheme with descriptions in 1934:

'Kap Sparre-formationen Sveanor-formationen Murchison bay-formationen Kap Hansteen-formationen Prim~irt liggende Ok/int.' (Primary layers unknown)

Cape Sparre Fm Sveanor Fm Murchison Bay Fm Cape Hansteen Fm

(ii) Hinlopenstretet Supergroup as defined just across the strait in Ny Friesland (see Chapter 7), for the Oslobreen and Polarisbreen groups (Harland, Wallis & Gayer 1966). The upper carbonate part of Kulling's (original Cape Sparre Formation has proved to be the equivalent of the Oslobreen Group with an Early Cambrian Krossoya unit and an Early Ordovician Sparreneset unit (informally introduced here). Krasil'shchikov's (1967) revision distinguished his Gotiahalv~ya Group (equivalent to the Polarisbreen Group) by making three formations that are equivalent to the three formations in the Polarisbreen Group as follows. The Klackbergbukta Formation (the equivalent of the Dracoisen Formation in Ny Friesland comprises the upper pelitic part of Kulling's Cape Sparre Formation. The Sveanor Formation follows Kulling and corresponds to the Wilsonbreen Formation in Ny Friesland The Backaberget Formation of Krasil'shchikov (equivalent to Ny Friesland's Elbobreen Formation) is the lower pelitic part of Kulling's Ryss6 Formation. ('fii) Kulling's (1932) Murchison Bay, rather than Murchisonfjorden of Flood et al. (1969), is retained as the name for this supergroup on the basis that whereas he did not distinguish the Franklinsundet Group formations

(thinking they repeated younger rocks in the opposing limb of an isoclinal fold, he nevertheless did include these rocks in his Murchison Bay unit, a name that has been widely used. (iv) The Cape Hansteen Formation of Kulling was widely used as the name for the rocks older than the Murchison Bay succession. Flood et al. (1969) in effect divided Kulling's Cape Hansteen Formation into two: the Kapp Hansteen Formation with a conspicuous acid volcanic component and the Brennevinsfjorden Formation largely of shales and sandstones. They noted a conglomerate between but were not certain which of the formations was the younger, opting tentatively (but as it proved mistakenly) for the Brennevinsfjorden Formation as the younger. They combined the two formations into the Botniahalvoya Group which was indeed Kulling's Cape Hansteen Unit. However, Ohta (1982) demonstrated that the Kapp Hansteen volcanic sequence rested with angular unconformity above the Brennevinsfjorden siliciclasts. This evidence was presented in more detail by Gee, Johanssen, Ohta et al. (1995) which scheme is followed here. The conclusion is that a significant folding episode divided the Botniahalvoya Group which therefore ceased to be a useful unit and Gee et al. instead transferred the name Botniahalvoya to the unconformity, and so presumably to the diastrophism. (v) Meyerbnkta and Austfonna rocks. There is some difficulty over the correlation of the extensive outcrops around Rijpfjorden and to the east. These were mapped by Flood et al. (1969) as the Austfonna Formation in the south and the Kapp Platen Formation in the north and were included at the top of their Botniahalvoya Group. However, Ohta (1982) in extending downwards the Murchison Bay Supergroup included within the outcrops on L~tgoya his new Meyerbukta Formation at the base. He then appeared to define it as a group by including the three formations of the Austfonna Group which he tabulated (p. 44) within his Murchisonfjorden Supergroup. Lauritzen & Ohta (1984) also

NORDAUSTLANDET Formation

Group

NY FRIESLAND Supergroup

Group

Sparreneset 100 (10-17) Kross~ya (10-17) Klackbergbukta 650 (6) Sveanor* 300 (2) Backaberget 290 (6)

Formation Valhallfonna (8)

Oslobreen 1200 (3)

Kirtonryggen (5) Ditlovtoppen (5)

Hinlopenstretet (11) (5) Gotiahalv~ya (6)

Polarisbreen 9OO (3)

Dracoisen (5) Wilsonbreen (5) Elbobreen (5)

Roaldtoppen (7)

Akademiker -breen 1350-2400 (3)

Backlundtoppen (3) Draken (3) Svanbergfjellet (5) Grusdievbreen (5)

Ryss~* 750 (1-2) Hunnberg* 500 (2)

Oxfordbreen (3)

Raudstup-S~ilodd* 550 (2) Norvik* 340 (2)

Celsiusberget (7)

Flora* 1250 (2)

Murchison Bay* (2)

I.o v t--

o ~0

~, E

Kapp Lord 1000 (7)

Glasgowbreen (5) Veteranen 3800 (3)

0 ..1

Westmanbukta 625 (7)

Kingbreen (5) Franklinsundet (7)

Persberget >150 (7) Meyerbukta (9)//~C~.ntr~" in i^1 / ...... "" J(Innvikhogda) ? j/ 400 m

Basal quartzite (9) -(-Ausffonna in C---

_ 9

Kontaktberget g. (13.) / ~ 1 6 ] Laponiahalv~ya ~ (13) 9 -Rijpdalen Laponiat]ellet g. (13)~ra~it-~s granites (13-16) ~ (16) Quartz porphyry, porphyrite, acid andesite and ~ tholeiite volcanics / / / i n Kapp and intrusive f m s j centre Hansteen inW ~ v " ..ane 2000(7) a J Botnia(16) ~-~-f~.~-~-~ ~/ halv~ya Upper sst. and sh. (9) in W , ~unconf. (13) Middle qtz. and sh. (9) ~ Lower sh. and sst. (9) ~ in centre BrennevinsBasal quartzite// fjorden >3000 (7) ( 9 ) ./ Helvetsflya _ ~ _ (16) _ Migmatites with gneisses and granites of Proterozoic age intrusive into above two groups 1950_10501 (16) Paragneiss and paleosomes in Duvefjorden Complex (12) (=metamorphic complex of Sandford 1956)

Kortbreen (5)

__

Vildadalen (5) Planetfjella 4750 (3) Fl~en(5) "-p ,-, ~ O "~ .o'= ~

i

,

9

r ,- .

Harkerbreen 4150 (3)

.

. ~ ~

.

i

,

(19) (14) Atomfjella Complex (4)

Finnlandveggen 2700 (3) ?,~Jv~,_, ?

~

(18)

Granitoids

~

(15)

Fig. 6.2. Preferred names for rock units in Nordaustlandet and their approximate equivalents in Ny Friesland, with estimated thicknesses in metres, mainly based on Harland (1997, table 2) with permission of Norsk Polarinstitutte. The origin of the names is indicated by the numbers in brackets: (1-2) Nordenski6ld in Kulling (1934); (3) Harland & Wilson (1956); (4) Abakumov (1965); (5) Harland et al. (1966); (6) Krasil'shchikov (1967); (7) Flood et al. (1969); (8) Fortey & Bruton (1973); (9) Ohta (1982); (10) Lauritzen & Yochelson (1982); (11) Lauritzen & Ohta (1984); (12) Gramberg, Krasil'shchikov & Semevskiy (1990); (13) Gee et al. (1995); (14) Johansson, Gee & Larionov (1995); (15) Larionov et al. (1995); (16) Gee & Teben'kov (1996); (17) this work. The Kapp Hansteen Group is defined by two formations in Botniahalvoya: Norgekollen (quartz porphyry) Formation, above and Gerarodden (volcaniclastics) Formation below, and in the Rijpdalen area it would include the Svartrabbane Formation as plotted. *, detrital zircons indicate maximum age of Strata: (18) Gee & Hellman (1996); (19) Hellman et al. (1997).

NORTHERN NORDAUSTLANDET showed the Meyerbukta Group as equivalent to the Austfonna Group in the east. However, already Flood et al. (1969) had shown that the Austfonna Formation was not only intruded by quartz porphyry but also cut by the Rijpfjorden granite. Moreover they had shown it to be continuous with the Brennevinsfjorden Formation, which was, however, then thought to lie above the Kapp Hansteen Formation. The outcome must be that the Austfjorden and Kapp Platen formations are older than the Kapp Hansteen Group and correlate with and belong to the Brennevinsfjorden Group whereas the Meyerbukta Unit is clearly the lowest unit so far recorded within the Murchison Bay Supergroup. It cannot thus be defined by the Innvikhogda, Djevlaflora and quartzite formations of the Austfjorden Group but rather as its own formation which is included here within the Franklinsundet Group as the rocks were originally so included by Flood et al. (1969). This has been clarified by Gee et al. (1995), Larionov et al. (1995) and Gee & Teben'kov as Fig. 6.2. (vi) The Granites. The granites were originally thought to be ancient but the relatively unfoliated and pink rather than grey granites generally appear to have intrusive contacts and would therefore be younger than the adjacent rocks. By analogy with the granites in northwest Spitsbergen which Holtedahl argued were 'Caledonian', it was thought by Kulling, and by most geologists until recently that the late tectonic granites would also be Paleozoic. Indeed isotopic investigations supported this view as shown in the compilations of Gayer et al. (1966) and Ohta (1992). Values consistently averaged around 400 Ma mostly by K - A r and Rb-Sr determinations mainly on biotite, muscovite and whole rock. However, the application of uranium-lead isotopic studies of zircons opened a new window on the problem. Many apparently younger granites are now yielding ancient zircons. Therefore if the zircons represent the age of original cooling of the granites it appears that many Precambrian granites have been subject to later, Paleozoic reheating. Making the assumption that the zircons were not inherited from an older basement we now have the prospect of a radical reinterpretation of the Nordaustlandet granites as Proterozoic (Gee et al. 1995; Larionov et al. 1995; Gee & Teben'kov 1996). (vii) The migmatites. Increasingly eastwards migmatites prevail. They invade older strata of which fragments of a ghost stratigraphy may be interpreted. They are clearly older than, through probably related to, Prins Oscars Land granites and probably the Laponiahalvoya granites. They would thus appear not to be Caledonian migmatites although modified in Paleozoic time, but rather developed from migmatites associated with the Kapp Hansteen magmatic events. (viii) Duvefjorden Complex. This name introduced by Teben'kov (Gramberg, Krasil'shchikov & Semevskiy 1990) usefully signifies the metamorphics, migmatites and granites east of Rijpfjorden, whose age is not established. It probably represents the Precambrian Barents Craton.

6.2.1

Hinlopenstretet Supergroup

This s u p e r g r o u p is set o u t here as c o m p r i s i n g t w o groups.

Oslobreen Group Sparreneset formation (informal) Krossoya formation (informal)

Gotiahalvoya Group Klackbergbukta Formation Sveanor Formation Backaberget Formation T h e H i n l o p e n s t r e t e t S u p e r g r o u p was defined in N y F r i e s l a n d to the west o f H i n l o p e n s t r e t e t ( H a r l a n d , Wallis & G a y e r 1966) c o m p r i s i n g the O s l o b r e e n G r o u p ( C a m b r o - O r d o v i c i a n f o r m a t i o n s ) a n d the P o l a r i s b r e e n G r o u p ( V e n d i a n f o r m a t i o n s i n c l u d i n g tillite horizons). Similarly o u t c r o p s in N o r d a u s t l a n d e t o n the east side o f H i n l o p e n s t r e t e t were described earlier by K u l l i n g as the C a p e Sparre F o r m a t i o n a n d the S v e a n o r F o r m a t i o n respectively. T h e C a p e Sparre F o r m a t i o n (850 m) was divided by K u l l i n g (1934) i n t o six series ( m e m b e r s ) thus: (6) (5) (4) (3) (2) (1)

Upper Upper Upper Lower Lower Lower resting

D o l o m i t e , 140-200 m Quartzite, 110 m Shale 1 3 0 - 1 4 0 m Dolomite 120m Quartzite 30-40 m Shale 250 m. o n the S v e a n o r (tillite) F o r m a t i o n .

99

Winsnes (Flood et al. 1969) redescribed and measured further sections of this unit which he renamed the Kapp Sparre Formation in the same arrangement, but increasing the thickness estimate to 1200 m. This scheme was followed by Lauritzen & Ohta (1984). A more detailed section of the Sveanor Formation was recorded by Edwards (1976). Krasil'shchikov (1967, 1973) had also recorded sections and redivided the succession so that Kapp Sparre Formation was limited to Kulling's division (6) above and the remainder was named Klackbergbukta Formation. This reclassification was followed by Harland (1985) and again by Harland, Hambrey & Waddams (1993), but mistakenly mistranslating the name Klackberget. Krasil'shchikov's Blackaberget Formation (which constitutes the upper pelitic part of Kulling's Rysso dolomite Formation) was also accepted by Harland et al. These revisions have the advantage of distinguishing an upper Early Paleozoic carbonate unit, a Vendian siliciclastic unit and a (mainly) preVendian carbonate unit. The upper two units correlate well with the Oslobreen and Polarisbreen groups in Ny Friesland and so this classification is applied. It is thus appropriate to rename the original Cape Sparre Formation by dividing it into the Sparreneset and the Klackbergbukta formations. Similarly the Ryss6 Formation as defined by Kulling loses its upper part to make the Backaberget Formation. Thus Krasil'shchikov's (1967) three (Vendian) formations combine to define his Gotiahalvoya Group (equivalent to the Polarisbreen Group of Ny Friesland) and so form the lower group of the Hinlopenstretet Supergroup as applied in Nordaustlandet by Lauritzen & Ohta (1984). T h e r e c a n be n o d o u b t as to the c o r r e l a t i o n w i t h N y F r i e s l a n d as s h o w n in F i g u r e 6.2.

Oslobreen Group. This group, named for the Ordovician and Cambrian formations in Ny Friesland as the uppermost of the two groups comprising the Hinlopenstretet Supergroup, is applied here for the time being pending a decision as to whether the equivalent strata in Nordaustlandet require a distinct group name. It is the uppermost unit 6 of Kulling's Cape Sparre Formation. He described this upper dolomite series (140-200 m) thus: at Sparreneset: Black grey dolomitic mudstone, 40 m with trail marks (originally observed by de Geer 1901, and identified as Helminthoidichnites) and inarticulate brachiopods (Lingulella and Obolus) Grey dolostone, 70-100 m. on Krossoya: Grey to dark-grey dolostone, with trail marks in upper part (Planolites) on Depotoya up to 700 m but poorly exposed. All these fossils have long time-ranges so no precise biostratigraphic correlation could be made, though Kulling took the age to be Early Cambrian. Winsnes (in Flood et al. 1969) described a further section north of Br~vika and measured others. At Sparreneset, in 1974, Harland found the contact with the earlier rocks to be faulted (Hambrey, Harland & Waddams 1981). He thought the nearest analogue in Ny Friesland to be the Nordporten Member of the Valhallfonna Formation of demonstrable Arenig a g e - just across Hinlopenstretet. More fossils had been sought in vain by several parties, but outcrops are between tides and of limited extent. He also noted a fault so that two formations could be present there. The difficulty was resolved by Lauritzen & Yokelsen (1982) who recorded Salterella at Sparreneset, and in Krossoya they also found olenellid tribolites so confirming a late Early Cambrian age. Moreover west of Krossoya they reported an Early Ordovician fauna so supporting Harland's suggestion. Until the matter has been taken further the Early Ordovician unit is referred to informally as the Sparreneset unit to distinguish it from the Early Cambrian Krossoya Formation, the names selected where ages are evident. The result is to match still more closely the successions in Nordaustlandet with those in Ny Friesland. Undifferentiated sections were measured by Kulling (1934) as about 500 m at Sparreneset and by Winsnes (Flood et al. 1969 p.20) at over 1100 m north of Br~tvika near the northwest of Storsteinhalvoya. Sparreneset (informal) formation. Lithologically at Sparreneset this would correlate with the Nordporten Member of the Valhallfonna Formation which in Ny Friesland is of late Canadian (Arenig) age. Biostratigraphically Lauritzen & Yochelson (1982, p.5) reported: 'on small islands northwest of Krossoya, an Ordovician fauna has been found indicating a break in the succession from Middle Cambrian to lower Ordovician time...'. The two unnamed islands near to the northwest coast of Krossoya were mapped by Kulling (1934) as part of his Cape Sparre Formation. Sparreneset is where Harland had noted this unit. No measured section has been published.

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Krossoya (informal) formation. This name is chosen for that part of the uppermost three units of Kulling's Cape Sparre Formation because it appears to be best developed there with a thicknesses of 700-800 m and was described there by Kulling and in 1966 by Winsnes (in Flood et al. 1969) and who collected the specimens identified by Yochelson (Lauritzen & Yochelson 1982) as Salterella. Olenellids were also found so that good correlation is established with the Tokammane Formation of Ny Friesland which, together, indicate a late Siberian (Early Cambrian) age i.e., the Bonnia-Holmia zone. At Sparreneset the succession was described by Kulling (1934) as containing Lingulella and Obolus types and with trace fossils: Helminthoidichnites type and estimated at 110 m in difficult circumstances thus (p. 191): 40 m black-grey dolomite mudstone with trail marks and brachiopods 70-100 m grey dolomite 3 m black-grey laminated dolomites. This may well include part of the Sparreneset formation. The section is clearly incomplete dipping west into the sea. Gotiahalvoya Group (Krasil'shchikov 1967) (equivalent to the Polarisbreen Group of Harland & Wilson 1956). The group comprises three formations: Klackbergbukta (top), Sveanor and Backaberget. Krasil'shchikov (1967) recorded the most detailed available petrographic description of these deposits, only some portions of this are added to this account. Klackbergbukta Formation (Krasil'shchikov 1967). This unit comprises the lower five units of Kulling's (1934) Cape Sparre Formation which he described thus: (5) Upper quartzite series, l l 0 m of variously coloured (red, grey, green, white) quartzite and slaty sandstone at Sparreneset and on Krossoya, also with some grey dolomitic mudstone. (4) Upper Shale Series, 130-140m, pink and grey shales with laminated dolostone and bands of chert (a thin middle quartzite occurring only on Krossoya). (3) Lower Dolomite Series, 120m. At Sparreneset, dark and black-grey dolostone also with some dolomitic limestone on Krossoya and Depotoya. (2) Lower Quartzite Series, 30-40m. White quartzite sandstone only at Sparreneset (subjacent rocks are not exposed possibly being tectonically disturbed). (1) Lower Shale Series, 250m. Green grey and red brown shale SW of Sveanor on S Russoya but more carbonaceous with 10 m dolostone at base resting directly on Sveanor tillite. Other outcrops in Murchisonfjorden and Wahlenbergfjorden were outlined by Winsnes (in Flood et al. 1969), Edwards (1976) and summarized by Harland, Hambrey & Waddams (1993). The age of these rocks has been confirmed as probably Vendian (Knoll 1982a). The dolostones of the upper horizons of the formation are characterized by flaggy parting with thin impersistent layering separated by a few mm of dolomitic siltstones. Krasil'shchikov described centimetre-scale 'convective' ruptures in the lamination, forming regular polygons in plan. Limonitized pyrite occurs higher up. The sandstone clasts are 90%, acid plagioclase dominating orthoclase with a wide range of accessory minerals. Below a sharp boundary are light coloured sandstones. Sveanor Formation (Kulling 1934), 100-168 m. At the type locality, south of Murchisonfjorden, is a diamictite which was the first in Svalbard to be identified unequivocally as a tillite and has been described in detail (Kulling 1934; Edwards 1976; Hambrey 1982). Whereas Flood et al. (1969) included part of Kulling's Rysso Formation, Krasil'shchikov (1967) distinguished that part as his Backaberget Formation (below). This classification is adopted here and so Kulling's Sveanor Formation is approximately retained. Within the formation lateral facies changes are m a r k e d - the typical tillite is best seen at Sveanor in Murchisonfjorden and at Aldousbreen in Wahlenbergfjorden. The diamictites, interbedded sporadically with sandstones, shales and carbonates, range in colour from greyish and green to maroon. The stones comprise: dolostone (50%), limestone (20%) and the rest sandstone, siltstone, granite, granite porphyry, aplite, quartz porphyry, syenite, keratophyre, amygdaloidal basalt, tuff, siliceous sericitic schist, garnet schist, gneisses, phyllite, quartzite, basic volcanic rocks and jasperised chert (Kulling 1934). The proportion of stones is about 5-10%. All shapes especially facetted and striated (up to 10%) stones being common. Krasil'shchikov described the stone petrography in detail noting oncolitic concretions and concretions with katagraphs. The facies vary from massive to weakly bedded diamictite, with conglomerate lenses. The environment of formation is interpreted as

lodgement and waterlain till deposit and ice rafted stones in more distal mudstones, all indicating an interplay of subaerial, subglacial, glaciomarine and glaciolacustrine and fluvial environments. The cessation of glacial conditions is marked by the sharp change to the Klackbergbukta Formation (Harland, Hambrey & Waddams 1993). The till facies were described by Chumakov (in Krasil'shchikov 1964) before he had accepted a glacial origin for such deposits. Many pages are filled with meticulous petrographic descriptions with few petrogenetic (environmental) conclusions. Selected from this account is the estimate that the larger intrabasinal clasts (stones) suggest local origin from the underlying formations down only to a maximum of 500 m. They confirmed Kulling's view that the basic volcanism preceded, but not by a long interval, the deposition of the diamictites. These basic igneous products unlike many of the acidic rocks were not metamorphosed. Attempts to deduce provenance of the stones were not productive. Krasil'shchikov and others correlated these Sveanor rocks with the Polarisbreen rocks acknowledging that Harland & Wilson (1956) had inferred a glacial origin for the same correlation as had Kulling for the Sveanor Formation. But having considered a glacial origin they preferred (with Klitin 1965) a purely tectonic origin for all such deposits. Baekaberget Formation (Krasil'shchikov 1967), 220-290m. Krasil'shchikov separated this unit from the top of Kulling's Sveanor Formation. Hambrey, Harland & Waddams (1981) and Harland, Hambrey & Waddams (1993) followed this scheme, partly because it correlated well with the succession to the west in Ny Friesland. The formation, based on Kulling's 1934 units east of Sparreneset comprises (4) 50 m laminated, cream-weathering, grey, partly cross-laminated dolostone with rip-up conglomerate at the top (3) 40m dark-grey quartzose slate (2) 150 m grey-black shale (15-20 m dolerite sill) (1) no exposure.

Langgruneset member. To the north at Langgrunnodden is a diamictiterhythmite-limestone-sandstone sequence included by previous authors in the Sveanor Formation. However, because of its distinctive composition (dolostone 65%, limestone 15%, quartzite 10% etc.), it appeared to correlate well with the Petrovbreen Member of the Elbobreen Formation in Ny Friesland (Hambrey 1982) and so would be the equivalent of the Early Varanger tillite (Smhlfjord). The diamictite is underlain by dark, cherty shaly limestone (10m), several tens of metres of marls, sandy towards the base overlying the Rysso dolostone. Well preserved acritarchs in the shales yielded to Knoll (1982a): Protosphaeridium sp., Trachysphaeridium spp., cf. stictosphaeridium sp., and Bavinella faveolata (Shepeleva) which indicate a Vendian age. Osagia svalbardica and Vermiculites irregularis had also been reported in Soviet literature (Krasil'shchikov, Golovanov & Mil'shtein 1965).

6.2.2

Murchison Bay Supergroup (Kulling 1932, 1934)

This s u p e r g r o u p n o w c o m p r i s e s three g r o u p s defined by their f o r m a t i o n s as follows, a n d illustrated in Fig. 6.3. Roaldtoppen Group Rysso Formation Hunnberg Formation Celsiusberget G r o u p Raudstup-Salodd Formation Norvik Formation Flora Formation Franklinsundet Group Kapp Lord Formation Westmanbukta Formation Persberget F o r m a t i o n Meyerbukta Formation K u l l i n g ' s (1934) M u r c h i s o n Bay f o r m a t i o n was raised in r a n k to a s u p e r g r o u p a n d r e n a m e d M u r c h i s o n f j o r d e n by F l o o d et al. (1969) in w h i c h K u l l i n g ' s original six 'series' were a d o p t e d as five f o r m a t i o n s b u t classified into two g r o u p s . T h r e e m o r e f o r m a t i o n s were defined at the base o f the succession for rocks t h o u g h t by

NORTHERN NORDAUSTLANDET

Fig. 6.3. Geological map of northwestern Nordaustlandet (after Flood et al. 1966; Gee et al. 1995).

101

102

CHAPTER 6

K u l l i n g to be repetitions by folding o f his lower f o r m a t i o n s a n d c o m b i n e d in the F r a n k l i n s u n d e t G r o u p . A f o u r t h unit was i n t r o d u c e d ( O h t a 1982) to a c c o m m o d a t e f u r t h e r strata below the F r a n k l i n s u n d e t G r o u p a n d to include the K a p p P l a t e n a n d A u s t f o n n a f o r m a t i o n s east o f R i j p f j o r d e n also within the s u p e r g r o u p .

Roaldtoppen Group (Flood et al. 1969). Both constituent formations were argued to be late Riphean (Knoll 1982). Rysso Formation (Nordenski61d 1863; Kulling 1934) was modified by Krasil'shchikov (1967) who, as already noted, placed the upper part of Kulling's Rysso Formation in his Backaberget Formation. The essential Ryss6 Formation middle and lower part is of relatively uniform massive dolomitic facies. Only this part was described as the Rysso Formation by Winsnes (Flood et al. 1969). It is one of the earliest formations to be named in Svalbard but not at first defined. It was probably the whole carbonate development of the Roaldtoppen Group and was thought to be Carboniferous (Nordenski61d 1863): 50-140m light grey dolomite 70-140 m dark dolomitic limestone - dolomite 500 m typical Ryss6 - dolomite (conspicuously oolitic and stromatolitic). The lower part contains yellow-weathered chert, further details were given by Winsnes and by Krasil'shchikov. Krasil'shchikov, Golovanov & Mil'shtein (1965), describing the biostratigraphy, recorded Vermiculites irregular& with a range Vendian through Cambrian. Silicified bituminous limestones with pyritic black shales near the top of the Ryss6 Formation contain vase-shaped microfossils which suggest correlation with the Backlundtoppen Formation in Ny Friesland and the upper Eleonore Bay carbonates in East G r e e n l a n d - all in the Sturtian interval (?750 Ma). Silicified carbonates in lower Ryss6 Formation match the biota of the Hunnberg Formation below, but have Chuaria in addition (Knoll 1982). Hunnberg Formation (Kulling 1934) 400-600m. Consists predominantly of grey black and grey limestones and dolomitic limestones, passing into mudstones, with lighter coloured, and subordinately reddish, limestones in the middle part. There are horizons of chert concretions, chert conglomerates and phosphorite concretions. The upper part of the formation is a shallowing-upward carbonate sequence passing upwards into open coastal marine facies with bioherms and columnar stromatolites overlain by laminated mud-cracked dolostones. The cherts contain microfossil assemblages (Knoll 1982). The restricted lagoonal biota is dominated by Myxococcoides cantabrigiensis Knoll (1982a) and Glenobotrydion aenigmatis Schopf (1968). The open coastal assemblage is a rich variety of plankton including: Chuaria circularis Walcott, Protosphaeridium cf flexulosum Timofeev (sensu Vidal 1976a), Kildinella hyperboreica Tim. K. jacutia Tim. Trachysphaeridium levis (Lopukhin) Vidal, Trachysphaeridium timofeevi Vidal, cf Stictosphaeridium, Phanerosphaerops capitans Schopf, Myxococcoides cantabrigiensis Knoll. Trematosphaeridium holtedahlii Tim. (Knoll 1982). This is a typical Late Riphean microfossil assemblage. The lowest first occurrence of pterospermopsimorphid acritarchs and other complex taxa suggest latest Riphean to Early Vendian (sensu Vidal). Knoll suggested 700800 Ma for the age. Organic geochemistry of the Raoldtoppen Group. In a s t u d y o f dispersed organic m a t t e r in P r e c a m b r i a n deposits o f N o r d a u s t l a n d e t , D a n y u s h e v s k a y a et al. (1970) analysed samples f r o m the R o a l d t o p p e n G r o u p a n d f o u n d t h a t clots o f biogenic c a r b o n a c e o u s material t e n d e d to be c o n c e n t r a t e d in stylolitic structures. T h e y also analysed basal (Vendian) K l a c k b e r g b u k t a a n d B a c k a b e r g e t strata f r o m the overlying H i n l o p e n s t r e t e t S u p e r g r o u p . Many data were tabulated including total organic carbon thus: Klackbergbukta Fm Backaberget Fm Ryss6 Fm (upper member) Hunnberget Fm

0.49% 0.54% 1.07% 0.19%

With transmitted light the organic matter is dark grey through brown to black, in reflected light it is whitish yellow to dark brown. UV luminescence studies showed the dark brown to black matter to be inert and surrounded by an inner luminescent dimly green aureole passing outwards to lighter luminescence. The black material was unevenly pyritized.

Spectroscopic analysis with (many detailed spectra reported) indicated abundant aromatic structures with linked carboxylic C = O groups possibly with (?)chione affinity and a significant aliphatic component of CH2 and CH3. The conclusion was that the material had resulted from the transformation of blue-green algae in the first instance in the Ryss6 carbonates and that at a later stage (a Caledonian event was suggested) fractionation with migration of the lighter hydrocarbon components into the overlying Vendian sandstones accounted for much of the TOC in those formations. In a final comment the authors remarked that their'results paralleled those from North America and Greenland.

Celsiusberget Group (Flood et al. 1969) Raudstup-Siilodd Formation (Kulling 1934; Flood et al. 1969). Kulling described two series in Murchisonfjorden (especially the north coast): (upper) Siilodd series (180-260) of greenish-grey dolomitic siltstones or redgrey shale of Ohta 1982; (lower) Raudstup series (300-440m) of reddish brown and green-grey slate partly carbonaceous and also quartzose with horizons of white quartzose sandstone. Flood et al. (1969) combined these two series into one formation because the lithologies are interbedded and there is no clear boundary between them. The formation occupies the core of the major synclinorium and thicknesses vary greatly from 400 to 2200 m (Ohta 1982). Small scale cross-bedding in the sandstones suggests a wave-dominated sub-littoral environment. Four fining-upward cycles were distinguished in the lower less deformed strata. A metaporphyrite stratum, 0.5 m with plagioclase and mafic phenocrysts (?after pyroxene) occurs in the lower part and is either an intrusive sheet or a lava flow. It is too altered to compare with the widespread Mesozoic dolerites (Ohta 1982). Norvik Formation (Kulling 1934) 350 m is of dominant green-grey to grey sandstone and slaty sandstone dolomite. Multicoloured slates and white quartzite also occur. Ohta (1982) described it as a formation of 900m of lithology intermediate between the overlying shale-rich formation and the thick Flora quartzites with two members: (upper) shale and quartzite alternation (300-700m); (lower) shale-dominated succession (200-550m) and with five cyclic sequences, the quartzite being 7-20 m thick at the base of each cycle. Flora Formation (Kulling 1934) 910m was described by Kulling: as the distinctive lower unit of his Murchison Bay succession, comprising white, pink and green-grey quartzose sandstone. 630m were measured at Floraberget in 13 divisions. Ohta (1982) gave a thickness of 910m divided into three members with detailed petrographic descriptions: (upper) white grey banded ortho-quartzite with thin flasers of shale and sandstone 50-150 m (middle) reddish quartzite with shales and slates and red shale fragments (lower) alternations of grey sandstone and reddish-white quartzite with abundant red shale fragments. There is a basal conglomerate Franklinsundet Group (Flood et al. 1969). The strata described here beneath the Flora Formation were included by Kulling in his Murchison Bay rocks, but assumed to be repetition of the younger strata by folding because of their similar facies. He perhaps exaggerated the steepness of dips in his postulated isoclinal folding. Flood et al. distinguished three older formations combined in the new grouping. Still older strata were distinguished by Ohta (1982: his Meyerbukta formation) and included at first in the Franklinsundet Group. However, Lauritzen & Ohta (1984) named a further Meyerbukta Group. These two new groups may total nearly the same thickness as the two upper groups of the Murchison Bay Supergroup. The upper two formations of the Franklinsundet Group are clearly distinguished from the conspicuous quatzites above (Flora) and (Persberget) below and it is not easy to distinguish the upper two formations as their mutual boundary is not well exposed. Kapp Lord Formation, 1000 m, in which a detailed succession of 43 units recorded by Gee (Flood et al.) comprising mudstones (various colours) quartzites, limestones and shales in that order of abundance. Westmanbukta Formation, 625 m is similar to Kapp Lord Fm. but with less limestone and more siltstone and fine sandstone. Persberget Formation is characterized by massive white and grey quartzite with subordinate grey shales and ripple marks and ferruginous spots. No complete section was measured and this may account for the lower part being underestimated (Flood et al.) which was later distinguished as the Meyerbukta Formation. Meyerbukta Formation (Ohta 1982). To the north of Kapp Lord and Westmanbukta, the large island of LAgoya yielded to Ohta (1982) a

NORTHERN NORDAUSTLANDET thickness of shales, east of and below the Persberget quartzites. The shales are in places calcareous and grey limestones occur. Ohta claimed 1400m in total for this Meyerbukta Formation. He also (1982 p. 29) argued for a series of megacycles into which the above successions could be divided. Djevleflota Formation (Ohta 1982; Gee & Teben'kov 1996). In central Nordaustlandet in the outcrops between Austfonna and Vestfonna and south of Rijpfjorden to inner Wahlenbergfjorden, Ohta had described three units: Innvikhogda, Djevleflota and a basal quartzite. The area was mapped in greater detail (Gee & Teben'kov 1996) which resulted in a revised stratigraphic scheme.The Djevleflota Formation was accepted as correlating with Ohta's Meyerbukta Formation in the west and at the base of the Murchison Bay Supergroup. In this area it was seen to rest unconformably on the Svartrabbane Formation correlated with the Kapp Hansteen Group. This formation is essentially the same as the Austfonna Formation originally mapped here (Flood et al. 1969).

6.2.3

Kapp Hansteen Group

Botniahalvoya. (Kulling 1932, 1934; Ohta 1982; Lauritzen & Ohta, 4G, 1984). The group comprises at least the Norgekollen and Gerardodden formations (introduced informally here to define the Kapp Hansteen Group), and probably includes the Svartrabbane Formation (Gee & Teben'kov 1996). Kulling (1934, p. 221) summarized his Cape Hansteen Formation as 'of considerable but little known thickness. Grey-green to green porphyry dominates the formation, but there are also violet-grey to red-grey porphyry, grey quartz-porphyry, greengrey quartz-phyllite (mostly more or less rearranged pyroclastic material), agglomerate, and conglomerate'. He gave detailed descriptions area by area. Flood e t al. (1969) described the petrographic types in the volcanogenic Kapp Hansteen succession. In spite of their uncer tainity as to the relative ages of the Kapp Hansteen and Brennevinsfjorden units they were clear that the magmatic rocks best seen around Norgekollen were later, being intrusive into the fragmental Kapp Hansteen succession. Ohta (1985) described the geochemistry of the igneous rocks in detail. He concluded that 'the porphyrites are calc-alkaline acid andesites and dacites of medium to high KaO type'. Two meta-diabase types are (i) of low K20 and high Fe tholeiite and the main body (ii) are acid andesites. Basic dykes suggest island arc volcanism and all are referred to continental rather than oceanic types.

Norgekollen (quartz porphyry) Formation. This is the large body cropping out at Norgekollen but representative of other quartz porphyry intrusions in the peninsula. Whereas it intrudes the rest of the Kapp Hansteen succession and the Brennevinsfjorden Group it is in turn intruded by the Kontaktberget granite in which it also occurs as xenoliths. The porphyries contain metasedimentary xenoliths. No such intrusions are known in the Murchison Bay Supergroup. Quartz porphyry clasts occur in a basal conglomerate in the Murchison Bay sequence due east of Hansoya. Flood et al. (1969), following Sandford (1950) reported that quartz porphyries are distinguished by smoky coloured quartz (up to 15%) phenocrysts, often corroded, (1-3mm diam) 3-7cm -2 and with sharp contacts. Somewhat larger grey, white and pink feldspar (albite-oligoclase) phenocrysts up to 25% occur in a fine groundmass. The composition is of rhyolitic to dacitic composition and a general potash-calc-alkaline affinity. Derivation from the thick continental crust has been inferred (Gee et al. 1995). Three facies occur; massive, sheared, and folded even within one body so that their regional significance cannot readily be inferred. Ohta (1982) referred to the rocks as phyllitized rhyolite. A later schistosity penetrates all these lithologies (Flood et al. 1969, p. 61). This is consistent with the schistosity being part of the post-Hecla Hock (Caledonian) deformation and not to be confused with the pre-Kapp Hansteen Group deformation to be considered below (and p. 109). The minor upheavals associated with the magmatism would account for the local angular unconformity that follows. No great discordance is evident because of the persistence of the succession from east to west. The age of the quartz-porphyries has been estimated at 766 + 87 Ma by Rb-Sr isochron (Gorochov et al. 1977), and a revised age of 970 Ma is expected from the same authors (Ohta 1992).

103

Gerardodden Formation. The stratified volcaniclastic sequence follows with five formations as outlined by Ohta (Gee et al. 1995). Agglomerate, tuff breccia and lava formation, c. 1 km. These include units 4 to 7 (downwards) as mapped by Ohta: (4) ignimbrite; (5) andesite; (6) porphyrite; (7) tuff, breccia and agglomerate. (8) Shale formation c. 50 m This contains tuffacious laminae and is of intermittent occurrence. Tuff and tuffaceous sandstone c. 10 m. These are finely laminated tufts often graded with sandy intercalations and locally with breccias. (9) Columnar jointed porphyrite c. 10m. This massive grey rock is of rhyodacite composition and appears as a conformable lava fow. (10) Basal conglomerate formation up to 20m. These conglomerates are clast supported with monomict basal beds dominated by quartzite clasts up to 1 m in diameter and well rounded at the base but increasingly angular and polymict upwards. Because of the immense variety of volcanic facies and the fine grain of much material, chemical analysis have been used in preference to petrography to characterise the rocks. Ashes and tufts are abundant and 'many of the non fragmental rocks were interpreted as lava flows' (Flood et al. 1969).

Rijpdalen area in Central Nordaustlandet Svartrabbane Formation. Gee & Teben'kov (1996), from further mapping of the outcrops between Vestfonna and Austfonna, defined a new formation with a basic volcaniclastic content already described by Teben'kov (1983) and Ohta (1985); they are interbedded with phyllites and quartzites. Gee & Teben'kov correlated this new unit within the Kapp Hansteen Group. On mapping it was found to rest unconformably on the Helvetesflya Formation of the Brennevinsfjorden Group.

6.2.4

Brennevinsfjorden Group

The formations of the Brennevinsfjorden Group are distinguished in two main areas. To the west of Laponiahalvoya is the type outcrop on Botniahalvoya and to the east are the outcrops of Rijpfjorden and Prins Oscars Land. To qualify as a group it must be defined by its constituent formations. These are three, as yet unnamed, units in the western outcrop as listed below.

Western outcrops. The unit as described by Flood e t al. 1969, p. 53), comprises a m o n o t o n o u s sequence of interbedded quartzites, siltstones and shales. The quartzites are only rarely more than a metre thick. The bedding dipping steeply to the east in the type area mainly coincides with the cleavage. Ripple marks and crossbedding occasionally signal inversion of strata. The quartz has slight undulatory extinction. Ohta (1982 p. 7) recorded 'a 3000m thick areno-argillaceous succession'; Lauritzen & Ohta (1984) referred to 4500 m in the type area. A narrow and distinct hornfels with large idioblasts of andalusite, poikiloblastic staurolite and garnet develops within 30 m of the contacts with the porphyritic gneiss and granite. Strong cleavages with the metasediments show conformable trends with the margins of the granite-porphyritic gneiss masses. Ohta's (1982) detailed observations in Botniahalvoya are significant both in determining that the group is older and not younger than the Kapp Hansteen Group and in identifying a basal conglomerate between them. Three unnamed formations have been distinguished on Botniehalvoya by Ohta (Gee e t al. 1995): Upper sandstone shale formation Middle quartz shale formation Lower shale sandstone formation

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Rijpdalen area in Central Nordaustlandet Helvetesflya Formation (Gee & Teben'kov 1996). In this area, further mapped by Gee & Teben'kov the lower formations of the Murchison Bay Supergroup, once approximately the Austfonna Formation and now established as the Djevleflota Formation, rests unconformably on the Svartrabbane Formation, which in turn has extensive unconformable contacts with the dominantly phyllitic shale and slate Helvetesflya Formation. This has a penetrative, finegrained sericitic schistosity and a superimposed crenulation in an isoclinally folded sequence. The map suggests that the Helvetesflya and Svartrabbane formations are isoclinally folded together. The Helvetesflya Formation is in contact with extensive outcrops of granitic augen gneiss (at Ringghsdalen). This gneiss as well as the above formation is cut and/or metamorphosed by the Rijpdalen-Winsnesbreen granites which were suspected to be coeval with the Laponiahalvoya granites and confirmed as 'Grenville age' based on U-Pb zircon age data (Johansson in Gee & Teben'kov). This would suggest that the whole of the outcrops from the east would also be Proterozoic basement.

North central Nordaustlandet The Kapp Platen Formation at Kapp Platen was mapped in some detail by Winsnes (Flood et al. 1969). This unit has been variously correlated with the Austfonna rocks but in the map of Gee et al. (1995) it was shown as Brennevinsfjorden Group.

6.3 6.3.1

Subjacent metamorphic complex Evolution of ideas

Parry is credited in 1928 for classifying the granites and gneisses together as 'primitive rocks'. Nordenski61d (1863) listed seven formations from Nordaustlandet of which the lower four were (4) (3) (2) (1)

Ryss6 Formation (which he thought might be Carboniferous) Hecla Hock Formation Crystalline limestone and dolomite Gneiss with granite veins and dykes.

He sampled the lowest unit on extensive sledge journeys along the north coast of Nordaustlandet. These 'crystalline' rocks were regarded as Archean basement and were included as Urgebirge in Nathorst's synthesis (Suess 1888 and Nathorst 1910) though he expressed doubt as to the certainty of this conclusion. De Geer (1909) took the same view. A similar opinion regarding the crystalline complex of north western Spitsbergen prevailed until Holtedahl (1914, 1926), in northwest Spitsbergen,argued that the metamorphism resulted from remobilization during the Caledonian orogeny. The status of the Nordaustlandet complex was then in doubt but it differed from the northwest in having an 'unmetamorphosed stratified cover'. Sandford (1926) inclined to the view that the granites were younger. Kulling, who had access to Nordenski61d's material, in 1932 (p. 132) tabulated beneath his Kap Hansteen formation. 'Prim~irt Liggende Ok~irt' (primary layers unknown). Sandford (1950, 1956) began to suspect, and later postulated, an unconformity between the Cape Hansteen rocks and the subjacent metamorphic complex as did Orvin (1940, p. 8) 'there can be no doubt that the Barents Sea shelf forms a continuation of the Fenno-Scandinavian Archean Shields'). That connexion was later in doubt as the postulated Iapetus ocean divided the two areas (Harland & Gayer 1972); but the concept of a (Laurentian) Barents Craton was not thereby undermined. Hamilton & Sandford (1964) showed that Paleozoic thermal activity was extensive from the earliest isotopic age determinations in Svalbard. Nevertheless the dominant view was for a basement to the Proterozoic strata (e.g. Sokolov, Krasil'shchikov & Livshits

1968a) and an ancient Barents shield was postulated to bound the Hecla Hock Geosyncline to the east. We thus depend on the new series of observations by Norsk Polarinstitutt geologists mainly from helicopter reconnaissance sorties and further work by their colleagues in Sweden and Russia. Flood and Gee (Flood et al. 1969, pp. 97-120) described their sub-'Botniahalvoya' complex as of granitic gneisses and migmatites, clearly post-Botniahalvoya in age from their contrasting relationships and some metasomatism. However their description of the supracrustal inclusions therein refers to occasional extensive stratiform rocks, dominantly pelites through to quartzites, and marbles with associated amphibolites. The amphibolite facies of these inclusions contrasts with the greenschist facies of the overlying Brennevinsfjorden rocks. At that time a Caledonian event was preferred. Gee et al. (1995) mentioned that 'pre-Grenvillian basement' is suggested by U - P b data on biotite schist xenoliths within the Laponiafjellet granite. Also augen gneisses at Fonndalen in central Nordaustlandet gave a zircon age of 1048 4-27 Ma with monazite suggesting metamorphism around 960 Ma and some latest Silurian evidence of 412 Ma. Gee &Teben'kov (1996) mentioned a 'Grenvillian' age for the Rijpdalen granites (communicated by Johansson) which would seem to settle the matter. That is to say that the granites and related migmatites of central (and therefore eastern) Nordaustlandet are essentially coeval with those of western Nordaustlandet in Laponiahalvoya so that the whole complex would be Proterozoic, but rejuvenated in some degree in Paleozoic time. Whereas much of the inclusion material may be Brennevinsfjorden Group paleosome, the amphibolites, some of likely sedimentary or at least stratiform origin and others possibly intrusive, do not match the overlying rocks and so are candidates for preBotniahalvoya, i.e. pre-Brennevinsfjorden rocks.

6.3.2

Migmatic and magmatic components

In the early accounts (e.g. Sandford 1926) emphasis was given to the contrast between grey, foliated granites and gneisses, and pink granites. This sub-section concerns the former which are earlier than the late-tectonic plutons (Section 6.4). This large tract of migmatic rock has been named the Duvefjorden Complex (Teben'kov in Gramberg, Krasil'shchikov & Semevskiy 1990). There are two large outcrop areas of these migmatitic gneisses (Flood et al. 1969). In the west: most eastern Laponiahalvoya and Sjuoyane are so mapped. In the east, from Duvefjorden and eastern Rijpdalen, the whole of the eastern half of the north coast outcrops of Nordaustlandet is similarly mapped. West of Rijpfjorden Hjelle (in Flood et al. 1969, p. 103) generalized their findings as follows: Quartz monzonitic rocks with considerable amounts of supra-crustal inclusions occur and at some places with transitions into migmatic gneiss. The modal composition of the migmatite metatect does not differ from that of the average quartz monzonite. The rocks are coarse-grained, grey, hypidiomorphic to porphyritic texture, with phenocrysts of K-feldspar (often microcline and microperthite). Texture varies from slight to well foliated gneiss. Plagioclase is An20m0 and often there are Rapakivi type rims. Quartz shows undulatory extinction and accessories are biotite, muscovite, titanite, apatite, zircon and iron ores. Whereas to the south the rocks are less foliated, and show facies transitional to the Brennevinsfjorden granite, to the north (Nordkapp and Sjuoyane) gneissic structure is typical. Quartzite inclusions with up 65% quartz, epidote and some titanite obtain; mica schist inclusions comprise quartz, albite, biotite; amphibolite inclusions have quartz, oligoclase to andesine, hornblende; and almandine, calcareous inclusions have quartz, calcite, diopside, wollastonite. The gneisses often contain lenses of tourmaline-bearing muscovite. East of Rijpfjorden, Flood & Gee (in Flood et al. 1969 pp. 105-120) suggested that the exposures from Rijpfjorden through Duvefjorden and to the extreme northeast may be just the northern fringes of a large outcrop area extending beneath the ice at least to Isispynten.

NORTHERN NORDAUSTLANDET At the contacts between the low-grade Botniahalvoya Group and the granites and migmatites there is a sharp transition to biotite- and garnetbearing schists, with hornblende in the more basic facies. For example at Innvika in Duvefjorden chlorite-muscovite assemblages in Austfonna (Meyerbukta Group) rocks occurring at a distance of 500 m from the contact give way to biotite-muscovite schists. Within 100 m garnet develops with feldspathic quartz lenses in the schistosity and in the immediate contact zone are staurolite-andalusite-biotite-muscovite~zluartz assemblages in tightly folded structures in which schistosity penetrates the contact zone as well as pegmatite veins. Where the contact is with homogeneous igneous rocks there is generally cataclastic deformation. The more detailed account (p. 108) favours intrusion of granitic magma during deformation but an envelope of quartz monzonite probably solidified first at the contact. Several other such contact phenomena were described in detail (pp. 108-112). The migmatites, gneisses and syno-orogenic granites show a great variety of facies, ranging from little or no foliation or inclusions to highly foliated gneiss with abundant, often large inclusions. A typical composition is 30% quartz, 30% plagioclase, 30% K-feldspar and 10% micas with apatite and zircon. There is an overall similarity of composition throughout, modified only by the various types of inclusion. Evidence of post-magmatic strains abound from cataclastic textures, strain-shadowed quartz, and augen gneisses (augen being typically microcline).

6.3.3

Supracrustal inclusions

Flood et al. (1969, p. 61) reported that their Botniahalvoya Group 'base is not known, and no evidence of an underlying old preCaledonian basement has been found'. Nevertheless (p. 62) 'observations have confirmed a general occurrence of amphibolites east of Duvefjorden as well as within the Austfonna Formation within the migmatite border' which Flood inclined to indicate, by the abundance also of feldspathites, a possible correlation with Harkerbreen Group in N y Friesland. Whereas feldspathites (i.e. metamorphic rocks with >50% feldspar, Wallis et al. 1968, 1969) abound in all the Lower Hecla Hoek of Ny Friesland (Stubendorffbreen Supergroup) amphibolites do not characterize the Planetfjella Group which is correlated here with the Kapp Hansteen Group. They are however abundant in the underlying Harkerbreen Group of N y Friesland so that it is pertinent to enquire as to the abundance of amphibolites within the sub-'Botniahalvoya' migmatites. Amphibolites were reported as a conspicuous element in the metamorphic complex at Isispynten (Sandford 1954) associated with the grey granites (probably migmatitic) in a sedimentary series. It is noteworthy that there is no match for the gabbro-noriteanothosite of Storoya and Kvitoya (p. 17) which appear to be higher in the sequence and possibly Caledonian (Ohta 1978).

6.4

Late tectonic plutons

Two main areas of granite outcrop have been mapped. I n the west is Laponiahalvoya and in the east, Prins Oscars Land. Laponiahalvoya exposes two adjacent bodies. (1) On the west side (east of Brennevinsfjorden) is the Kontaktberget granite. This was so named by Kulling and by Gee et al. 1995. It was also referred to as the Brennevinsfjorden granite by Flood et al. (1969). Further east is the larger outcrop of the Laponiafjellet granite and migrnatite which also forms the islands to the north. There is an isolated outcrop to the southeast south of Sabinebukta mapped by Flood et al. as a subglacial extension of the Kontaktberget granite round the south of the Laponiafjellet outcrop and northeast into some small islands. This is referred to as the Sabinebukta granite. To the south and adjacent to it is a Sabineberget acid rock, probably a Kapp Hansteen quartz porphyry. (2) The eastern granites crop out in Prins Oscars Land. The main body e x t e n d s along the east coast of Rijpfjorden south of Platenhalvoya and again further south near the head of Walhenbergfjorden. There is a further outcrop to the east south of

105

Duvefjorden. These rocks were all mapped (Flood et al. 1969) as adjacent to and probably penetrating synorogenic granites and migmatites which then develop extensively to the east. Kulling (1934) first noted that the granites were not affected by Caledonian folding. Isotopic ages of the granites are the youngest in the area i.e. 400-350 (Hamilton, Harland & Miller 1962; Krasil'shchikov 1965, Winsnes 1965). However, later isotopic work (Gee et al. 1995) requires a radical reapraisal. Hjelle (Flood et al. 1969, pp. 121-128) described the two postorogenic granites': Brennevinsfjorden in the west and Rijpfjorden in the east. The most frequently observed mineral association is quartz-microcline-plagioclase (albite-oligoclase)-biotite-muscovite. Nordaustlandet granites are more alkaline, less calcic and femic than analogous granites in N y Friesland and Northwest Spitsbergen. This is not surprising with the new evidence that they were not coeval.

6.4.1

Laponiahalvoya granites (Hjelle in Flood et al. 1969; Gee, Johansson, Ohta et al. 1995)

The Kontaktberget granite outcrop, if continued beneath fjord and ice cover, appears as an arc with the Botniahalvoya outcrop on the outside (W and S) and the Laponiafjellet foliated granite and migmatic complex on the inside to the east and north so disposed as a broad antiform plunging to the south. The Kontaktberget granite is light grey to red, medium grained, part porphyric, somewhat foliated and cataclastic. Quartz (30-35%) exhibits undulatory extinction bluish with brittle deformation; K-feldspar (30-35%) occurs mostly in medium grained ground mass but also as phenocrysts up to 3 cm long. It is often perthitic and with microcline twinning. Plagioclase (0-20%) is often sericitized with An from 5 to 15%. Biotite (10%) and muscovite (5%) occur with tourmaline, fluorite, ilmenite, zircon and apatite. Intrusive contacts are observed with Kapp Hansteen Group strata exibiting fine-grained marginal facies. Such relationships seen to the east at Sabineberget contradict Sandford's (1950) unconformity interpretation based on air photographs. Anomalous compositions by assimilation of micaceous and calcareous metasediments occur. An occasional orbicular facies is rich in tourmaline. The Laponiafjellet granite is a coarse porphyrite variety, almost an augen gneiss. The foliation and shearing as seen against the quartzmonzonite of the migmatic complex is related to the final stages of the emplacement orogeny rather than as flow during intrusion. The granites are thus late rather than post-orogenic. The composition is quartz 25-30%, Kfeldspar 25-30%, plagioclase 20-25%, and micas 10-15% and accessory minerals parallel those in the Kontaktberget granite. Whereas the Kontaktberget granite has distinct xenoliths near the margin, the Laponiafjellet granite with larger xenoliths merges into migmatite complex with large paleosome rafts both pelitic and psammitic, and occasional marble. Chemical composition of both granites suggests an origin from melting of upper crustal rocks. The Nordkapp granite. The northernmost island of Svalbard, north of Nordaustlandet was sampled by Hjelle (1966) who classified it with the second of his divisions (i.e. with the late tectonic plutons described above and distinct from those that follow. The structural relationship has not been determined. There is one record of isotopic age. Hamilton & Sandford (1964) by Rb-Sr on feldspar obtained 537 Ma. This leaves the age of the intrusion open. However, by analogy with related granites in Nordaustlandet an early Neoproterozoic origin seems probable with later reheating.

Isotopic ages.

Isotopic ages (recalculated) were by Krasil'shchikov

et al. (1964) K - A r on biotite 388 and 393 M a and on whole rock 413 and 428 M a from the southwestern outcrop and by Gayer et al.

(1966) K - A r on biotite 390-399 M a and on muscovite 443 Ma. On the time scale adopted for this work the biotite ages are Early to Middle Devonian and thus the shearing phase could be Late Devonian (i.e. Svalbardian). However, Johansson & Balashov (in Gee et al. 1995) reported zircon ages in the Kontaktberget granite of 939 + 8 and of the Laponiafjellet granite of 961 4- 17 Ma. This is consistent with the contact evidence that the Laponiafjellet

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rock was earlier than the Kontaktberget granite, but the difference between the apparent ages may not be significant. The implications of these results are far-reaching, if the zircons crystallised with the granites and are not inherited. Because all the other ages are Silurian-Devonian, which would then indicate a major Paleozoic regional thermal event to reset all but the zircon crystals and some R b - S r ratios. If this be the case it calls into question the whole area of granites and migmatites to the east where already several values around 600Ma indicated some Precambrian event in addition to the ubiquitous Silurian early Devonian thermal activity.

6.4.2

The pink or red rock is of normal granitic composition with hypidiomorphic, medium-grained and often shear structures. Post-magmatic strain is evident from the undulatory extinction of quartz. Muscovite exceeds biotite and accessories include iron hydroxides and fluorite. Feldspar margins and fissures are embayed by quartz. The K-feldspar is typically microcline-microperthite, the plagioclase is Ans_~0. Biotite content increases near contacts and xenoliths as does more calcic palgioclase. Intrusive sharp contacts with supracrustal rocks are common, but may be transitional with some migmatites. Xenolith distribution gives the impression of an unroofed batholith. Moreover, the pink granite also intrudes homogeneous grey augen-gneiss approximating to quartz diorite, as do apophyses of aplite and pegmatite. A typical sequence is: (a) supracrustal relicts, (b) synorogenic quartz monzonitic gneisses, (c) late-orogenic Rijpfjorden granite, (d) aplite and pegrnatite dykes. The dykes are occasionally foliated and thus are also late-tectonic. K - A r isotopic determinations by Krasilshchikov et al. 1964 (recalculated) on whole rock gave 362, 362, 347, 352, and 438 Ma, on muscovite 387Ma; and on biotite 377Ma. These are all Silurian-Devonian ages and again suggest final Devonian stability. On the other hand Gee & Teben'kov (1996) reported a 'Grenvillian' age in zircon by Johanssen from the Rijpdalen granite. No zircon determinations are available.

6.5.1

Minor igneous bodies Acid intrusions

The granitic, aplitic and pegmatitic dykes belong to the Late tectonic granitic episode treated above.

6.5.2

6.5.3

Dolerite sills and dykes

Relatively unaltered dolerite dykes and sills abound especially in western Nordaustlandet and Hinlopenstretet. They are most probably part of the Cretaceous igneous episode which was extensive throughout most of eastern Svalbard. They can best be dated where related to lavas in K o n g Karls Land to the south and are discussed in Chapter 5.

The Rijpfjorden, Rijpdalen and Duvefjorden granites

Outcrops of this facies are more complex, extending in a N - S strip from the east of Rijpfjorden south through Rijpdalen and with outliers east of Wahlenbergfjorden and south of Duvefjorden. Contacts are with both Botniahalvoya and younger Meyerbukta formations and with the large eastern migmatite complex (Hjelle in Flood et al. 1969).

6.5

determinations. If they are the product of island arc magmatism of Neoproterozoic or Paleozoic age the Barents Craton concept as including the Duvefjorden Complex is challenged.

Basic layers to northeast

In the northeasternmost corner of this study area (Nordmarka, Storoya and Kvitoya) occur basic igneous complexes which are not matched elsewhere in Svalbard (Hjelle, Ohta & Winsnes 1978, Ohta 1978). Basic stratiform rocks appear to be higher in the sequence than the relatively flat-lying migmatic gneisses. Moreover, structurally and petrographically the basic rocks appear to be syntectonic (with the migmatites). Their calc-alkalic and tholeiitic compositions suggested thick continental terranes that would be consistent with a Caledonian foreland to the east. Ohta (1978) in particular described the detailed mineralogy and geochemistry of the Storoya gabbro-diorite complex. Whether the strata were formed as flows or sills near the surface or as part of 'an island arc setting with a thick continental crust' as Ohta suggested is an open question. He argued for a Caledonian origin in 1978 a view that might be modified in the light of later extensive Proterozoic age

6.6

Summary of isotopic ages

All numerical values in this list are in Ma. Analytical details with estimated errors etc. must be obtained from the original papers. Such early data were abstracted up to that time by Gayer et al. 1966. The values given here have been recalculated as necessary according to 1976 constants. They are plotted on the map (Fig. 6.4) on which the following numbers give the references. (1) Hamilton & Sandford (1964) by Rb-Sr at Oxford: from biotite in gneiss at Isispynten 358, 411, 415; from 'Southern Land' muscovite in granite and aphite 373, 378; from Nordkapp feldspar in granite pegmatite 537; from Rijpdalen schist, biotite 618, muscovite 636, whole rock 581. (2) Krasil'shchikov, Krylov & Aljapysev (1964) by K-At at Vinbukta on the E coast of Rijpfjorden, whole rock grey granite 362, pink granite 362, porphyritic granite 347, granosyenite 352, muscovite in pegmatite 388; Rijpfjorden (Wordiebukta) biotite in biotite gneiss 438; from E coast of Brennevinsfjorden (Zeipelbukta) rapakivi granite whole rock 413, rapakivi granite biotite 388; medium granite biotite 393; granite in coastal gravel whole rock 428. (3) Gayer, Gee, Harland, Miller, Spall, Wallis & Winsnes (1966) compiled previous Svalbard determinations including the above with some analytical data etc., converting Russian to western constants and in addition reported from Nordaustlandet material collected by Winsnes determined by K-Ar from north Laponiahalwya west Beverlysundet on musconvite from granite pegmatite 443; from altered biotites in unfoliated pink granite 399; from head of Wahlenbergfjorden on muscovite from foliated granite 420. (4) Krasil'shchikov (1970) also from head of Wahlenbergfjorden by K-Ar whole rock 376. (5) Edwards & Taylor (1976) from a large granite boulder in the Vendian tillite at Aldousbreen north of Wahlenbergfjorden obtained 1275. (6) Gorochov, Krasil'shchikov, Mel'nikov & Varsavskaja (1977) Reported a whole rc-:k Rb-Sr age of 766 from (probable Kapp Hansteen volcanics in) Botniehalv~ya. Because of the high initial strontium content this was later revised to 970 (see Ohta 1992 and Gee et al. 1995). (7) Ohta (1982) reported a whole rock Rb-Sr determinations in the lower Murchison Bay Supergroup of 520. (8) Lauritzen & Ohta (1984) reported Rb-Sr determination on whole rock from Nordre Repoya of c. 600. (9) Ohta (1992): compiled previous Svalbard data making corrections for 1976 constants as necessary. In addition he reported a whole rock Storoya age by K-Ar of c. 600 and gave a revised age of 970 from the original 786 whole-rock Rb-Sr determination from the ?Kapp Hansteen acid rocks of Botniahalvoya. (10) Gee, Johansson, Ohta, Tebenkov, Krasil'shchikov, Balashov, Larionov, Gannibal & Ryungenen (1995) gave details of new U-Pb and Pb-Pb determinations of zircons, by laboratories in Stockholm and Apatity, with selected ages of the Kontaktberget granite 939+8 and of the Laponiafjellet granite 961-4-17 which in view of uncertainties were taken as c. 950. Also noted were tentative ages by Larionov from migmatite rafts in NE Laponiahalvoya by Pb-Pb indicating a pelitic paleosome at c.1600 and also tentative zircon results from the Brennevinsfjorden Group at c. 1500. (11) Krasil'shchikov, Kuno & Sirsova (1996) reported earlier unpublished age determinations on metagabbros from Storoya c. 677 Ma and for Kapp Laura, 442 Ma. (12) Gee & Teben'kov (1996) reported, without details, on 'Grenvillian' age of the granites of southern Rijpdalen based on U-Pb zircon determinations and plotted on their maps the value 1050Ma.

NORTHERN NORDAUSTLANDET

107

Fig. 6.4. Summary of isotopic ages from Nordaustlandet. Outcrops mainly from Gee et al. (1995), and Gee & Teben'kov (1996). Sources of data indicated by numbers in parentheses are as follows: (1) Hamilton & Sandford (1964); (2) Krasil'shchikov, Krylov & Alpapyshev (1964); (3) Gayer et al. (1966); (4) Krasil'shchikov (1970); (5) Edwards & Taylor (1976); (6) Gorochov et al. (1977); (7) Ohta (1982); (8) Lauritzen & Ohta (1984); (9) Ohta (1992); (10) Gee et al. (1995); (11) Krasil'shchikov et al. (1996); (12) Gee & Teben'kov (1996).

6.7

Structure of Nordaustlandet

From the structural reconnaissance reported by Gee (Flood et al. 1969) it seemed that an igneous-migmatic contact rather than

Earliest maps typically show the few rock types recorded to be separated by faults. The first detailed structural traverse was recorded by Kulling (1934) in which the Murchison Bay strata were steeply f o l d e d - mainly upright but with an eastward-verging recumbent fold rooted at Floraberget. Subsequent work by Ohta (1982) showed that the repetition of strata required for KuUing's isoclinal interpretation was indeed better explained by the downward succession into similar but still older strata. Therefore the easterly vergence cannot be sustained. Sandford (1956), using Kulling's data and interpreting from air-photographs plus his own and other available observations, published the first structural map of northwestern Nordaustlandet (Fig. 6.5). It makes little structural difference whether the sub-jacent complex was formed earlier or later than the Hecla Hoek sequence. Sandford mapped a nearly straight N-S shear zone just west of D u v e f j o r d e n - his 'Dove Bay Fault'. He noted that no Hecla Hoek strata are known east of it. It could certainly fit later hypotheses of strike-slip displacement. It would also be consistent with the evidence ofpost-pluton shear in the granites. However, Gee (in Flood et al. 1969) did not observe any post-migmatite displacement there. There are minor shear zones in which porphyritic granite has developed into augen-gneiss. From further fieldwork Gee et al. (1995) seeking evidence i.a. for terrane boundaries did not report any other major shear zone in Nordaustlandet. Such a Duvefjorden Fault was mapped east of Duvefjorden, trending N N W SSE, by Krasil'shchikov (1973) east of which he mapped a pre-Riphean basement, later referred to as the Duvefjorden Complex. However, Krasil'shchikov et al. (1996) marked only a N-S anticline just east of Duvefjorden within the North East uplift (Fig. 3.10).

an unconformity separates the subjacent complex from the supracrustal strata. However, from the discovery that the westerly granite plutons, at least, yielded early Neoproterozoic zircons a new model appears to emerge (Gee et al. 1995). A Proterozoic migmatic-magmatic invasion of metasediments was somehow subsequently altered thermally so that K - A r and R b - S r ages therein appear to be midPaleozoic. This somewhat enigmatic result, albeit with work still in progress, is addressed in Section 6.8 below. Three east-west sections (Flood et al. 1969, p. 68) show mainly open upright folds without great amplitude so that coeval strata have wide distribution. Many faults plotted on a map (p. 94) were shown as vertical. The faults and fold axes are generally N S or N N W - S S E and are interpreted as strike-slip both dextral and sinistral. The migmatic-magmatic (crystalline) areas tend to be positive and determine the main fold structure which is of broad anticlines plunging south with the youngest strata to the west and south. Gee's syntheses noted that the Nordaustlandet structure is dominated by a Caledonian (post-Canadian/pre-Pridoli) fold system. The cleavage, dipping steeply eastwards, is axial planar to the folds which are asymmetric towards the west i.e. as in Ny Friesland and verging westwards. The Hinlopenstretet synclinorium gives the strata on both sides a similar sequence with the oldest rocks away from it. One group of faults is related to the E - W compression of the Caledonian folding with srike-slip displacement dextrally on W S W - E N E trends and sinistrally on W N W - E S E trends. The youngest strata, the Sparreneset formation, dip steeply west into Hinlopenstretet at both Sparreneset and west of Krossoya. The oldest strata appear east of Lady Franklinfjorden on the western flank of the Vestfonna antiform which plunges south beneath

108

CHAPTER 6

Fig. 6.5. Outline geological map of Nordaustlandet and adjacent areas of Ny Friesland illustrating the major structural featues, mainly from Gee (in Flood et al. 1969). Vestfonna. In its core to the north is the Laponiahalvoya intrusion. Not enough is known of the structure further east. It is possible that an analogous synform could occupy Nordenski61dbukta. Then further east there is the option to continue the gentle fold pattern with a Kapp Platen antiform or to treat that as the western edge of the Duvefjorden Complex-Barents Craton (Fig. 6.5). Other dominantly strike-slip faults trend NNW-SSE and N N E SSW. Carboniferous strata are not thereby displaced so that they may have formed during the Late Devonian Svalbardian movements. The Murchison Bay Supergroup strata were undeformed prior to the Caledonian folding. Gee's (1969) discussion of the relationship with the Botniahalvoya rocks was overtaken by the 1982-1984 stratigraphy already recounted so that there must be an unconformity beneath in the Murchison Bay Supergroup and another break beneath the Kapp Hansteen Group. The E-W sections south of Kapp Platen sketched by Winsnes (Flood et al. 1969, p. 66), show an open (upright) fold structure without sensible vergence and apparently cut by the Rijpfjorden granite. Assuming that the latter is early Neoproterozoic then the folding might be part of the tectonism represented by the Botniahalvoya unconformity. This might confirm the correlation of the Kapp Platen strata within the Brennevinsfjorden Group. Correlation with Ny Friesland is suggested in the Chapter 7 and discussed in Chapters 12, 13 and 14.

6.7.1

A Barents Craton

Throughout the fluctuating interpretations of the role played by Phanerozoic diastrophism in Nordaustlandet, there has been a

persistent opinion that the Duvefjorden Complex could be part of a Precambrian shield. This could be confirmed by further isotopic investigations in eastern Nordaustlandet. If it be so then Barentsia would not be part of Baltica but rather an extension of Laurentia and separated by the ensialic Hecla Hoek aulacogen from the East Greenland part of Laurentia (as discussed further in Chapter 12).

6.8

The Lomonosov Ridge in relation to Nordaustlandet

Little is known of the Lomonosov Ridge except that it is a markedly linear, non-magnetic submarine feature now bordering the Eurasian Ocean basin. This basin opened by Cenozoic spreading along the mid-oceanic Nansen Gakkel Ridge as the northerly terminus of the De Geer transform separating Svalbard from Greenland. The pre-Cenozoic configuration is constrained by simply closing the Eurasian and the Greenland and Norwegian basins. This brings the Lomonosov Ridge adjacent to the northern coasts of Svalbard and perpendicular to the widespread Caledonian grain of Svalbard. From its positive morphology and non-magnetic nature the Ridge would appear to be of continental rather than of oceanic affinity. Indeed such a relict 'orogen' could have focused the Cenozoic thermal fission, so determining the initial location of the NansenGakkel Ridge. That might be as far as speculation should be taken; but it may be worth considering this situation in relation to Nordaustlandet and to the mid-Paleozoic strike-slip model developed in this work. That model (e.g. Harland 1966, 1969) postulated the origin of the Lomonosov Ridge as a compressional feature that formed across the front of the eastern terranes of Svalbard as they progressed from the East Greenland province by strike-slip to

NORTHERN NORDAUSTLANDET their Carboniferous-Cretaceous location north of Greenland and Canada and so adjacent to where the Lomonosov Ridge is now. That northward progression could have been accomplished by the continental foreland of Svalbard's eastern province overriding the intervening Thalassic ocean. The subducted ocean floor would have sunk i.a. beneath northern Nordaustlandet and the ridge would develop from the scrapings of the ocean floor sediments. The above speculation is entered because the later phases of this translation would be Devonian and the later thermal rejuvenation along the E-W northern margin of Nordaustlandet from early radiometric determinations tend to be Devonian.

(3)

(4) (5)

(6)

Conclusion

(7) (8)

A model is suggested for further criticism and testing in which the following events in Nordaustlandet would be accommodated.

(9)

(1) (2)

Early to mid-Proterozoic sedimentation to form the Brennevinsfjorden Group. Early Neoproterozoic migmatism/magmatism (Grenvillian) Kapp Hansteen volcanics and Laponiahalvoya granites.

109

Later Neoproterozoic through Early Paleozoic sedimentation of the relatively unaltered Murchison Bay and Hinlopenstretet supergroups. Silurian (Ny Friesland) orogenic folding in NS axes with EW compression to transpression. Later Silurian through Devonian northward migration of Svalbard with subduction around North Greenland towards Ellesmere Island. Late Devonian accumulated thermal effects of subduction with Lomonosov orogen transverse to progression and hot fluids or magma from buried slab rejuvenating the E-W zone of Early Neoproterozoic granites etc. Late Paleozoic denudation and sedimentary cover. Renewed uplift in Late Cretaceous Cenozoic time as heat accumulated beneath northern Nordaustlandet and the Lomonosov Ridge leading to Spreading of the Eurasian Ocean Basin with the thermal tilting of the pre-Carboniferous basement so that northern Nordaustlandet exposes the deeper roots of the earlier structures whereas Late Paleozoic and Mesozoic platform strata obscure the basement further south.

Chapter 7 Northeastern Spitsbergen W. B R I A N 7.1 7.2 7.2.1 7.2.2 7.2.3 7.3 7.4 7.4.1 7.4.2 7.4.3 7.4.4 7.5 7.6 7.6.1 7.6.2 7.7 7.7.1 7.7.2

Geological frame, 110 Younger (cover) rocks, 112 Cenozoic lava, 112 Mesozoic dolerites, 112 Triassic to Carboniferous Strata, 112 Post-Permian deformation, 112 Ny Friesland plutons, 112 The Chydenius (breen) Batholith, 113 The Lomonosovfonna pluton, 113 Origin of magnos, 113 Lamprophyre dykes, 113 The Hecla Hoek Complex: the continuing debate, 113 Hinlopenstretet Supergroup, 116 Oslobreen Group, 116 Polarisbreen Group, 117 Lomfjorden Supergroup, 118 Akademikerbreen Group, 119 Veteranen Group, 119

The land (area) considered here is bounded on the west by Wijdefjorden and on the east by Hinlopenstretet and Storfjorden. The southern boundary is somewhat indefinite. For descriptive convenience Carboniferous through Triassic stratigraphy is treated in Chapters 4 and 5 and Devonian strata to the northwest in Chapter 8. It makes geological sense for these chapter areas to overlap where they meet. Ny Friesland was the name for most of the area under consideration. However, after the accession of the Norwegian King Olav V in 1957 his name was given to what had previously been a somewhat indefinite territory, mostly ice covered (the Terre Glac6e Russe of some older maps) to the south east of Ny Friesland. Olav V Land was defined to take in some of what had been referred to as Ny Friesland and early accounts should be read with this in mind (Miloslavskiy et al. 1993, map D8G). This chapter thus concerns Ny Friesland and north western Olav V Land and for descriptive economy Ny Friesland will be used for the area where most of the older rocks crop out. Much of the interior is covered by highland ice rather than an ice cap, meaning that the ice is not thick enough for the surface to be independent of the underlying relief. Indeed the ice cover is broken here and there by rocky cliffs of submerged valley glaciers. The three largest areas of continuous ice are Lomonosovfonna, Asg~rdfonna and Valhallfonna. The inland ice flows out along valley glaciers, often to the sea. In Olav V land the second largest glacier in Svalbard, Negribreen, meets the sea in a continuous ice cliff (Fig. 7.1). In addition there are independent valley and corrie glaciers. The two highest mountains in Svalbard (Newtontoppen 1717 m, and Perriertoppen 1712 m), each typically supporting a small ice cap, are not conspicuous in this highest mountainous region. An advantage of the area for geologists is the admirably clear rock surfaces in cliffs and glaciated pavements. When the Cambridge group began a systematic investigation of the geology of Ny Friesland there was no topographic base for most of the interior. Thus a combined survey was necessary in which the position of geological features was fixed by triangulation, thus producing a topographic map at the same time. The contours were plotted by a simple photogrammetric plotting table made for the purpose in Cambridge (Harland & Masson-Smith 1962). The main focus of Cambridge research until about 1965 concerned Ny Friesland, hence the balance of this Chapter may seem one-sided. The early work of Blomstrand (1864), Nathorst (1910), Tyrrell (1922), Odell (1927), Fairbairn (1933), Kulling (1934) and Fleming & Edmonds (1941) formed the basis of these investigations.

HARLAND 7.8 7.8.1 7.8.2 7.8.3 7.9 7.9.1 7.9.2 7.9.3 7.10

7.10.1 7.10.2 7.10.3 7.10.4 7.10.5 7.10.6

7.1

Stubendorffbreen Supergroup: succession, 121 Planetfjella Group, 121 Harkerbreen Group, 122 Finnlandveggen Group, 124 Stubendorffbreen Supergronp: genesis, 125 Petrology, 125 Geochemistry, 126 Isotopic ages, 127 The Hecla Hock Complex: mid-Paleozoic structure and metamorphism, 128 Fold and nappe structure, 128 Fabric and shear zones in the Stubendorffbreen Supergroup, 129 The Billefjorden Fault Zone, 129 Planett~ella schists, 129 Kinematic interpretation of transpressive shear in the Stubendorffbreen Supergroup, 130 Metamorphism, 131

Geological frame

The rocks divide naturally into three: older, younger and 'drift'. The older rocks comprise the Hecla Hoek complex and later batholiths. Unconformably overlying this are the cover strata: the northern extension of the Spitsbergen Basin sequence, being mainly Carboniferous and Permian with conformable softer Triassic rocks above. The youngest rocks are Q u a t e r n a r y - generally Late Quaternary glacial and marine beach deposits of trivial bulk. These three units are separated by two or three surfaces. (1) The older surface is the obvious unconformity which oversteps most of the older rocks. It is continuous in the south where it dips to sea level but occurs in Ny Friesland with small Carboniferous and Permian outliers. Indeed this is an unconformity with both overstep and some overlap. Originally a peneplane, it now emerges, with a southerly dip, from beneath the Central Basin and Eastern Platform to rise with an arched surface: enveloping the summits of the high mountains formed of the older rocks. Indeed Ny Friesland mounts the highest peaks in Svalbard. Towards the margins outliers of Carboniferous strata are perched on the flat unconformity at the mountain tops. More often the flat top is covered by ice or snow. Elsewhere the summits of sharp peaks fall within, or define, the smooth projected unconformity surface. (2) The younger surface is not so obvious because in the higher ground it is postulated to coincide with the older one, i.e. as an exhumed peneplane, or to truncate and cut down into it. It is indeed the present summit height envelope which encompasses all mountain tops whether of older or younger rocks. In this area it is demonstrably post-Triassic; further south it is at least post-Eocene. This is the surface that gives Svalbard a flat-topped appearance when seen from a distance and when the sharp peaks and steep cliffs are not evident. It represents the Late Cenozoic erosion surface that i.a. truncates the West Spitsbergen (Paleogene) Orogen. (3) The youngest surface is the most conspicuous being of latest Neogene or Quaternary dissection of the younger surface and is being actively formed today. It is the surface on which the youngest Quaternary deposits and glaciers rest so giving rise to the present day topography. Each of these surfaces represents a major diastrophic and erosional event. The older surface marks the Ny Friesland (Caledonian) Orogeny and its reduction to a peneplane. The younger surface marks the West Spitsbergen Orogeny and related tectogenesis in this area and its reduction again to a peneplane.

N O R T H E A S T E R N SPITSBERGEN

111

Fig. 7.1. Topographic and place name map of Ny Friesland. Based on Harland & Masson-Smith (1962). Spitsbergen, southern Ny Friesland 1 125 000, Royal Geographical Society and Geological Map of Svalbard 1:5000 000, sheet 3, Norsk Polarinstitutt.

112

CHAPTER 7

The youngest surface marks the relative uplift of that peneplane, in relation to sea level and its dissection to the distinctive relief seen today. The rock units are bounded by faults as well as by unconformities. Faults which displace the relatively flat-lying younger rocks are easy to map. They are demonstrably postPermian and probably belong to the Paleogene diastrophism as the eastern response of the West Spitsbergen Orogeny. Most faults within the older rocks did not continue to be active beyond the N y Friesland Orogeny. However, the Billefjorden Fault Zone (BFZ) was active in Paleozoic and Mesozoic as well as Cenozoic time. It bounds the Hecla Hoek rocks, faulting them against (Devonian) Old Red Sandstone to the west which is lacking in this sector and will be treated in the northwest sector (Chapter 8). The Lomfjorden Fault Zone is demonstrably post-Carboniferous; its earlier history is uncertain. It was certainly active during the Paleogene West Spitsbergen Orogeny. The main part of this chapter concerns the older rocks, i.e. the Hecla Hoek complex with its related intrusions (mainly the large late tectonic granite plutons). However, in conformity with this systematic descriptive approach the rocks are treated from the top down and the story interpreted from oldest to youngest follows in Part 3. This has the advantage of leaving the most difficult problems concerning the possibility and identity of a more ancient basement within the Hecla Hoek Complex till last. The youngest (Quaternary) rocks will not be treated here because there is little to distinguish their nature between the different sectors of Svalbard. Any generalizations belong to Chapters 21 and 22. The older rocks to the northeast pass without significant disconformity across Hinlopenstretet into the Hecla Hoek sequence of Nordaustlandet.

7.2

7.2.3

Sassendalen Group, 316 m (Mid- and Early Triassic). The Sassendalen Group strata mainly, shales and silstones, are as usual less resistent than the underlying Kapp Starostin Formation. The outcrop probably accounts for much of the low-lying ice covered area of Olav V Land and is discussed in Section 5.4. It is best known where it emerges southeast of Sassenfjorden in the type Sassendalen area as described in Chapter 4.4. The rocks are peripheral to the area considered in this chapter. The underlying three groups are also detailed mainly in Chapters 4 and 17 and the eastern outcrops in Chapter 5. Tempelfjorden Group, 381m (Late Permian). In many areas of Svalbard the Kapp Starostin Formation, a siliciclastic to cherty unit is a resistent marker of relatively uniform facies. Gipsdalen Group, 828+m (Early Permian and Pennsylvanian). The Gipsdalen Group of five formations is mainly formed of carbonates and evaporites. Facies vary markedly and are thicker in the Billefjorden Trough. The upper units extend westwards across the Billefjorden Fault Zone (BFZ) on the Nordfjorden High. The lower units thicken to the abrupt margin of the Fault Zone. It is noteworthy that the western margin of the older rocks of the Ny Friesland orogenic structure is also formed by the BFZ which continued active and controlled the western margin of the Carboniferous Billefjorden Trough. Billefjorden Group, 316m (Mississippian). The Billefjorden Group consists of two formations in the Billefjorden Trough. They are largely of continental sandstones with plant beds and some coal. Whereas these strata form the base of the cover or platform succession of the Central Basin (Chapter 4) they are preserved in a series of down-faulted outliers far to the north in western Ny Friesland just east of the BFZ. They may well have covered much of the older surface of western Ny Friesland before erosion. Differences are most evident in the lowest strata of the Billefjorden Group as seen in the map and section (from Cutbill, Henderson & Wright in Harland, Pickton & Wright 1976).

Younger (cover) rocks 7.3

7.2.1

Post-Permian deformation

Cenozoic lava

Teben'kov & Sirotkin (1990) reported the presence of a single small nunatak at the head of Manbreen, on the south side of Valhallfonna in eastern Ny Friesland, that consists of lava overlying Precambrian schists of the Planetfjella Group. The nunatak is only 10-30m high and is at an altitude of 800-820 m. The lower contact of the lava with the schist is subhorizontal. The lava is flaggy with subhorizontal joints and little internal structure; it was interpreted as a single lava flow. The lava is partly vesicular and scoriaceous, especially at the top, and contains phenocrysts, mainly of olivine, but also plagioclase and minor clinopyroxene. By analogy with the Woodfjorden plateau lavas, a mid-Miocene age was suggested, and it may once have covered the whole area. At the same time they rejected correlation with either the Mesozoic dolerites or the Quaternary trachy basalts from Bockfjorden. A non-oceanic magmatic source common with the Miocene lavas with TiO2-KzO-P202 ratios respectively 52.6-54.5%; 37.0 38.6%; 8.3 8.8%.

7.2.2

Triassic to Carboniferous strata

Mesozoic dolerite

A dolerite outcrop beneath the ice cap at Bivrastfonna, west of southern Lomfjorden, was included in the survey of dolerites by Tyrrell & Sandford (1993) and was mapped in more detail by Cutbill (1968) who showed it resting on sandstones of the Billefjorden Group. The ice cap is on a flat-topped mountain of truncated Veteranen Group Hecla Hoek strata and the dolerite is presumed intrusive into the overlying Carboniferous sandstones the upper contact of which is obscured if not removed by the ice. It must now be presumed to belong to the extensive Early Cretaceous magmatic event evident in many other outcrops east of Lomfjorden where black sills in Carboniferous and Permian strata are conspicuous in cliff sections.

The N-S Balliolbreen Fault is the main fault of the BFZ and it is seen best in the cliff north of Alandvatnet where a preCarboniferous reverse high-angle fault juxtaposes Old Red Sandstone on the footwall and metamorphic rocks of the Hecla Hoek complex on the hanging wall. This key exposure, first noted by Vogt in 1923 and later investigated by McWhae (1953) and by Harland in 1953 (1959), has been the subject of detailed structural mapping by Lamar, Reed & Douglass (1986) and Lamar & Douglass (1995). But as their area was predominantly of the Old Red Sandstone rocks, discussion of their work fits better into the following chapter in which the Billefjorden Fault Zone must be addressed from another point of view. In southwest Bfinsow Land not only are the strata folded in a compressive sense, but the upper gypsiferous strata are deformed penetratively so that original anhydrite 'spheres' have been sheared into westward-dipping elongated ellipsoids. The other main N - S fault that cuts the younger rocks is the Lomfjorden Fault, with its associated splays. This is perhaps the most conspicuous fault in the map of Ny Friesland though not so active as the BFZ in pre-Carboniferous time. It also concentrated Paleogene reworking of Mesozoic strata. The two fault zones are associated with normal dip-slip faults which, striking with the older structures, are only evident where the cover rocks are present.

7.4

Ny Friesland plutons

Pre-Carboniferous acid plutons intrude deformed Hecla Hoek strata. The boundaries are generally concealed beneath ice and Carboniferous cover, and so are mainly conjecture on the map except where the thermal aureole can be mapped. Three plutons have been identified, possibly the northern two are connected at depth.

NORTHEASTERN SPITSBERGEN

7.4.1

The Chydenius(breen) Batholith (Odell 1927; Harland 1959; Teben'kov et al. 1996)

This is the largest outcrop and is fairly well delineated by a thermal aureole superimposed on the regional metamorphic zones where the rocks are exposed. It forms the body of the highest mountain, Newtontoppen, which is mostly ice covered. The rock is a porphyritic granite with large rectangular pink orthoclase phenocrysts (not unlike Shap granite of England). The mineral composition from 40 samples ranged from adamellite to granodiorite (Harland 1959). This is typical of late tectonic plutons without noticeable foliation. Where marginal facies can be seen xenoliths and hybrid facies are evidence of stoping. The typical light-coloured coarser facies gave quartz 17%; potash feldspar (mostly microcline, often perthitic; the large phenocysts are typically orthoclase) 25%; plagioclase (oligoclase where determined) 11%; hornblende and occasional augite with associated chlorite 7%; titanite 0.6%; apatite 0.2%; zircon, allanite, muscovite, pyrite and ilmenite total about 0.25% (Harland 1959). It was from this pluton that early K Ar age determinations were made of a few samples, a small exposure on the flank of Newtontoppen at Eplet (Newton's apple). The values recorded by Gayer et al. (1966) are 385, 4 0 1 + 8 , 4024-8, 388+14; 406+15. Early to Mid-Devonian ages are suggested. A minor pluton occurs at Raudberget to the north of lower Chydeniusbreen and may have a subterranean connexion with the Newtontoppen granites. Teben'kov et al. (1996) in a historical introduction to their investigation omitted to mention the above work from the Cambridge reconnaissance which mapped and named most of the area topographically and geologically, the granite outcrops being virtually the same as the more detailed 1996map. They did, however, suggest a change in name to the 'Chydeniusbreen granitoid suite' to conform to the Norwegian Stratigraphic Committee and against the principal of priority and that names should be proposed according to official maps at the time. However, Teben'kov et al. described a more detailed survey of the individual outcrops, their structural features, with petrological and geochemical data. They described the following rock types: 1, melanosomes and dark grey granosyenites; 2, pink-grey granosyenite and pink quartz monzonite; 3, grey granite; 4, granosyenite with aligned K-feldspar phenocrysts; 5, aplitic veins; 6, pegmatites; 7, quartz-feldspar porhyry; 8, lamprophyre, their sequence of emplacement in that order. They concluded that the Newtontoppen granitoids are mainly granite and granosyenite intermediate between alkali-calcic and alkalic as between S and I-type granites. New Rb-Sr age determinations (Teben'kov et al. 1996) by whole-rock apatite isochron method gave 432 + 10 i.e. 30million years older than the earlier K - A r values which they interpreted as a cooling age. An Early Silurian age might challenge the Gee & Page (1994) Early to mid-Silurian age for the main metamorphism to the west, the granites being clearly intruded into already deformed strata as a batholith. Unfortunately the successive intrusive phases were not distinguished isotopically, and the innermost ?latest grey granites may not have been dated.

7.4.2

The Lomonosovfonna pluton

This is exposed only in the upper reaches of Nordenski61dbreen at Terrierfjellet, Ferrierfjellet and Ekkoknausane, but is projected to cover a large area beneath the ice field and so may qualify as a batholith. Evidence for its eastern subglacial extent is seen in granite boulders in the moraines of Tunabreen and Von Postbreen at the head of Sassenfjorden. From morainic specimens in Nordenski61dbreen, Tyrrell (1922) described pegmatites, quartz, veins and a syenitic suite. The syenite was confirmed in situ (Harland 1959). An unfoliated granite boulder from the moraine of Tunabreen at the head of Tempelfjorden yielded a Rb-Sr ?Late Silurian age of 421 + 11 (Gayer et al. 1966). Its most likely source

113

would be from a subglacial outcrop of the eastern extension beneath Lomonosovfonna of the Nordenski61dbreen Batholith. Teben'kov et al. (1996), without further work or reference to Tyrrell, referred to this as the Ekkoknausane group of small intrusives, more likely into the root of the batholith.

7.4.3

Origin of magmas

Harland (1971) suggested that shearing in the Silurian transpressive regime could have raised temperatures in the deeper Stubendorffbreen Supergroup rocks to generate granitic magmas. The Chydenius Batholith, especially, while marked by a thermal aureole extending horizontally to 1 km may have completed its diapiric emplacement in a relatively cool state so as to give the strength to shoulder away the near vertical N-S-striking strata and so causing significant attenuation. The thicknesses are locally reduced to about half. An ensialic origin is assumed. However, the early stages of intrusion truncated the Hecla Hoek strata.

7.4.4

Lamprophyre dykes

Some lamprophyre intrusions, long noted in Ny Friesland, and a monchiquite dyke by Teben'kov et al. (1996), but not investigated fully. They would appear to be related to the late phases of granitic intrusion. The lamprophyre dykes are unlikely be of the same suite as that at Krosspynten (monchiquite and camptonite), on the west side of BFZ, which are possibly of Bashkirian age (Gayer et al. 1966) and in another (allochthonous) terrane.

7.5

The Hecla Hoek Complex: the continuing debate

Hecla Hoek rocks are the core of Ny Friesland. The name, coined by Nordenski61d in 1863, comes from the mountain (now Heclahuken) named after Parry's ship H M S H e c l a that wintered at its foot in Sorgfjorden in 1827-8. Nordenski61d at first used the name for most of the rocks of Svalbard older than the (Carboniferous) Mountain Limestone. He included the ?strongly metamorphosed rocks, on the one hand, and the Old Red Sandstone on the other and all rocks of intermediate age. Nathorst (in Suess 1888) excluded the metamorphics as Archean and the Old Red Sandstone as the Liefde Bay System. His Hecla Hoek in Ny Friesland is equivalent to the upper two of the three supergroups earlier referred to as Upper, Middle and Lower Hecla Hoek. As already argued the use of the name Hecla Hoek for rocks west of the Billefjorden Fault Zone is not recommended. Many, however, still use it for any pre-Devonian rocks in Svalbard, seemingly on the assumption that all basement was Caledonian and then related spatially as now. A recurring question concerns the relationship between (a) the metamorphic rocks of western Ny Friesland i.e. Nathorst's Archean; Tyrrell's (1922) pre-Devonian basement complex; Fairbairn's (1933) 'western schists and gneisses' and (b) the relatively unmetamorphosed strata to the east regarded by all as Hecla Hoek. Such was a common problem in many Caledonian terranes in Europe, Greenland and North America. Three main options were under consideration: (i) that the western metamorphic rocks are basement i.e. much older than the eastern, being separated by a major diastrophic event; (ii) that the western rocks are older but pass relatively conformably up into the eastern; (iii) that the western rocks are the metamorphosed equivalents of the eastern. In both options (ii) and (iii) the age of metamorphism would be later than the age of the eastern rocks. These questions persisted as long as no comprehensive geological maps were available. Until 1955 no fossils had been found in Ny Friesland to give a clue as to the age of the eastern rocks. The problem was addressed over many years by the Cambridge group (from Fairbairn 1933; Harland 1941). This involved surveys:

114

CHAPTER 7

topographical (Harland 1952; Harland & Masson Smith 1962) as well as geological (e.g. Harland 1959; Harland et al. 1992). Annual expeditions from 1949 to 1964mostly by man-hauled sledges and small boats) involved many geologists especially: M. B. Bayly 1951, 1952, 1953; R. A. Gayer 1961, 1962, 1963; D. Gobbett 1958, 1959; W. B. Harland 1938, 1949, 1951, 1953, 1964, 1974, 1981, 1982; J. R. H. McWhae 1949; G. Vallence 1965, 1967; R. H. Wallis 1964, 1965, 1967; C. B. Wilson 1952, 1953, 1955, 1956, 1957. By 1955 the main problem seemed to be solved favouring the second option above: namely that a whole succession of strataabout 18km thick passed down from unmetamorphosed into metamorphosed strata and the age was Precambrian except for the top kilometre of strata which first revealed Early Cambrian S a l t e r e l l a r u g o s a to Wilson in 1955. The whole sequence was first published in outline (Harland & Wilson 1956) and revised with more information and international terminology (Harland, Wallis & Gayer 1966; Harland e t al. 1992) as shown in Figs 7.2 and 7.3. Further research enhanced the value of this succession, modified it, and is recounted in detail in Section 7.6-8. However, the succession as published was not at first challenged. Supporting evidence included: (a) the concordance of the main groups of rocks in similar sequence throughout Ny Friesland except for the lower units; (b) mapping of granitic gneisses as meta-sedimentary strata (volcanic or arkosic) within the succession, with some melting, remobilisation and minor intrusion; (c) the intense transpressive tectonism with bedding strike-slip juxtaposed higher and lower grades of metamorphosed rocks; (d) the chlorite zone boundary transgresses the stratigraphic boundary so that in the north even 'upper' Hecla Hoek rocks are so tectonized; (e) no major unconformity surface had then been identified though such might have been expected to be obscured within the intensely tectonized older rocks. On the other hand Harland (1941) described some of the rock units as nappes with attenuated lower limbs, i.e. thrust sheets. Moreover, Harland & Wilson (1956) admitted that the lowest units were so complex that they could well constitute a basement. It was also realised that with such intense shearing, discordant contacts could be smeared into concordance. It seemed unlikely that any major tectonism punctuated the succession above the lowest group. It was not thought that the overlying apparently regular and concordant sequence could contain a distinct orogenic episode. However, this tentative conclusion depended only on the rapid reconnaissance mapping of the whole area completed about 1965 which is inadequate in detail (e.g. Harland 1959; Harland et al. 1992). The above interpretation has been questioned and so it must be considered provisional. That is because a basement to the regular succession may be distinguished. Abakumov (1965) regarded the two lowest groups as basement, combining them in the Atomfjella Complex. D. G. Gee visited northern Ny Friesland with a view to collecting specimens to demonstrate by isotopic dating that there is indeed an ancient basement. For some time older Proterozoic dates had been rumoured (i.a Gee 1986) and the data when published (Gee et al. 1992) gave evidence for ages of granitoid rocks of 1700 1800Ma, said to be intruding sediments in the Harkerbreen Group. If the zircons analysed were not derived from an arkosic or igneous protolith it must be accepted that at least part of the Harkerbreen Group is Late Paleoproterozoic. Such an age by itself identified a tectonothermal event. But without accompanying structural stratigraphic evidence of a discontinuity in the sequence it need not represent an orogenic episode. This matter was developed by Gee e t al. (1992). One option thus appeared for a sequence without interruption back to at least 1800 Ma. This would not be impossible considering that a likely age for the oldest Veteranen Group rocks probably exceeded 800 Ma (Harland & Gayer 1972; Knoll & Swett 1985) and the underlying Planetfjella Group, first correlated with the Kapp Hansteen Group of Nordaustlandet, which appears to have consistent ages between 900 and 1000 Ma. G. M. Manby in an account (1990) used a structure radically different from that of Harland (1959). Applying an already agreed

Supergroup

Group

Formation

Member and character

Valhallfonna (220 m)

Profilbekken Olenidsletta

(S)

Z Kirtonryggen

(750 m)

S S n," S

S~ 8 Tokammane

(192 m)

Z

Dracoisen (245 m)

s

z

5

(N)

Nordporten Basissletta Spora

Upper Limestone Mbr i Middle Limestone Mbr! I Dolostone Mbr Lower Limestone Mbr

Didovtoppen Topiggane Bl~revbreen

Dolostone Shale Sandstone

Shales

Wilsonbreen (160 m)

6 members

Gropbreen (tillite) Member Middle carbonate Member Ormen (tillite) Member Slangen MacDonaldryggen

Dlostone Dolostones & siltstones

Petrovbreen

1111ite

Elbobreen

(362 rn)

Age Llanvirn Late Arenig

Arenig mremadoc-Arenig mremadoc

Early C a m b r i a n

? Ediacara Late V a r a n g e r

Early V a r a n g e r

Lower carbonate Member Mainly limestone Upper dolostone Backlundtoppen

wZ

Shale Middle dolostone Oolitic limestone

(360-700 m)

U.I~ n" E ~oo v ~ .~ o I~ ~ ~v

Draken (25-300 m) Upper limestone Stromatolitic dolostone Lower limestone Lower dolostone

Svanbergfjellet

(100~625m)

'~

Upper (pale) Member

6 limestone beds

Lower (dark) Member

4 limestone & dolostoee beds

Grusdievbreen (865 m)

Oxfordbreen (550 m)

Fulmarberget shale Enpiggen Upper Greywacke Upper Quartzite Lower Greywacke Lower Quartzite

Glasgowbreen

ilZl•

(540 m)

o

Kingbreen (-1500 m)

>

Cavendishryggen -J-- Rheaninden Beds Quartzite L _ Bl&rinterBeds BogenLimestone 6 divisions Galoistoppen 2 divisions

Kortbreen (1200 m) Vildadalen

(3250 m)

E i o ' O._o v.=_ 8_

Fl&en (1500 m)

Sturtian

Sturtian

Late R i p h e a n

Quartzite Member Limestone Member Ros~nflella (=Eosletta skam zone Manby & Lybeds) Albreen Alryggen T~breen upper Member Middle Member Lower Member

[? 950 Ma]

Sorbreen

(250 m)

o

x

Vassfaret (600 m)

zI.U

Bangenhuk

LLI~

~IT

g

Lower Member

(2000 m)

Femmilsjoen Flatoyrdalen

Rittervatnet

Amphibolites, feldspathites and psammites, with metatillites at the top

Feldspathic bodies

z

Upper Member Middle Member

(350 m)

[c.1750

Ma] (I) (3)

Psammitic pelites with graphite Marble and quartzite

P o l h e m (2000 m) incl. near basal Inastadse~lga conglomerate ' "lnstrumentberget

(5)

.1_

--

-

Granitic gneiss

Smutsbreen

Westbyf]ellet Bohryggen

,~t-e,l v

Ingstadseggaconglomerate

Fl&tan (3)

[< 131 7 Ma] (8) [C.1750

Ma] (3)

[ 160 m the upper surface is truncated by a thrust surface: it consists of alternating conglomerates, sandstones, shales, coaly shales and coal seams of which the Josefine Seam is at the base of the Member with Ragnhild, KBI and KB seams higher up. Leirhaugen Mbr, 5-20 m consists of alternating conglomerates, sandstones, shales, coaly shales and the Agnes-Otelie coal seam at the base. It is distinguished because interpreted as transitional between the overlying continental unit and the underlying marine unit. Kongsfjorden Fm (Orvin 1934; Livshits 1974)= Grey Sandstone of Orvin (1934) and Grey Sandstone Member of Challinor (1967). Similary three members have been proposed. Tvillingvatnet Mbr, 15-70 m (SKS 1995 from Midboe unpublished). It is of coarse and medium grained marine bioturbated sandstone, pebbly sandstones and conglomerates resting with erosional unconformity on the Kolhaugen Mbr in the SE and on the Morebekken Mbr in the NW. Borehole log 38/76 shows only the upper part as conglomeratic and the lower part, sandy, pebbly and contorted. Morebekken Mbr, 10-20m (SKS 1995 from Midboe) consists of mainly coarse conglomerates with thin beds of coarse sandstone. The pebbles are of chert and glauconitic sandstone as from the underlying (Permian) Kapp Starostin Formation. Kolhaugen Mbr, 0-40m (SKS 1995 from Midboe) consists of rapidly alternating fine-grained sandstones, shales, coaly shales and coal with welldeveloped coal seams from the top: Advocaten seam, Sofie seam and Ester seam at the base of the member where the coaly beds rest directly on the (Early Triassic) Vardebukta Formation (Lower shale of Orvin 1934). It thins, as does the Vardebukta Formations to the west of the coalfield. 9.1.2

Forlandsundet Graben

The sedimentary strata appear in a scattered a r r a n g e m e n t dependent on the complex tectonic sequence of the G r a b e n which is

discussed in Chapter 20. The m o s t recent stratigraphic w o r k by RyeLarsen has only been partially published by SKS ( D a l l m a n n et al. 1995), which the notes below follow (Fig. 9.4). Despite the fragmentary nature of the stratigraphic evidence, a composite succession has been established that indicates an apparent thickness of as m u c h as 5 km. A l o n g the eastern and southwestern margins of the basin, alluvial-fan deposits are well d o c u m e n t e d . They are characterised by poorly sorted, unstratified conglomerate beds of debris-flow origin, and are associated with fine-grained, flat- and cross-stratified conglomerates originating as streamflow deposits (Steel et al. 1985). In the southwestern part of the area, the fan deposits apparently grade laterally (basinwards) into possible fandelta and nearshore deposits comprising a sequence of black shales, siltstones and cross-stratified or ripple-laminated sandstones. The northwestern region, with a succession 3 k m or m o r e thick, is

Atkinson1963

Livshits19671

SKS(Dallmannet al. 1995) basl~de?LaWsOrk by

Adoptedin thiswork (a possiblealternative) I KAFFI~YRACOMPLEX

McVitie (McVitiepynten) Fm

Selv~gen (conglomerate) Fm

AberdeenflyaFm MarchaislagunaFm KrokodillenFm ReinhardpyntenFm Sessh~gdaFm

r--

Ii

~ Balanus- SarstangenMbr ~

SarsbuktaMbr

I:Iil I I I

c.~ I ~ [ Kr~176 Fm ! ;~ ~o~-~1ReinhardpyntenFm !

Selv&genFm I! I I ~ ~ r J [ pyntenFm SarsbuktaMbr L /

AberdeenflyaFm

Fig. 9.4. Summary of the Paleogene stratigraphic units in Forlandsundet, modified from Rye-Larsen in SKS (Dallmann 1995, fig. 2c).

158

CHAPTER 9

characterised by black shales; associated turbidite a n d c o n g l o m e r a t e beds interpreted as a submarine-fan association. T h e marginal alluvial-fan sequences (e.g. Selvgtgen, Sarsbukta and Sarstangen formations) are laterally equivalent to the n e a r s h o r e and shallowm a r i n e deposits (Sesshogda, R e i n h a r d p y n t e n , K r o k o d i l l e n and M a r c h a i s l a g u n a formations) and to the s u b m a r i n e - f a n succession (Aberdeenflya F o r m a t i o n ) . The B u c h a n a n i s e n G r o u p was investigated by M a n u m (1962) and Livshits (1965, 1974) and E o c e n e to early Oligocene ages were obtained. M o r e recently, palynological dating on samples from the eastern m a r g i n o f the basin at Sarsbukta by M a n u m & T h r o n d s e n (1986), based on dinoflagellate studies, suggest a Late Eocene age, a l t h o u g h precise age constraints are n o t available (Kleinspehn & Teyssier 1992). C u r r e n t data therefore place the age of the F o r l a n d sundet G r o u p as Late Eocene to Late Oligocene (Feyling-Hanssen & Ulleberg 1984; Steel e t al. 1985).

Buchananisen Group (SKS 1995). This name replaces Forlandsundet Group (Harland 1969) which name is now restricted to the structural graben (Harland 1969). From seismic traverses at sea it is probably about 5 km thick. Balanuspynten Fm (SKS 1995)=Sars Fm (Atkinson 1963). Atkinson's name for the rocks on the east of the sound had priority before the rules for acceptance of names was laid down by the Committee. It conveniently combines the two members. Sarstangen Mbr (SKS 1995 from Rye-Larsen), 1050m in drill holes to metamorphic basement. It comprises fine to coarse-grained sandstones or conglomerates and siltstones. SarsbuktaMbr (SKS 1995 from Rye-Larsen unpublished) 600+ m with faulted contact to east and lower boundary not exposed consists of pebbly to boulder sized multicolored conglomerates with medium to coarse sandstones and rare thin siltstones. Coal and plant fragments are abundant. Feyling-Hanssen & Ulleberg (1984) suggested a mid- to late Oligocene foraminiferal age. Aberdeenflya Fm (SKS 1955 from Rye-Larsen) 2800+ m. Crops out on the northwest of the sound (northeast of the Prins Karls Forland) of alternating polymict, pebble-sized conglomerate and fine to medium-grained sandstones interbedded with siltstones and claystones. Horizontal burrows are common. Its stratigraphic relationships are not exposed. MeVitiepynten Subgp (Atkinson 1963). The following four units were named and described by Livshits (1967 and 1974) as formations and said to be equivalent to Atkinson's McVitiepynten Formation. It crops out on the west of the sound. Marchaislaguna Fm (Marchais Fm of Livshits 1967) 55 to 600+m of alternating polymict, stratified, grey to yellowish, pebble-sized conglomerates and medium-grained sandstones with siltstones and claystones with S k o lithos, Arenicolites and Diplocraterion burrows. There is a sharp, possibly erosive, boundary with the underlying member. Krokodillen Fm, 400+ m of dark silty claystones interbedded with 2 40 m thick light fine grained sandstones rests directly on Selvgtgen Fm to W and contact with the Reinhardpynten Mbr is not exposed. Reinhardpynten Fro, 210+ m of dark clay-stones, with carbonate concretions and quartzite lonestones, coarsening down to very fine sandstones and siltstones with pyrite and siderite concretions. Sesshagda Fm, >120 m of light grey medium to coarse-grained conglomeratic sandstones alternating with siltstones and clay stones in the lower part with sideritic concretions and pyrite in the upper part. The lower boundary is gradational. Selvfigen Fm (Atkinson 1963; Livshits 1972, 1974) 40 170m of pebbly to boulder-size greenish grey to yellow and red conglomerates and breccias near the graben faults from which they thin to the east. Rests with angular unconformity on the Vendian Scotia Group of Prins Karls Forland. Katfiayra Complex. The scattered exposures through much of the eastern flatland of Sarsoyra and the hills to the east, as well as the similar coastal flat of Kaffioyra to the south, have long been a puzzle because of their incoherent and disjointed arrangement. From successive short visits up to 1992 by the Cambridge group a (dextral) strike-slip melange was inferred. However Ohta, Krasil'shchikov e t aL (1995) not only detailed such a strikeslip shear zone but from petrogenetic and geochemical studies identified low-temperature, high-pressure metamorphic rocks. These green-brown dolostones and serpentinites match those of the Vestg6tabreen (?subduction) Complex at Motalafjella to the south. The Motalafjella rocks are described below (Section 4.2) where an Ordovician metamorphic age is generally accepted. The Kaffioyra Complex appears to have been part of the Vestg6tabreen Complex, but involved in Paleogene dextral shear and so forms a shear zone north of Motalafjella and Ankerfjella. The Complex is

thus (Spitsbergian) Paleogene, the original metamorphism was Ordovician, but the protoliths were probably basic volcanics in the Lovliebreen Formation of the St Jonsfjorden Group argued here (as by Harland, Hambrey & Waddams 1993) to be Early Varanger in age. Ohta et al. were of the same opinion except that they stated a middle Proterozoic age for the same rocks. A distinct facies is the green-brown dolostone, which is a magnesite rock with fuchsite, accessory chromite and chromium spinel. They are, as at Motalafjella, associated with tectonic blocks of serpentinite. Geochemical analyses confirm these affinities. Larger units have been juxtaposed in a zone to the east of the Kaffioyra Complex. From the investigations of Ohta et al. (1995), they also correlate with the Ordovician rocks south of St Jonsfjorden. In particular, the Aavatsmarkbreen Formation, taken to lie at the top of the Vendian sequence in the Comfortlessbreen Group, should belong to the Bullbreen Group. The Sarsoyra Formation is exposed as a series of white carbonate hills to the northeast of Sarsoyra. In a conglomerate clast W. T. Horsfield found a rugose coral and Scrutton, Horsfield & Harland (1976) took this to correlate with the Bulltinden Formation of ?Silurian age. Because the poorly preserved coral could equally have been Carboniferous, the age of the Sarsoyra Formation was in doubt and possibly late Paleozoic. However, the Makarjev's work reported by Ohta et al. (1995) confirms the original opinion of Scrutton et al. (1976). The Aavatsmarkbreen and Sarsoyra formations are coherent bodies within the Paleogene transpression complex so in themselves cannot be regarded as Paleogene; but they are integral parts of the graben structure. The Pinkie Formation or Complex, referred to in Section 9.6.6, has been taken as possibly the oldest part of the Prins Karls Forland sequence. It is an allochthonous thrust unit and was thought to have derived from a similar basic volcanic protolith of Early Varanger age (Harland et al. 1993). Ohta et al. (1995) also relate this to the same material, but whether it is related to a Paleogene shear zone is another matter.

9.2

Mesozoic strata of Oscar II Land

Cretaceous and Jurassic outcrops are limited to two areas on the northwest coast o f Isfjorden where they complete the n o r t h e r n frame of the Central Basin underlying the Paleogene elliptical brachysyncline. T h e y are a m a j o r consideration in C h a p t e r 4 and are omitted here. Triassic strata extend from n o r t h to south of Oscar II L a n d and are intimately involved in the fold and thrust belt o f the West Spitsbergen Orogen. The i n c o m p e t e n t Triassic shales o f the Sassendalen G r o u p dramatise the fold and thrust structures with the contrasting c o m p e t e n t K a p p Starostin F o r m a t i o n . Before the Paleogene o r o g e n y the upper Triassic units h a d already been progressively e r o d e d towards the n o r t h so that within a distance o f 100km from Selmaneset in the south to NyAlesund in the north the whole remaining Mesozoic succession was reduced to zero thickness beneath the overstepping Paleocene strata. With the loss of Cretaceous and Jurassic strata just n o r t h of Isfjorden the Triassic succession was reduced to 725m at Iskletten (without the K a p p Starostin G r o u p and the u p p e r m o s t Botneheia F o r m a t i o n ) . Southeast o f N y - A l e s u n d the V a r d e b u k t a F o r m a t i o n (Bottom Shale of Orvin 1934) is only 50 m and to the n o r t h w e s t of the coalfield Paleogene strata rest directly on P e r m i a n rocks. This section of the chapter in effect treats mainly the Sassendalen G r o u p defined by the three formations: Botneheia, Sticky K e e p and V a r d e b u k t a .

9.2.1

Kapp Toscana Group

Occurs only in southern Oscar II L a n d with a m a x i m u m thickness of a b o u t 200 m. The D e G e e r d a l e n F o r m a t i o n is of typical greenish-grey sandstones and siltstones a n d with no Tschermakfjellet F o r m a t i o n facies between it a n d the underlying Botneheia Formation.

CENTRAL WESTERN SPITSBERGEN

9.2.2

Sassendalen Group

T h e g r o u p as a whole thickens westwards a n d s o u t h w a r d s in Oscar II L a n d t o w a r d s a m a x i m u m exposed thickness between Isfjorden and Bellsund (Buchan et al. 1965). The thickening is related to a s o m e w h a t coarser grain size which led M o r k et al. (1982) to p r o p o s e a distinct n o m e n c l a t u r e for the western succession. This was partly based on the a s s u m p t i o n of a sharp increase in thickness to the west o f a postulated N - S fault. H o w e v e r , the intermediate Oscar II L a n d thicknesses of the g r o u p also fit a gradual increase in thicknesses which f r o m Sveaneset to Festningen is a b o u t from 400 to 820 m over a distance of a b o u t 55 k m as seen in the fence d i a g r a m o f B u c h a n et al. whose same three constituent f o r m a t i o n s can be recognized t h r o u g h o u t Spitsbergen as confirmed by Worsley & M o r k (1978). The Botneheia Fm, 262m in southern Oscar II Land, occurs only in southern Oscar II Land. It is characterized by laminated dark shales, often bituminous. The silty to sandy facies may be characterized by phosphatised burrow infills. The coarser facies tend to increase upwards with ripple cross lamination and with both calcareous and phosphatic cement. At Sveaneset it yields Gymnotoceras, Posidonia and Daonella f r a m i which may be more characteristic of the lower horizon. Mork, Knarud & Worsley (1982 et seq) and some later publications refer to this formation by the name Bravaisberget for the somewhat coarser and thicker facies southwest of Isfjorden. The Sticky KeepFm, 230 m at Iskletten, is a coarser unit than the Botneheia Formation. The unit also tends to coarsen upwards. In Oscar II Land this has led to a division into two members of the original Sticky Keep Fm. Kaosfjellet Mbr is a distinctive cliff-forming unit of yellow to brown weathering, laminated, shaly siltstones alternating with harder more calcareous siltstones. This competence contrast may promote small scale chevron folding, hence the name of the unit. Isldetten Mbr is a more shaly unit and typically with grey septarian limestone concretions. The Sticky Keep Fm has been referred to in the west, south of Isfjorden as the Tvillingodden Fm (Mork et al. 1982). The Vardebukta Fm, 253 m. This unit was defined in the Festningen section south of Isfjorden. At Selmaneset it is 258 m. The formation is typical of sandstones to siltstones with interbedded shales. As with the two higher formations the coarser facies predominate in the upper part which has led to the division of the formation into two members (Buchan et al. 1965). Siksaken Mbr, c. 100 m comprises alternating grey calcareous siltstones and silty limestones passing to calcarenite, light grey and white sandstones, hard siltstones and calcareous shales. Selmaneset Mbr, c. 150 m comprises somewhat softer dark grey, often calcareous, silty shales with thin hard calcareous siltstones interbeds, sandier towards the top with clay-ironstone concretions. Fossils are few. The lower boundary with the Permian Kapp Starostin Fm is conspicuous. The Bottom Shale of Orvin (1934) in the Ny-~,lesund coalfield= Vardebukta Fro, 0-50m of Challinor (1967). This formation is thickest in the east of the coalfield, where it underlies the Kongsfjorden Formation. It is overstepped in the west. Exposure is limited to a few gully sections, and the main information derives from drill cores. No fossils have been recorded. The upper part is distinguished by variable green, brown and red shales and claystones with conglomerate. Orvin (1934) suggested that it had been derived by erosion of rocks equivalent to the lower part. The lower part is of more uniform shale and is characterised by basal breccias and limestone. The breccias are clearly derived from the cherts of the underlying (Zechstein) Kapp Starostin Formation. Although Orvin postulated a Cretaceous age, the Early Triassic (Scythian) age accepted here is based on lithological correlation (Challinor 1967) with the Vardebukta Formation of the Central Basin (defined at Festningen). It is also consistent with the generalisation by Challinor (Buchan et al. 1965, p. 50) that in Oscar II Land the Triassic strata progressively lose their higher units from south to north.

9.3

Late Paleozoic strata of Oscar II Land (Biinsow Land Supergroup)

Late Paleozoic rocks in this part of Spitsbergen occur in two belts (Fig. 9.2). The m a i n exposures of P e r m i a n rocks are in Broggerh a l v o y a a n d a line extending southeastwards to E k m a n f j o r d e n and

159

N o r d f j o r d e n . A less extensive zone occurs within the Tertiary folda n d - t h r u s t belt, with exposures of C a r b o n i f e r o u s a n d P e r m i a n rocks trending roughly N-S from the eastern end of St J o n s f j o r d e n south to T r y g g h a m n a / Y m e r b u k t a on the n o r t h side of Isfjorden, a n d thence into Nordenski61d L a n d at Festningen ( K a p p Starostin). T h e section at Festningen affords almost complete exposure o f strata f r o m Early C a r b o n i f e r o u s t h r o u g h Early Cretaceous. A d v a n t a g e of this was taken by earlier workers which resulted in the s t a n d a r d stratigraphic description for those intervals in Svalbard. The section was described a n d m e a s u r e d in great detail by H o e l & Orvin (1937). As the n o m e n c l a t u r e used there is the same as for Oscar II L a n d , but different f r o m that in southern Spitsbergen, the Late Paleozoic rocks o f Nordenski61d L a n d will be treated here r a t h e r t h a n in C h a p t e r 10. T h e lower part o f the Gipsdalen G r o u p (approximately Carboniferous) is k n o w n mainly from B r o g g e r h a l v o y a a n d southwestern Oscar II L a n d (St J o n s f j o r d e n a n d T r y g g h a m n a areas). As n o c o m m o n stratigraphic names have been applied across the region, each area is described separately.

9.3.1

Tempelfjorden Group

Kapp Starostin Formation. This f o r m a t i o n is approximately 200 m thick in Oscar II L a n d (Fig. 9.2), w h e r e it is similar to exposures further east. It contains u n i f o r m siliceous limestones and cherts and a rich b r a c h i o p o d a n d b r y o z o a n fauna. H o w e v e r , it is typically s a n d y a n d glauconitic at the top as elsewhere.

9.3.2

Dickson Land Subgroup (Gipsdalen Group)

This u p p e r part of the Gipsdalen G r o u p as defined in the Central Basin ( C h a p t e r 4) represents a laterally extensive depositional unit covering central a n d western Spitsbergen. Exposures in Oscar II L a n d are b r o a d l y similar to those in central Spitsbergen. It comprises two formations.

Gipshuken Formation. The G i p s h u k e n F o r m a t i o n is approxim a t e l y 146m thick w h e r e it is exposed on B r o g g e r h a l v o y a (Fig. 9.1). T w o m e m b e r s are recognized (at Ny-Alesund): an upper dolostone member (60 m) and a (lower) Kloten Breccia (80 m). The latter is u n i f o r m a n d extensive, and p r o b a b l y resulted f r o m solution collapse at the edge o f a large evaporate basin lying to the southeast, as at G i p s h u k e n itself. W o r d i e k a m m e n Formation. The f o r m a t i o n comprises two m e m bers in Oscar II L a n d (the same u p p e r two m e m b e r s of the replaced Nordenski61dbreen F o r m a t i o n ) . Tyrrellfjellet Mbr, Cutbill & Challinor (1965) described three units in this member. At the top the Ki~rfjelletBeds which are approximately equivalent to limestone B (now Finlayfjellet Beds) of the Central Basin. It is of incompetent thinly-bedded to laminated dolostones. The middle unit is an unnamed dolostone sequence; and the lower unit is the Brucebyen Beds - a bituminous fusuline coquina overlying sandy limestones with a thin conglomerate (up to 8 m) at its base. A local unconformity cuts out the Brucebyen Beds at Scheteligfjellet. The MorebreenMbr 115 140 m of Cutbill & Challinor (1965) is equivalent to the Cadellfjellet Formation. Up to 140 m thick on Broggerhalvoya, it consists equally of interbedded dolostones and limestones. Deposition probably occurred on a quiet marine shelf with high salinity. Although no macro fossils have been recorded, fusulinids indicate a Late Moscovian-Gzelian age. No lithological subdivision is possible, but the Gerritbreen and Jotunfonna beds present to the east can be traced on the basis of fusulinid zonation. The topmost beds contain Waeringella usvae zone fossils of Gzelian age. The dolostone is buff-coloured, generally thick-bedded, blocky and with a micritic or silty texture. It commonly contains nodules of chert. Grey limestones occur interbedded with the dolostones. They are generally fairly pure biomicrites with abundant fusulinids and bryozoans, but no macrofossils. Beds are occasionally sandy at the base and chert nodules are common. Massive beds of grey, poorly bedded, stylolitic micrite occur at the top of the formation in the north of Broggerhalvoya. Faunas and age. Two sets of beds were distinguished on the basis of fusulinid zones further east by Cutbill & Challinor.

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The Gerritbreen Beds. These are carbonates containing the W. usvae zone fauna, occurring at the top of the formation in Broggerhalvoya, where they are about 83 m thick. They pass laterally onto the Nordfjorden Block with some thinning and form part of the Kapitol Member. Within the St Jonsfjorden Trough, the beds are cut out rapidly to the south by the Permian unconformity and at St Jonsfjorden, the Permian Tyrrellfjellet Fm rests directly on the TSrnkanten Fm. The Jotunfonna Beds. These are distinguished by the presence of the earlier Wedekindellina zone fauna and are about 60m thick in Broggerhalvoya. They thin slightly to the east and pass laterally into the Kapitol Mbr. They are also cut out to the south by the basal Permian unconformity. No benthic macrofauna has been recorded, only bryozoans and foraminifers. Cutbill (pers. comm.) listed the following: upper W. usvae zone (Gzelian) species from the top of the formation at Scheteligfjellet: Waeringella usvae, Quasifusulina longissima, Triticites sp. A, 'Schubertella' sp., Montiparus montiparus, Protricitites ovatus, Pseudoendothyra sp. Other species, representative of the lower W. usvae zone (Kasimovian) and the upper Wedekindellina zone (Late Moscovian), occur lower down in the unit. The Morebreen Mbr can therefore be correlated with the Jotunfonna and Gerritbreen beds in Billefjorden, as well as the lower part of the Kapitol Mbr of the Nordfjorden Block. The W. usvae zone correlates with the Gzelian and Kasimovian stages of the Russian Platform, so the unit is of Late Moscovian-Gzelian age.

9.3.3

Charlesbreen Subgroup (Gipsdalen Group)

This c o m p r i s e s the lower f o r m a t i o n s o f the G i p s d a l e n G r o u p in the west (Fig. 9.2) a n d is a p p r o x i m a t e l y e q u i v a l e n t to the C a m p bellryggen S u b g r o u p o f the C e n t r a l Basin. A C h a r l e s b r e e n G r o u p was i n t r o d u c e d by Dineley (1958) for the St J o n s f j o r d e n strata a n d was e x t e n d e d also to include the B r o g g e r h a l v o y a f o r m a t i o n s as a s u b g r o u p by S K S (1996). It c o m p r i s e s two pairs o f e q u i v a l e n t f o r m a t i o n s thus:

St Jonsfjorden and Isfjorden T~rnkanten Fm Petrellskaret F m

Broggerhalvoya Scheteligfjellet F m Broggertinden Fm

Scheteligfjellet Formation. This f o r m a t i o n consists o f c a r b o n a t e s , calcareous s a n d s t o n e s a n d c o n g l o m e r a t e s f o r m i n g sequences u p to 150 m thick (Fig. 9.5). It was d e p o s i t e d in Early to M i d - M o s c o v i a n time, a n d represents a m a r i n e transgression over terrestrial rocks o f the B r o g g e r t i n d e n F o r m a t i o n a n d Billefjorden G r o u p . It c o n t a i n s a varied f a u n a i n c l u d i n g fish remains. Definition. The Scheteligfjellet Fm is a distinctive 150m thick unit recognized only in western Broggerhalvoya. It is cut out eastwards by the Pretender Fault. Gobbett (1963) introduced the term Scheteligfjellet Beds for the Middle Carboniferous strata lying beneath the Cyathophyllum Limestone. Cutbiil & Challinor (1965) redefined the Scheteligfjellet Mbr as part of the Nordenski61dbreen Fm occurring only in Broggerhalvoya and coeval with the T~rnkanten Fm of Central Oscar II Land. Their member is here

Fig. 9.5. Fence diagram show the stratigraphic relationships within the St Jonsfjorden Trough (From Cutbill & Challinor 1965).

upgraded to formation status in line with the replacement of the Nordenski61dbreen Fm. The 'Leinstranda Fm' described by Barbaroux (1968) is probably equivalent to the Scheteligfjellet Fm. The type section is at Scheteligfjellet. The formation lies conformably beneath the Jotunfonna Beds of the Morebreen Mbr, the top being marked by a downward passage from rather pure carbonates to interbedded cherty carbonates, calcareous sandstone and some conglomerates which are red in part. The lower boundary is an unconformity marked by a basal conglomerate. It overlies Billefjorden Gp sediments to the west of the Kvadehuken Fault, and the red clastics of the Broggertinden Fm to its east. Lithologies. The formation comprises a distinctive, but somewhat heterogeneous, unit of carbonates, calcareous sandstones and breccias, with a basal conglomerate. Shelf carbonates make up the bulk of the formation (75%). They are generally grey or dark grey micrites or biomicrites, commonly with interbedded calcareous sandstones. Holliday (1968) noted a ~ 3 m coral biostrome occurring locally above the basal conglomerate: it is almost completely dominated by the species Chaetetes radians Fischer and Campophyllum kiaeri Holtedahl, with rare Syringopora sp., which are usually in positions of growth and built on top of each other (this is the 'coral limestone' of Holtedahl 1913). On Ki~erfjellet and northern Kulmodden, the formation contains breccias up to 50 m thick, comprising fragments of grey and yellow-weathering dolostone and limestone up to 10 cm across. The mass splits into several layers when traced laterally. The breccias are probably of intraformational origin, formed by erosion of the underlying beds, but a solution mechanism cannot be ruled out. Greenish-grey or reddish calcareous sandstone interbeds are the distinctive feature of the formation and occur throughout, making up 15% of the total. Red and green shales and siltstones occur with sandstones near the base of the formation. The base of the formation is marked by a conglomerate 0 8 m thick, that fills in topographic irregularities in the pre-Moscovian surface. It is largely quartzose, but with more variable clasts than the underlying Billefjorden Group conglomerates, with indications of channelling and reworking of sediments. Beds and lenses of black laminated limestones, red shales and red or green sandstones occur. The matrix is calcareous and shows signs of algal binding (Holliday, 1968). Palaeontology and age. The formation contains an abundant marine fauna, including brachiopods, fusulinids, corals, crinoids, bryozoans, gastropods, trilobites and fish. Holtedahl (1911, 1913) first described a rich Moscovian fauna from Braggerhalvaya, collected from limestones and conglomerates at the base of the formation. The brachiopod fauna is of general 'Middle Carboniferous' character and resembles that of the Minkinfjellet Mbr in Billefjorden and the TSrnkanten Fm of St Jonsfjorden (Gobbett 1963). The fusulinids are typical of the Wedekindellina zone in the upper part of the member and the Profusulinella zone lower down as defined by Cutbill & Challinor (1965). This implies an Early to Mid-Moscovian age for the formation, and strongly supports the correlation with the Minkinfjellet Fm.

Braggertinden Formation, 350 m. T h e B r o g g e r t i n d e n F o r m a t i o n is a variable sequence o f s a n d s t o n e s , c o n g l o m e r a t e s a n d c a r b o n a t e s f r o m B r o g g e r h a l v o y a a n d n o r t h e r n Oscar II L a n d (Fig. 9.3). It is correlated with the E b b a d a l e n F o r m a t i o n o f the Billefjorden area (Cutbill & C h a l l i n o r 1965). It occurs only to the east o f the K v a d e h u k e n Fault. T h e s a n d s t o n e s are generally flaggy a n d micaceous, a n d are o f variable c o l o u r f r o m red a n d b r o w n to yellow. I r o n is c o m m o n a l t h o u g h i r o n s t o n e b a n d s are rare. D e p o s i t i o n p r o b a b l y o c c u r r e d in a fluvial e n v i r o n m e n t . N o m a r i n e f a u n a have been r e c o v e r e d a n d the o t h e r f a u n a (including fish remains) are n o t age-diagnostic. H o w e v e r , the f o r m a t i o n is generally r e g a r d e d as being o f B a s h k i r i a n age. Definition. The formation is well exposed at several localities on Broggerhalvoya. The type section is at Broggertinden, where it is 361 m thick. The formation is absent to the west of the Kvadehuken Fault, where Billefjorden Gp sandstones occupy an analogous position. The formation lies concordantly beneath limestones of the Scheteligfjellet Mbr. The boundary is an unconformity marked by the basal conglomerate of the overlying member, dividing the largely carbonate lithologies above from arenaceous ones below. The base is marked by a sharp unconformity, overlying pre-Devonian mica-schists. Nowhere does the formation rest on Early Carboniferous Billefjorden Gp strata, which are present in Broggerhalvoya only to the west of the Kvadehuken Fault.

C E N T R A L WESTERN SPITSBERGEN Two lithological units are present in the type section at Broggertinden. The Upper Mbr, about 185m thick, comprises sandstones with conglomerates and rare limestones, e.g. at Ki~erfjellet. The Lower Mbr consists of about 163 m of conglomerates with few finergrained interbeds. Lithologies. The formation consists predominantly of sandstones (45%) and conglomerates (45%). Fine, medium and coarse-grained sandstones occur throughout the formation, interbedded with the conglomerates. They are commonly flaggy and micaceous, in places shaly. Iron is abundant, and hematite cement occurs in some beds. They are generally red or brown, but white and grey beds are found. Yellow, red and brown conglomerates occur throughout, predominating in the lower part. Clasts are rounded and 2-3 cm across. They consist of quartzite and chert derived either from pre-Devonian rocks or secondarily from the Orustdalen Formation. The matrix is sandy. Red shales occur interbedded with the sandstones and conglomerates. A thin ironstone occurs near the top of the formation at Broggertinden. At Kia~rfjellet, the middle of the upper part contains yellow shaley dolomites, conglomeratic limestones and grey, blocky calcarenite. One such carbonate bed contains rare fossils. Palaeontology and age. Poorly preserved fish fragments were found in the sandstones in the Scheteligfjellet section by Orvin (1934) who first supposed a Devonian age; otherwise the clastic facies appears to be unfossiliferous. The limestones on Kia~rfjellet contain poorly preserved brachiopods, crinoids and fusulinids which are certainly of Carboniferous age. Thiedig (1988) reported mid-Carboniferous microfossils in limestones associated with the red beds. As the formation lies below the Moscovian Scheteligfjellet Member and resembles facies of the Ebbadalen Formation it is assumed to be of Bashkirian age.

Tfirnkanten Formation. P r e s e n t along the I s f j o r d e n c o a s t o f Oscar II L a n d , the Tgtrnkanten F o r m a t i o n is a u n i t u p to 250 m thick o f m a i n l y q u a r t z arenites w i t h m i n o r c o n g l o m e r a t e , shale a n d limestone. C a l c a r e o u s n o d u l e s a n d desiccation cracks c a n be o b s e r v e d in places, a n d the s a n d s t o n e s are c o m m o n l y r e d d e n e d . T h e limestone b a n d s c o n t a i n a varied f a u n a w h i c h indicates Early a n d M i d - M o s c o v i a n ages. D e p o s i t i o n was w i t h i n a c o a s t a l / i n t e r t i d a l e n v i r o n m e n t w i t h b o t h fluvial a n d m a r i n e c o n d i t i o n s represented. Definition. Dineley (1958), in his description of the 'Charlesbreen Group', distinguished the higher red sandstone and conglomerate unit as the Tfirnkanten Sandstone. It was defined as The Tgtrnkanten Fm by Cutbill & Challinor (1965). The formation is the lateral equivalent of the Scheteligfjellet Fm of Broggerhalvoya (see above). The type section is on Tfirnkanten, where the formation is 251 m thick. The sequence reappears in the south of Oscar II Land at Trygghamna and south of Isfjorden at Orustdalen where 253 m are present below the Permian Tyrrellfjellet Mbr. Further south in Bellsund, the formation is cut out by prePermian erosion and the Tyrrellfjellet Mbr limestones rest directly on Early Carboniferous Billefjorden Gp sandstones of the Vegard and Orustdalen fms. The upper boundary is an unconformity beneath the Permian Wordiekammen Fm limestones which appear to cut down into the T~trnkanten Fm sandstones. These have been leached at the top and bright yellow limonite coats the bedding surfaces and joints. The lower boundary is at the base of the lowest massive sandstones under which lie the soft red shales of the Petrelskaret Fro. Lithologies and division. The formation consists of arenites (80%), conglomerates (5%), thin shales (10%) and limestones (5%). Massive, mature quartzose red and white coloured sandstones and grits, which are quartzitic or calcareous in places, form the bulk of the formation. Feldspar is rare. Cross-bedding is common, generally on a small scale, with foresets inclined at a low angle. Asymmetrical and oscillation ripple marks also occur, but there appears to be no preferred orientation. There is syn-sedimentary contortion near the top of some sandstone beds. The sandstones have sharp bases, and commonly grade upwards into finer sediments. The beds are occasionally conglomeratic at the base, with vein-quartz pebbles. Intraformational conglomerates are common, and may also contain rolled fossils. Thin marls or shales of a variety of colours occur regularly interbedded with the sandstones. They often contain small calcareous nodules scattered in bands. Polygonal desiccation cracks commonly affect the thin shales between the sandstone beds, ranging in diameter from 2-30 cm and penetrating downwards for up to 60 cm. There are several bands of thin grey limestone, commonly containing marine fossils, in the middle and upper part of the formation. They contain varying amounts of silt and sand and in places grade into coarse sandstone. Dineley & Garrett (pets. comm.) have recognized three major cyclothems within the formation at St Jonsfjorden, separated by two distinct

161

marine bands. At the base of each are massive quartzites which are overlain by calcareous grits and sandstones, conglomerates and thin shales with a marine band at the top. The latter is several metres thick and consists of poorly sorted sandstone with trace fossils which passes upwards into shale followed by limestone with marine fossils, then more shale then finally finegrained sandstone. The upper cyclothem is incomplete, and is represented by the highest massive and thin-bedded quartzites with thin red and brown shales exposed beneath the Permian unconformity. It has the Tfirnkanten marine band (c. 4 m thick) at its top, below which lie about 21 m of mottled calcareous sandstones and conglomerates containing at least one fossiliferous sandy limestone. These are underlain by a 44 m thick unit of massive red and white quartzose sandstones and quartzites. The lower cyclothem is similar: its top is defined by the fossiliferous Robertsonfjellet marine band (7.5 m), underlain by 20m of calcareous sandstone and 68m of red calcareous and quartzose grits, with massive red and white quartzites at the base. Palaeontology and age. varied marine faunas are common in the limestones, especially in the upper part of the formation. The faunas of the two marine bands are distinctive and consist predominantly of one species of brachiopod (a spiriferid in the Robertsonfjellet marine band and a large chonetid in the T~rnkanten marine band), with other brachiopods, crinoid ossicles, echinoid spines and rare coral fragments, trilobites and molluscs. Other limestone beds yield corals, brachiopods and crinoids. Rare lingulids are present at some horizons and fragmentary plant remains occur locally. The brachiopods compare closely with those of the Scheteligfjellet Formation of Broggerhalvoya (Gobbett 1963; Dineley & Garrett 1950, and CSE), suggesting that the unit is probably of Early and Mid-Moscovian age.

PetreHskaret Formation, 350 m. This f o r m a t i o n consists m a i n l y o f shales a n d m u d s t o n e s , c o m m o n l y p u r p l e in c o l o u r b u t also black a n d even b i t u m i n o u s in places. Also p r e s e n t are t h i n s a n d s t o n e interbeds, i r o n s t o n e b a n d s a n d rare e v a p o r i t e beds. T h e age o f the f o r m a t i o n is e s t i m a t e d as Bashkirian, a l t h o u g h the f a u n a is very sparse. D e p o s i t i o n was o n a coastal alluvial plain, m a i n l y fluvial or lacustrine b u t with a m a r i n e influence, especially early o n w h e n m o s t o f the l i m e s t o n e s a n d evaporites were f o r m e d . Definition. The Petrellskaret Fm is a sequence of shales having limited outcrop in Oscar II Land. It was originally described by Dineley (in Gobbett 1963) from St Jonsfjorden. Cutbill & Challinor (1965) gave it formational status and correlated it with the Broggertinden Formation. The type section is on Petrelskardet, St Jonsfjorden (Fig. 9.5). It is present at Orustdalen south of Isfjorden, but is absent around Bellsund owing to Permian erosion. The upper boundary is conformable, at the base of the massive quartzites of the TArnkanten Fm. The base is conformable and marked by a group of hard sandstones, silicified limestones, shales and evaporites 12.5 m thick, below which are dark shales and grey sandstones of the Vegard Fm (Billefjorden Gp). Lithologies. The bulk of the formation (80%) is composed of shales and laminated mudstones, generally purple, but in places black and bituminous, especially in the upper part, where conspicuous bands of ironstone are found. A remani6 band of ferruginous grit, 23 m thick, containing phosphatic nodules, clay pellets, rare quartz pebbles, fish scales, bones and teeth occurs near the top of the formation. There are thin sandstone interbeds, with rare intraformational conglomerates. The shales are occasionally marly towards the base of the formation and calcareous nodules occur. At the base are grey silicified limestones and evaporites interbedded with hard sandstones and shales. Light-coloured sandstone beds, generally quite thin, occur throughout, forming about 15% of the formation. They are sharply defined, commonly with erosive bases and are irregular in thickness or lenticular. They become finer upwards. Clay intraclasts are locally present in the basal layers. A thick white quartzite occurs 90 m below the top. Evaporites are a minor constituent of the sequence, occurring as thin intercalations at the base and as a gypsum band about 65 m below the top. Palaeontology and age. Fossils are rare in this formation. On Petrellskaret, indeterminate corals, resembling cyathophyllids and ?Syringoporaare found in the limestones near the base, and fish scales, bones and teeth occur in the remani6 grit near the top. As the formation lies below sediments of Moscovian age and above the Serpukhovian Vegard Fm, it is probably of Bashkirian age. 9.3.4

Billefjorden Group

T h e Billefjorden G r o u p in w e s t e r n Spitsbergen consists o f the V e g a r d a n d O r u s t d a l e n f o r m a t i o n s , u p to 1 1 2 0 m thick, d e p o s i t e d

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in the St J o n s f j o r d e n T r o u g h , w h i c h appears to have been isolated f r o m the rest of Svalbard in Early C a r b o n i f e r o u s time. P r e - P e r m i a n uplift a n d erosion has r e m o v e d some of the V e g a r d F o r m a t i o n and later C a r b o n i f e r o u s sediments in m a n y areas. The full extent of the t r o u g h is not known; but it stretched, at least, f r o m B r o g g e r h a l v o y a to Bellsund The eastern m a r g i n was the N o r d fjorden Block. T w o f o r m a t i o n s were recognized in western Spitsbergen by Cutbill & Challinor (1965) in the Culm of N a t h o r s t (1914; 1920), H o l t e d a h l (1912) and Orvin (1940). These are the (upper) Vegard F o r m a t i o n , consisting of thinly-bedded sandstones and shales; a n d the (lower) O r u s t d a l e n F o r m a t i o n o f coarse sandstones and conglomerates.

Vegard Formation, 358 m. The V e g a r d F o r m a t i o n consists of sandstones with c a r b o n a c e o u s shales a n d subordinate conglomerate. It is a fluvial unit o f p o o r l y constrained age as f a u n a are sparse, but it is generally regarded as Serpukhovian. Definition. This is a formation of sandstones and shales which is 358 m thick in the type section in Orustdalen in Nordenski61d Land. It was first described in Oscar II Land by Dineley (1958), who divided the 'Culm' into two formations. Cutbill & Challinor (1965) extended this upper formation southwards to Nordenski61d Land, where maximum thicknesses occur. The upper boundary in the type section is sharp, but conformable, and is marked by an abrupt upward lithological change from sandstones with interbedded shales to the beds of the basal Petrellskaret Fm (Gipsdalen Gp). The latter consists, at its base, of silicified limestones and evaporites interbedded with hard sandstones and shales (see above). Elsewhere, however, later Carboniferous erosion has resulted in removal of the top of the formation and an unconformity with the Permian Wordiekammen Fm limestones. The base is conformable above massive sandstones of the Orustdalen Fm. Lithologies. Light grey, white and locally reddish, thinly-bedded/flaggy or blocky sandstones are interbedded with dark grey-black carbonaceous shales. The sandstones are generally fine-medium grained, but occasionally coarse-grained, and there are local conglomerate horizons and lenses. Poorly-preserved plant remains are common in both sandstones and shales; the latter may be coaly. Palaeontology and age. Nathorst (1914), in his studies of the Billcfjorden Group, included detailed lists of plants from the 'Culm' of western Spitsbergen. Although the Vegard and Orustdalen fins were not differentiated, on the basis of locality the stratigraphic position of some can be ascertained. He distinguished three separate floras (Nathorst, 1920), of which the uppermost Diabasbukta flora, containing Cardiopteridium nanum, is from the Vegard Fm. However, this flora has not been identified elsewhere. The poor preservation of spores has frustrated palynological studies, and nothing is published on this formation. Hence correlation of the formation is tentative, but if the Orustdalen Fm, below, is of Late Visean to earliest Serpukhovian age (see below), then this formation is probably Serpukhovian. There are lithological similarities, (sandstones and shales with some red beds and thin coals), to the earliest Serpukhovian Hultberget Mbr of the Billefjorden Trough (see Chapter 4), with which it may be contemporaneous (Cutbill & Challinor, 1965). Orustdalen Formation. Sandstones and shales are the predominant constituents of this formation, which varies in thickness up to several h u n d r e d metres. The sandstones are invariably quartz rich but also contain clasts o f m e t a m o r p h i c rock and chert. Plant remains are c o m m o n but coal has only been recorded f r o m a single horizon on Broggerhalvoya where it is k n o w n only west of the K v a d e h u k e n Fault. There are no m a r i n e fossils but the flora indicates a Late Visean or Early S e r p u k h o v i a n age. The f o r m a t i o n represents a fluvial e n v i r o n m e n t on a growing alluvial fan building out from a fault scarp into a m a r i n e basin. Definition. Dineley (1958) divided the 'Culm' in Oscar II Land into two formations. His lower Trygghamna Fm is the equivalent of the Orustdalen Fm of Cutbill & Challinor (1965) which can be traced from Reinodden to Broggerhalvoya. It is 759 m thick in the type section at Orustdalen, thinning to 654 m north of Bellsund and only about 200~50 m at St Jonsfjorden. The upper boundary is conformable with the overlying Vegard Fm. The junction is marked by a change to a thick sandstone sequence with a sudden reduction in shales. The base is marked by an angular unconformity above pre-Devonian schists. Locally there are basal conglomerates. Lithologies. They are generally more arenaceous than the Vegard Fm. Monotonous light grey or white, thickly-massively bedded sandstones are

interbedded with thin, black, red or grey shale horizons (up to 20 cm locally). Sandstones are mainly medium-coarse grained and quartzitic, with common cross-bedding and ripple-marks. Lenses and beds of coarse quartz-conglomerate occur, especially within the bottom 50 m and there is a locally developed basal conglomerate (Orvin 1940; Hjelle 1962) that is rich in hematite in places. The conglomerates contain sub-rounded pebbles, not only of white veinquartz, but also of red and black chert and jasper, feldspars, schist and plant fragments up to 5 cm in diameter. They are associated with interbedded sandstones and shales. Thicker (20-40 cm) shales appear downwards, which are usually dark, but are locally grey or red. Plant remains are very common, though they are generally poorly preserved as carbonaceous impressions. There are no coals, except near the base on Braggerhalvoya, where a 3 m thick unit of poor quality coal (ash content 30%), and carbonaceous shale occurs (Orvin 1934). Fairchild (1982) mentioned a 7 cm in-situ coal seam with a 1 cm underclay in the same area and also another rootlet horizon 100 m further up. Palaeontology and age. Nathorst (1914) listed the flora of the Billefjorden Group, including many species which, by inference, came from the Orustdalen Formation. In addition, he distinguished three distinct floras, the lower two of which must be from the Orustdalen Formation (Nathorst 1920). The Hagerup Haus flora is the younger and contains Sphenopteridium norbergii and Thysanotesta sagittula. It is separated from the Camp Millar flora below by beds containing only Stigmariaficoides. The Camp Millar flora is characterized by Adiantites bellidulus, Lagenospermum arberi and Lepidodendron mirabile. However, these assemblages, which are almost certainly pre-Serpukhovian, have not been identified elsewhere. Forbes, Harland & Hughes (1958) noted the similarity of the Hagerup Haus flora to that found east of Festningen and at Billefjorden in the Svenbreen (or possibly the Horbyebreen) Formation which suggested a possible correlation, confirmed in 1982 by Fairchild (see below). Lepidodendron Nordenskidldii, L. heerii, Sphenopteridium norbergii, Adiantites bellidulus and Cardiopteridium ?spetsbergens, found at Billefjorden in the Svenbreen/ Horbyebreen formations, are also recorded by Nathorst from the Orustdalen Formation and Lepidodendron rhodeanum, Lepidodendron robertii and Sphenopteris bifida are common to both the Svenbreen and Orustdalen formations (Cutbill & Challinor 1965). Earlier attempts to describe the palynology of these strata were frustrated by the very poor preservation of microfossils in this western region, probably a result of the Tertiary orogeny. However, one horizon low in the sequence on Broggerhalvoya has yielded spores which indicate a Visean/earliest Namurian age (Fairchild 1982). Lycospora pusilla and small Densosporites are common. Thus the Orustdalen Formation is probably of Late Visean or possibly Early Serpukhovian age and correlates with the Mumien Formation, a correlation supported by its lithology which resembles that of the lowermost member of the Mumien Formation.

9.4

Early Paleozoic rocks

Early publications on this area were few and include H o l t e d a h l ' s (1913) observations and Orvin's (1934) detailed study o f Broggerhalvoya as part o f a t h o r o u g h description of the N y - A l e s u n d coalfield. Post-war research increased greatly beginning with B i r m i n g h a m University expeditions in 1948, 1957 and 1958 (Baker, Forbes & H o l l a n d 1952; Weiss 1953, 1958; Dineley 1958). Structural studies by B a r b a r o u x (1966a, b) and Challinor (1967) followed. The blueschists of Motalafjella were intensively studied after their discovery by C a m b r i d g e parties in 1961 (Horsfield 1972; O h t a 1979, 1985a, 1992; Ohta, Hiroi & Hirajima 1983; Ohta, H i r a j i m a & Hiroi 1986; K a n a t 1984a, b). Ordovician-Silurian fossils were reported by Scrutton, Horsfield & H a r l a n d (1976) a n d by A r m s t r o n g , N a k r e m & O h t a (1986). The rocks, largley Ordovician are described in two distinct units: the Bullbreen G r o u p and the Vestg6tabreen Complex.

9.4.1

Bullbreen Group (Harland, Horsfield et al. 1979)

Different stratigraphic schemes have been proposed for the rocks, n o w k n o w n to be of Early Paleozoic age a n d occurring mainly as outliers in the area south of St J o n s f j o r d e n (Motalafjella t h r o u g h Holmesletfjella across Bullbreen to Bulltinden) and n o r t h of the

CENTRAL WESTERN SPITSBERGEN fjord at Ankerfjella, Kaffioyra a n d Sarsoyra. T h e successive cont r i b u t i o n s are r e c o u n t e d a n d a unified n o m e n c l a t u r e is p r o p o s e d . Holtedahl (1913, p. 57) reconnoited the southeast shores of St Johnsfjorden and noted a conglomerate with boulders matching, for example, his Alkhorn limestones. This was most probably at Bulltinden, west of Bullbreen. In 1959 from a temporary anchorage at Copper Camp, Harland noted the extensive flysch sequence of calcareous argillites and polymict conglomerates referring them to his Holmesletfjella unit (1960), although mistakenly placed earlier than the Comfortlessbreen Group. Wilson & Harland (1964), Winsnes (1965) and Flood, Nagy & Winsnes, 1G, (1971) related the conglomerate to the Comfortlessbreen tilloids but the stone content did not match. In 1968 Horsfield & Harland suspected fossils from limestone clasts and in 1969 Horsfield collected fossils from the conglomerates in Motalafjella. The fauna was tentativelly identified with late Ordovician or early Silurian forms. In 1971, Harland revisited the locality and made a small collection from a penecontemporaneously slumped limestone within the conglomerate. The two collections together suggested a Wenlock or Ludlow age (Scrutton, Horsfield & Harland 1976) where the scheme in Harland et al. (1979) was used because it had been submitted in 1975. Horsfield (1972) in describing the Vestg6tabreen Complex metamorphism described all the later rocks as the Bulltinden Fm (Harland, Horsfield et al. 1979). As part of a stratigraphic scheme for the whole of Oscar II Land, they made the Bulltinden conglomerate a member within the Homesletfjella Fm, and placed the underlying strata-mainly limestones in another formation the Motalafjella Fm. Ohta (1979) followed Horsfield (1972) his paper being in the same publication as Harland et al. (1979). Ohta, Hiroi & Hirajima (1983) identified the contact between the metamorphic complex and showed it to be an overturned unconformity which they mapped. They used the name Bulltinden Formation for the conglomerate and the older basal limestone above the complex, supposedly following Harland et al. (1979) for this usage. Armstrong, Nakrem & Ohta (1986) reported significant conodont studies which suggested a Caradoc or earlier age for the basal limestone and also for a limestone lens within the overlying sandstone and shale member. The overlying boulder conglomerate with slumped olistostromes were suggested to be of Early Silurian age. These three members were of the Bulltinden Fm. Kanat & Morris (1988) in describing this general succession in the St Jonsfjorden area followed Harland, Horsfield, Manby & Morris (1979) referring to the two formations Holmsletfjella (above) and Motalafjella (below) and comprising the Bullbreen Group. They described the sequence in detail for the first time. Their scheme is followed here except for the Bulltinden conglomerate member. It has proved to be the most conspicuous unit, occasionally of great thickness, has been frequently referred to in the literature, was first noted with fossils, later yielding a distinct fauna. Therefore it was upgraded to formation rank and the two members beneath it were transferred into the Motalafjella Fro. The proposal is thus, details follow.

BuUbreen Gp Holmesletflya Fm (probably Silurian) Bulltinden (conglomerate) Fm (Early Silurian) Motalafjella Fm (Late Ordovician)

HolmesletfjeUa (slate) Formation, first identified as W6, by W i l s o n in 1958, the e p o n y m o u s m o u n t a i n was revisited a n d n a m e d ( H a r l a n d 1960) b u t in m i s t a k e n order, s o m e w h a t rectified by H a r l a n d e t al. (1979). T h r e e m e m b e r s were described ( K a n a t & M o r r i s 1988). Siliceous slate mbr, 20m (BH6 of Kanat & Morris) is best exposed in northern Holmesletfjella, is a friable siliceous slate, upper contact not known. Elongate irregular dark features were interpreted as trace fossils. Lower boundary is sharp and conformable . Sandstone slate mbr, 100m+ (BH5 of Kanat & Morris) exposed in Holmesletfjella and Motalafjella, Bulltinden, Ankerfjella etc. interbedded calcareous sandstones (65%), slates (25%) and immature and impersistent conglomerate horizons (10%) show cross bedding, conspicuous from a distance due to colour-banding (grey to buff) and reveals fiat-lying nearisoclinal folds giving a first impression of much greater thickness. The base is transitional with decrease in conglomerate content. Slate Mbr, 30 m (BH4 of Kanat & Morris) is black, slightly calcareous and of similar extent to the above member. Its base is sharp. Bulltinden (conglomerate) Formation, 10 60 m (BH3 o f K a n a t & M o r r i s ) is m a i n l y a p o l y m i c t c o n g l o m e r a t e with clasts r a n g i n g in

163

size f r o m granules u p w a r d s t h r o u g h b o u l d e r s to s l u m p e d olistost r o m e s , a n d is variably i n t e r - b e d d e d with s a n d s t o n e s a n d slates similar to the Holmesletfjella F o r m a t i o n . It has been described in detail by K a n a t & M o r r i s (1988) with clasts o f l i m e s t o n e 4 0 % , schist 2 5 % , s a n d s t o n e 2 0 % , d o l o s t o n e 10% c o n g l o m e r a t e 5 % , dolerite < 1 % . T h e clast lithologies m a t c h either those o f the Bullbreen G r o u p or the m e t a m o r p h i c s o f the V e s t g 6 t a b r e e n C o m p l e x ; s o m e o f the l i m e s t o n e s m i g h t be V e n d i a n . Fossils were first noted in the limestone clasts and a distinct coral, gastropod, bryozoan, echinoid fauna was collected from a 100+m 3 olistostrome (Scrutton, Horsfield & Harland 1976) estimated to be of late Llandovery to Wenlock age. Work on conodonts confirmed an Early Silurian age (Armstrong, Nakrem & Ohta 1986). Harland's opinion was that this slumped mass, unlike some conglomerate clasts was penecontemporaneous. The base of the formation is a sharp erosive sedimentary contact.

Motalafjella (slate and limestone) Formation, 2 6 0 m ( H a r l a n d , Horsfield e t al. 1979). This f o r m a t i o n newly includes the two lower m e m b e r s f r o m the Holmesletfjella F o r m a t i o n o f K a n a t & M o r r i s w h i c h is d i v i d e d here into t w o units, the lower o f w h i c h was classified by t h e m with the V e s t g 6 t a b r e e n C o m p l e x . T h e r e are t h u s five m e m b e r s . Slate Mbr, 10 m (BH2) a black ferruginous slate (with bands of subhedral pyrite. The base is transitional. Sandstone-slate Mbr, 150m (BH1 of Kanat & Morris) best seen in western Motalafjella, but also Holmesletfjella, Ankerfjella and in Bulltinden, where the upper contact is under the Bulltinden conglomerate. Within the sandstones up to 10% of conglomerates may occur and both sandstone and conglomerate may give way to slate. The carbonate content here is greater than in the Holmesletfjella sandstones. The lower contact is sharp but conformable. Limestone Mbr 100 m (BM1 of Kanat & Morris). This is predominantly of limestone which forms the peak of Motalafjella and is only 3 m at Ankerfjella. a gritty (up to 30% detritus) fossiliferous (crinoid stems and coral fragments) cryptocrystalline grey, buff-weathering, limestone. This limestone seems to be the source of the fossiliferous clasts in the Bulltinden conglomerate. It was also the source of the Caradoc or even Arenig conodonts described by Armstrong, Nakrem & Ohta (1986). The (somewhat tentative) conclusion of their study combined with the macrofossil evidence is for a Caradoc age. Conglomerate slate Mbr (BM1 of Kanat & Morris). A thin member or bed at the base of the limestone is indicative of a basal conglomerate. Dolostone Mbr, 0 - 2 0 m (VOD of Kanat & Morris). This distinctive orange-weathering dolostone is consistently found below the Motalafjella unit (BM1) where it is in contact with the Vestg6tabreen Complex, except at Ankerfjella and Bulltinden where it is in contact with the Comfortlessbreen Group. Ohta, Hiroi & Hirajima (1983) demonstrated a basal unconformity contact with the complex and limestone and metamorphic fragments in the succeeding dolostone. The rock is a coarsely crystalline grey siliceous dolostone with 5% or even 10% of chromium phengite (mariposite) weathering to a distinctive orange. It has the fabric of a thrust breccia in places. The high magnesium, chromium and nickel content suggest a carbonated metasomatized ultrabasic rock, associated with the Vestg6tabreen Complex. The conclusion here is that, from its consistent occurrence at the base of the Motalafjella Formation and from the description of Ohta et al. it belongs to that formation but it has been selected as a thrust horizon. This would reconcile the apparently conflicting observations; but it leaves unresolved the contact at Ankerfjella, which while clearly a thrust contact may yet have been unconformable there also. Some mineralization may well have been selected by the thrust surface. Ferruginous waters pour down from a spring in the scree on northern Motalafjella at about this horizon, east of Copper Camp. The mineralization could well be Paleogene (see Chapter 20). Sarsoyra Formation, 450 m. This f o r m a t i o n is seen in c o n t i n u o u s white cliffs w h i c h b o u n d the S a r s o y r a plain to the east. W i t h i n the S a r s o y r a plain leading o u t to the n a r r o w a n d shallow passage at S a r s t a n g e n are scattered o u t c r o p s with a N - S o r i e n t a t i o n investigated by C S E as follows. C. B. W i l s o n suggested a h o r s t structure, W . T . Horsfield n o t e d s l u m p e d blocks o f the n e i g h b o u r ing T e r t i a r y facies related to it a n d t h a t all were a l l o c h t h o n o u s . H a r l a n d first suggested a step-faulted s t r u c t u r e at the m a r g i n o f the graben, w i t h fault scarps f r o m w h i c h blocks slipped a w a y in a

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CHAPTER 9

rapidly accumulating sedimentary sequence. On this basis some of the larger outcrops would be in s i t u horsts. From further investigation in 1992 he found it difficult to fit the various exposures into a systematic pattern of outcrop or strike. The original idea of strips of rock units could be ruled out, nor did it seem likely that the larger masses could have slipped off fault scarps. They were too large and internally coherent. Nearly every exposure was associated with tectonic breccias. It therefore seemed most likely that the area contains disoriented slices in a large-scale melange strike-slip zone. The lithologies include unsorted clast-supported conglomerates and breccias with pebbles up to 15 cm of white quartzite and vein quartz, finely bedded sandstone to siltstone and psammitic schists. There were also units of dolomitic marble (some of reddish tint) these were generally brecciated. The quartzite and dolostone facies were closely associated. The age of these rocks has been debated as between Carboniferous or Silurian. The earlier age was suggested from a pebble (in a conglomerate in the formation) which contained a lykophyllid coral. The conglomerate was first taken as part o( the Bullbreen Group (see below) by Scrutton et al. (1976). However, C. L. Forbes suggested that a Late Paleozoic age was just as likely. In any case the formation does not have to be the age of its constituent pebbles. Therefore a Carboniferous or possibly Permian age was then preferred. However the new age determination by Makanjev (pers. comm. in Ohta et al. 1995) supports the original opinion of Scrutton et al. (1976).

Aavatsmarkbreen Formation, 600 m. This formation comprises a thick succession of dark grey phyllite, volcanites, psammites and subordinate carbonate. It is isoclinally folded and thickness is difficult to estimate. The lower boundary is not exposed but a transition by alternation with facies of the underlying formation is likely. Three informal divisions have been suggested (Harland, Hambrey & Waddams 1993): (3) c. 300-400 m of highly deformed grey and black phyllite, with thin black marble, white marble, sandy dolostone and quartzite interbeds; (2) 6 - 1 0 0 m of dark green black slate with some quartzite beds At Snippen (south of the Annabreen Formation section) there are soft light green and purple banded shales. (1) c. 400m of dark phyllite and black limestone with thin conglomerate and pink psammite interbeds. Whereas Harland et al. (1993) took this to be the top formation of the Comfortlessbreen Group and of probable Ediacara age, Ohta et al. (1995) with further evidence identified the sequence as belonging to the Bullbreen Group and so of Ordovician to Silurian age. This revision is followed here. 9.4.2

Vestg6tabreen Complex

On Cambridge expeditions in 1958 C. B. Wilson noted high-grade metamorphic rocks in the Eidembreen moraine, D. G. Gee in 1962 located their source showing the presence of glaucophane schists at Motalafjella. Horsfield worked in the area from 1968 (1972) when he showed isotopically that the metamorphism was Paleozoic, probably Ordovician (i.e.c. 470 Ma) and he suggested a subduction zone. These finds led to further mineralogical work e.g. Ohta (1979), Kanat (1984a, b), Ohta, Hirojima & Hiroi (1986) and Kanat & Morris (1988). Age of the Complex. Motalafjella is also noteworthy for its Ordovician and Silurian fossils (see 9.6.1 and 14.4.4) which show the complex to have been metamorphosed not later than Caradoc time and further deformed and thrust in late or post-Silurian time and part at least in Paleogene time. Subduction models have been proposed which if valid would have to reflect an early to midOrdovician Eidembreen event. The age of the protoliths is unknown. The basic igneous composition might match that of the Early Varanger volcanics The limited exposure in only three mountain inliers gives no regional handle to speculate further. These would be from the Lovliebreen Formation suggested by Harland, Hambrey & Waddams (1993) and by Ohta e t al. (1995) which authors differ as to to its age.

Structure of the Complex.

The Vestg6tabreen Complex is closely associated with the Bullbreen Group and crops out in four mountains: Motalafjella, two spurs of Holmesletfjella, north and south of upper Hydrografbreen (formerly Skipperbreen), and Bulltinden. A further outcrop, a distinct klippe of Bullbreen strata occupies the top of Ankerfjella north of St Johnsfjorden. All these outcrops appear to be part of a single folded thrust unit in which the rocks are overturned, so that the OrdovicianSilurian Bullbreen rocks dip beneath the complex in the limbs of a west-dipping overturned syncline seen well in the Bulltinden conglomerates. The Vestg6tabreen-Bullbreen unit has been thrust up and over Vendian rocks from the west or southwest. The contact between the Bullbreen Group and the Varanger groups is not well exposed, but is probably everywhere a thrust surface. It is perhaps best seen north of St Jonsfjorden at Ankerfjella where it is almost horizontal. The nature of the contact between the Complex and the younger Bullbreen Group is critical. Ohta, Hiroi & Hirojima (1983) argued for an unconformity (overturned) on the basis of evidence at seven localities where the Motalafjella limestone contains fragments of an older dolostone which it also penetrates. In addition there are clasts of the metamorphic complex. This conglomeratic zone extended 3 to 5 m from its structural upper surface. The limestone contains gastropods. Moreover, fossil bearing limestone pebbles occur still further from the contact. At one locality the conglomerate layers are cross-bedded and confirm that the strata are inverted. K a n a t & Morris (1988) who surveyed the area, including Ankerfjella, were puzzled by the ochre weathering dolostone (their unit VOD) that occurs nearly everywhere at or near the contact of the complex and the Bullbreen Group, and also at Ankerfjella. They placed it within the Vestg6tabreen Complex and to be subject to thrusting. It is thought here more likely to belong to the basal facies of the Motalafjella Formation of the Bullbreen Group, but agreed that some thrusting has taken place along the unconformity surface. There would thus have been a complex history of successive erosion and deposition phases first of metamorphics, then of dolostone, then of limestone followed or accompanied by folding and thrusting in places along this zone. Lenses of the dolostone are found near the contact with the schists and there are some mylonitic textures. The dolostone itself is often rich in metamorphic clasts similar to those of the complex. On Motalafjella the complex is divided into at least two units by a thrust as depicted by Ohta, Hirajima & Hiroi (1986). Moreover, that the whole complex has been subject to penetrative shearing is evident from the ubiquitous schistosity. The thrusting appears to be a part of the (Eocene) West Spitsbergen Orogeny. Five lines of evidence support this conclusion. (i) The whole of the orogen of which this unit is a part, exhibits eastwards or northeastwards verging overfolding and thrusting, including Paleozoic and Mesozoic rocks. (ii) To the west, as at Farmhamna, fossiliferous Carboniferous strata are seen vertically adjacent to Vestg6tabreen-Bullbreen Varanger strata. (iii) The schistose complex dips beneath glaciers, to the west of which rise Carboniferous mountains. This relationship is easiest to explain by postulating a further arcuate thrust occupying the ice-covered area rather than by an arcuate normal dip-slip fault. (iv) The Vestg6tabreen-Bullbreen thrust mass swings round from eastwards verging in Motalafjella to northwards verging in Bulltinden which is consistent with a dextral transpression. (v) In 1968 Harland showed Horsfield, on the south flank of the spur of Motalafjella north of Skipperbreen, a lens of fossiliferous limestone of Carboniferous facies in an apparent thrust surface. It is not impossible that it could have been Silurian. That possibility was not then in mind. A post-Bullbreen Group pre-Carboniferous tectonic episode might also have taken place.

Succession of the Complex. In view of the complexity of the metamorphic rocks, which all show evidence of shearing, any succession may not relate to an original stratal or thrust sequence. Nevertheless, Kanat & Morris mapped the following sequence, listed here from the (?) thrusted unconformity:

CENTRAL WESTERN SPITSBERGEN their orange weathering dolostone medium grey micaceous marble dark grey micaceous marble mafic schist serpentinite pelite schist greenstone psammite garnet glaucophanite eclogite

(VOD) VM2 VM1 VSH VSP VPE VGT VP3 VGG VEC

up to 20 m 50+ m 50+ m c. 200 m 15 m 10 m 50 m 4m 50+ m 40+ m

Ohta, Hirajima & Hiroi (1986) described two units separated by a west-dipping thrust. The lower unit (structurally is mainly of sericite chlorite phyllites with scattered lenses of dolostone, quartzite, metabasite and serpentinite. The upper unit is of garnet mica schists, schistose limestone and lenses of garnet glaucophanite and eclogite.

Mineralogy and chemistry of the complex.

The blue-schist facies has attracted much research. Horsfield (1972) described glaucophane schists (but did not find lawsonite, aragonite or pumpellyite) in the course of his chemical analysis and isotopic dating of them. Ohta (1979) reported both the bulk chemical composition and that of individual mineral species analysed by a number of workers. Typical mineral assemblages were:

glaucophane schists: garnet-glaucophane schist with muscovite and chlorite; garnet-muscovite-glaucophane schist; garnet-epidote-muscovite-glaucophane schist; eclogitic rocks: schistose glaucophane-garnet-omphacite (up to 90%) eclogite; epidote amphibolites: actinolite-epidote sericite-chlorite-plagioclasequartz schists; epidote calcite-chlorite-actinolite-plagioclase-greenstone; garnet-bearing epidote amphibolites: garnet-epidote-actinolite-chlorite meta-diabase; garnet-epidote-sericite-actinolite schist; garnet-actinoliteepidote-chlorite-sericite-plagioclase schist; garnet-chlorite-sericite-plagioclase-quartz-metagabbro; glaucophane-muscovite-quartz schists: variably with garnet or hematite. Ohta (1979) compared the above with other west-coast basic rocks. But in referring them to Late Riphean he was not aware of the evidence that the basites are intertillite and if so of Varanger age. He concluded for the origin of the Vestg6tabreen complex as follows. 1. Most epidote amphibolites were derived from intermediate differentiates of basaltic magma. 2. Some relatively acidic varieties are not later differentiates of basaltic magma, but mixtures of intermediate differentiates and argillo-siliceous sediments. 3. The muscovite-quartz schists with or without glaucophane were formed from impure argillaceous quartzite. 4. The glaucophane schists are mixtures of early differentiates of the basaltic magma and argillo-siliceous sediments. 5. Na enrichment is not prominent in the glaucophane schists and the original rocks were not typically spilitic. 6. The original volcanic rocks of these basic rocks are unknown, and they have large variation presumably by tectonic stirring. Kanat (1984) described jadeite from the upper member and estimated pressures between 9.9 + 0 . 5 k b as at 300~ and 12.8kb as at 450~ Horsfield's first estimate from the garnet-biotitehornblende assemblages suggested 300~ at peak metamorphism with a palaeogeothermal gradient of 30~ km -1. Ohta, Hirajima & Hiroi (1986) reported i.a. lawsonite and jadeite-quartz-albite assemblages.

9.5

Proterozoic strata of Oscar II Land

The overall stratigraphy of the area was first reconnoitred by C. B. Wilson in 1958 (Harland 1960) and with further work was synthesised by Harland, Horsfield, Manby & Morris (1979), and by Hjelle, Ohta & Winsnes (1979) and by Kanat & Morris (1988) and then by Harland, Hambrey & Waddams (1993). The rocks are described in three groups: Comfortlessbreen; St

Jonsfjorden and Kongsvegen.

9.5.1

165

Comfortlessbreen Group

The group is now defined by the Annabreen and Haaken formations. A meta-tillite was first suspected and the rocks so named (Harland 1960) since when a complex series of reinterpretations of the stratigraphy end with the scheme presented here (Harland, Hambrey & Waddams 1993). In that work, Aavatsmarkbreen was described in detail with four sections plotted from Sarsoyra and Kaffioyra. They regarded it as the highest formation in the Comfortlessbreen Group and possibly Late Vendian (Ediacara) age to correspond to the Scotia Group in Prins Karls Forland. However, from Ohta et al. (1995) the evidence suggests that the formation belongs to the Bullbreen Group where it is treated under Section 9.4.1.

Annabreen Formation (thickness variable, about 2 km). Wilson referred to Annabreen Quartzites and although the eponymous locality Anna Sofiebreen is south of St Jonsfjorden. The best sequence is seen around Aavartsmarkbreen. Cutbill & Challinor (1965) renamed them Irenebreen Quartzites as [?] Carboniferous whereas Hjelle, Ohta & Winsnes (1979) incorporated them in the Bullbreen Group. Harland, Hambrey & Waddams (1993) made it a constituent formation of the Comfortlessbreen Group. The formation comprises quartzites and shows gradational transitions above and below with thin phyllite interbeds above and dispersed dolostone and quartzite pebbles, up to 30 m at Dahltoppen, towards the base. Haaken Formation, 2-3 km (Harland, Hambrey & Waddams 1993). The name Haaken schists was used informally by C.B. Wilson (his horizon 7 in Harland 1960) and is best seen at Engelskbukta. Hjelle et al. 1979 referred to the same unit as tillitic conglomerate. The outcrop width of 6 km of steeply dipping strata was estimated by Waddams (1983) to have been duplicated by folding and thinning to about twice the original thickness. An eastern belt of the same formation is accessible from the head of St Jonsfjorden. The formation consists of stone-bearing orange to grey weathering psammitic schist - or schistose diamictite, interbedded with blue and grey weathering quartz-rich schist and laminated quartzite, the schistose foliation follows approximately the original bedding. The stones, comprising about 10% of the rocks, consist of dolostone, limestone, quartzite and both foliated and unfoliated granitoids up to lm long (the largest seen 2 • 1 • 0.7 m). Whereas the Annabreen facies is of proximal turbidite facies the Haakon facies is of distal turbidite facies, both with ice-rafted stones.

9.5.2

St Jonsfjorden Group

Defined by Harland et al. (1979) as comprising the four following formations, Harland, Hambrey & Waddams (1993) argued that the whole Group is Vendian (early Varanger). Hjelle et al. 1979 made them pre-Vendian, referring to them as Middle Hecla Hoek, and Ohta et al. (1995) implied a Mesoproterozoic age.

Alkhorn Formation 1+ km. The name is from 'Alkhornkalk' of Holtedahl (1913) conspicuous at Alkhornet on the southern cliffs of Oscar II Land where the lower part of the formation is exposed. Independently in north Oscar II Land, Harland (1960) recognized Holtedahl's Alkhornkalk, whereas Wilson used the name Dahlbreen limestone which Harland et al. (1979) regarded as the same unit and so adopted the earlier name. It was also referred to by Hjelle et al. 1979 as the Calc-argillo-volcanic Formation, metavolcanic and intrusive rocks having been recognized mainly in the upper part. A complex succession of facies (Harland, Hambrey & Waddams 1993) may be summarized as an alternating sequence of marble or grey limestone (often oolitic) and a variety of metabasites. Ohta (1984) referred to the igneous assemblage (the rich tholeites) as of oceanic type. Lovliebreen Formation, 1 km. The Formation is named for a glacier south of St Jonsfjorden (Harland et al. 1979). This unit corresponds to the dark quartzites of Holtedahl (1913), the massive quartzite bodies of Weiss (1953) and broadly equivalent to the Quartzite Shale Formation of Hjelle et al. (1979). A modified map (Ohta 1984) plots a broad belt from Loveliebreen to Isfjorden whereas north of St Jonsfjorden there is only a small outcrop. Two members have been distinguished (Harland et al. 1979).

CHAPTER 9

166

(2) Upper: massive dark quartzites with intercalated pelites the quartzites, are cut by thin white quartz veins - they are well- sorted fine-grained metasandstones. (1) Lower: foliated dark brown, green and purple volcanic rocks, with amygdaloidal basalts and pyroclastics. Some are reddened suggesting subaerial weathering. Unlike the Alkhorn Fm the igneous facies suggest sodaalkaline lava flows with some pillow structures. Geochemically they are of a non-oceanic type (Ohta 1984). Kanat & Morris (1988) made the Loveliebreen younger and than the Alkhorn units. Harland, Hambrey and Waddams (1993) disagreed believing i.a. that intrusive dolerites and the Loveliebreen volcanics had been confused. The latter may not have seen by Kanat & Morris.

Moefjellet Formation, 500-800m. C. B. Wilson named this massive, uni-form, unfoliated, cream-weathering bluish grey dolostone with a gritty or sandy texture and some cherty layers. Shallow water deposition with algae mats has been suggested. Daudmannsodden Formation (Ohta 1985) of highly sheared dolomitic marble could be a tectonised equivalent of the Moefjellet Formation (Harland, Hambrey & Waddams 1993). Trondheimfjella Formation (1.3 km). This schistose calc-diamictite was so named by Wilson as a conglomerate. His map was available to the Norsk Polarinstitutt who (Hjelle, Ohta & Winsnes 1979) remapped it as part of their Tillitic Conglomerate Formation and near the top of their sequence. Harland e t al. (1979) in the succession followed here, placed it at the bottom of their succession as did Wilson. Waddams (1983) found a tillite facies north of Engelskbukta and identified it with the earlier Varanger tillite (i.a. lacking granitoid stones). This was accepted by Harland, Hambrey & Waddams (1993) as evidence that the overlying formations of the St Jonsfjorden Group lie between the upper and lower tillite horizons and so must all be of Varanger age. Perhaps this realisation encouraged the solution to problem of correlation along the west coast, where, as in Oscar II Land, thick successions, with a basic igneous component, were all formed between or within the two Varanger glacial episodes and so restrict much of the west coast Proterozoic sequence to Vendian age. The meta-diamictites are distinguishable from those of the Haaken Formation by a matrix-rich carbonate rather than a phyllite and by the lack of exotic clasts such as granites and gneisses, the stone content being typically intrabasinal. These characters suggest an origin by ice rafting into a distal turbidite basin. A band of stromatolites near F a r m h a m n a indicates shallow marine carbonate shelf, or proximal environment. Harland e t al. (1979) proposed three members. (3) Marble flags (500 m). (2) Dark phyllitic semi-pelites and psammites with minor quartzites and calcareous beds (300 m). (1) Thin orange-weathering bands of calcareous in conglomerates a sequence of quartzites, psammites and massive dolostones (300 m). The upper contact is transitional and the lower contact faulted. There is no basal conglomerate with clasts matching the underlying formations.

9.5.3

Kongsvegen Group

In his survey of Broggerhalvoya Orvin (1934) set up 11 units of metamorphic rocks as follows, unit 1 at the top: 1-9 10 11

'Quartzite and mica schist series' (2520 m) Steenfjellet Dolomite (270 m) Bogegg Mica Schist (1500 m). The matter proved complex as follows.

Orvin (1934) identified a further unit, 'dolomites and limestones', beneath with his units 1-11 (see below) and Challinor (1967) referred to this as the Bjorvikfjellet Formation. Harland et al. (1979) identified this with the overlying Trondheimfjella Formation (confirmed by Harland, Hambrey & Waddams 1993).

Correlating northwards across Kongsfjorden, Orvin made the Blomstrandhalvoya marble (Genaralfjella Formation) his topmost unit of the Hecla Hock succession above unit 1; the schists of Signehamna Formation (equivalent to his units 1-9), and the Nissenfjella Formation with its feldspathic rocks (migmatites) as the granite of the pre-Hecla Hock basement. Little was then known of other pre-Devonian successions and proceeding with this sequence as seen from the north his scheme was coherent. Wilson's reconnaissance of the rocks of Oscar II Land south of Broggerhalvoya in 1958 led to his reversing the succession with his Trondheimfjella rocks above the Bogegg schists, as reported and followed by Harland (1960). However, when revising the Hecla Hock succession in Ny Friesland, Harland et al. (1966) referred to the Kongsvegen Gp comprising Orvin's three formations and (knowing Challinor's t967 conclusions) followed Orvin's order of succession. Challinor (1967), while not accepting Orvin's correlation north of Kongsfjorden, named Orvin's units 1-9 the Nielsenfjellet Fm (at the top) and Orvin's 'dolomites and limestones of Forlandsundet' as the Bjorvigfjellet Fm at the bottom of the Kongsvegen Gp (Harland et al. 1966) underlying the 'Bogegga Fm' so again following Orvin's order of superposition. However after a reconnaissance survey of the whole of Oscar II Land Harland et al. (1979) concluded that Wilson had been correct in that the Kongsvegen Gp was the oldest in that area (and probably younger than the rocks further north). Nevertheless, it was assumed that the metamorphic grade of the Kongsvegen Gp made it significantly older than that of St Jonsfjorden G p - that, indeed, it was a potential basement to the St Jonsfjorden Gp. They retained Orvin's sequence, adding detail of the Bogegg Fm. Further study of Oscar II Land (Harland, Hambrey & Waddams 1993) led to the view that the Mfillerneset Fm (south of St Johnsfjorden) which was correlated with, and included in, the Kongsvegen Gp might have been conformable (at least concordant) with the Trondheimfjella Fro. In 1992 CSE concluded that, as seen north of Engelskbukta, the Boggegg, Trondheimfjella, and the Moefjellet fms lay in a normal sedimentary sequence with interbedding and transitional facies at the boundaries. No evidence for any major discontinuity (unconformity, thrust or both) was evident locally. Inadavertently they tabulated Orvin's order of the Kongsvegen Gp which they had not investigated. The conclusion here is quite clear in spite of the above confusion. Wilson was correct: the Trondheimfjella Formation at the base of the St Jonsfjorden Group rests concordantly on the Bogegga Formation at the top of the Kongsvegen Gp. In the light of the above complex sequence of opinions the conclusion is summarised below. The apparent differences in metamorphic grade are probably accounted for partly by composition of the protolith and partly by depth in the succession.

Kongsvegen Group North of St Jonsfjorden Bogegg Formation, 1500m, is a varied sequence, dominantly pelitic Member (3), 500 m. Half the bulk is of pelites and semi-pelites of biotite and garnet schists containing quartzo-feldspathic bands and lenses. These are intercalated with orange-weathering marbles and psammites. The other half is of coarse grained marbles Member (2) 500m. Dark feldspathic and garnetiferous semipelite with quartz feldspathic bands and segregations. Member (1) 500m. Gneissic porphyroblastic (augen) feldspathites and semipelites and schistose garnetiferous pelites dominate with bands of dolostone and impersistent concordant amphibolites. Steenfjellet Formation, 270 m a convenient prominent marker formation of grey to cream coloured dolomitic marbles separates the formations above and below. Nielsenfjellet Formation (2+km) (Challinor 1967, Orvin's Quartz Mica Schist Series) of monotonous dark phyllitic semi-pelites interspersed with paler, dolomitic quartzite bands. Orvin's description of these rocks (unit 1-9) applies to the cliffs north of Austre Broggerbreen. The mountains further east - towards Nielsenfjellet yield a variety of schists and gneisses with an igneous component and whose relationships have yet to be determined. South of St Jonsfjorden Miillerneset Formation. Occupying the west coast between St Johnsfjorden (Mfillerneset) and Eidembukta, the Formation consists of phyllitic and schistose pelites interbedded with semipelites and white quartzites (Harland et al. 1979; Hjelle, Ohta & Winsnes 1979; Ague & Morris 1985; Kanat & Morris 1988).

CENTRAL WESTERN SPITSBERGEN North of Eidembukta the strata appear concordant and transitional beneath the Trondheimfjella Formation. The metamorphic contrast which has led to the view of a much older unit may stem from the tectonic juxtaposition of M~illerneset and Comfortlessbreen rocks where the whole intervening St Johnsfjorden Group (>4 km) is not seen.

Oscar II Land an Ordovician to Silurian age. That no fossils have yet been recorded may be the consequence of such a mobile environment. How much and what parts of Early Paleozoic time is represented can only be guessed.

9.6.2 9.6

Pre-Carboniferous rocks of Prins Karls Forland

A p a r t from Q u a t e r n a r y cover no D e v o n i a n or y o u n g e r rocks have been identified on Prins Karls F o r l a n d and an apparently uninterr u p t e d sequence o f strata m a y contain a u n i q u e passage for Svalbard from V e n d i a n t h r o u g h early Paleozoic strata; but with little palaeontological evidence to confirm it (see Fig. 9.8). The island is easily accessible and m u s t have been visited m a n y times. H o w e v e r , the evident lack o f macrofossils m a y have t u r n e d geologists elsewhere until the systematic study by Tyrrell (1924) and later by A t k i n s o n (1956, 1960 and 1962). E x p l o r a t i o n h a d tended to be a British interest since t o p o g r a p h i c surveys u n d e r Bruce's leadership of the Prince of M o n a c o expeditions in 1907, 1908 and 1910, and the attentions of the Scottish Spitsbergen Syndicate (Tyrrell 1924). The rocks were described by M a n b y & Morris (in H a r l a n d et al. 1979) a n d by Hjelle, O h t a & Winsnes (1979). W h e r e a s the second of these gave valuable description of the rocks only the first p a p e r a r g u e d a stratigraphic sequence. H a r l a n d , H a m b r e y & W a d d a m s (1993) in their synthesis followed that sequence. The detailed occurrence and origin of the names is given in the 1979 paper, w h e r e possible names were taken from the previous w o r k o f Tyrrell a n d Atkinson.

9.6.1

Grampian Group (Early Paleozoic)

This g r o u p is typically siliciclastic and flyschoid, it is defined by the following five formations.

Geddesflya Formation >1800m. This upper-most unit occurs in the northern part of the island. It is mainly quartzitic with dolostone banded siltstones, breccias, thin siltstones and slates. Lower down are slate-pebble breccias with banded siltstones. Lower still are thinly bedded quartzites and banded siltstones. Fugelhuk Formation 400-1000 m. Massive bedded quartzites occur in the cliffs at the north of the island. Beds, commonly one metre thick, are interbedded with banded siltstones. They thicken northwards to 1000 m. Barents Formation, 500m. This formation is dominated by siltstones which locally become black to dark grey slates. Below this is a sequence of folded banded siltstones and below again flaggy calcareous sandstones and then green pelitic quartzites with black limestone and pebbly quartzite. The remarkable Sutorfjella Conglomerate is treated by us (as by Atkinson) as a member within this formation although others have regarded it as a younger independent unit such as Devonian (Hoel 1914; Craig 1916) or Tertiary (Tyrrell 1924). They were first reported by Hoel. Krasil'shchikov favoured a Tertiary age. But CSE observed near the shore to the south evidence of interbedding with the Barents slates. The conglomerate contains clasts of underlying formations- mainly brown weathering, pale grey quartzite. Some horizons are rich in green cleaved siltstone, similar to that of the matrix. Another clast type is black mudstone with quartz~lolomite veining. These rock types are sufficiently distinctive to give confidence in this order of superposition. The quartzite boulders show red oxidized skins suggestive of subaerial weathering. The whole assemblage could have formed on a fault scarp. The cleavage of the matrix and of many clasts parallels that of the Barents Formation as a whole. Conqueror Formation, 500-850 m. Transitional with the Barents Formation at the top of the Conqueror Formation is a distinctive sequence of quartzites and slates. Below this are dark grey slates alternating with quartzite. Pebbly calcareous beds then overlie thick slate with more quartzite bands. The formation thickens northwards. Utnes Formation, 80m. This formation is transitional between the Conqueror and the underlying Roysha Formation. The distal turbidite facies, especially of the Barents Formation but also elsewhere in the Grampian Group suggest by litho-correlation with the Hohnsletfjella beds of

167

Scotia Group (Late Vendian-Ediacara)

Tyrrell (1924) and M a j o r , H a r l a n d & Strand (1956) referred to this as the M o u n t Scotia series and A t k i n s o n as the Scotia G r o u p . It is defined by the following three formations.

Roysha Formation c. 400 m. The Roysha Formation is of very soft black carbonaceous slate interbedded with dolomite siltstones. Manby (1986) referred to this unit as the Omondryggen formation. Kaggan Formation c. 300 m. The Kaggan Formation consists of tight isoclinally folded slate phyllonites. The distinctive green and purple striped slates suggest a minor volcanic component metamorphosed with chloritoid. Baklia Formation. Exposed near lake Baklia in a passage downwards from black slates with quartzites to a black carbonaceous slate sequence containing grey-orange dolomitic limestones with inraformational breccias. The lower part of the formation consists of grey, frequently cherty, dolomitic siltstones with black slates. Below this are quartzites, frequently conglomeratic, with green and black slaty laminae and then dolomitic cherty limestones. When the sequence, described here from Prins Karls Forland, was published no fossils had been found in situ on the island. However, the cherts in the Baklia Formation, referred to as the Black Carbonate Pelite (BCP), have yielded microfossils (Knoll & Ohta 1988). The dolostone is oolitic in places. The following taxa were described and figured. Eomycetopsis robusta Schopf, emend. Knoll & Golubic (1979); Eomycetopsis sp.; Siphonophycus inornatum Zhang; Siphonophycus sp.; Myxococcoides sp.; Obruchevella Reitlinger (1959); ?Obruchevella sp. Poorly preserved acritarchs include leiosphaerid-like vesicles and rare spheres with vesicles and with an outward layer of hollow processes, typical of Late Riphean and Vendian strata in Russia; of the Doushantuo Formation of central China and of the Pertatateka Formation of central Australia, these occurrences being of latest Proterozoic age. Knoll & Ohta (1988) concluded that 'the most likely age for the BCP beds is Late V e n d i a n - i.e. post-tilloid but Precambrian in age' and they stressed the uncertainty of this age because Hjelle, Ohta & Winsnes (1979) had placed this unit below the tillite horizon. From their localities on the map Harland, Hambrey & Waddams (1993) matched the lithology with the Baklia Formation. It seems that the BCP of Knoll & Ohta is the Black Shale Formation of Hjelle et al. (1979). It is likely that these units belong to the Scotia Group. Whatever the detailed stratigraphy, Prins Karls Forland thus contains the first Ediacara biota to be recorded in Svalbard. This age fits well the sequence of Harland et al. (1979).

9.6.3

Peachflya Group

These rocks were first n a m e d by Tyrrell the Ferrier Peak Series a n d m a y have been referred to by A t k i n s o n as the K e r r G r o u p . It was defined by four f o r m a t i o n s w h i c h were defined by H a r l a n d et al. (1979) and followed by H a r l a n d , H a m b r e y & W a d d a m s (1993).

Knivodden Formation, 400 m. Incompetent chloritoid phyllites pale grey, dark grey and pale green. Hornnes Formation, 350m. Siliceous-phyllite, sandstone quartzite, limestone alteration. Alasdairhornet Formation, 190m. Volcanic suite- banded and welded tufts with some basic lava flows. Thin carbonate interbeds occur near top and base, marked by reworked volcanogenic and siliciclastic material. Fisherlaguna Formation, 350 m. Incompetent blue phyllites.

9.6.4

Geikie Group

This g r o u p ( H a r l a n d et al. 1979 following Atkinsons, 1960, name) unlike the overlying groups has thrust r a t h e r t h a n sedimentary contacts at the b o t t o m .

Rossbnkta Formation (>300 m) of dark siliceous phyllite which becomes increasingly calcareous towards the base.

168

CHAPTER 9

Gorden Formation (>470 m). Calcareous phyllite with 3 to 4m massive dolostone-limestone laminated horizons with intraformational breccias, carbon-rich beds, and pisolitic limestones.

9.6.5

Ferrier Group

The Ferrier Group comprises four formations. All are typically schistose diamictites of biotite grade. They have been interpreted (Harland et al. 1979) as distal flyschoid marine tillites. They dominate the mountains of central Prins Karls Forland south of Selvgtgen.

Neukpiggen Formation (270 m). Consists of calcareous and chloritic schist with discontinuous psammite, marble and conglomerate beds. Dispersed dolostone and quartzite stones occur throughout the schist and phyllite. Granite stones 10 mm to 0.4 m long and marble stones 50-100 mm long were recorded. Small folded psammite blocks suggest slumping, pene-contemporaneous erosion and resedimentation at some horizons. Peterbukta Formation (160m). Comprises pink-, grey-weathering, psammitic schist, grey calcareous schist and dark pelitic schist with discontinuous beds of clear crystalline psammite and dolostone orthoconglomerate, and intraformational conglomerates. Outsize stones occur throughout. Hardiefjenet Formation (120-500m). Upper division of pale, calcareous siliceous schist and lower division of dark green schist. Similar to Neukpiggen Formation but darker in colour and higher metamorphic grade. Isachsen Formation (> 150 m). Consists of dark green quartz chlorite schist with brown interlayers and numerous pressure solution quartz segregations. Thin layers of diamictite occur, but mostly thin-bedded or laminated and somewhat sorted. Beds of tuff 1-2 m thick are disposed through the formation. The base is not exposed. Alfred Larsentoppen Unit. In addition to the main outcrop there is an isolated klippe on Alfred Larsentoppen - the only such diamictite north of Selvgtgenand Scotiadalen. The upper 20 m are of orange weathering, coarse dolomitic psammite with dispersed stones of grey dolostone - more numerous and larger than in the four formations described above. The lower unit is rich in granitoid boulders. Because both of their granitoid content and their stratigraphic position we correlate all these tilloids with the Comfortlessbreen Group; that is the Later Varanger glacial episode (Mortensnes).

9.6.6

Pinkie Formation

The Pinkie Formation occurs as a thrust slice between overlying Conqueror quartzites and underlying Geddesflya siltstones and quartzites. It consists of quartz biotite schist, feldspathic magnetite biotite schist, felsite, and a calcareous brecciated slate rich in biotite. The formation is of higher metamorphic grade than any other rocks recorded on the island and, as it does not match any of them closely in composition, it has been presumed to be a slice of an older complex. Considering the mainland succession, the strata preceding the Comfortlessbreen Group diamictites are rich in basic igneous material. This suggests that the Pinkie Formation was derived by (?Ordovician) metamorphism from the Lovliebreen Formation (Harland, Hambrey Waddams 1993; Ohta et al. 1995) in the St Jonsfjorden Group. So in this work it would be part of the Early Varanger sequence

9.7

Structure of Oscar II L a n d

Triassic through Carboniferous strata crop out extensively in northern and eastern Oscar II Land and their deformation displays the structure of the Paleogene West Spitsbergen Orogen. In Western Oscar II Land the pre-Carboniferous basement was affected by at least one earlier tectonic episode as well as by the Paleogene orogeny. Oscar II Land is a prime region for the study of structures related to the West Spitsbergen Orogeny (e.g. Orvin 1934; Challinor 1967; Maher 1988; Manby 1988; Winsnes & Ohta 1988; Bergh & Andresen 1990; Bergh et al. BSG, 1993; Andresen,

Bergh & Haremo 1994; Bergh, Braathen & Andresen 1997). Localized structural studies have been carried out in three areas: Broggerhalvoya in the northwest, eastern St Jonsfjorden in the centre, and the Lappdalen/Mediumfjellet area in the southeast. Most of the interior has been mapped from aerial photographs, but many western parts have yet to be mapped in detail. Oscar II Land is divided here into four areas: northwest, southwest, centreeast and centre-west (9.7.1-9.7.4).

9.7.1

Northwest Oscar II Land

Broggerhalvoya and Kongsfjorden. Broggerhalvoya is located in the northwest part of Oscar II Land and represents a significant change in the vergence of structures in this orogen, from an essentially easterly to a northerly vergence. This is particularly evident along the southern margin of Kongsfjorden, where structures tend to strike parallel to the coast (Challinor 1967). The area between Broggerhalvoya and Engelskbukta in the northwest part of Svalbard illustrates the involvement of basement (pre-Devonian) in the Paleogene fold-and-thrust belt. The large-scale structure of the area consists of a series of northto northeast-vergent thrust nappes dominated by post-Devonian strata in the northwest part of Broggerhalvoya and by preDevonian strata in the southeast part of the peninsula, Engelskbukta and northern Oscar II Land. A major N-S-trending fault zone in the vicinity of Broggerbreen (referred to as the Scheteligfjellet Fault Zone by Challinor (1967) separates the nappes in the northwest from those to the southeast and south, but does not continue into the structurally higher nappes of the southern part of the area. Manby (1988) interpreted this structure as a transfer zone along which the more northerly displacement of the southeastern nappes has been accommodated by sinistral shear. In northwest Broggerhalvoya, the younger rocks are stacked into three major nappes. The Broggertinden Formation is deformed into broad open folds along the Kongsfjorden coastline indicating that the floor thrust to the lowest exposed thrust nappe is ramping up at this point (Manby 1988). Structures within the Wordiekammen Fm are well exposed in Scheteligfjellet, with the upper duplex considerably more deformed than the lower. The whole of the higher nappe is folded into an overturned, north-vergent, anticline-syncline pair, where a late thrust repeats part of the lower limb of the syncline that carries Gipshuken over Kapp Starostin rocks. The highest of the three nappes in the northwest comprises a pre-Devonian to Early Permian sequence that is floored by a low-angle south- to southwest-dipping thrust, where the high cut-off angle between this thrust and the steeply dipping, overturned hangingwall rocks indicates that overfolding preceded thrusting. According to Manby (1988) a minimum of 12 km of shortening is necessary to account for the deformation in the uppermost nappe, and at least 18 km when taking the whole nappe sequence in northwest Broggerhalvoya into consideration. To the southeast of the Broggerbreen Fault, the lowest nappe contains a sequence of Paleogene to Broggertinden (Bashkirian age) strata that are folded into a broad northwest-plunging syncline which is itself overthrust by the recumbent Zeppelinfjellet syncline. This thrust sheet is characterized by small-scale imbricates, duplex structures and folded thrusts (Challinor, 1967). The pre-Devonian rocks in the overthrust sheet consist of metamorphic rocks of the Kongsvegen Group (Harland et al., 1979), the whole sequence being characterized by a well-developed anisotropy with shear fabrics and mylonitic zones refolded on various scales by north to northeast vergent crenulation-type folds, consistent with Paleogene deformation of the lower nappe. Moefjellet marbles have been strongly deformed into an imbricated sequence above the Trondheimfjelletnappe and are unconformably overlain by a synclinally folded and cleaved sequence possibly of Billefjorden Group at the head of Nordenfjeldskebreen. Waddams (1983) noted that these rocks were subsequently overthrust by the Haaken tillite succession. To the southeast of the col, at the head of Nordenfjeldskebreen, the Haaken and Moefjellet rocks are defined by thrusts in which Alkhorn marbles also became incorporated (Harland et al., 1979). The presence of post-Devonian rocks in the higher nappes and identical vergence directions in both sequences indicate that the deformation of the pre-Devonian rocks is related to the Paleogene West Spitsbergen Orogeny.

CENTRAL WESTERN SPITSBERGEN

Kongsvegen to St Jonsfjorden.

The area between Comfortlessbreen and Sarsoyra is defined by a shallow southwest sheet dip of the Haaken tillites. Along the southern shore of Engleskbukta the Caledonian S1 foliation is refolded by open box-like folds overturned to the northeast, with a characteristic pressure-solution cleavage developed. Interpreting the structure of the pre-Carboniferous basement depends on some knowledge of its stratigraphy. Harland, Hambrey & Waddams (1993, p. 56) outlined a scheme for Oscar II Land with a tentative thrust extending from the snout of Comfortlessbreen southeast through Lovenskioldfonna to make stratigraphic sense; but there are many more faults. Detailed mapping is awaited. On this interpretation the thrust would be consistent with a Paleogene dextral transpressive motion. To the west of Kapp Graarud, Tertiary conglomerates lie above the pre-Devonian strata, with both sequences cut by steep westdipping to vertical faults, striking broadly N-S. The conglomerates show small-scale sinistral and dextral displacements of pebbles that can be related to anastomosing fractures parallel to the faults. Ohta et al. (1995) described the structure of Sarsoyra and Kaffioyra as a complex strike-slip fault system with variable orientations of each domain as evidence of dextral transpression in a deep shear zone.

9.7.2

169

conglomeratic horizons containing clasts showing evidence for a pre-depositional deformation fabric. The immature nature of the Bulltinden Conglomerate suggests rapid deposition from a local source. The presence of the conglomerate indicates that there was a significant uplift phase. The timing of deposition is derived from the late Llandovery to Wenlock ages of the, the Motalafjella Limestone, lowest formation of the Bullbreen Group (Scrutton et al. 1976). Svalbardian (Late Devonian) movements, sinistral transpression according to Harland (1985), was later than deposition of the Bullbreen Group. Kanat (pers. comm.) suggested that the Bullbreen Group should have suffered some degree of deformation. This episode may have been concentrated in the shear zones. Tight small scale sinistral isoclinal folds are conspicuous in the westernmost outcrops of Daudmannsodden in southwest Oscar II Land (Harland, Hambrey & Waddams 1993). This would imply, therefore, that younger sediments deposited on the Bullbreen Group should be in unconformable contact, although this type of contact has not been identified. Weiss (1953) identified an unconformity at the base of the Carboniferous rocks where they were in contact with lithologies associated with the metamorphic complex. However, a sedimentary contact between the Bullbreen Group, of inferred Silurian age, and younger rocks has yet to be recognized. It is unfortunate that the outcrop of Bullbreen strata is limited to so few exposures.

Southwest Oscar II Land

Weiss (1953) identified two deformation phases in the preDevonian basement rocks to the south of St Jonsfjorden. Horsfield (1970) similarly defined two major phases, corresponding to Paleozoic and Paleogene events. More recently, K a n a t & Morris (1988) suggested a more complex tectonic history.

The Eidembreen phase (D1 of Kanat & Morris 1988) of early to mid-Ordovician age. Throughout southwest Oscar II Land, the metamorphic complex, particularly that of the Vestg6tabreen Formation, exhibits evidence of an intense deformational phase; this episode also produced a penetrative cleavage (S1) and related metamorphism. Structures such as folds and boudinage, which have a consistent relationship to S 1, are attributed to D 1. The style and intensity of folding, as well as the development of the S 1 fabric, is inhomogeneous and can be attributed to the largely anisotropic behaviour of the basement rocks. The following is based partly on Kanat (pers. comm.). The penetrative $1 cleavage is variably developed in the preCarboniferous Vestg6tabreen Fm as a mineralogical banding, particularly in the more massive lithotectonic units such as the brecciated dolostone, psammite, eclogite and serpentinite divisions. The S1 fabric has a variable orientation throughout the area to the south of St Jonsfjorden, although in general many of the platy metamorphic minerals are parallel to S1. On the mesoscopic scale the mineralogical banding in the psammite division is correlated with the S1 fabric of the associated divisions of the Vestg6tabreen Fm. SO (bedding) if preserved is expressed as helical inclusion trails in garnet porphyroblasts; in general SO is indistinguishable from S1 within the metamorphic complex, i.e. they are parallel. Inclusion trails within garnets, flattened chloritoid rosettes and the alignment of amphiboles and mica, suggest that metamorphism was pre- to syn-D 1. On the megascopic scale, D1 is associated with metamorphism, uplift of the Vestg6tabreen Fm, and thrusting and folding of the metamorphic complex. The general positions of the main lithological units of the metamorphic complex (i.e. the Comfortlessbreen Gp to the west and the St Jonsfjorden Gp in the eastern part of the St Jonsfjorden area), and the development of the (now) tight asymmetric folds within the metamorphic complex were formed at this time. The vergence of minor folds within the Vestg6tabreen Fm shows no significant correlation with that of the major fold structures (e.g. at Motalafjella) and they are therefore of different ages. Similar structural fabrics to those recognized in the Vestg6tabreen Fm are also found in the Comfortlessbreen and St Jonsfjorden groups. The Bullbreen Group was deposited later (Caradoc to Wenlock). This group has a distinct molasse-type character with major

Tectogenesis of the Eocene West Spitsbergen Orogeny. This second main deformational phase (Spitsbergian) accounts for the present structural pattern in Oscar II Land, with most of the large-scale structures, folds and thrusts so generated (D2 of some authors). This phase may have produced a well-defined cleavage ($2) in the finergrained horizons (fine sands and slates) of the Bullbreen Group. The coarser lithologies of this group (sandstones and conglomerates) are strongly cleaved in some areas, but not in others, although cleavage is generally evident to some extent. Sedimentary structures (e.g. crossbedding, graded bedding, sole markings, flame structures and ball and pillow structures), vergence directions and bedding-cleavage relationships indicate large-scale stratigraphic inversion, particularly along the Skipperbreen-Vestg6tabreen ridge and Motalafjella. F2 folds show gently to moderately dipping axial planes and fairly tight fold geometries, with wavelengths of 0.5-1 kin. Bedding and cleavage are poorly defined in the Motalafjella Limestone, and the orange-weathering dolostone unit lacks any internal structure. The Bullbreen Group was not affected by the mid-Ordovician orogeny (D1). Weiss (1953), in contrast, did not distinguish the Bullbreen Group from the metamorphic complex and therefore suggested that the structures in southwest Oscar II Land were related to a mid-Paleozoic orogeny. Evidence for a mid-Paleogene age for the basement structures attributed to the D2 phase comes from the following observations. (a) Fold wavelengths of deformed Carboniferous rocks at Broggerhalvoya are similar to those in the Bullbreen Group. (b) The orange-weathering dolostone unit may represent a mineralized thrust zone, typical of Paleogene thrusting (Harland et al. 1979). (c) The east-verging emplacement directions are consistent with the regional plate tectonic regime in the North Atlantic and Arctic regions during early Tertiary time (Harland 1965, 1966; Wilson 1965; Horsfield & Maton 1970; Pitman & Talwani 1972; Talwani & Eldholm 1977; Eldholm et aL 1984). (d) Part of the Bullbreen Group is of mid-Silurian age (i.e.) Post-D1. (e) The Bulltinden Conglomerate contains clasts with a pre-depositional deformation fabric. (i.e) post-D1. (f) The Bullbreen Group shows one less deformational fabric than is evident in the metamorphic complex (Morris, 1988) (i.e) Post-D1. (g) Based on fold geometry, dip direction of fault zones and truncations of lithological units of the Bullbreen Group, the emplacement direction of thrust and fold nappes was inferred by Kanat (1985) to be towards the NNE; this is supported by stretching lineation data within the Bullbreen Group (Ratliff, Morris & Dodt 1988). The orange weathering dolostone unit is inferred to have developed along thrust zones during D2 time and forms the

170

CHAPTER 9

discordant zone between the Vestg6tabreen Complex and the base of the Bullbreen Group (Ohta et al. 1983; Morris 1988; Kanat & Morris 1988). The rock is commonly brecciated and the interstices are filled with a light grey limestone derived from the Motalafjella Formation. Quartz grains show evidence for strong deformation (deformation bands, deformation lamellae, undulose extinction and a shape fabric). Overall the chemistry and structural and metamorphic styles indicate a close relationship to the Vestg6tabreen Complex. This unit is best developed in the overturned limbs of major folds where the Bullbreen Group is separated from the Vestg6tabreen Fm. It is well exposed at southern Bulltinden, but also occurs at southern Holmesletfjella and Motalafjella. In addition, Ratliff et al. (1988) noted the presence of a heterogeneous mylonitic fabric that indicates a detachment zone for northeasterly directed folding and thrusting of the Bullbreen Group over other basement units (Morris 1988). To the south of St Jonsfjorden the Bullbreen Group and underlying dolostone are folded into a recumbent synformal syncline below the overthrust Vestg6tabreen Complex (Ratcliff, Morris & Dodt 1988). Ratliff et al. (1988) suggested that the Bullbreen Group was deposited within a fault-bounded linear extensional basin related to uplift of the Vestg6tabreen Complex as part of a convergent orogenic wedge. Continued contraction forced both the Bullbreen and Vestg6tabreen units over the underlying pre-Devonian shelf and basin sediments. They argued (p. 341) that the Bullbreen deformation was pre-Carboniferous on the, possibly doubtful, evidence that the Carboniferous rocks (sandstones and conglomerates) to the west of the Bullbreen outcrop do not share the Bullbreen penetrative tectonic fabrics. The structure is conspicuously over-thrust to the N N E (with the Vestg6tabreen Complex), with elongation of pebbles in the conglomerate parallel to the fold axes (WNW-ESE) direction with a shear displacement (transpression) of 4 km. The structures could certainly be D2 on the above system, only the age remains uncertain. If the timing of Ratcliff et al. is correct, a major deformation similar to that of the West Spitsbergen Orogeny occurred after the Eidembreen event (taken by some as D1) and before the Carboniferous Cretaceous succession deformed in the Paleogene West Spitsbergen Orogeny. This could be a Devonian event, but dextral rather than sinistral, and for which no other such intense tectonism is known in the west. Alternatively the structure, which conforms in most respects with those of the West Spitsbergen Orogen (thrust and fold belt) would be Eocene as favoured here. In this case the dextral transpression would match the model of a Paleogene transpressive orogen. Indeed, on this basis the dextral transpressive structure described in detail by Morris (1988) would be Paleogene and not Paleozoic. Moreover two phases are distinguished: (i) a N S compression with concomitant dextral strike-slip and (ii) easterly directed thrusting. A late stage event within the West Spitsbergen Orogeny and associated with the development of N-S normal faults, and also with the development of broadly E-W-trending strike-slip faults (Waddams, 1983) has been distinguished as a later phase within D2. This phase is not easily distinguished from the more evident D2 phase (Manby 1978). Though Kanat (pers. comm.) described a later D4 event, there is only clear evidence for the three principal events discussed here but their age attribution is not altogether reliable. There is a further consideration. At F a r m h a m n a (SW of the snout of Idembreen) the strata are vertical with a NNW-SSE-strike and are clearly tectonized in some degree. However limestones with Carboniferous corals to the west are concordant with Early Varanger tillites to the east over a short distance as seen in cliff sections. This suggests an absence of any regional Vendian through Devonian (Caledonian) orogeny. The most recent available study (Maher et al. 1997) focused on the strip of mainly Carboniferous rocks, within pre-Carboniferous basement, extending parallel to the Spitsbergen Orogen from St Jonsfjorden to Isfjorden, along the eastern margin of the Forlandsundet Graben (their Svartfjella, Eidembukta, Dandmannsodden lineament). It is faulted throughout and clearly belongs to the Spitsbergian tectogenesis. They interpreted a sequence of phases:

1 E N E - W S W contraction; 2 orogen-parallel sinistral motion; 3 dextral orogen-parallel motion. Their study related the three phases to those somewhat different interpretations of graben history by Lepvrier (1990), Gabrielsen, Grunnaleite & Ottesen (1992) and Teyssier, Kleinspehn & Pershing (1995) and of the origin in Nordenski61d Land to the south by Braathen, Bergh & Maher (1995).

9.7.3

Central and eastern Oscar II Land

Structural observations in the interior of Oscar II Land are still mainly based on reconnaissance mapping and on the interpretation of aerial photographs (Challinor 1964; Harland & Horsfield 1974; Maher 1988a, b), although new data on eastern parts have been presented (Bergh et al. 1988a, b; Bergh & Andresen 1990; Bergh et al. 1993; Wennberg et al. 1992, 1994) and demonstrate the typically thin-skinned style of deformation. Maher (1988a, b) compiled a regional structure map of central and eastern parts, and identified three zones of distinctive structural style or geometry as follows. (i) A zone characterized in the north by thrusts with a complex geometry emplacing pre-Devonian rocks into and over the lower cover strata (Broggerhalvoya to St Jonsfjorden). In the south this zone is characterised by a series of stacked monoclinal to overturned folds of Kapp Starostin Formation strata, forming a 'staircase' geometry. (ii) A central zone characterized by folds within upper Kapp Starostin Formation and Triassic strata without obvious major thrusts (displacement greater than 1 km). (iii) A zone with at least two major thrusts that have emplaced Kapp Starostin Formation strata over Triassic strata. Fold geometries may be correlated with fault-bend folds, with angular hinges and flat tops (Suppe, 1985); smaller thrusts are also evident. The apparently regular and consistent orientation of many of the fold structures within the interior parts of Oscar II Land are a direct reflection of underlying fault geometries. The nature of the underlying structure is inferred as ramping in the pre-Devonian rocks, propagating, and flattening out in the weak gypsum horizons of the Gipshuken Formation; all slip would therefore be transferred along this horizon farther east (Harland, Mann & Townsend 1988; Maher 1988b). The central zone of folding displays open to tight folds in Kapp Starostin Formation and Triassic strata, with varying styles from conjugate to more rounded forms. Considering the mechanical competence of Kapp Starostin Formation strata it is unusual to find such tight fold geometries, e.g. to the south and west of Isfjorden (Maher & Welbon 1992). According to Maher (1988b) the folds interpreted from aerial photographs have neutral vergence, with axial planes essentially vertical; numerous small thrusts are likely, but large thrusts (displacements greater than 1 kin) are absent in most areas. The Kapp Starostin Formation upper boundary is identified repeatedly at the surface suggesting a sub-horizontal, envelopment surface for the folds, the implication being an underlying subhorizontal detachment. The gypsum horizons within the Gipshuken Formation form an obvious candidate for the underlying detachment (Harland & Horsfield 1974; Harland, Mann & Townsend 1988), and thus the gypsum horizons promote a zone of thin-skinned deformation. The folds that form above this 9-10 km wide detachment may represent buckle folds (Maher 1988b). Such a simple model, assuming concentric fold geometries, necessarily implies space problems at depth. On the basis of idealised fold geometries, Maher suggested that a perfectly concentric fold geometry provides an upper limit for the shortening estimate, for which estimates lie in the range 14-25% (of original length) with an average linear shortening of 2.2 km (about 20%) across the width of the central zone. The inferred depth to detachment is calculated to be in the range 364-694m and is consistent with a basal detachment within the lower parts of the Kapp Starostin Formation, or more likely within the underlying Gipshuken Formation (Challinor 1967; Maher 1988a, b).

CENTRAL WESTERN SPITSBERGEN

1000-

HALGSMARKA

SVEABREEN

171

LAPPDALEN

-- 1 0 0 0 LUNDBOHMFJELLET

50O-

m

./;....... U

Dg

.500 -0

o500-

I~S: ~ - : : - ~ ____-::---~Z //

Carboniferou-~.,""

............

............

-- 5 0 0

......

2 ~_~_o_~~_"_ . . . . . . . . . . . . . . . . . . . . . . . . . .

-

1000--Devonian

Fig. 9.6. Structural cross-section showing the major folds and thrusts in the Mediumfjellet-Lappdalen area (simplified from Bergh & Andresen 1990).

.

----

1000

Hecla Hoek 0

lkm |

m

The Lappdalen-Mediumfjellet segment. The Lappdalen-Mediumfjellet thrust front in east Oscar II Land presents a structural profile through the stack of thrust sheets allowing an interpretation of the geometric relationship between the folding and thrusting; a detailed analysis was given by Bergh & Andresen (1990). Figure 9.6, summarized from that paper, shows the essentials of the structure. They described their traverse under the following heads from east to west.

(a) The Mediumfjellet-Lappdalen thrust front with west dipping stacked and imbricated thrusts with repetition of Sassendalen, Kapp Starostin and Gipshuken units. Incompetent Triassic strata display upright folds but the competent Permian strata form large amplitude chevron and box folds. Decollement zones select the incompetent Gipshuken and Botneheia Formations. (b) The Lappdalen transition zone about 2 km wide separates (a) and (c). (c) The Lappdalen fold and thrust zones. Four distinct thrust or fold structures were described (Bergh & Anderson). They are interpreted as the leading edge in an eastward propagating thrust system, based in a sole thrust within the Gipshuken Formation with advancing piggy-back thrusting. (d) The Mediumfjellet fold and thrust zones also exhibit four thrusts, with box-like disharmonic folds based on the Gipshuken evaporite zone, generally dipping west. Analysis of these profiles extending 10km E-W by balanced sections gave a minimum shortening of 4 km. Blind thrusts, hidden detachments or out-of-sequence thrusts would increase this estimate.

The T r y g g h a m n a - L a p p d a l e n segment. Structural mapping of Paleozoic and Mesozoic rocks in Oscar II Land within the West Spitsbergen Orogen, reveal a system of major asymmetric to overturned, east-vergent folds with NNW-SSE-trending axes, a c o m m o n feature throughout the orogen in this area. In addition the folds are accompanied by complex thrust faults and imbricates with a shallow to moderate southwesterly dip.

Structural studies in the Trygghamna-Lappdalen area of southern Oscar II Land reveal a variation in the geometry of the major folds, from asymmetric with wavelengths of up to 2 km, to typical chevron and box-like geometries. The movement along frontal ramps generated complex folds, stacked imbricate thrusts and associated backthrusts and backfolds within the Mesozoic (Triassic) cover. There is a clear genetic relationship between folding and thrusting where thrusts die out or pass along strike into major folds. Most of the imbricated thrusts developed by forelimb cut-offs of inverted major folds, with the imbrications producing numerous repetitions of sandstone-dominated Triassic formations in the area to the north of Erdmannflya. The Permian layers contain most of the mapped frontal ramps since these units are mechanically more competent, but flatten or sole out in the less-competent shaly Mesozoic formations, e.g. the Botneheia Fm and Janusfjellet Subgp. A major NE-SW-trending and essentially vertical strike-slip fault, the Isfjorden Fault (Challinor 1967; Harland & Horsfield 1974), separates highly deformed Mesozoic rocks to the northwest from the largely flat-lying Cretaceous/Tertiary rocks to the southeast on Erdmannflya and is interpreted as an oblique ramp structure (Bergh et al. 1988). The rocks adjacent to the fault (Cretaceous and Tertiary strata) are characterized by numerous

minor reverse faults, imbricate thrust sequences and tight upright folds with an axial planar cleavage. The throw on this fault is approximately 400 m based on the correlation of the Jurassic-Cretaceous boundary in the hanging-wall and footwall blocks. Bergh & Andresen (1990) proposed a model for the Paleogene structure of Oscar II Land whereby compressional deformation is transferred eastwards by a combination of fault propagation folding and thin-skinned d6collement thrusting. The western area can be considered a buried/blind thrust system. To the northeast the deformation style is typically that of an emergent thrust system with fault propagation folds and thrusts reaching the surface; similar structural styles are observed in Mesozoic rocks of Nordenski61d Land and along the Billefjorden and Lomfjorden fault zones of eastern Spitsbergen (Andresen, Bergh & Haremo 1994; Nottvedt et al. 1988). The implication is that a thin-skinned tectonic model can be applied to the West Spitsbergen Orogen in eastern Oscar II Land, in which orogenic stresses within the main part of the fold-and-thrust belt are transferred eastwards to the more central areas of Spitsbergen by regional d6collement or detachment beneath the Central (Paleogene) Basin (Nottvedt et al. 1988; Bergh & Andresen 1990).

9.7.4

The St Jonsfjorden area

The St Jonsfjorden area of West Spitsbergen lies within the Tertiary fold-and-thrust belt and has been studied by Horsfield, Kanat, Welbon & Maher (1992) and Maher & Welbon (1992). In the eastern part of the St Jonsfjorden area (Wittenburgfjellet to Klampen), Permian Kapp Starostin Formation cherts and limestones and the Triassic Sassendalen Group shales and sandstones form large northeast-vergent, close to tight folds within which smaller thrusts are common. Further west, Kapp Starostin Formation strata and underlying Gipsdalen Group strata are imbricated and form duplexes that underlie large-scale northeast-vergent monoclinal structures. Welbon & Maher (1992) summarized the St Jonsfjorden region, and supplement the earlier work of Horsfield. Mann & Townsend (1989) suggested a simple model whereby the St Jonsfjorden Trough formed in the hanging wall of the west-dipping fault zone, with the southern margin of the basin offset by a major NW-SEtrending transfer fault in Van Keulenfjorden. Vegardfjella and Wittenburgfjella (southeast end of St Jonsfjorden) are on the eastern edge of the basement high that parallels the west coast of Spitsbergen. Mapping (by Challinor & Horsfield, CSE) indicated a northeast-vergent thrust stack involving basement rocks and platform cover strata including Triassic units (Welbon & Maher 1992). Three major thrusts were defined by Maher & Welbon (1992) in the Vegardfjella-Wittenburgfjella area of inner St Jonsfjorden: the Lower Vegardfella Thrust, the Upper Vegardfjella Thrust, and the Vegardbreen Thrust (see also Welbon & Maher, 1992). This is a complex structure with units separated by the three thrusts mapped namely: Lower and Upper Vegardfjella thrust and the Vegardbreen thrust.

172

CHAPTER 9

Vegardbreen Thrust.

The Vegardbreen Thrust is the most prominent structure in the southern part of Oscar II Land. The thrust geometry is complex with significant Wordiekammen and Botheheia formation flats and a truncated, overturned fold limb with numerous minor structures in the eastern hanging-wall. The overall northeast dip is due to rotation above the underlying thrusts. The Vegardbreen Thrust was interpreted by Welbon & Maher (1992) to be the roof thrust with which the Upper Vegardfjella Thrust merged.

The repetition of Permian Kapp Starostin and Triassic strata to the northeast of Wittenburgfjellais mainly due to folding, but with the occasional development of minor thrusts; this is particularly evident at Klampen where six fold pairs are present. This zone of folding is about 8 km wide and was interpreted to have formed above a flat within the underlying Gipshuken Formation gypsum (Harland & Horsfield 1974; Maher 1988; Bergh & Andresen 1990). If this interpretation is correct, the eastern zone is clearly thin-skinned in character, which contrasts with the Vegard thrust stack where basement rocks are involvedin the thrusting and significant thrust ramps exist. Shortening across the Vegardfjella and Wittenburgfjella area was estimated to be about 13 km (Welbon & Maher 1992).

9.8

Structure of Prins Karls Forland

Whereas Oscar II Land exposes pre-Devonian and Carboniferous through Cretaceous strata, and so enables a distinction to be made between pre-Carboniferous and post-Early Cretaceous deformation, Prins Karls Forland lacks post-Silurian strata. Therefore suspected Paleogene deformation cannot be confirmed nor characterized by tectonism in younger strata. As in Oscar II Land, however, a post-Vendian pre-?Silurian tectonism sufficient to produce schistose and phyllitic lithologies, seen in the Sutorfjella conglomerate clasts in a turbidite sequence (Barents Formation), may correspond to the mid-Ordovician (Eidembreen) event in Oscar II Land. The structure of Prins Karls Forland has been investigated by many authors (e.g. Tyrrell 1924; Atkinson 1956, 1960; Harland et al. 1979; Hjelle, Ohta & Winsnes 1979; Morris 1982, 1989; Manby 1983a, b 1986; Dallmann et al. 1993; Lepvrier 1990). The structure reflects the stratigraphy trending and striking generally N N W - S S E parallel to the long axis of the island. Dips are often steep but the thickness of the strata generally yields broad outcrops. Distinct folds may be observed in E-W cliff sections with typical asymmetrical and occasional recumbent folds. Each investigation resulted in a different stratigraphic sequence which affected the structural interpretation and vice-versa. Despite the many uncertainties in Prins Karls Forland geology this author is reasonably confident in the essential correctness of the succession worked out by the Cambridge group as in Section 9.6. However, the ages of most units are uncertain.

9.8.1

Sequence and age of deformation

Because of the prevailing Caledonian deformation in much of Spitsbergen it was natural to assume that strong tectonism in older (unfossiliferous) rocks would probably be Silurian if not older. Atkinson (1956) described his structures as Caledonian without question or evidence. Harland & Horsfield (1974) in establishing the West Spitsbergen Orogen as a Tertiary entity included Prins Karls Forland (with the Pre-Carboniferous rocks of Oscar II Land) as zones (1 and 3) of probably Caledonian basement in which it was difficult to distinguish the effects of the Paleogene Orogeny so evident further east in Oscar II Land. Harland, Horsfield, Manby & Morris (1979) concluded an agreed stratigraphy based on work by Harland and Horsfield in Oscar II Land, then Harland followed by Manby and Morris in Prins Karls Forland. Tectonic interpretation was developed by individual authors.

Hjelle, Ohta & Winsnes (1979) covering the same area (Prins Karls Forland and Oscar II Land) concluded a Tertiary age of deformation of the island in conformity with that of the mainland. Manby (1986) described 'mid-Paleozoic metamorphism and polyphase deformation of the Forland Complex'. He assumed a Caledonian structure interpreted in three phases D1, D2 and D3. He did not distinguish which rock groups exhibited which characteristics nor did he specify the criteria by which D 1 and D2 could be distinguished, they being essentially homoaxial. Whereas D3 was a mild tectonism thought to be Tertiary, the conclusion on D2 was somewhat equivocal. Morris from his (1982) map plotted the en Ochelon Scotiadalen fault zone and concluded (1989) that 'the relatively simple geometrical relationships and the lack of secondary modification of the Scotiadalen fault zone argue against a Paleozoic origin'. The distributed shear zone is well orientated to accommodate shear strain developed during Tertiary time, and probably formed prior to the transitional phase of this deformation (Late Eocene to midOligocene, say 40-30 Ma; Steel et al. 1984; Lepvrier et al. 1988). Lepvrier (1990), possibly following Harland & Horsfield, assumed that his Tertiary graben structure adjoined Caledonian basement. The conclusion here, in conformity with interpretations of other parts of the western terranes is that there is some evidence for an early metamorphic post-Vendian, pre-Silurian phase which could be part of the mid-Ordovician Eidembreen event. It would thus only be seen in four lower groups and not in the Grampian Group and some of the D 1 characters as described by Manby could be of this age. No evidence is available of Silurian tectonism and it is concluded here that the main tectonism was part of the West Spitsbergen Orogeny of Eocene age.

9.8.2

Vergence of deformation

Whereas all agree that the structural trend is NNW-SSE, hence the linear shape of the island, the vergence could be either way towards the ENE or the WSW; it is not immediately obvious. Authors adopted one or other direction to conform with their overall interpretation. Thus Atkinson (1956) and Manby (1986) thinking the structure was Caledonian chose the westward vergence independently of the Paleogene eastwards thrusting on the mainland. On the other hand Hjelle, Ohta & Winsnes (1979), treating the island in conformity with Paleogene structures of the mainland, opted for an eastwards vergence as was followed, without discussion, for the northern part of the island by Dallmann et al. (1993). Figure 9.7 shows somewhat different interpretations of the same structures. Manby's sections show a thin-skinned tectonic d e v e l opment on a floor thrust not far beneath the surface. This author's prejudice has been towards a westward vergence and this need not be inconsistent with a Paleogene age as is discussed in Section 9.10.

9.8.3

Faulting

(a) Sequence of faulting. The Scotiadalen N-S Fault shown on most maps is not a major fault but a zone of minor en ~chelon faults trending N N E which, as Morris (1989) demonstrated, was a late event. A map of pre-Carboniferous groups of southern Prins Karls Forland is shown in Fig. 9.8. The island is crossed by many faults, typically ENE to ESE which appear to cut most structures including the boundary faults of the Paleogene graben. No systematic displacement has been noted. The principal single feature on the island is the boundary between the older deformed strata and the relatively undeformed Paleogene strata of the Buchananisen Group. The boundary appears to be one main fault or a series of stepped faults dipping steeply into the graben. It does, however, differ from north to south. Cliff sections north of

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CHAPTER 9 The re-emergence of the Prins Karls Forland Block was largely the result of extensional displacements along NNW-SSE-trending faults, along which there is also evidence for oblique-slip and pure strike-slip movement (e.g. Lepvrier & Geyssant 1984; Lepvrier 1990). Structural evidence for this is the presence of southeast-plunging folds in the Tertiary rocks of Prins Karls Forland. The generation and orientation of these folds can be explained by a resolved NE-SW principal compression (rl) of the rocks resulting in an overall northward movement of Prins Karls Forland with respect to mainland Oscar II Land. The latest identifiable events on the island are the broad E-W flexuring and ENE-WSW faulting of the Forland Complex and Tertiary infill, which resulted in the displacement of the main NNW-SSE-trending fault (Manby 1986).

(c) Structural units. In the north of the island the major thrusts were used first by Atkinson and then by M a n b y to define (respectively) five and four tectono-stratigraphic sub-areas. The map from M a n b y (1986) in Fig. 9.7 shows the named thrusts and sub-areas numbered. The sections are not altogether consistent with observed stratigraphy on the ground, but the overall style of deformation may well be correct.

Fig. 9.8. Lithostratigraphic formations and geological map of south-central Prins Karls Forland (adapted with permission from Morris 1982, 1989). Selv~tgen show typical normal faulting. However, at the northern tip of the island the boundary, whether or not faulted, shows vertical concordance between Grampian Group strata and indurated Paleogene strata. This indicates certainly that some Paleogene strata were involved in a compressive-transpressive phase and possibly that it is an up-ended parallel unconformity. If the latter, this would be no surprise in so far as mid- or late Paleozoic tectonism has not been established in the western terranes. The main boundary fault, generally steep to ?vertical appears to cut the folds and thrusts of the core of the island. The thrust faults all belong to the same homoaxial folded structure and have not been distinguished by age. The following hypothesis develops from (a) this author's prejudice for westward vergence of the thrusting, (b) the structure south of Scotiadalen according to the map of Morris (1989) and (c) the thin-skinned tectonic interpretation (in principle though not detail) as depicted by M a n b y (1986). It is conjectured here that the lower three groups exposed in the south of the island, being relatively competent, were folded in a simple anticline. The upper two groups were thrust westwards over this arch with d+collement in the incompetent Scotia Group. This would distinguish the thinskinned structures in the north. The break in the plan of the island suggests that the southern anticline might have continued northwards to the east had it not been downfaulted in the graben. (b) Strike-slip components. Dextral displacements in the Scotiadalen fault zone have been noted above (Morris 1989). Hjelle, Ohta & Winsnes (1979) referred to sinistral components but without localities. Possibly they had in mind the strong sinistral shear seen at Daudsmannsodden on the mainland (Harland et al. 1993). On the island some stones in the Ferrier Group tilloids are elongated possibly in the same sense. These and other indications cannot be dated directly. It is, however, generally accepted that the West Spitsbergen Orogeny resulted from Paleogene dextral transpression. Sinistral shear would fit the hypothesis of major Devonian strike-slip faulting which might have operated along the Forlandsundet Graben and so focused the Paleogene shear zone.

The principal feature of Manby's four (northern) units or subareas are as follows from the top down. Sub-area 4. A large part is formed of an uninverted Scotia-Grampian group succession in the upper limb of a large, essentially flat-lying F1 fold, the lower limb and core of which are truncated and replaced by the Northern Grampian Thrust (NGT). Sub-area 3. The central part of northern Prins Karls Forland is occupied by rocks of sub-area 3. In the north, this unit is covered by the Tertiary sediments of the Forlandsundet Basin and in the far north it is overthrust by the Northern Grampian Thrust (NGT). Structurally the rocks (Geikie, Peachflya and Scotia gps) form an inverted sequence in the lower limb of an F1 fold with an essentially fiat-lying anticlinal fold closing to the west; however, further south in the Selv~gen area, the strata around the F1 closure are right way up. Two prominent klippe structures are present to the north of Selvgtgen where they are infolded with Scotia Gp rocks. Sub-area 2. This forms a laterally extensive tectonic unit in north Prins Karls Forland, comprising rocks of the Scotia and Grampian gps. The rocks occur in a southward-plunging synform which verges southwest, with the rocks forming an inverted succession (Manby 1986). Conglomerates, stratigraphically equivalent to those in sub-area 1 have been more intensely deformed when compared with those in sub-area 1 with axial ratios greater than 6:1 aligned parallel to the major fold axis. Sub-area 1. This thrust sheet is the structurally lowest tectonic unit, lying beneath the Western Grampian Thrust (WGT), and largely consists of Grampian Group rocks; Scotia Group rocks are restricted to a small area to the north of this sub-area. The succession is uninverted with no evidence for stratigraphic repetition by minor thrusts. F1 folds range in size from microscopic to large-amplitude structures, e.g. the box or kink-like folds in the south of sub-area 1.

9.8.4

Metamorphic environments

Northern Prins Karls Land. The presence of biotite in the youngest exposed rocks of the Forland Complex indicates that the minimum metamorphic conditions reached were biotite grade (Manby 1983b). The stability of the chlorite-muscovite-quartzchloritoid assemblage in pelites, the absence of staurolite, cordierite or almandine garnet (in strata up to and including the Ferrier Group) suggest that metamorphic conditions remained within the greenschist facies and largely within the biotite grade. There is some evidence for higher temperatures in the Pinkie Group as shown by the higher aluminium content of some amphiboles and the presence of scapolite and oligoclase (Anl7), though this could be compositional; these rocks were also within the greenschist facies. According to M a n b y (1983b) the ambient conditions of prograde metamorphism prior to the start of D1 were within the 380-560~ and 4.0-7.5 kbar range, equivalent to geothermal gradients in the range 18-23~ -1. These are in broad agreement with data published by Ohta (1978) and Morris (1982).

CENTRAL WESTERN SPITSBERGEN Atkinson (1956) discussed chloritoid in the Forland. According to Manby (1986) evidencefor metamorphism occurring before D1 comes from the presence of randomly orientated and rosette clusters of chloritoid and other chloritoid crystals with rotational inclusion trails suggesting some syntectonic growth. However, non-aligned syntectonic mineral growth is not unusual. The phlogopites and chlorites overgrow S1 with minor pressure shadow development in sub-area 3 indicating that metamorphism continued late into D1. Manby (1986) suggested that the formation of the Forland Nappe closely followed the peak of metamorphism, the development of which was facilitated by the elevated temperatures and fluid phase activity.

Southern Prins Karls Forland. Metamorphism was first discussed by Tyrrell (1924) who identified chloritoid and muscovite referring the rocks to the biotite zone and the chloritoid as a stress mineral which Atkinson (1956) amplified as associated with the thrusting. Morris (1982) considered four compositions and described and interpreted their mineral assemblages: carbonates, pelites, psammites and mafics. The metamorphism accompanied or preceded the first recognisable structural event. Subsequent structures were not accompanied by metamorphism. Carbonate lithologies (>60% carbonate minerals) with dominant calcite, dolomite and quartz, with tremolite and epidote related to thermal (contact) metamorphism muscovite and chlorite. Consideration of possible mineral reactions suggest that it was low grade. Pelites (15-50% quartz, >25% Mg-A1-Fe silicates, 50% quartz). After quartz the above assemblages occur as minor constituents. Production of biotite implies a minimum temperature of 300~ Mafies (>15% quartz, >10% carbonates, >75% Mg-A1-Fe silicates) These are essentially found as metavolcanic flows, tufts, other pyroclastics and mixed with other sediments. Temperatures between 380~ (5 kbar) and 520~ (7 kbar) have probably obtained in retrograde metamorphism with degassing. In conclusion, thermal isograds approximately parallel the stratigraphic boundaries. Tectonic depth of metamorphism is, of course, highly relevant; but there is nothing to suggest more than a minor orogenic episode.

9.8.5

Conjectural synthesis

Whereas there is stratigraphic continuity between the northern and southern segments of the island, their structural characteristics are quite different. Of the five groups of formations the upper two are limited to the north, the lower two to the south and only the Peachflya Group is common to both (Fig. 9.8). The major deformation of the whole island is taken here to be part of the Paleogene West Spitsbergen Orogeny. Paleozoic (?Ordovician) tectonic episodes and possibly Devonian sinistral shear zones are probably recorded in the rocks but have yet to be clearly distinguished. The main features of Manby's D1, D2 and D3 would be Paleogene as affecting all groups of strata, whereas the Grampian Group would probably be post-middle Ordovician. Boudinage, rodding and mullion structures seen in the Ferrier Group might reflect the Eidembreen Event or Late Devonian shear. It is provisionally accepted that a westward-vergent Paleogene Orogeny folded the three lower groups in a coherent, competent anticline, with a possible bedding thrust above the oldest Ferrier Group rocks. The Scotia Group strata are conspicuously incompetent and provided for some d~collement over the lower groups. The map suggests that the northern thin-skinned structures slid westwards over the older rocks, but the northern continuation of the southern anticline is cut out by the Paleogene graben. The Scotiadalen shear zone with its mild deformation would have been protected from the overriding transpressive thrusting in the shadow of the lower anticline.

9.9

175

Structure of the Forlandsundet Basin

The structure and evolution of the Tertiary Forlandsundet Basin is not well understood, largely because of its location along the axial zone of the West Spitsbergen fold-and-thrust belt (Gabrielsen et al. 1990; Steel et al. 1990). The dimensions of the basin are approximately 30 km wide and 80 km long. The palaeostress history of the Forlandsundet Basin has been attempted (e.g. Lepvrier & Geyssant 1983, 1985; Lepvrier 1990).

9.9.1

Structure of the infill

Early Paleozoic rocks. The tectonic m~lange exposed in scattered outcrops in Kaffioyra and Sarsoyra has been interpreted as a sheared body of distinctive rock types, with Motalafjellet deep facies affinities (Ohta et al. 1995). The implication is that probable Ordovician rocks have been sheared dextrally northwards in a steeply dipping zone. The dextral shear would indicate a Paleogene transpressive phase probably preceding most of the Paleogene strata whose deformation is the subject of section 20.6.3.

Paleogene strata. In the area of Selvfigen (Prins Karls Forland), on the western side of the basin, Kleinspehn & Teyssier (1992) noted contacts where Palaeogene sediments rest on a pre-Devonian palaeo-regolith. This led them to question the concept of a simple extensional graben with several kilometres of dip-slip offset on the boundary faults (e.g. Manby 1986). The basin fill also shows multiple thrusts, strike-slip faults, open to tight folds, refolded isoclinal folds and foliated shears. Some high-angle fault surfaces display slickenside striations indicating normal slip. The strata show a dominant dip toward the basin axis, but are locally overturned; the age relationship between various structures has not been resolved. Clastic dykes with slickenside striations and softsediment folding were inferred to indicate that deformation was in part coeval with basin subsidence and deposition (Kleinspehn & Teyssier 1992). Other faults studied by them were found to have cut and displaced conglomerate clasts together with the adjacent matrix, indicating a high degree of lithification at the time of displacement. Several generations of cross-cutting brittle deformational structures have been defined from within single exposures, indicating a multiphase deformation history. Kleinspehn & Teyssier (1992) reported widespread evidence of ductile deformation in the Tertiary strata at SelvSgen, Buchananryggen and at Sarsoyra on both sides of the Forlandsundet Basin. It occurs within single exposures indicating multiphase deformation under different tectonic/thermal conditions. Petrographic studies of sandstone samples indicated the development of a foliation and the recrystallisation of micas. Strain is localised along narrow ductile shear zones along which a macroscopic foliation is evident; microstructural work has shown that the foliation is pervasive but poorly developed away from the shear zones. Karen Kleinspehn (in an oral presentation in Oslo in 1990), suggested that the presence of dynamically recrystallized chlorite was evidence of growth at or close to the brittle-ductile transition (i.e. at about 10-15 km depth), the inference being that the Forlandsundet Basin cannot be considered a simple upper crustal graben as previously documented (e.g. Steel et al. 1985). Manby (1990) argued that if the sediments were buried to such great depths then there would be evidence for a thermal event within the pre-Devonian basement rocks and resetting of radiometric ages in Prins Karls Forland. No evidence for such an event is known. Gabrielsen et al. (1992) also demonstrated that the basin-fill has suffered stronger deformation than previously assumed. Syndepositional deformation is inferred to have occurred locally, with the basin-fill affected regionally by mild folding and locally by more intense brittle deformation; two fold sets are defined. High-angle reverse faults are common in some parts of the basin; the basin clearly shows evidence for compressional deformation. Intense

176

CHAPTER 9

d e f o r m a t i o n is localized in areas that are characterized by the r a m p i n g o f thrust faults; several systems of late extensional fractures are developed (Gabrielsen et al. 1990). K l e i n s p e h n & Teyssier (1992) as well as Gabrielsen et al. (1992) confirmed that, f r o m the degree o f lithification, the deposits on the western side o f the basin were buried m o r e deeply than those on the eastern side. Limited vitrinite reflectance d a t a f r o m conglomeratic beds in the Selvgtgen area show significant variations on either side of the F o r l a n d s u n d e t Basin. Vitrinite reflectance values (R0) on the west side of the basin are in the range 2.55-5.50 with an average of R0 = 4.01; in contrast, 20 k m away at Sarsoyra, values o f R0 = 0 . 4 3 - 0 . 4 6 are indicated (Rye-Larsen in SKS 1995). This indicates significant differential subsidence a n d differing thermal histories over relatively short distances, with the Tertiary sediments on the west side of Prins Karls F o r l a n d having been buried to a substantial d e p t h and well b e y o n d the oil w i n d o w (anthracite to m e t a - a n t h r a c i t e coal rank).

9.9.2

Palaeostress history of the Forlandsundet Basin (phases 1-3)

A n analysis o f faults in the F o r l a n d s u n d e t Basin a n d their use in determining the principal palaeostress tensors, has shown a polyphase tectonic d e v e l o p m e n t of the basin (Lepvrier 1990); and c o m p l i m e n t s the w o r k of K l e i n s p e h n & Teyssier (1992), Gabrielsen et al. (1992) a n d N o t t v e d t et al. (1992). The tectonic synthesis o f Lepvrier (1990) led on from earlier studies of the West Spitsbergen O r o g e n (Lepvrier & Geyssant 1984, 1985), w h i c h c o n c e n t r a t e d on n o r t h w e s t Oscar II L a n d and the F o r l a n d s u n d e t Basin area. The later study indicated that the basin has suffered b o t h extensional and compressional phases, the m a i n details of which are summarised below. Still later was the interpretation of the zone o f intense transpressional strike-slip causing scattered exposures on Sarsoyra and Kaffioyra on the east side (Ohta et al. 1995).

Phase 1: transpressional event.

Preserved horizontal fault striations (Steel et al. 1985) relate to a phase of broadly NE-SW compression, the N20 transpressional event of Lepvrier (1990).

Phase 2: E N E - W S W compression. This event gave rise to the basinward dip of the Tertiary strata; it generated a general synformal geometry to the basin. Seismic data across the basin also indicate a general synform structure (Nottvedt et al. 1990). The maximum compressional stress tensor (al) has an azimuth of 070 080 ~. Deformation related to this compressional event can be correlated on both sides of the basin, where rare tight folds or thrust faults, similar to those in the West Spitsbergen Fold Belt, are recognized (Lepvrier 1990). A component of dip-slip movement towards the basin axis can be observed at some localities, conformable with the bedding dip; according to Lepvrier (1990) this demonstrates that strike-slip faulting preceded tilting and represents the earliest stage of deformation under this stress regime. Along the eastern margin of the basin the alluvial fan conglomerates of the Sarsbukta-Sarstangen formations are affected by two sets of strike-slip faults. In the area of Sarsoyra (near Kapp Graarud and Nyflua) a set of dextral (035-070 ~ and sinistral (100-130 ~ faults, steeply dipping to the south and north respectively, are present, with striations indicating a component of normal displacement, caused by the later tilting of the strata. Conglomerate pebbles are cut and display a 1-2cm lateral offset. The faulted contact of the Tertiary strata with the pre-Devonian basement at Kapp Graarud is defined by a sinistral strike-slip fault (130 ~ that was active during this phase. In the Sarsbukta section, similar sets of faults are present, but extension (NW-SE to N-S) is generally dominant and defined by oblique to normal fault striations (e.g. at Sarstangen). The analysis of the dextral shear zone affecting the Kaffioya Ordovician basement (Ohta et al. 1995) confirmed the earlier interpretations. A similar stress pattern is evident on the western side of the basin at several localities, determined as 075 ~ from the existence of two sets of transverse (relative to the basin trend) strike-slip faults; locally some pebbles of the SelvSgen Formation conglomerate are laterally displaced (Lepvrier & Geyssant 1985; Lepvrier 1990).

Fig. 9.9. Simplified structural map and cross-sections of the Forlandsundet Graben (from Gabrielsen et al. 1992).

Phase 3: E S E - W N W and N N W - S S E to N - S extensional phases. Faults related to each of these extensional phases are sometimes difficult to distinguish. However, the final NNW-SSE to N-S extension is well defined by oblique to dip-slip movements on the two sets of earlier strike-slip faults, associated with the ENE-WSW compression; this extension eventually becomes a prominent tectonic event. At Marchaislaguna, faults striking 060-075 ~ and 095-115 ~ cut N W S E to N-S faults and show oblique striations that are inferred to relate to an extension direction trending 167 ~.

9.9.3

Origin of the Forlandsundet Basin: current models

The F o r l a n d s u n d e t Basin presently appears as an asymmetric 'graben-type' structure b o u n d e d by high-angle dip-slip marginal faults (Fig. 9.9). However, the origin of the basin, located within the fold-and-thrust belt of the West Spitsbergen Orogen, is problematic. Several attempts have been m a d e to explain the subsidence of the F o r l a n d s u n d e t Basin within this compressive regime, that was d o m i n a t e d by N N W - S S E strike-slip faulting ( H a r l a n d &

CENTRAL WESTERN SPITSBERGEN

9.10

Fig. 9.10. Schematic diagram of 'flower structure' within a convergent strike-slip fault zone (reproduced with permission from Lowell 1972, fig. 9). Horsfield, 1974; Harland 1979, 1985; Lepvrier & Geyssant 1984, 1985; Steel e t al. 1985; Lepvrier 1990). Harland (1979) proposed a model comprising four tectonic phases to explain the development of the Forlandsundet Basin: (1) transpression; (2) transtension; (3) minor transpression; and (4) minor transtension. The first phase of transpression resulted in the compressional deformation that caused the uplift of the West Spitsbergen Fold Belt further east; this suggests that the extensional phases occurred late in the West Spitsbergen Orogeny. Steeply dipping Palaeogene strata adjacent to the West Forlandsundet Fault in Prins Karls Forland are cited as evidence of a third minor transpressional phase. These predominantly strike-slip episodes were related to horizontal movements along the Spitsbergen Fracture Zone. The palaeostress analysis of Lepvrier & Geyssant (1985), based on faults in the Forlandsundent area suggests that four tectonic regimes can be defined: (1) extension along NW-SE-trending faults related to 'graben' formation; (2) E-W transtension (pre-Oligocene); (3) ENE-WSW compression; and (4) NNW-SSE to N-S extension. They proposed that the graben subsided as a pull-apart basin between two right-stepping dextral strike-slip faults defined by the East and West Forlandsundet faults, shortly after the main Tertiary deformation along the West Spisbergen Fold Belt. It is accepted here that some graben formation preceded the transpression phase of Harland (1979). Steel et al. (1985), in contrast to the above models, proposed that the graben formed partly during and partly after the main phase of deformation along the fold belt, with two possible models suggested. The first model proposes that the basin formed in the lee of a left-stepping restraining bend to the north of Forlandsundet; in the second model the basin is envisaged as a collapse graben in the central part of the uplifted and arched orogenic belt. Additional evidence for the development of the Forlandsundet Basin within a strike-slip regime as a pull-apart basin comes from an analysis of the sedimentary sequences. In an extensional basin the initial rifting phase is normally followed by thermal subsidence giving rise to overlapping unconformities along the basin margins. The 'flower-structure' model as proposed by Lowell (1972) for the West Spitsbergen Orogenic Belt (see Fig. 9.10) has been commonly discounted (Manby 1988; Ohta 1988; Faleide et al. 1988) but deserves reassessment (Section 9.10) in relation to the origin of the Forlandsundet Basin (Steel et al. 1985) and in this work. Kleinspehn & Teyssier (1992) assessed two new hypotheses for the origin of the Forlandsundet Basin: (1) the basin formed as the result of extension and/or transtension followed by orthogonal shortening or strike-slip deformation, and (2) the basin originated in a compressional regime, piggy-back on top of the eastward-transported thrust sheets that formed the internal part of the orogenic zone. Folding and thrusting of the basin strata occurred first (e.g. Lepvrier 1988, 1990) followed by a period of extension, probably transtension, that generated the 'graben' structure that is observed at present.

177

A tectonic interpretation of the West Spitsbergen Orogen; northern segment

The West Spitsbergen Orogen (Harland & Horsfield 1974) north of Isfjorden is the study area of this chapter. In common with the orogen south of Isfjorden, Paleocene strata (in this study area the Ny-Alesund Subgroup) were deformed by the orogeny which was demonstrably post-Paleocene with an Eocene climax (Harland 1965). The cover sequence (Carboniferous through Albian) with its varied and distinctive strata facilitated, and indeed encouraged, the many structural studies of the thrust and fold belt comprising the eastern zone of the orogen. These studies demonstrated ENEverging thin-skinned thrust and fold structures over the Nordfjorden Block utilising incompetent Triassic shale and Permian evaporites. These same d~collement layers extended over the Billefjorden Trough (e.g. Harland, M a n n & Townsend 1988; Welbon & Maher 1992) and even to the Lomfjorden Fault Zone (Andresen e t al. 1992). The northernmost segment of the orogen swings round from the general N N W - S S E trend to N W - S E trend in Broggerhalvoya with vergence trending from E N E generally to N E and then to northerly thrusting with signicant crustal shortening. The northerly component of the dextral plate suture was thus severely constrained to the north and the simple early transpressive oblique transport was resolved into E N E compression seen in the eastern fold and thrust belt and strike-slip, notably in the Forlandsundet root zone. Much less attention has been paid to the western zones of the orogen where pre-Carboniferous basement prevails. It has been argued that these basement terranes along the west coast of Spitsbergen mostly expose (Precambrian) Varanger or older strata (Harland, Hambrey & Waddams 1993). However, north of Isfjorden Early Paleozoic strata are also exposed. The Early Paleozoic and Proterozoic rocks were all deformed by the Paleogene orogeny. Moreover the Eidembreen event, dated both istopically and biostratigraphically as mid-Ordovician preceded the Bullbreen Group strata in Oscar II Land (Chapter 14). The Grampian Group strata of Prins Karls Forland may correlate approximately with the Bullbreen Group. Both groups contain conglomerate with earlier metamorphosed clasts which could result from the Eidembreen tectonism. Both groups reflect unstable conditions and may be of Late Ordovician to mid-Silurian age. There is no Devonian outcrop in the study area. The main body of Svalbard to the east suffered major Silurian and minor Devonian tectonism, typical of the Caledonides: but so far no decisive evidence has been forthcoming for significant Silurian tectonism. Indeed it would be surprising if there were, because at this time the location of this terrane was probably nearer to that of Pearya in northern Ellesmere Island and far from the Iapetus-Caledonian developments. This accounts for the difficulty in distinguishing a Caledonian event in the detailed study by Morris (1989). This palinspastic arrangement is only part of the hypothesis of Harland & Wright (1979) that makes Svalbard a composite terrrane with this western province being joined by the central and eastern provinces by Silurian and Devonian sinistral strike-slip. The postulated Kongsfjorden-Hansbreen Fault Zone along which this docking took place is obscured by the later Carboniferous sedimentation and the Paleogene orogeny. However, such a fundamental fault may well have located the boundary between the Nordfjorden Block and the St Jonsfjorden Trough and also the subsequent boundary within the West Spitsbergen Orogen between the thrust and fold belt with its thin-skinned structures to the east and the deeper deformation to the west. The above hypothesis is retailed at this point to take account of some enigmatic problems discussed in the three foregoing sections. (a) In Oscar II Land Ratliff, Morris & Dodt (1988), in analysing the structure of the Bullbreen Group, argue for a N W - S E dextral shear zone with E N E verging thrust folds and not easily distinguished from the E N E verging Paleogene structures. Their argument that the structures were pre-Carboniferous is tenuous and, if mistaken, this structure is probably an integral part of the

178

CHAPTER 9

Paleogene orogeny with which the dextral transpression is consistent. Morris (1988) suggested that the later deformation involved northward, followed by easterly, directed thrusting. Thus two Paleogene phases may be distinguished here. (b) In Prins Karls Forland Manby (1986) could not in the end distinguish clearly between his D 1 and D2. He was expecting D 1 to be Caledonian and D2 to be Tertiary. In so far as some D1 structures deform Grampian Group strata it is possible that they should be D2 in his terminology. This would leave D1 for the schistosity and other fabrics in the Scotia and other earlier Groups that occur as pebbles in the Sutor Conglomerate. Making this assumption then the conspicuous D2 structures all verge to the SSW. (c) The Forlandsundet structure is no superficial graben. It has a complex history, with not only relatively porous and coal-beating strata in the later Balanuspynten Formation, but indurated vertical sandstones not easily distinguished from the subjacent Grampian Group strata in the northern cliff section of Prins Karls Forland. This would suggest that pre-orogenic as well as syn- and postorogenic Paleogene strata are preserved. (d) Putting these possibilities together, the model for the West Spitsbergen Orogen proposed by Lowell (1972) may again be considered with an axial-root zone for the orogen with WSW verging structures in Prins Karls Forland and ENE verging structures in eastern Oscar II Land. He also adopted the transpression hypothesis (Harland 1971) (Fig. 9.10) which is consistent with the plate-tectonic motions at that time. This model is consistent with the deep dextral Kaffioyra and Sarsoyra shear zone elucidated by Ohta et al. (1995).

On this basis a NNE-SSW dextral fault zone occupied Forlandsundet. (1) Paleocene transtension would have allowed deposition in a pull-apart basin. (2) During the main orogeny extreme transpression would have generated the steep thrusts along the axis, now mostly covered by water and late Paleogene strata, and pushed the strata outwards on each side to the ENE and WSW. (3) Late orogenic (Late Eocene) strike-slip continued with transtension and the development of the main pull-apart basin. In such a dynamic situation local and/or short term transpression complicated the depositional story. (4) The main dextral strike-slip may have continued without transpression or transtension into Neogene time. It might account for the large low flat area of Prins Karls Forland if it had been opposite Isfjorden when it was a wide valley. This speculation is an optional extra. However, the main dextral strike-slip was entirely taken up in faults west of Prins Karls Forland. The location of this Forlandsundet axis of the Orogen need be no surprise because of the location of the intense sinistral shearing of Vendian strata seen both in western Oscar II Land at Daudmannsodden, and in eastern Prins Karls Forland in the deformation of the tillite stones. That could have been part of the Eidembreen event but a Devonian age is preferred here. It is a fundamental fault zone with a long history. It fits the 'Tertiary orogen-parallel motion in the crystalline hinterland of Spitsbergen's fold-thrust belt' of Maher et al. (1997).

Chapter 10 Southwestern and Southern Spitsbergen W. B R I A N 10.1 10.1.1 10.1.2 10.2 10.2.1 10.2.2 10.3

HARLAND

with contributions with PAUL

Paleogene strata, 180

10.7.1

Calypsostranda Basin, 180 Oyrlandet Basin, 180

10.7.2 10.7.3

A. D O U B L E D A Y

Mesozoic strata in southwest Sarkapp Land, 182

Adventdalen Group, 182 Kapp Toscana and Sassendalen groups, 182 Permian and Carboniferous strata of southern Spitsbergen,

(W.B.H. & I.G.) 183 10.3.1 Kapp Starostin Formation (Tempelfjorden Group), 184 10.3.2 Tokrossoya Formation (Tempelfjorden Group), 184 10.3.3 Treskelodden (Reinodden) Formation (Treskelen Subgroup, Gipsdalen Group), 184 10.3.4 Hyrnefjellet Formation (Treskelen Subgroup, Gipsdalen Group), 186 10.3.5 Sergeijevfjellet Formation (Billefjorden Group), 186 10.3.6 Hornsundneset Formation (Billefjorden Group), 187 10.3.7 Adriabukta Formation (Billefjorden Group), 187 10.4 Devonian strata, 187 10.5 Proterozoic strata of western Nordenskiiild Land, 188 10.5.1 Sequence of the rock units, 188 10.5.2 Mineralization, 189 10.6 Proterozoic strata of western Nathorst and northwestern Wedel

10.7.4 10.8 10.8.1 10.8.2 10.8.3 10.9 10.10 10.10.1 10.10.2 10.11 10.12

& ISOBEL GEDDES

West of Hansbreen, 192 Early Paleozoic and Proterozoic strata east of Hansbreen, 194 Comparison of stratal schemes for southwest Wedel Jarlsberg Land, 195 Mineralization, 197 Early Paleozoic and Proterozoic strata of Sorkapp Land, 197

Early Paleozoic strata, 197 Neoproterozoic strata, 198 Mineralization around Andvika, 199 Correlation of pre-Devonian through southwest Spitsbergen, 199 Structure of western Nordenskiiild Land, 200

Eastern margin of the fold belt, 200 Main fold belt, 201 Structure of western Natborst Land, 201 Structure of Wedel Jarlsberg Land (W.B.H. & P.A.D.), 201

Neoproterozoic succession of northwestern Wedel Jarlsberg Land, 189 10.6.2 Proterozoic basement, 191 10.7 Early Paleozoic and Proterozoic strata of southwestern Wedel Jarlsberg Land, 191

10.12.1 10.12.2 10.12.3 10.12.4 10.12.5 10.12.6 10.13 10.13.1 10.13.2 10.13.3 10.13.4 10.13.5

This chapter treats that part of the West Spitsbergen Orogen south of Isfjorden (Figs 10.1, 10.2, 10.3). It follows the same pattern as the last in treating the stratigraphy of the area, then the structure. Southwestern differs from central western Spitsbergen in being of greater length, more stratigraphic variety but less pronounced Cenozoic deformation. This appears to decrease in intensity southwards. There is, moreover, a conspicuous contrast south of Isfjorden from a fold belt with many thrusts to one with less evident crustal shortening south of it. This correlates with the Central Basin to the east. The younger rocks vary in facies gradually enough to be treated together. They are, in effect, the western margin of the Central Basin the subject of Chapter 4. They are admirably described in the standard section for Svalbard at Festningen at the northern limit of the area, where the rocks of the cover sequence were overfolded and overthrust at the western limit of the basin in the West Spitsbergen Orogeny. They are seen well exposed in vertical strata in almost uninterrupted sequence. Of the younger rocks only the Calypsostranda Group is described briefly in Section 10.1 and the Oyrlandet Basin in Section 10.2 as they are isolated outcrops in the west. The Cretaceous and Jurassic strata are treated entirely in Chapters 4 and 5 and have no detail here. The Triassic strata may also be seen as an extension of the Central Basin and are so described in Chapter 4. However, the structural peculiarity in the south is worth noting again in this regional context and so has a small section (10.2). The Permian and Carboniferous strata extending beyond the Central Basin are described in Section 10.3. The small outcrops of Devonian strata in the south are described briefly in Section 10.4. The older rocks (pre-Devonian) have suffered three or more major tectonic episodes in Proterozoic, Paleozoic and Cenozoic time and it is often not easy to distinguish these in so far as the latest two, at least in the south, were both overthrust eastwards. The older rocks are also difficult to correlate and have received distinct nomenclature for each of four areas. The difficulty in correlation stems from differences of opinion. To avoid introducing

controversial assumptions at the initial descriptive stage in this investigation further nomenclature was introduced and has been followed to complete the independence of each descriptive area of strata between the areas and so to facilitate discussion of correlation at the end of the chapter. The differences of opinion on correlation present a problem for description of strata. It so happens that, especially in the southwest of the area (southwestern Wedel Jarlsberg Land and Sorkapp Land) the Polish group under the leadership of K. Birkenmajer have done the lion's share of the work and the early scheme established about 1960 has been continued and refined by that group. It has also been largely adopted by Norwegian, Russian and American groups. Therefore the initial description of strata will follow that scheme. However, the Cambridge group working independently and extending their correlation anticlockwise from the northeast of Svalbard came to different conclusions on reaching southwest Spitsbergen. Their interpretations were based in part on the opinion that in pre-Carboniferous time the different once distant terranes could lead to different correlations. Other work has also diverged. Therefore, alternative stratigraphic schemes have been formulated to challenge and modify the established scheme. Discussion of this challenge follows the descriptive sections which are arranged in areas to facilitate comparisons. Discussion of the West Spitsbergen Orogeny fold belt is similarly divided by Van Mijenfjorden, Van Keulenfjorden and Hornsund physically into four a r e a s - namely Nordenski61d Land, Western Nathorst Land, Wedel Jarlsberg Land, and Sorkapp Land. A distinctive feature of this sector of Spitsbergen is the occurrence of metallic sulphide minerals. They have been long known but only since about 1950 have they been considered systematically (e.g. Hjelle 1962; Birkenmajer & Wojciechowski 1964; Flood 1969; Czerny, Plywacz & Szubala 1992; Cerny, Kieres & Manecki 1992). With few exceptions they occur within Precambrian and entirely within pre-Devonian strata (Chapter 3.6.3). The only other economic exploration which resulted in a very limited coal mine was in the late Paleogene strata of Calypsobyen.

Jarlsberg lands, 189

10.6.1

Structure of the West Spitsbergen Orogen, 201 Postulated Silurian-Devonian strike-slip faulting, 204 Caledonian structures, 204 Jarlsbergian diastrophism, 204 Proto-basement deformation, 205 Post-proto-basement deformation of Precambrian rocks, 205 Structure of Surkapp Land (W.B.H. & P.A.D.), 205

The structural units, 205 Proterozoic structures, 205 Paleozoic structures, 206 Mesozoic structures, 207 Paleogene structures, 207

180

CHAPTER 10

Key to numbered localities 1 2 3 4 5 6 7 8 9 10 11 12

Adriabukta 13 Barentsburg 14 Bredichinryggen 15 Brepollen 16 Burgerbukta 17 Calypsostranda 18 Elveflya 19 Fannypynten 20 Fridtjovhamna 21 G&shamna 22 Hansvika 23 Hyrne~ellet 24

Isbjornhamna KappMineral Konglomeratfjellet L~gnesbukta Linn60ella Linnevatnet Luciakammen Magnethogda Nottinghambukta Paske~ella Pulkovafjella Recherche~orden

25 26 27 28 29 30 31 32 33 34 35

Revdalen Rochesterpynten Samarinbreen Slyngfjellet Sofiekammen Treskelen Tsjerbysjovfjellet Van Muydenbukta Vimsodden Vrangpeisbreen Werenski61dbreen

Fig. 10.1. Topographic and place name map for Isfjorden to Sorkapp, based on Topographical Map o f Savlbard 1:500 000, sheet 1, Norsk Polarinstitutt.

10.1

Paleogene strata

T h e Paleogene strata belonging to the Central Basin, which b o u n d this study area to the east are treated in C h a p t e r 4. However, there is a faulted outlier, possibly a half-graben, on the coastline near K a p p Lyell. A n a l o g o u s to the F o r l a n d s u n d e t Graben, its stratig r a p h y is quite distinct f r o m that of the Central Basin. A n o t h e r possible half-graben is at Oyrlandet.

I0.I.I

Calypsostranda Basin

Calypsostranda Group (SKS 1995) comprises for the Tertiary strata of Renardodden (Thiedig et al. 1980) near Kap Lyell. Renardodden Fm (Thiedig et al. 1980) >217m. Mainly sandstone with occasional pebbles and coal fragments, some beds with ferruginous concretions. A basal conglomerate which rests on the Skilvika Fm. Skilvika Fm (Livshits 1967; Thiedig et al. 1980) 115.5 m. Mainly siltstones with some shales, thin sandstone beds and coals, also with coal pebbles, plant beds and a basal conglomerate which rests unconformably on the Rochesterpynten Fm. The age of the Renardodden and Skilvika formations had been determined as Oligocene by Livshits (1974) on the bases of pollen and spores and by Head (1984) and Manum & Throndsen (1986) as Late Eocene-Early Oligocene on the basis of dinocysts. Rochesterpynten Fm (Harland, Hambrey & Waddams 1993, p. 100). The description of this unit by Pickton & Harland in 1975 was inadvertently omitted from Thiedig et al. (1980). It comprises a tectono-sedimentary melange, formed largely of derived meta-diamictite blocks from the Kapp Lyell Group some of which are some metres across, probably resulting from collapse and slumping at an active fault scarp. There was possibly some induration event before deposition of the Skilvika Formation. These rocks were also described by Dallmann (1989). He extended an Inner Hornsund Fault Zone through Recherchebreen to make the Calypsostranda graben structure. He also noted the constituents of boulder conglomerates consolidated prior to 'Caledonian' metamorphism. He observed the effects of weathering of these blocks prior to the red-weathering and overlying sandstone horizon.

10.1.2

Oyrlandet Basin

O y r l a n d e t is the lower g r o u n d in s o u t h w e s t e r n m o s t Sorkapp L a n d west of the H o r n s u n d H i g h (e.g. Kistefjellet) at that latitude a n d east of the western fold zone of the West Spitsbergen Orogen at Oyrlandsodden. The only p r e - Q u a t e r n a r y rocks are tiny inliers of Paleogene strata towards the south and Cretaceous strata towards the n o r t h a n d also Paleogene coastal sections on the east side of Sommerfeldtbukta.

SOUTHWESTERN AND SOUTHERN SPITSBERGEN

181

Fig. 10.2. Generalized outcrop map of central and southwestern Spitsbergen, based on Harland, Hambrey & Waddams (1993), and Geological Map of Svalbard 1:100 000 sheets B9, B10, B11, B12 and C13. KHFZ, Kongsfjorden-Hansbreen Fault Zone. The Paleogene strata were regarded by Atkinson (1963) as an extension of the Central Basin. They are however separated structurally by the Hornsund High though Paleogene strata may once have extended throughout the area. It is now a distinct small basin bounded to the southwest by Tempelfjorden Group strata and to the east by a fault so it may be regarded as a half graben or graben. It is based on the diagrammatic map in Dallmann et al. (1993) as the Oyrlandet Graben. The fullest account is by Dallmann et al. (1993) who reported that whereas the Firkanten (Barentsberg) Formation is c. 140150 m thick to the east it may reach 300 m in the Graben. The most complete exposures appear against the eastern fault of the graben on the east coast of Sommerfeldtbukta. It is divided into three members, which are also recognizable in the outcrops to the east, following Kalgraff in Steel et al. (1981). Firkanten Fm ?c. 300. Endalen Mbr, 200+m comprises immature, light grey, porous fine- to medium-grained sandstone with coaly flakes and flazer bedding. Dark grey quartzitic sandstones and silty shales are interbedded. Kolthoffberget Mbr, c. 20+m of black or dark grey silty shales with brownish red-weathering colours and spheroidal cleavage. It weathers characteristically into small steep incised valleys only a few metres deep. Todalen Mbr, c. 30m of bioturbated, occasionally ripple-marked finegrained sandstones with plant remains and occasional coal seams. There is a (?basal) gravel conglomerate.

182

CHAPTER 10

Fig. 10.3. Simplified tectonic map of central and southwestern Spitsbergen.

10.2

Mesozoic strata in southwest Sorkapp Land

The Mesozoic stratigraphy of Svalbard is very largely treated in Chapters 4 and 5 so that the western margin of the Central Basin practically defines the artificial division between Chapters 4 and 10.

10.2.1

Adventdalen Group

The Adventdalen Group (Cretaceous-Jurassic) strata extend in a SSE direction within the main (eastern) fold and thrust belt of the West Spitsbergen Orogen. This reaches the southern shore of Sorkapp Land east of Mathiasbreen and, in effect east of the Hornsund High (see below). On the Hornsund High, at Kistefjellet, Janusffjellet Subgroup strata rest at the summit on Triassic strata which rest directly on folded Precambrian rocks. Further west and occupying low ground corresponding to Sommerfeldtbukta is the Oydandet plain just above sea level and exposing only small patches of pre-Quaternary strata. These include the Oyrlandet Paleogene and some exposures of the Cretaceous Helvetiafjellet Formation. Whether the basin contains a fuller Mesozoic succession is uncertain.

10.2.2

Kapp Toscana and Sassendalen groups

The Kapp Toscana and Sassendalen groups have been described generally in Chapters 4 and 5 as there is sufficient uniformity o f facies throughout the outcrop area in Spitsbergen for the strata most conveniently to be treated together as in Chapter 4. This southwestern sector of Spitsbergen contains contrasting successions between northern and southern Triassic outcrops.

(a) The northern outcrops. From Nordenski61d Land to northern Wedel Jarlsberg Land are exposed the thickest Triassic developments in Svalbard. Their extension to the west has been lost to erosion after the Paleogene folding and uplift. The succession from the Festningen coastline to southern Nordenskirld Land, Nathorst Land and Western Wedel Jarlsberg Land is relatively uniform and is summarized here.

Kapp Toscana Gp Wilhelmoya Fm. The overlying 'Lias' conglomerate (Brentskardhaugen Bed), taken in this work as the base of the Janusfjellet Subgroup of the Adventdalen Group, extends throughout this sector, the underlying Wilhelmoya Fm is generally about 5 to t0m in the northrn development but may thicken in the southern succession to about 25 m and up to 75 m (Worsley & Mork 1978).

SOUTHWESTERN AND SOUTHERN SPITSBERGEN

De Geerdalen Fm. This typical sandstone facies forms the bulk of the main northern development reaching a thickness of 327 m at Festningen and about 200 m at Van Keulenfjorden. Tschermakfjellet Fin. Whereas this distinctive marine facies is established as a formation it is not noticeable in this northern thicker development but develops in the south up to about 25 m (Worsley & Mork 1978). Sassendalen Gp Botneheia Fro, 210 m (thinning south to 8 cm at Kistefjellet). It is from this section at Bravaisberget (in SW Nathorst Land) that Mork, Knarud & Worsley (1982) renamed the Botneheia Fm (Birkenmajer 1977). Worsley & Mork (1978) divided the formation into two members. Somnovbreen Mbr is coarser grained in which silstones dominate shales. Passhatten Mbr is typical of the Botneheia Fm in the Central Basin with soft black, often bituminous shales with thin siltstone interbeds containing phosphatic nodules. Sticky Keep Fro, 220m up to 278m at Bravaisberget and thinning southwards to 110m. Similarly from the section at Festningen, at the southern entrance to Isfjorden, Mork, Knarud & Worsley (1982) renamed the Sticky Keep Fm at Tvillingodden where it also crops out. It is typically a coarsening-upward unit of siltstones and sandstones with shales. In Bellsund brachiopod-bearing limestones (the Retzia Limestone of Lundgren, 1887) are well known and occur near the base of the formation, possibly correlating biostratigraphically with beds in the underlying formation but occurring in the basal shales of the Sticky Keep Fm. Vardebukta Fm, 290 m thinning southward to 70 m. This formation also becomes coarser near the top where sandstones contrast with the overlying shales. At the bottom the top shales may rest on the resistant Kapp Starostin Fm and are typically obscured. The upper sandstones are cross-bedded, often with carbonate cement and with infilled burrows. In the south two members were proposed (Birkenmajer 1977) which may be the equivalent of the lower (Selmaneset) Member established at Isfjorden (Buchan et al. 1965).

(b) The southern outcrops. The s o u t h e r n outcrops f r o m s o u t h e r n W e d e l Jarlsberg L a n d s o u t h w a r d s are distributed over a complex structural terrane in w h i c h four zones f r o m east to west have been recognized. Thicknesses reduce to less t h a n h a l f that at Festningen. (i) The southern extension of the foldbelt. In the east the familiar stratigraphical relationships within the fold belt c o n t i n u e southwards. (ii) T h e Hornsund H i g h is distinguished by relatively flattying Triassic strata resting u n c o n f o r m a b l y on, a n d truncating, d e f o r m e d P r e c a m b r i a n a n d Early Paleozoic strata. T h e earliest Triassic strata are Dienerian a n d the reduced V a r d e b u k t a a n d Sticky K e e p f o r m a t i o n s are distinguishable, b u t n o t so easily. Therefore M o r k , K n a r u d & Worstey (1982) i n t r o d u c e d the n a m e Kistefjellet F o r m a t i o n to c o m b i n e these two units a n d c o n t i n u e d the easily recognisable B o t n e h e i a F o r m a t i o n using their n a m e (Bravaisberget) for the f o r m a t i o n . In s u m m a r y the succession in zone (ii) is:

Kapp Toscana Gp. As indicated in the northern part of this sector where the De Geerdalen Formation comprises almost the whole of the Group in its thicker development these southern successions contain significant thicknesses of all three formations for example at Treskelen in Hornsund and Kistefjellet in southern Sorkapp Land thicknesses respectively are (Worsley & Mork 1978) Willkelmoya Fm, 20 m and 35 m De Geerdalen Fin, t 15 m and 30 m Tschermakfjellet Fin, 250m and 12m Sassendalen Gp Botneheia Fm is an upward-coarsening sequence divided into three members. Somnovbreen Mbr of fine bioturbated sandstones with carbonate cements. Karentopgen Mbr develops locally (up to 43 m) is of coarse-gained planar cross-bedded sandstones, with conglomerates and large channel-fill structures which indicate sediment transport to the east and southeast. Passhatten Mbr is of dark shales with the characteristic phosphatic nodules of the Botneheia Fm with middle Triassic fossils. Kistefjellet Fin, 38 m. This formation combined the Upper Vardebukta and the Sticky Keep fms in this new name by Mork et al. (1982). Mork & Worsley (1979) had redefined the Brevassfjeltet conglomerate of Birkenmajer (1977) which corresponded approximately to the Vardebukta Fm as below.

183

The main body of the formation is of interbedded fossiliferous shales and medium to very fine sandstones which may contain ripples or carbonate cement. This would correspond to the Sticky Keep Fm. The Vardebukta unit is distinguished by conglomerate beds at the top and base. At the top is the Urnetoppen (conglomerate) Mbr and at the base is the Brevassfjdlet (conglomerate) Mbr. This is a basal conglomerate resting on deformed and truncated Precambrian and Early Paleozoic strata on the Hornsund High. It extends to the west, zone (iii), where it rests on Carboniferous strata. Its age is Dienerian to Spathian or even early Anisian (Mork & Worsley 1979). (iii) West of the H o r n s u n d High, a n d west o f the s o u t h e r n extension o f the H a n s b r e e n F a u l t Z o n e is a wide o u t c r o p of C a r b o n i f e r o u s strata, m a i n l y sandstone, which are relatively fiat-lying. O n these rest the Brevassfjellet c o n g l o m e r a t e s with little obvious discordance. H o w e v e r , the w h o l e o f zones (i) to (iv) have suffered Paleogene tectonism and whereas in zone (i) the Triassic overlie Permian, C a r b o n i f e r o u s a n d D e v o n i a n strata a n d are infolded with them, in zone (ii) they have suffered only relatively horizontal bedding thrusts which are still m o r e obvious in zone (iii). (iv) S o r k a p p o y a a n d T o k r o s s o y a are islands to the SSE o f O y r l a n d s o d d e n the s o u t h e r n m o s t tip o f Spitsbergen w h e r e the Triassic strata are steeply infolded with a p p r o x i m a t e l y c o n c o r d a n t K a p p Starostin F o r m a t i o n strata. T h e strike of these structures, extended n o r t h w a r d s , passes in a N N W - S S E direction t h r o u g h T o k r o s s o y a , O y r l a n d s o d d e n tangentially offshore to the rest o f S o r k a p p L a n d a n d Wedel Jarlsberg L a n d a n d so represents a western fold belt in the West Spitsbergen Orogen. Just to the northeast o f this foldbelt is the small g r a b e n basin of O y r l a n d e t already referred to above.

10.3

P e r m i a n and Carboniferous strata o f southern Spitsbergen

In s o u t h e r n Spitsbergen Late Paleozoic strata occur within the Tertiary fold-and-thrust belt. T h e y are exposed in a thin bett trending N N W - S S E f r o m Akseloya across the western tip o f N a t h o r s t L a n d , across eastern Wedel Jarlsberg L a n d into central S o r k a p p L a n d . Exposures also occur in a separate, small, belt at the s o u t h w e s t e r n tip o f S o r k a p p L a n d a n d extend across to Sorkappoya. T h e C a r b o n i f e r o u s evolution o f the region was c o n t r o l l e d by the presence o f t w o b a s e m e n t highs: the W e d e l Jarlsberg L a n d H i g h a n d the S o r k a p p - H o r n s u n d High. O n the n o r t h side o f the f o r m e r lay the St J o n s f j o r d e n T r o u g h extending f r o m O s c a r II L a n d into Nordenski61d L a n d a n d N a t h o r s t L a n d . H e n c e the rocks in those areas share C a r b o n i f e r o u s stratigraphic n o m e n clature a n d are all described in C h a p t e r 9. Between the two b a s e m e n t highs lay the I n n e r H o r n s u n d T r o u g h , c o n t a i n i n g m o s t o f the rocks described in this section. S o u t h o f the S o r k a p p H o m s u n d H i g h there p r o b a b l y lay a n o t h e r basin, but the resultant sediments are n o t well exposed or described. P e r m i a n rocks b l a n k e t e d the region including the highs, such that the K a p p Starostin F o r m a t i o n can be traced into the area. H o w e v e r , it is n a m e d s o u t h o f the H o r n s u n d H i g h as the T o k r o s s o y a Formation. As elsewhere in Svalbard, the rocks fall into the three groups, as follows.

lh?msow Land Supergp Tempelfjorden Gp Kapp Starostin Fin (correlated with the) Tokrossoya Fm Gipsdalen Gp Treskelen Subgp Treskdodden Fin HyrnefjeHet Fin

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Billefjorden Gp Sergeijevfjellet Fm Hornsundneset Fm Adriabukta Fm E a c h is described below.

10.3.1

Kapp Starostin Formation (Tempelfjorden Group)

T h e K a p p S t a r o s t i n F o r m a t i o n (defined in C h a p t e r 4) is best d e v e l o p e d in n o r t h e r n a n d central Spitsbergen, as it thins a n d d i s a p p e a r s s o u t h w a r d s in S o r k a p p L a n d . H o w e v e r , it did f o r m o n the W e d e l Jarlsberg L a n d High, e x t e n d into the I n n e r H o r n s u n d T r o u g h a n d o n to the H o r n s u n d H i g h , s o u t h w e s t o f w h i c h it was named Tokrossoya Formation. From Nathorst Land (Midterhuken) the Kapp Starostin Fm thins from 385 m to 150 m at Zittelberget in Wedel Jarlsberg Land/Torell Land. There, the three main divisions of the formation can be recognized (Dallmann e t al., B11G, 1990) as follows. The upper Hovtinden Mbr, 80-215m of chertified siltstones and very finegrained sandstones with glauconite, as well as pure spiculitic cherts. The Svenskeegga Mbr, 60-160m contains sandy, sparry limestone with abundant fossil remains, interbedded with some sandstones, rounded quartz and chert-pebble conglomerates and pure chert layers. Some of the limestones show cross-bedding which indicates a variety of current directions. There is also a thin lignite horizon interbedded with the limestones at one locality. The lowermost Voringen Mbr is barely distinguishable, containing only 6-12 m in the north of calcitic fossiliferous packstone. In northern Wedel Jarlsberg Land the sections at Reinodden were described with biostratigraphic detail by Nakazawa et al. (1990). In particular the three members of the Kapp Starostin were characterised in successive beds. Of most interest is their uppermost fossil records from the Hovtinden Member which they correlate with the Chinese sequence where late Permian biotas are better represented and argue Late Leonardian and Early Roadian ages (Ufimian into Wordian). This leaves Capitanian and Lopingian time not recorded. Southwards, the lower two of the three members appears to die out towards the Hornsund High, with a notable decrease in thickness. At Treskelodden (Hornsund), the uppermost Hovtinden Mbr lies directly on the Treskelodden Fm, cutting out the entire Gipshuken Fm. Calcareous siltstones are underlain by basal conglomerates which were deposited on different units of the Treskelodden Fm and infill karst surfaces in the limestones. About 12km further south, the Kapp Starostin Fm is even thinner, only 5.5m at Austjokeltinden. There, fossiliferous, glauconitic, calcareous siltstones, sandstones and limestones occur, with repeated conglomerates and lags containing abraded phosphatic steinkerns, lie on the Treskelodden Fro. There appears to be only one possible explanation to the generalization that in Wedel Jarlsberg Land west of Recherchebreen, Paleozoic through Mesozoic strata are not recorded. The exception would be the blocks of Kapp Starostin facies inland of Calypsobyen near the snout of Scottbreen (Kowallis & Craddock 1982). These are few and limited to a small area, but flat-lying and not tectonized. If they are not erratics they might suggest (i) that mid-Permian rested unconformably on Vendian strata and (ii) that the deformation evident in the Kapp Lyell strata was earlier. Neither conclusion can be certain because the Kapp Starostin Formation is remarkably strong.

10.3.2

Tokrossoya Formation (Tempelfjorden Group)

In s o u t h w e s t e r n S o r k a p p L a n d this f o r m a t i o n c o n t i n u e s the K a p p S t a r o s t i n F o r m a t i o n , w i t h w h i c h it has m a n y similarities. It is at least 400 m thick, a l t h o u g h the base a n d t o p are n o t seen. It consists o f cherts, limestones a n d arenites with an a b u n d a n t f a u n a w h i c h indicates a K u n g u r i a n - W o r d i a n age. It coarsens u p w a r d s overall, a n d was p r o b a b l y d e p o s i t e d in a m a r g i n a l m a r i n e e n v i r o n m e n t . This formation, first described by Siedlecki (1964), consists of sandstone, limestone and chert which occurs in the extreme southwest of Sorkapp Land and on the offshore islands. It was the lateral equivalent of the Kapp

Starostin Fm, preserved in a separate basin southwest of the Hornsund High. It is included as a member within the Kapp Starostin Formation by some authors; for example in the map of Sorkapp (Dallmann et al., CI3G, 1993; Winsnes et al. 1993). The formation consists of about 50% cherts, 30% limestones and 20% arenites of essentially the same lithologies as the Kapp Starostin Fm (see above). Two divisions have been recognized. Fossils are plentiful, but few have been described specifically from this formation. Malecki (1968) described bryozoans, and brachiopods also occur. The fauna correlates with the Kapp Starostin Fm (Malecki 1968). In the earlier description (Siedlecki 1964) the sequence was thought to be the other way up, so Siedlecki's Upper Tokrossoya Beds are equivalent to the Lower Mbr described here. Upper Mbr. This consists of over 200 m of interbedded limestones and arenites containing an abundant, but rather restricted fauna of productids and spiriferids, with two distinct bryozoan horizons. Lower Mbr. This is relatively poorly fossiliferous and consists of 200 m of massive, dark-coloured cherts which are resistant to weathering. On purely lithological grounds, the more arencaceous Upper Mbr may correlate with the Hovtinden Mbr and be of Late Ufimian-Wordian age. The Lower Mbr would then correlate with the Svenskeegga and Voringen mbrs and be of Kungurian-Ufimian age.

10.3.3

Treskelodden (Reinodden) Formation (Treskelen Subgroup, Gipsdalen Group)

T h e T r e s k e l o d d e n F o r m a t i o n was defined in the H o r n s u n d n e s e t area, a n d its equivalent, the R e i n o d d e n F o r m a t i o n was described f r o m Bellsund. S K S ( D a l l m a n n e t al. 1996) has ruled t h a t the T r e s k e l o d d e n F o r m a t i o n , h a v i n g priority ( B i r k e n m a j e r 1959) s h o u l d apply to b o t h . T h e rocks at R e i n o d d e n were described as n a m e d by Orvin (1940) a n d b o t h units were described as n a m e d f o r m a t i o n s by Cutbill & C h a l l i n o r (1965) a n d N y s a e t h e r (1977). It c o n t a i n s cyclic sequences o f yellow, red or b r o w n s a n d s t o n e c o m m o n l y c r o s s - b e d d e d , c o n g l o m e r a t e with q u a r t z a n d chert clasts, limestone sparry or sandy, a n d d o l o s t o n e , c o m m o n l y with p l a n t f r a g m e n t s a n d desiccation cracks at the top. Lateral facies v a r i a t i o n is a characteristic o f the unit, with s a n d s t o n e s c h a n g i n g laterally into l i m e s t o n e or c o n g l o m e r a t e which f o r m only a small b u t significant p r o p o r t i o n o f the total, increasing in i m p o r t a n c e to the south. T h e f o r m a t i o n shows evidence o f d e p o s i t i o n in b o t h m a r i n e a n d terrestrial settings, p r o b a b l y in a n alluvial system at the base a n d a fan delta for the r e m a i n d e r . Tidal channel, intertidal, offshore bar a n d l a g o o n a l facies are all represented. There was an increasing m a r i n e influence u p w a r d s t h r o u g h the f o r m a t i o n . T h e limestones c o n t a i n an a b u n d a n t f a u n a , a l t h o u g h the age is n o t tightly defined. It is p r o b a b l y Late C a r b o n i f e r o u s (Gzelian) to Early P e r m i a n ( A s s e l i a n - S a k m a r i a n ) . (a) Hornsund. The Treskelodden Fm consists of rhythmically deposited sandstones, conglomerates, limestones and dolomites. There is rapid facies variation from west to the east which is complicated by overthrusting during Tertiary deformation. The lower 20-50m appear to be unfossiliferous, in contrast to higher levels which are rich in fossils, notably corals. Nysaether (1977) attempted a litho-correlation of the lower unit of his 'Drevbreen beds' with the upper Treskelodden Fm which he considered is their partial lateral equivalent and downward continuation. He correlated the latter lithostratigraphically with his Reinodden Fm. The type section is at Treskelodden, Hornsund, where the sequence is 129 m. The formation has a limited outcrop, largely confined to inner Hornsund, although some outcrops occur inland; in west-central Torell Land it is 185 m at Polakkfjellet where the top of the formation can be seen. It appears to thin rapidly onto the Hornsund High and is only 50 m at Kopernikusfjellet and 70 m at Urnetoppen. South of Hornsund, 280 m of coarse clastics at Bautaen possibly belong to the Treskelodden Fm and the formation appears again further south at Ausjokeltinden where 125 m are exposed (Hellem & Worsley 1978). To the east it is obscured by younger strata and northwards it seems likely that this facies is replaced by carbonate of the Tyrrellfjellet Mbr (Wordiekammen Fm). The upper boundary is the unconformity below the siliceous Hovtinden Mbr of the Kapp Starostin Fm. In the Hornsund area, the Hovtinden Mbr is cut out westward by the Triassic unconformity and locally Triassic shales rest on the Treskelodden Fm. There is evidence of erosion on the top surface

SOUTHWESTERN A N D SOUTHERN SPITSBERGEN of the uppermost beds. However, at Polakkfjellet the top can be seen to be conformable beneath the Gipshuken Fm which has not been eroded here (Birkenmajer 1977, fig. 15). According to Birkenmajer (1984), the lower boundary is unconformable on the red conglomerates and sandstone of the Hyrnefjellet Fro, which is probably of Carboniferous age. Prior to Birkenmajer's detailed account, the lower boundary was considered to be transitional to the Hyrnefjellet Fm, which, except for the colour, is lithologically similar to the lower Treskelodden Fm. Sandstones make up the bulk of the formation (60%). They are commonly calcareous, and in the upper part are closely interbedded with, and pass laterally into, limestones. They are hard, compact, and generally well-sorted, but conglomeratic lenses and layers are common. Large colonial and solitary corals are present. Cement is usually calcite or quartz. In the lower part sandstones pass westwards into conglomerates. There are some ferruginous horizons. South of Hornsund, the sandstones become increasingly conglomeratic and they pass into conglomerates, which make up about 10% of the whole formation. Thin bands of extremely heterogeneous, poorly rounded and sorted conglomerate contain pre-Devonian and possibly Early Carboniferous pebbles. The conglomerate of the lower part of the formation consists of quartz and pre-Devonian pebbles with fair sorting and rounding. In the structural unit south of Hornsund, over 200m of texturally mature, grain-supported, massive quartz conglomerate occurs. Its base is not seen and it is overlain by Early Triassic rocks, (possibly overthrust), so its relationship to the rest of the Permian sequence is not known. Gjelberg & Steel (1981) described it as the 'Bladegga conglomerate', underlying the Hyrnefjellet Fm and considered it to belong to the Carboniferous sequence. Further south still, at Austjokeltinden in Sorkapp Land, 125m of Treskelodden F m are exposed beneath the Kapp Starostin Fm, consisting of conglomerates, sandstones and minor shales. A fossiliferous horizon here is the uppermost shale, which contains corals (Hellem & Worsley 1978). The fossiliferous limestones constitute 25% of the formation and appear in the upper part as thin interbeds in the predominantly arenaceous sequence. They contain large coral colonies, solitary corals and brachiopods. At the top of the formation a thicker limestone occurs. The limestones are generally grey calcarenites and biocalcarenites, and may grade into calcareous sandstone. There are some horizons of dolomite and thin red shale. The rocks are arranged in predominantly upward-fining cycles on both a large and small scale, described in detail by Birkenmajer. Fossiliferous (coral-bearing) conglomerates and biogenic limestone are generally confined to the base of the cycles. They usually show sharply delimited erosional bases and commonly begin as channels cutting into the top part of the preceding cycle. The middle part of the cycle is dominated by calcareous sandstone and quartzite, with large-scale planar cross-bedding and subordinate conglomerates. The tops of many cycles are characterized by fine sediments with plant fragments and desiccation cracks. This part of the cycle is commonly missing in many cases due to intraformational erosion. Some dolomitic limestone or dolomite intercalations, devoid of fossils, occur in the highest parts of the formation, near the evaporites of the overlying Gipshuken Fro. At Svartperla, in the northeast of the area, 200m of deformed limestones were recorded by Birkenmajer (1964). This possibly suggests that there is a gradation into limestones in this direction. Palaeontology and age. The upper two thirds of the formation contains a diverse fauna including abundant brachiopods, and corals as well as trilobites, bryozoans, crinoids, bivalves, gastropods, nautiloids, foraminifers, trace fossils of marine worms, calcareous algae and land plant detritus. The lower part is unfossiliferous, except for indeterminable plant remains. Czerniecki (1969) concluded that the brachiopod assemblage has a Gzelian age although comparison of his species with those listed by Gobbett (1964) shows a much closer comparison with the ~Tyrrellfjellet Mbr (Asselian/Sakmarian) that had already been noted by Gobbett. The limestones in the upper part of the formation contain an abundant redeposited coral fauna, which was described by Fedorowski (1965, 1967) and Birkeumajer & Fedorowski (1980). This fauna is quite different from that of the Carboniferous Cadellfjellet Mbr which is beneath the Tyrrellfjellet Mbr and would seem younger. This supports evidence from the brachiopods. The fauna is dominated by the typically Permian genera Wentzelella and Londaleiastraea, and as Sakmarian species, common to the Tyrrellfjellet Mbr, seem to form a relict group; the age was revised to earlier Permian. The corals resemble Early Permian rugose corals of the Arctic Province. They also show an affinity to those of the Hambergfjellet Fm (Sakmarian-Artinskian; Fedorowski in Simonsen 1987).

185

Of the trilobites present, the Ditomopygae species has a close relative in the Gzelian Stage of Russia. A gastropod reported by Karczewski (1982) is very weak supporting evidence for a Permian age. A number of foraminifers were identified by Liszka (1964). Unfortunately, index fusulinids are lacking, and no direct comparison with the zones of Cutbill & Challinor can be made. The assemblage resembles the Asselian/ Sakmarian Schwagerina and Tastubia zones of the Urals. Nysaether (1977) from a litho-correlation with his Drevbreen beds, made the upper Treskelodden Fm equivalent to the lowermost Drevbreen beds in which he found Late Carboniferous (Gzelian) foraminifers. However, the fossil evidence make it seem more likely that the fossiliferous part of the Treskelodden Fm is laterally equivalent to the middle and upper Drevbreen beds and also the Tyrrellfjellet Mbr which are probably all early Permian in age. The lower, unfossiliferous beds may belong to the Late Carboniferous period. The presence of bioherms in the upper part was mentioned by Birkenmajer (1984); This provides a link with the lower Tyrrellfjellet Mbr and the Kapp Dun6r Formation of Bjornoya.

(b) Bellsund (e.g. at R e i n o d d e n ) The succession consists of alternating sandstones, siltstones, limestones and dolomites with subordinate amounts of conglomerates and shales, of which terrigenous clastics make up about 75% and carbonates 20% (Nysaether 1977). A more or less cyclic pattern is present, starting with carbonate followed by generally upward-coarsening clastics. The formation occurs below the Gipshuken Fm from Bellsund southwards until it is cut by the unconformity below the Hovtinden Mbr of the Kapp Starostin Fm. Nysaether (1977) correlated the formation at Ahlstrandodden with the Drevbreen beds which he described at Drevbreen in Torell Land. The formation is generally about 200 m thick, but on Kopernikusfjellet, only 15km south of Zittelberget, where it is of similar thickness, the formation is represented by only 35 m of conglomerate. Moreover, a similar distance of the south-southeast, the Drevbreen section has 180 m exposed. The top of the formation is marked by a conformable transition from grey carbonate above, belonging to the Gipshuken Fm. The base is unconformable and rests on Early Carboniferous rocks at Reinodden and directly on pre-Devonian basement elsewhere. The formation becomes increasingly conglomeratic towards the south, while north of Bellsund it appears to pass into the carbonates of the Tyrrellfjellet Mbr. The sandstones, which occur throughout, are well sorted, unimodal and fine- to medium-grained, with colours varying from brown to yellow, grey and reddish. They are predominantly quartzose and commonly conglomeratic. Cement is usually calcite or dolomite, occasionally chert. Rock fragments of chert, quartzite and quartz-schist are common. Feldspar is present, but not common, and heavy minerals are rare. The sandstones are thin- to thick-bedded with some cross-stratification. The conglomerates occur as lenses or well-defined thin beds throughout. They are composed of angular and well-rounded quartz, chert and quartzite pebbles which are usually less than 3 cm in diameter. The matrix is generally medium-grained sand. The shales are silty and fairly pale, green to dark grey, and are interbedded with the sandstones, especially in the upper part. The interbedded carbonates are thin to thick-bedded. The limestones are highly fossiliferous, sparry and sandy in the lower part at Drevbreen, though no fossils have been recorded elsewhere. At the top they are micritic, bioturbated, slightly bituminous and contain chert nodules; elsewhere they are of fine texture. Stylolites are common. The dolostones are grey, micritic and sandy, in places silicified and comonly vuggy with silica and dolomitefilled geodes locally. Nysaether (1977) distinguished upper, middle and lower units at Drevbreen on the basis of the type of carbonate present. The topmost 27 m contains only limestone, some of which is slightly bituminous, with chert nodules and a sparse fauna of bivalves and gastropods. The middle unit, 83 m thick, is characterized by dolostones containing corals, limestones being absent. Some of the dolostones are silicified and many are vuggy, with silica and dolomite-filled geodes in the upper part. In the lowermost 70 m exposed, the carbonates are almost exclusively limestone with abundant and varied fossils. Palaeontology and age. Almost the only fossils recorded from this formation are from Drevbreen where corals, brachiopods, crinoids, gastropods, bryozoans and fusulinids have been found in the lower unit (Nysaether 1977). The rich fusulinid fauna is of Late Carboniferous (Gzelian) age except at the top of this unit where there is a possible

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transition to Asselian (Permian) affinities. The middle unit contains only corals, other fossils perhaps having been destroyed by dolomitization, while the upper unit has only a few gastropods and bivalves in the limestones. If the top of the lower unit marks the Carboniferous-Permian boundary, then the higher two units must be earliest Permian. Corals were reported in sands at Ahlstrandodden by a CSE party in 1985. Thus Nysaether's lithocorrelation with the Drevbreen beds is crucial to the dating of the Reinodden Fm. As the Drevbreen beds underlie Gipshuken Fm lithologies at Drevbreen, it seems a logical correlation.

10.3.4

Hyrnefjellet Formation (Treskelen Subgroup, Gipsdalen Group)

Exposed t h r o u g h o u t the H o r n s u n d area, the Hyrnefjellet F o r m a tion (Birkenmajer 1959; Cutbill & Challinor 1965; Siedlecka 1968; B i r k e n m a j e r 1964) is variable in thickness f r o m 30 m to 500 m. It is d o m i n a t e d by r e d - b e d s - m u d s t o n e s , sandstones, c o n g l o m e r a t e s a n d breccias, a l t h o u g h white quartz-rich sandstones and conglomerates b e c o m e increasingly significant t o w a r d s the top. It is also characterized by rapid lateral facies variations. In general there is m o r e c o n g l o m e r a t e in the west and southwest f r o m where the sediment is t h o u g h t to have been derived. The coarser lithologies c o m m o n l y show large-scale cross-stratification, channelization and erosive structures. Clasts include quartzite, limestone, dolostone, schists and red-beds; all are p r o b a b l y derived from a D e v o n i a n source. D e p o s i t i o n o c c u r r e d in a fluvial alluvial fan e n v i r o n m e n t , with channel, overbank, point-bar a n d possibly lacustine deposits present. Evolution o f the basin was controlled by local tectonics, resulting in occasional m a r i n e incursions. N o fauna have been f o u n d in the f o r m a t i o n to date, but it is considered to be of Late C a r b o n i f e r o u s age on the basis of regional correlations. The formation is not widely exposed, seen well at Kopernikusfjellet, and is controlled by Paleogene structures. It consists of 30 m of conglomerates there, 95m at Urnetoppen and about 70m are exposed at Hyrnefjellet. Thicknesses increase rapidly southeastwards to about 270 m at Adriabuka. Gjelberg & Steel (1981) gave a thickness of over 500m. The upper boundary of the formation is an unconformity at the base of the Treskelodden Fm, which separates the predominantly grey deposits of the Treskelodden Fm from the red Hyrnefjellet Fm (Birkenmajer 1984). The formation rests on deeply weathered and eroded shales of the Early Carboniferous Adriabukta Fm on Urnetoppen. It is not known elsewhere. The succession is characterized by repeated upward-coarsening sequences in which texturally immature red clastic sediments (mudstones and sandstones grading up into conglomerates and breccia) are overlain by texturally mature white quartzitic sandstones and thin conglomerates which increase in volume upwards. Three major lithotypes occur, sandstones (60%), conglomerates (30%) and shales (10%), rhythmically interbedded throughout the formation. They show rapid lateral facies variation and become more conglomeratic to the southwest. Red and pink sandstones, fine to coarse-grained and commonly cross-bedded and lenticular, predominate in the section on Hyrnefjellet but are less common to the west, where thicker rudaceous rocks occur. Finer grained rocks are more common to the east and north. The colouration is due to the relative abundance of hematite and ilmenite, which may be partly due to the derivation of these rocks from the ferruginous Devonian deposits. Cementation is commonly siliceousferruginous in the lower part, with the appearance of carbonate and sulphate higher up. Porosity is usually low. In contrast, at the top or base of the sandstone-conglomerate cycles, well-sorted, pale, quartzitic, fine- to medium-grained sandstones occur, showing occasional large-scale crossbedding (wedge, trough-shaped or planar), with white quartz-conglomerate intercalations. The red conglomerates which occur interbedded with the sandstones in the cycles are more predominant in the west. The beds are irregular, commonly lenticular and generally less than 1 m thick. Large-scale crossbedding is a frequent feature and the conglomerates usually fill channels eroded in the siltstones and shales. The conglomerates became finer upwards, passing into sandstones. The topsets of these cross-bedded units are commonly truncated by erosion. The matrix is usually red and arenaceous. Clastics are usually less than 10cm across, but may be up to 3 m. They consist of white or grey rounded quartz and sub-rounded to highly angular red and black sandstones. The clasts consist of white, pink,

grey and yellow quartzites, limestones, dolomites and schists as well as red quartzitic sandstones. The sandstone clasts may be intraformational, or derived from Devonian strata. The other lithologies are almost certainly derived from pre-Devonian rocks. A decrease in sorting and an increase in angularity occurs in a southwesterly direction, with a transition to very poorly sorted, angular breccias. At the base of the formation at Adriabukta and also at Meranpynten to the south, on the strongly weathered top of the Adriabukta Formation, are red medium to coarse breccias/conglomerates with angular to sub-angular fragments of red, yellowish and pink sandstone, 2-60 cm in diameter, and some 1-3 cm diameter rounded quartz pebbles, contained in a similar, but finer matrix. Stratification is absent and the fragments are chaotically arranged, with no imbrication. Horizontally bedded siltstones and shales form a minor constituent of the formation, but become more important to the east. They are red, purple and variegated due to the presence of iron oxides, and in general have the same mineralogy as the sandstones. Clay minerals are almost entirely absent, although muscovite, sericite, biotite and chlorite occur with finely divided quartz. Occasional ripple-marks can be found, some irregular and parallel, others of linguoid form. Casts of irregular large desiccation cracks up to 100cm in diameter occur at the base of the sandstones in places and small cracks are found in the siltstones. Truncated, convolute lamination, associated with fine-grained, laminated sandstones is also present in places. Palaeontology and age. The only recorded fossils are conifer branches found in the highest part of the succession at Treskelen (Birkenmajer 1984). As it is lies beneath the Treskelodden Fm, it may be of Late Carboniferous age. It is possible that it is the lateral equivalent of the lower Reinodden Formation/Drevbreen Beds, which are also cyclic and upward-coarsening. The lower unit of the Drevbreen beds is of Late Carboniferous age (Nysaether 1977). The formation post-dates the Early Carboniferous Adriabukta Fm (Tournaisian/Visean) and the Adriabukta tectonic phase which folded it, so may be Bashkirian to Moscovian in age. Cyclic conglomeratic red-beds are also found interbedded with marine sediments in the Bashkirian Ebbadalen Formation and the Bashkirian-Moscovian Landnordingsvika Fm, which could well be its lateral equivalents in central Spitsbergen and Bjornoya respectively. The Ebbadalen Fm also contains evaporites, which provide another environmental link in view of the sulphatic cement in the higher levels of the Hyrnefjellet Fm. The Moscovian Pyramiden Conglomerates (Minkinfjellet Fm) of central Spitsbergen, which overlie the Ebbadalen Fm are another possible correlative. They also contain conglomeratic red-beds derived from the west, interbedded with evaporites and marine carbonates. Similarly, the Moscovian T~rnkanten Fm of the Isfjorden area has cyclic red beds and marine limestones.

10.3.5

Sergeijevfjellet Formation (Billefjorden Group)

The Sergeijevfjellet F o r m a t i o n (Siedlecki 1960) consists of approximately 180 m of shales with fine-grained sandstones and siltstones. The sandstones are cross-bedded in places, the shales contain a b u n d a n t plant debris, and thin coals are c o m m o n . They were clearly deposited in a fluvial e n v i r o n m e n t with localized flood basins and swamps. T h e r e was no m a r i n e influence. It is of Early C a r b o n i f e r o u s age, p r o b a b l y Serpukhovian, although this is not well-defined. Early Carboniferous deposits in the northern Sorkapp Land-Hornsund area have been known since early investigations (Nathorst 1910; Freebold 1935; Orvin 1940). Siedlecki (1960) originally recognized the Sergeijevfjellet beds as a distinct unit, and they were given formation status by Cutbill & Challinor (1965). This is the youngest formation of the Billefjorden Group in this area. It crops out mainly in northwest Sorkapp Land and has also been recognised further east at Tsjernajafjellet.The formation lies beneath Triassic sandstones in northwest Sorkapp Land, separated by an angular unconformity. Further east, west of Tsjernajafjellet, it appears to be conformably overlain by the Bladegga Conglomerates (?lower Hyrnefjellet Fm: see Gjelberg & Steel 1981). The base of the formation is conformable with the massive sandstones of the Hornsundneset Fm. Siedlecki (1960) described the sequence on Sergeijevfjellet, which may be taken as the type section. The lithology is shaley: lighter grey and yellow to black shales, with intercalation of grey and brown fine-grained sandstone and siltstone. These latter interbeds are generally less than 30 cm thick, except for three major sandstones, 30, 20 and 15 m above the base. Some of the sandstone units are cross-bedded. Plant detritus is found in the shales,

SOUTHWESTERN AND SOUTHERN SPITSBERGEN especially in the upper part of the sequence. A coal seam 0.95-1.0 m thick occurs near the top of the section on Sergeijevfjellet, overlying carbonaceous shale. Additional coals, which are thin and clayey, are found in the black shales at the base of the formation. These shales also contain limonitic concretions. The shales contain plant fragments, including imprints of Stigmaria and stems of Lepidophyta. The formation has yielded abundant miospores (Siedlecki & Turnau, 1964) that indicate an Early Carboniferous age, probably earliest Serpukhovian (though possibly Late Visean-Late Serpukhovian). The assemblages found do not show any clear correlation with those described by Playford (1962, 1963) for the Billefjorden Group of Central Spitsbergen. Turnau suggested that this may be due to the younger age of the Hornsundneset and Sergeijevfjellet Fm.

10.3.6

Hornsundneset Formation (Billefjorden Group)

Originally recognized as a distinct unit by Siedlecki (1960), a n d given f o r m a t i o n status by Cutbill & Challinor (1965) this is the thickest, (750 m) and m o s t coarse-grained unit of the Billefjorden G r o u p in southern Spitsbergen. It is d o m i n a t e d by fine- to m e d i u m grained sandstones, a l t h o u g h granular a n d pebbly sandstones also occur. Clasts are derived f r o m P r e c a m b r i a n basement. Plant remains are c o m m o n a n d thin coal seams are present in places. It was deposited in the Early C a r b o n i f e r o u s (probably late Visean to early Serpukhovian) within an alluvial system, p r o b a b l y by braided streams. There is no evidence of a m a r i n e influence. The Hornsundneset Fm is a sequence of largely arenaceous around 700-750 m thick in the type area of northwest Sorkapp Land. It has been noted in inner Hornsund where it is 500-700 m. The formation lies conformably below the Sergeijevfjellet Formation. The lower boundary is a 60 cm quartzitic conglomerate lying unconformably on pre-Devonian basement in the type area. However, in inner Hornsund it overlies the Adriabukta Formation, apparently conformably (Gjelberg & Steel 1981). Siedlecki & Turnau (1964) and Birkenmajer (1964, 1979) showed the formation to consist predominantly of light grey, light yellow and brown quartzose sandstones, which are generally fine- to medium-grained although grain-size ranges up to 5 ram. They are thick-bedded (0.25-2.0 m), blocky and commonly contain large-scale cross-bedding (10-100 cm sets) which are generally indicative of eastward-flowing currents. The cement is siliceous, clayey or sideritic. Locally, plant impressions are common. Pebble-lag conglomerates occur occasionally at the base of the sandstone units in the lower part of the sequence and at the base, where it lies on pre-Devonian basement. They are slightly imbricated, and pebbles consist of rounded quartz and angular local Precambrian basement fragments. Inter-bedded layers up to 1 m thick of dark-grey, fine-grained sandstone, siltstone and shale occur in places, especially at the base. The dark colouration is due to the presence of carbonised plant remains and there are local coal seams. Plant remains have a widespread occurrence: Stigmaria and Lepidophyta (probably Cordaitales) have been found in the sandstones which indicate an Early Carboniferous age. Miospores have been investigated (Siedlecki & Turnau 1964) and, although not abundant, also indicate an Early Carboniferous age, probably earliest Serpukhovian, although possibly Late Visean.

10.3.7

Adriabukta Formation (Billefjorden Group)

U n c o n f o r m a b l y overlying D e v o n i a n basement, the A d r i a b u k t a F o r m a t i o n (Birkenmajer & T u r n a u 1962; Cutbill & Challinor 1965) consists of black, d a r k grey a n d green 'unfossiliferous' shales. Some thin sandstone interbeds and c o n g l o m e r a t e lenses are present. The unit was deposited in a shallow near-shore m a r i n e e n v i r o n m e n t , in a basin that b e c a m e increasingly restricted and possibly a n a e r o b i c later in the deposition of the formation. Plant imprints are quite c o m m o n and a p o o r l y preserved bivalve f a u n a has been found. As in the overlying two formations, the age is poorly defined but is p r o b a b l y T o u r n a i s i a n to Early Visean. The Adriabukta Fm crops out in the inner Hornsund area and Sorkapp Land, south of Treskelodden. It is absent in northwest Sorkapp Land,

187

where the Hornsundneset Fm lies directly on basement. This incompetent formation suffered severe deformation as a thrust horizon during the Paleogene West Spitsbergen Orogeny. Thicknesses are thus difficult to measure, but at least 500 m are present in central Sorkapp Land, thinning to about 300m in Adriabukta. The formation appears to lie conformably beneath the Hornsundneset Fm on Hyrnefjellet and in Sorkapp Land, but mid-Carboniferous uplift has, however, caused erosion of the top of the formation in places, where it is overlain by Triassic strata and the Hyrnefjellet Fro. It has a basal angular unconformity (of 10-20 ~ on both Devonian and pre-Devonian basement. The formation, which is about 300 m thick in the type section, consists predominantly of black, dark-grey and dark-green unfossiliferous shales. Thin arenaceous intercalations are quite common, these are generally poorly sorted, fine-grained sandstones which are usually less than 15 cm, but may be up to 50 cm thick. Graded bedding has been observed in some of these sands. Conglomerate lenses and layers, up to 2 m thick, also occur in the lower half of the sequence. They consist of angular and sub-angular quartz pebbles 0.5-5.0cm in diameter, contained in a sandy matrix. North of Adriabukta, there are basal conglomerates 2-3 m thick, lying unconformably on Devonian sandstones. The bottom 25m of the formation at Adriabukta is more arenaceous. It consists of grey, fine-, medium- or coarsegrained sandstones in beds 2-50cm thick, alternating with subordinate black arenaceous shales and conglomerates. The sandstones show crossbedding and the bottom of some beds contain groove- and prod-casts. A poorly preserved assemblage of unidentifiable concentrically-ribbed bivalves was reported by Birkenmajer (1964) from the basal arenaceous beds on Marietoppen (north of Adriabukta). The basal beds also contain frequent plant imprints, generally Lepidophyta, including Stigmaria 2-3 cm wide and up to 50 cm in length (Birkenmajer & Turnau 1962). Miospores (Birkenmajer & Turnau 1962) indicate an Early Carboniferous age. The occurrence of Velosporites echinatus in one of the lowermost samples (Sample A1) may indicate a Tournaisian age for this assemblage while Turnau stated that the presence of Densosporites cf. granulosus Kosanke in the lower sample (Sample A2) suggested a Visean age. However, a Tournaisian/Early Visean age for the lower samples (A1 & A2) is quite consistent with other palynological data. The sample taken from higher up in the shale sequence (Sample A3), yielded a much wider variety of miospores which indicate an Early Visean age.

10.4

Devonian strata

D e v o n i a n strata, so well developed in n o r t h e r n Spitsbergen (Chapter 8), a p p e a r n o r t h of H o r n s u n d a n d south in S o r k a p p L a n d as one f o r m a t i o n . The n o r t h e r n o u t c r o p has been described by B i r k e n m a j e r (1964) a n d the s o u t h e r n by D a l l m a n n et al. (C13G, 1993). B i r k e n m a j e r noted early historical events with the discovery o f the o u t c r o p by de Geer in 1899 a n d soon confirmed as D e v o n i a n (1910) a n d reported by N a t h o r s t (1910). T h e y were m o r e fully described by H o e l (1922, 1929) a n d included in the general a c c o u n t by Orvin (1940). Monaspis fragments (Heintz 1929) a n d ostracodes (Solle 1935) m a t c h e d the W o o d Bay F o r m a t i o n in the north. Orvin t h o u g h t that bivalves resembled G r e y H o e k F o r m a t i o n forms a n d suggested that the lower 150 m of red beds, limestones and c o n g l o m e r a t e s m i g h t correlate with W o o d Bay and the u p p e r d a r k 200 m unit with Grey H o e k strata, both m i d d l e D e v o n i a n . Sandstones and shales were taken as G r e y H o e k . Orvin postulated a substantial D e v o n i a n thickness south of the m a i n basin, to the north. T h e r e m a y have been a further 650 m as estimated, by B i r k e n m a j e r a n d possibly of W i j d e f j o r d e n F o r m a t i o n age with d a r k grey a n d black clastics.

Marietoppen Fm. Birkenmajer (1964) introduced the name Marietoppen for these rocks now referred to as a formation and described it as follows. Upper Mbr, 150-200m of green, grey-green or black shales cleaved and slightly phyllitized. Undetermined bivalves were collected (F6yn & Heintz 1943). Fish were found in 1960 (tuberculated arthrodire bones, Porolepis plates, holoptychiid scales and crossopterygian teeth). Only the lower part of the Grey Hoek Formation may be represented here. This is suggested by the bivalve ?Myalina formed in the Forkdalen Member of the Grey Hoek Fm. Murashov & Mokin (1979) correlated it with the Wijde Bay Fm.

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Middle Mbr, 550m of alternating green and red, often variegated arenaceous shales in layers 0.1-1 m intercalated with thin, yellow and pink, silty limestones of which the three uppermost yielded indeterminate ostracods, fish plates and teeth. There are no outcrops of this member north of Marietoppen but south of Hornsund the member probably occurs. Various (some problematic) finds of fossils led Birkenmajer to conclude that the member correlates with the Wood Bay Formation. Murashov & Mokin (1979) suggested Grey Hoek Fm age. Plant remains suggested Givetian age. Lower Mbr, 300-350 m of typically red (hematite) fine-grained sandstones, siltstones and arenaceous shales as well as calcareous sandstones and arenaceous limestones, the latter two facies are often nodular. There are also some variegated sandstones and quartzite with current bedding. Sedimentary breccias occur and may contain Porolepis type fragments. Fossil fish in the lower part of this Middle Division may correlate with the upper Wood Bay (i.e. Stjordalen Division). This is the most reliable biostratigraphic age estimate. At the base is a quartz conglomerate or sedimentary breccia with fragments of limestones and cherts from the underlying strata beneath an unconformity surface. Correlation of this unit is most likely with the Wood Bay Formation except that the Lower Wood Bay strata are not represented here. Birkenmajer (1964) gave detailed sections and profiles of this member in different localities. The later publication (Dallmann et al. 1993) concerns the outcrops in narrow strips on both sides of Samarinbreen south of Hornsund. The structure here is probably synclinal, the axis being occupied by the glacier and appears to have formed in Late Devonian or Early Carboniferous t i m e - probably Late Devonian Svalbardian diastrophism. Beyond this syncline erosion has removed Devonian strata. South of Hornsund the thickness of the Marietoppen Fm is about 800 m with possibly more beneath the glacier, compared with 1000m to the north. The lower contact is a distinct angular unconformity on metamorphic basement often with a weathered horizon and local basal polymict conglomerate or breccia with boulders up to 1 m.

With its descriptive text it addressed this problem thoroughly with extensive structural observations (Hjelle, Lauritzen, Salvigsen & Winsnes 1986). In the meantime Russian geologists had made general and geochemical observations (Turchenko et al. 1983). Hjelle had already noted the similarity between the metabasites and those of Chamberlindalen in north Wedel Jarlsberg Land and Turchenko extended this comparison with the basites in southwest Wedel Jarlsberg Land. Krasil'shchikov & Kovaleva (1979) made a different and comprehensive scheme for the whole of the west c o a s t depending heavily on the Polish work, extending it from the south. Barkhatov (1985) argued for a Vendian Complex with tillite and an older complex, but not mapped. The main difference between the above and a later interpretation (Harland, Hambrey & Waddams 1993) is that whereas the earlier authors agree that the tilloids at Kapp Linn6 in the north are Varanger glacial deposits (being rich in granitoid stones), Harland e t al. identified them with the Later Varanger glacial epoch. They correlated the diamictites and conglomerates in the south of Nordenski61dkysten with the earlier Varanger tillite horizon partly because they lack granitoids and are closely associated with basites. It was then postulated that most of the other rock units were found between the two tillite horizons and therefore that almost the whole outcrop of older rocks is of Early Vendian, i.e. Varanger age. As stated by Harland e t al. confidence in their interpretation here is less than that either north of Isfjorden or south of Bellsund. It is to a large extent influenced by comparison with these adjacent areas. Nevertheless this hypothesis was applied to describe the succession, while commenting on alternatives. The interpretation entails one major thrust fault from eastern Van Muydenbukta northwest and out to the sea north of Orustosen. This displaces the successions on either side and makes a feasible succession from the map.

10.5

10.5.1

Proterozoic strata of western Nordenski61d Land

Western Nordenski61d Land (west of Gronfjorden) boasts the classic Festningen section along the Isfjorden coast where Paleogene down to early Carboniferous strata are displayed in a sequence younging eastwards. The Orustdalen Formation rests with steep angular unconformity on the older rocks, which occupy a wide strandflat west of the mountains along which this unconformity is exposed south to Bellsund. To the west of this line, this strandflat, rarely exceeding 50 m in height above sea level, is named Nordenski61dkysten and is entirely occupied by Proterozoic rocks, save for at least two infaulted outliers of Carboniferous rocks. This line marks the western edge of the Central Basin. A convenient limit to our study area for this section is Gronfjorden to the north and Fridtjovbreen draining down into Fridtjovhamna in the south. This is approximately along the line of strike of the rocks which, continuing southwards across Van Mijenfjorden, include the remarkably linear Akseloya in our area and the western tip of Nathorst Land further south. So the area is neatly divided by the N - S unconformity into the Precambrian outcrop of Nordenski61dkysten, with the tip of Nathorst Land in the west and the obvious foldbelt with Carboniferous through Cretaceous rocks occupying the mountain front. Following the primary survey by Nathorst (1910), the principal investigations of this area have been carried out by Norsk Polarinstitutt geologists resulting in the following publications. Orvin's (1940) outline of Spitsbergen Geology paid particular attention to the western foldbelt and the basites which characterise the older rocks in the western coast. A planned series of investigations led to the definitive description of younger rocks at the Festningen section (Hoel & Orvin 1937). A general idea of the presence of tilloids and conglomerate at Kapp Linn6 and in the south at Kapp Martin was familiar. However, the first systematic survey of the whole of Nordenski61dkysten was by (Hjelle 1962, 1969) who took into account earlier Norwegian work. This work was later consolidated in the 1 : 100 000 geological maps with descriptions and, in particular, sheet B10G.

Sequence of the rock units

Kapp Linn6 Fm, 1+ km. Hjelle (1962) named the northern diamictite the 'Kapp Linn6 Tillite Series'. The top of the formation is not preserved being synclinal. The rock is stone-rich in an orange to grey-weathering psammitic schist, with thin greenish grey-weathering schist and sandy dolostone interbeds. Alternation with thicker more quartzitic layers up to 15 mm thick gives a visible banding. The stones are mainly quartzites, dolostones and granites. The base of the formation is at B~todden (B~todden member). Linn6fjella fro/unit, 1.2+ km. The outcrop in fig. 37 of Harland et al. (1993) is taken from Hjelle et al., B10G, (1986) and numbered '5?' and '3-4'. Hjelle (1962) proposed the name Linn~fjella for this thick conformable sequence of phyllite and quartzite with limestone beds. Malmberget unit/fm. Below the Linn&jella strata the map (B10G) shows three numbered units (3) limestone marble as at Malmberget; (2) phyllite; (1) quartzite as at Jainbreen. Hjelle et al. regarded this succession as comprising the lowest units in the area because they equated diamictites and conglomerates both north and south of the strandflat. For this unit the name: Malmberget fm with the three members 1 2 and 3 is tentatively suggested. L~gnesbukta Gp. Four formations are grouped here (Harland, Hambrey & Waddams 1993) and altogether are correlated with the Earlier Varanger glacial episode. L~gneset Fro. This is the Lfigneset tillite of Hjelle (1962, 1969) and is unit 10 of Hjelle et al. (1986). It is included in the Vendian tillite conglomerates of Turchenko et al. (1983) - their unit 8. It is well displayed at six localities other than L~gneset and includes the diamict formation at Slettneset and at Millarodden. At Lfigneset two N-S bands 70-90 m thick are separated by 100-125m of calcareous phyllite, white marble, oolitic limestone and pale green chloritic schistose diamictite. The two bands cropping out may be repeated by folding or faulting. The stones are mostly dolostone, quartzite and limestone with diameters typically 20-100 ram. Sedimentation was probably by ice rafting into a shallow carbonate sea with clastic and basic tuff input. The diamictite at Millarodden is correlated with this unit.

SOUTHWESTERN AND SOUTHERN SPITSBERGEN Diabaspynten is dominated by dark green amphibolite, probably lava flows and related tufts. They were noted by Orvin (1940) as gabbros along the west coast. Gravsjoen unit/division. This unit of varied facies is dominantly phyllites with metavolcanics and quartzites associated with massive basites. Thinner beds of dolostone and limestone are also present. Hjelle et al. mapped these rocks as units, 7, 6 and 9. From their map the unit would underlie the L~tgneset Formation. L~gnesrabbane Fro, 1-2 km. Following Hjelle (1969), his LSgnesrabbane calcareous beds are placed above the Kapp Martin conglomerates. The formation comprises two members. Upper (limestone) Mbr (light grey, laminated, partly oolitic interbedded with calc phyllite, black phyllite, white crystalline marble and minor conglomerates. Lower (dolostone) Mbr, 600 m, is a thick stone-free dolostone 600 m thick forming the rocky headlands west of Kapp Martin. Kapp Martin Fro, 800 m. This formation is dominated by massive polymict conglomerate occurring in beds 0.05-4 m thick in an assemblage of phyllites coarsely crystalline black limestone and subsidiary quartzite and dolostone. Waddams (1983) suggested deposition from sediment flows from material released by ice on an unstable slope.

10.5.2

Mineralization

Mineral occurrences, mainly of sulphides, invited mining that proved uneconomic. They occur by the coast at the northern and southern limits of the area. The rocks in between may also repay further investigation (Hjelle 1962). In the north at Kapp Mineral 2.5 km east of Isfjordradio Flood (1969) reported on the early workings where galena and some sphalerite occur in intensively brecciated rock in a zone a few metres wide near a fault zone. Further investigation showed the presence also of pyrite and chalcopyrite. However, continuation at depth was disproved. In the south 3 km west of the mining camp at Millarodden is a small island, Sinkholmen, which may be the richest exposed mineral deposit in Svalbard where 240 tons were mined mainly of sphalerite. Sulphides occurring in the breccia are sphalerite, galena and pyrite and in the associated calcite mass Flood (1969) recorded sphalerite, pyrite, chalcopyrite, bornite, idaite, chalcocite, neodigenite and covellite. Tetrahedrite occurred in both hosts; the gangue was fluorite and quartz in the breccia. The occurrences according to the above stratigraphy would be hosted in Late Varanger carbonates in the north and early Varanger in the south. Detailed stratigraphy was not recorded.

10.6

Proterozoic strata of western Nathorst Land and northwestern Wedel Jarlsberg Land

Observations in 1838 and 1839 were made from the ship L a R e c h e r c h e when interest was shown in mineral and coal occurrences. (Nissan 1941). Garwood & Gregory (1898), on Conway's expedition, first noted an ancient boulder bed thought to be equivalent to Reusch's Moraine in N o r t h Norway (Varangerhalvoya). The general outcrop pattern was established by Orvin (1940). This was supplemented by further mapping of the younger rocks by the Polish group about 1938 (Rozycki 1959). Much of the area of older rocks was surveyed systematically by the Wisconsin group led by Craddock (Kowallis & Craddock 1984; Craddock et al. 1985; Bjornerud 1990, 1992). All these observations were compiled in the 1:100 000 map sheet ( B l l G ) with the accompanying memoir (Dallmann et al. 1990). CSE stratigraphic traverses enabled the above results to be related to those from other areas in Svalbard (with respect to the older rocks) (Harland 1978; Hambrey & Waddams 1981; Waddams 1983; Harland, Hambrey & Waddams 1993). The main feature of the area is a northward-plunging open syncline which concentrates the youngest rocks at the north in the Kapp Lyell area. Older rocks then occur successively in a V outcrop

189

pattern. The variety of facies is such that correlation between one limb and the other is not at first obvious, but is confirmed by continuous mapping round the southern corner of the V. Thus even within this small area a duel nomenclature developed between the east and the west limbs (e.g. Dallmann et al. 1990; Bjornerud 1990; Harland et al. 1993). As in Oscar II Land, formations were assigned to two groups by Harland, Hambrey & Waddams (1993) for the rocks which were interpreted as Vendian and which overlie unconformably an older basement. There is general agreement on the mapping of sheet B 11G (Van Keulenfjorden). It is a key area in interpreting and correlating the strata to the north and south of the sheet. This general problem is reserved for discussion in Section 10.9 below.

10.6.1

Neoproterozoic succession of northwestern Wedel Jarlsberg Land

The following succession is based on early CSE work (Harland 1978; Hambrey & Waddams 1981; Waddams 1983), on University of Wisconsin work (Kowallis & Craddock 1984; Craddock et al. 1985) synthesized by Norsk Polarinstitutt mapping (e.g. Hjelle 1969; Dallmann et al. 1990, B l l G ) and followed with some reinterpretation by Harland, Hambrey & Waddams (1993) which forms the basis of the succession below and recounts how it came about (Fig. 10.4).

Kapp Lyeil Gp. This group comprises map units 27-31 of Dallmann et al. and three formations with ten members as listed below.

Lyellstranda Fm, 1.3kin. This formation was first described with two divisions by Waddams (1983b), the upper division (Lyellstranda) and the lower (Kolvebekken). He described the upper division, 3.0 km, as graded polymict conglomerate and buff-weathering dolomite psammite with occasional slate and calcareous phyllite containing dispersed dolostone and quartzite boulders up to 1.6m. He mapped six units by stone content and described the lower unit, 0.7 kin, as grey laminated quartzite and psammite with rare beds of conglomerate and occupying the coastal plain north of Longnedalen. It was not identified on the eastern limb of the syncline. However, the work by Craddock and colleagues was more detailed and their divisions are followed here with five members (unnamed). Mbr 5, Upper dolostone clast unit Mbr 4, Upper no dominant clast unit Mbr 3, Middle dolostone clast unit Mbr 2, Upper quartzite clast unit Mbr 1, Lower no dominant clast unit. Harland et al. (1993) concluded that the Lyellstranda Fm was influenced by a variety of glacially related processes. Good indications are dropstones in the psammitic diamictites formed by ice-rafting in a proximal glacio-marine environment. More distal glacio-marine conditions give phyllites with dispersed stones. The conglomerates are of similar material to the diamictites and probably formed from reworking of glacial deposits by gravity-driven sediment flows, as postulated from the older Kapp Martin Conglomerates (Waddams 1983b). Loading of the underlying bed is also evident. Logna Fro, c. 200 m. This is a soft, finely laminated dark grey phyllite with isoclinal folds parallel to the bedding. Dundrabeisen Fro, c. 1.4 km. This variable formation consists of alternating beds of psammite and phyllite, often with dispersed stones, conglomerate, and stone-rich diamictite. The stones (up to 1 m diameter) are mainly dolostone and quartzite with a minority of limestones and granites. Genesis was similar to the Lyellstranda Fm but reworking of till by subaqueous flows was less significant. Four members are listed following Craddock et al. as above. Mbr 4, Limestone clast unit Mbr 3, Lower dolostone clast unit Mbr 2, Lower quartzite clast unit Mbr 1, clast-poor unit Konglomeraffjellet Gp. This group was defined by four main formations in the east (Harland, Hambrey & Waddams 1993) following Hjelle (1969), Harland (1978) and Waddams (1983), and additional basal formation in the west above the unconformity. Different nomenclature has been applied to coeval rock units in east and west limbs of the syncline.

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Fig. 10.4. Vendian geology of northwest Wedel Jarlsberg Land (redrawn from Harland et al. 1993).

Vestervfigen Fro, c. 340m in the east. Massive grey quarzites are interbedded with quartzitic slate and soft phyllite. It is equivalent to HjeUe's (1969) Konglomeratfjellet shale and quartzite beds. It is recorded only in the east and is similar to the rocks above, except for the absence of stones. Chamberlindalen Fm, about 1-2 km, in the east was described from the eastern outcrop (Harland 1978) where the succession is thicker, more varied and better exposed, but tectonically divided by thrust faults. The outcrops occupy the two broad valleys Chamberlindalen in the east and Dunderdalen in the west. Upper mbr, exposed southwest of Vestervfigen, is of grey slate with calcareous concretions, thin amygdaloidat lava flows and calcareous pyroclastic rocks. Middle mbr comprises well-bedded grey limestone, with dolostone clasts, above cream weathering dolostone, grey oolitic limestone and dark amygdaloidal basalt. Interbedded phyllites are not so well exposed. (Lower) Asbestodden Mbr is of basic lavas (some pillow tavas), pyroclastics and small intrusions interbedded with pelites and carbonates. At Asbestodden the basites have been altered to an asbestos-beating assemblage. Turchenko et aL (1983) described the igneous rocks as porphyritic picrites, both porphyritic and amygdaloidal basalts, andesites with myrmekites (up to 25% quartz), ophitic porphyritic gabbro-dolerites and volcanogenic sediments (e.g. green phyllites). All belong chemically to a single tholeiitic basalt-trachy-andesitic series.

Dunderdalen Fin, 1.9 kin, map unit 35 of Dallmann et al., is the western facies of the Chamberlindalen Fm. The outcrop was mapped by Orvin (1940) as a thick succession of pelite with discontinuous quartzites. Flood et al. (1978) and Harland (1978) suspected a pelitic schist and phyllite up to 1 km thick, and Bjornerud (t990) named it. Within a dominantly pelitic unit, quartzite and carbonate units, sometimes brecciated, often isolated, were interpreted as olistoliths. Whereas exposure is limited in the north, easy access is afforded from Storvika through Orvindalen or Tunsfjodalen in the south of the west limb of the syncline where way-up and relation to underlying strata is well confirmed. Sollwgda Fro, 300+ m in the east. Cliffs of carbonate units are conspicuous in the hills to the east of Chamberlindalen and with many, but minor, tectonic complications, lie beneath the Chamberlindalen Formation. Three members are easily distinguishable at a distance by colour; Upper mbr mainly bedded grey limestone and dolostone, Middle mbr yellow-weathering dolomitic marble and black bituminous limestone. Lower mbr pale yellow-weathering dolomite marbles with dark volcanics and silts. Slettfjelld~den Fin, 50-100 m. In the west this was referred to informally by Bjornerud (pers. comm.) as the Slettfjelldaten F m of dolostones and limestones with sedimentary breccias, digitate stromatolites and chert beds.

SOUTHWESTERN AND SOUTHERN SPITSBERGEN In the south, (at the head of Chamberlindalen) on the flanks of Konglomeratfjellet a substantial thickness of dolostone breccia/conglomerate with clasts up to 0.5 m long occurs at the base of the formation. In the southwest Hambrey estimated 285 m (ofCSE informal Orvindalen formation) suggesting offshore distal turbidites (phyllites) to shallow marine tidal facies, with oolitic and channeled stromatolitic dolostones. The dolostone diamictite could be a shallow marine deposit with some ice rafting. Fluykalven Fin (in the west). At Floykalven, south of Dunderbukta, is a diamictite rich in quartzite and carbonate stones the latter with occasional oncolites and stromatolites typical of the lower tillite facies already described north of Bellsund and Isfjorden. Bjornerud divided her equivalent Konglomeratfjellet Fm into two divisions: upper green-coloured, 500 m and lower brown-coloured, 400 m. East of Storvika in the south, two divisions were observed by CSE in 1983. Upper division, 330 m, dark grey phyllite with dispersed stones (dolostones, quartzite and vein quartz up to 0.35 m long, but no granitoids), which may be concentrated locally in a matrix of silty carbonate with chlorite in the foliation. Lower division (160m) light brown-weathering dolostone with dispersed clasts locally concentrated to a dolostone-quartzite conglomerate. In many respects this formation resembles the Trondheimfjetla Fm of Oscar II Land. Gaimardtuppen Fm (in the east). This name is applied to the lower of the three divisions which Hjelle (1969) included in his Konglomeratfjellet unit. Two members are distinguished after Harland et al. (1993). Upper mbr (= Gaimardtoppen division of Harland 1978) and phyllite limestone of the Wisconsin group (about 0.5km) is a dark calcareous sequence of psammites and pelites with dispersed stones; some facies are pebbly. A distal turbidite with dropstones is suggested. Lower mbr is the Konglomeratfjellet conglomerate beds of Hjelle (1969), Foldnutane division of Harland 1978, and Conglomeratfjellet Fm of Bjornerud (pers. comm.). Bjornerud (1990) noted that about 5% of the stones are granitic or gneissic and suggested that they could be derived from the Magnethogda sequence a few km to the east. ThiLq'jdlet Fro, 0-50m. This is a black, pyritic, phyllitic limestone (50-100m), with isolated beds of quartz pebble conglomerate. Below is the basal gritstone conglomerate 0-50m with dolomitic matrix resting on the unconformity seen only in the west (Bjornerud 1990). This unconformity is the base of the above which Harland, Hambrey & Waddams (1993) interpreted as the Varanger (Early Vendian) succession in the area with a total thickness of about 6 km.

10.6.2

Proterozoic basement

A m a j o r u n c o n f o r m i t y was m a p p e d in the west by the Wisconsin G r o u p ( B j o r n e r u d 1991) with little overlap b u t m a r k e d overstep, the underlying rocks h a v i n g suffered a m a j o r phase o f d e f o r m a t i o n before V e n d i a n time. I n the east where such an u n c o n f o r m i t y m i g h t also be expected the rocks are obscured by the wide R e c h e r c h e b teen a n d R e c h e r c h e f j o r d e n .

Nordlmkta Group (Proterozoic basement) in the west (Fig. 10.4). A sequence of eight formations was described by Bjornerud in her unpublished map, of which CSE observed the two lower formations in 1983 referred to as the Storvika formation. Not mapping the area CSE did not identify the unconformity in the two traverses made. The whole sequence mapped, and totalling 3.3 km consists largely of dolomitic marbles, phyUites and quartzites not much different from the overlying rocks, but with a distinctive structure. The succession below follows Bjornerud as printed by Harland et al. (1993, p. 102). (8) Dordalen Fro, 150m of heterogeneous dolostone and phyllite. (7) Thiisdalen Fro, 200 m of red brown phyllite and quartzite. (6) Trinutane Fm Ferroan doiostone and pink marble members, 150 m Resinous phyllite member, 30 m Pink cross-bedded quartzite member, 200m (5) SeljehaugfjeHet Fm Grey dolostone member, 150 m Black limestone member, 50 m (4) Botnedalen Fro, 300 m of platy limestone, dolostone and phyllite. (3) Peder Kokkfjeilet Fro, 600 m of sandy dolostone. (2) Evafjellet Fro, ?1 kin, of quartzite and phyllite. (1) Kapp Berg Fm, ?1 km, of phyllite and quartzite.

191

Magnethugda Group (the sequence to the east). East of Recherchebreen and Recherchefjorden is a sequence first referred to by the above name (Harland 1978) (Fig. 10.4). From Bjornerud's ms map and earlier work it seemed possible to correlate these rocks with the Nordbukta sequence so connecting the basal Vendian unconformity in the eastern limb of the syncline. Harland (1978) had noted also a possible similarity between the feldspathic rocks of Magnethogda and those gneissic bodies in the SkSlfjeUet Formation. However, further observations of critical localities in 1992 in the south from Isbjornhamna, Vimsodden, east of Recherchefjorden at MartinfjeUa and Berzeliustinden, supported the view that the Magnethogda does not easily correlate with any other sequence and that most likely the boundary between the central and western terranes of Harland & Wright (1979) passes through Recherchefjorden and Recherchebreen. The account of Dallmann et aL (1990) also implied doubt as to the Nordbukta correlation. Whereas the massive dolomitic marble (map unit 50 of Dallmann et al.) is extensive and might conceivably match one or more of the dolostones in the Nordbukta sequence, there is no match to the feldspathic rocks (map unit 49 augen gneiss and feldspathic quartzite). These rocks amongst so many dolostones, phyllite and quartzite are conspicuously pink. The outcrop area of map unit 49 beside Recherchefjorden is somewhat exaggerated: there is very little feldspathite along the foothills beside the fjord, it is mostly dolomitic marble. However, in the foothills of Berzeliustinden massive gneisses occur without interbeds of non-feldspathic facies though the facies do vary from feldspathic psammitic schists to augen schists and even coarse granitic gneisses. The rocks are intensely foliated and lineated. Rare specimens along the side of Recherchefjorden are almost mylonitic. No associated basic rocks were seen. Thus, the minor feldspathic development in the dominantly basic Sk~dfjellet Fm further south bears no comparison with the Magnethogda rock. Indeed no similar facies have been recorded in the south of Spitsbergen or in the West Spitsbergen Orogen. It is concluded that these feldspathic rocks, with their associated marbles, quartzites, phyllites and schists may belong to a different, once distant, terrane. The Van Keulenfjorden sheet B11G (Dallmann et al. 1990) maps a close association of units 49 (feldspathic rocks) and 50 (massive dolostone). Outcrops of Unit 49 extend about 7 km on each side of Antoniabreen and Unit 50 crops out intermittently for 20 km to the south. In the southern part of the sheet it is associated with units 51 to 55 described as carbonates, phyllites and quartzites. However, the adjoining preliminary sheet to the south, B12G (Ohta & Dallmann 1992), with slight overlap, maps the phyUites as G~shamna Formation and associated carbonates units 50 & 51 (to 14 N) as Hrferpynten Formation. The authors admit that their research is unfinished. It would also be affected by alternative interpretations of the succession to the south (as discussed below in Section 10.9)

Westernmost Nathorst Land. T h e small o u t c r o p of marbles a n d quartzites on the p r o m o n t o r y of M i d t e r h u k e n belong to the M a g n e t h o g d a sequence (as also m a p p e d by D a l l m a n n e t al. 1990)

10.7

Early Paleozoic and Proterozoic strata of southwestern Wedel Jarlsberg Land

This area lies south o f Torellbreen a n d n o r t h of H o r n s u n d a n d east as far as H a n s b r e e n , penetrating the s o u t h e r n part of the Central Basin. F o r descriptive convenience it is distinguished f r o m the area just treated (Section 10.6) because f r o m the Polish base at I s b j o r n h a m n a it has been intensively investigated by Polish geologists since that base was o p e n e d a b o u t 1957 as a c o n t r i b u t i o n to the I n t e r n a t i o n a l G e o p h y s i c a l Year. The base facilitated research in m a n y disciplines, especially Q u a t e r n a r y , and latterly seismic. F o r the p u r p o s e here, the bed-rock geology was comprehensively surveyed u n d e r the leadership o f K. B i r k e n m a j e r and published d u r i n g the years 1958 to 1994. W h a t e v e r was d o n e before has been superseded by Birkenmajer's t e a m so that their accounts f o r m the basis o f this section. M a n y others have visited the area, not least the I n t e r n a t i o n a l Geological Congress excursion in 1960. The Cambridge g r o u p f r o m visits on several occasions was able to f o r m i n d e p e n d e n t opinions on some questions which a p p e a r e d to be controversial. Latterly the N o r s k Polarinstitutt has c o l l a b o r a t e d in m a p p i n g the area: 1:100 000 sheet B12G (Ohta & D a l l m a n n 1992).

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CHAPTER 10

Birkenmajer consolidated the results of the Polish Group north of Hornsund with those of the Norsk Polarinstitutt south of the fjord in a unified stratigraphic scheme developed over the years but essentially the same as that issued to the International Congress in 1960. This scheme in its latest available version is listed below but only down to formation rank. It has the advantage of a single tidy scheme for a large and complex area to which most maps have been related and it has been largely followed by Russian and Norwegian groups (e.g. Krasil'shchikov & Kovaleva 1979, Sheet C13G; Dallmann et al. 1993). The scheme has, however, been challenged (e.g. Harland 1978; Harland, Hambrey & Waddams 1993) on the grounds that stratigraphic units north and south of Hornsund and given the same name, do not necessarily correlate and that a major N-S terrane boundary along Hansbreen and west of H6ferpynten would mean that correlation east and west of that line is also suspect. The assumption that distant units correlate and so receive the same name leads to definitions that may not serve discussion well and possible reappraisal. It may be safer to introduce additional names and eliminate them if and when identity is established. A second cause for discrepancy between Birkenmajer's scheme and that adopted here is that formations are the primary rock units and their combination into groups may reflect different opinions as to their relationships whereas Birkenmajer defined groups and divided them into formations. Birkenmajer's scheme has priority and will be described first. However, the possibly different terranes will be described separately so as to enable discussion of correlation in Section 10.9. Birkenmajer's correlation of his units with those of Ny Friesland and Nordaustlandet are also in question because he assumed a relatively fixistic palinspastic relationship. Birkenmajer throughout indicated that the main groups were separated by diastrophic events which are inserted in the following table in upper case lettering.

*Brattegga (amphibolite) Fm, 300-500m *Angellfjellet (amphibolite) Fm, 0-200 m *Gangpasset (migmatite) Fm, 0-100 m *Torbjornsenfjellet (amphibolite) Fm, 350-600m Steinvikskardet Fm, 100-250 m Gulliksenfjellet (quartzites) Fm, 500-850 m Isbjornhamna Gp Revdalen Fro, 250-350m Ariekammen Fm, 500-1500 m Skoddefjellet Fro, 1000+ m These older rocks, listed above, generally have been referred to as Hecla Hoek. However, on the basis of not assuming correlation until it has been satisfactorily demonstrated this name is avoided here preferring the more descriptive 'pre-Devonian' or 'basement' attribute. Moreover, around eastern Hornsund overlying Devonian strata have been mapped and dated palaeontologically. The successions are described below, west and then east of Hansbreen.

Stratigraphic scheme from Birkenmajer 1978 and 1992

Duneyane Fro, 750m. A dolomitic rock forms much of Dunoyane. It is of light dolostones interbedded with dolomitic oolites and pisolites with Collenia. A t Storoya off Dunoyane it appears to pass upwards into black quartzite and quartzite schist. It has been correlated with Winsnes' Oolitic Limestone Member of the H6ferpynten Formation south of Hornsund which Birkenmajer named as the Dunoyane Member. There it is only 40m thick and was also correlated with the 25m north of Hornsund at Fannytoppen. A distinct name is preferred so as not at first to assume identity. According to Birkenmajer this would be the youngest formation in the Vimsodden-Isbjornhamna terrane, younger than the SlyngfjeUet Conglomerate. It is an isolated island outcrop with no direct evidence as to its relationship with the other rocks of our terrane. The nearest mainland rocks belong to the Vimsodden Subgroup. Projection of local dips suggest that it may be older than the Vimsodden Subgroup. Both formations have similarities with the Akademikerbreen Group of Ny Friesland and have been so correlated. If this be correct the Dunoyane Formation would be pre-Vendian and Late Sturtian or Riphean. Slyngfjellet (conglomerate) Fro. This distinctive formation is the uppermost in the succession both in Birkenmajer's description and his map. The fullest descriptions were given by Birkenmajer (1990, 1991, 1992). At the type locality, Slyngfjellet, the formation may be 500m in this area and divides into two informal members. Upper mbr. Green meta-conglomerate with subordinate sandstone with siltstone and shale intercalations of yellow/brown conglomerate. The unit at the type locality is a green meta-conglomerate with 70 to 80% light green/ yellow lenticular or tabular sharp-edged, sometimes subrounded, homogeneous or laminated quartzite clasts 1-30 cm in diameter; some quartzite slabs 1000m) consists of grey, green to yellowishweathering garnet mica schists, predominantly with muscovite and paragneisses, with plagioclase and biotite as described by Smulikowski (1960b, 1965).

Isotopic ages have been proposed for these oldest rocks as follows: Gayer e t al. (1966) found a K - A r age for biotite from the lowest formations as 565 and 594 Ma. Peucat, Dallmeyer & Teben'kov (Ohta 1992) from zircons gave tentative ages of 1130 and 1135 Ma. Teben'kov e t al. (in prep) recorded garnet twomica schist with a preliminary metamorphic Rb-Sr age e. 940-950 Ma (text of map C13G, p. 42). An alternative scheme of Czerny e t al. (1992) redefined the Eimfjellet Gp as below. That part of their scheme is favoured here because it distinguishes established early Neoproterozoic strata from the overlying Elveflya Fm. Thus units in Birkenmajer's Vimsodden Subgroup are separated by the major Vimsodden-Kosibapasset Fault (VKF). Eimfjellet Gp (Middle Proterozoic) s e n s u Czerny e t al. Pyttholmen Fin (with acid igneous rocks from which Balashov e t al. (1995), suggested a magmatic age of 1200 Ma, a regional metamorphic age of 930 Ma, and with inherited zircons of 2500 Ma).

GulliksenfjeHet Fm Bratteggdalen Fm Skfilfjellet Fin (in part equivalent to the upper two formations). The Sk~dfjellet rocks yielded Rb-Sr and zircon (magmatic) ages of 1100-1200 Ma (Balashov e t al. 1996b) and detailed petrological data.

Eimfjellbreane Fm Skjerstranda Fm The Eimfjellet Group follows conformably on the Isbjornhamna Group. This reclassification is supported by Birkenmajer's correlation table (1992, p. 29) simplified here Fig. 10.5. In this work the Vimsodden-Kosibapasset Fault is taken as marking a major break in the sequence (i.e. a faulted unconformity) which divides a more restricted Vendian Vimsodden Group above (to the north) from a much older basement comprising a newly defined Eimfjellet Group (Czerny e t al. 1992) and a relatively concordant Isbjornhamna Group below of established mid-Proterozoic age (Balashov e t al. 1995). Formations are the observed stratal units which may (to express an opinion about their relationships) be combined into groups. The opposite procedure to define groups and divide them into formations has led to some of the above confusion and is not an international convention.

10.7.2

Early Paleozoic and Proterozoic strata east of Hansbreen

T h e rocks in this s u b t e r r a n e are described as in B i r k e n m a j e r ' s sequence, a n d m a i n l y with his description, while using s o m e o t h e r n a m e s to a v o i d implicit c o r r e l a t i o n either west o f H a n s b r e e n or south of Hornsund.

Hornsund Supergp Sorkapp Land Gp, 1400 m no fossils have been recorded from Wedel Jarlsberg Land. By correlation with Sorkapp Land fossiliferous units the group is Canadian in age. Birkenmajer (1978) consolidated earlier results from Major & Winsnes (1955) for Ordovician and Cambrian stratigraphy of the Hornsund area (southern Wedel Jarlsberg Land and Sorkapp Land). His accounts were given according to a unified nomenclature for the whole of southern Spitsbergen. Hornsundtind (limestone) Fro, 500 m in Sorkapp Land. The formation is of light to dark grey to black bituminous limestones passing down transitionally into pinkish grey limestones. Whereas this unit is best developed in Sorkapp Land it crops out as the most extensive unit throughout the length of the mountain range (Luciakammen) that extends north from Luciapynten nearly 20 km to the northernmost exposure at Aulrabben with only one small outcrop east of Mfilbacherbreen (Birkenmajer 1978, fig. 2). Two members have been distinguished south of Hornsund and no fauna was described from Wedel Jarlsberg Land. The correlation is lithological with that to the south and the fauna is as described in the south by Major & Winsnes (1955). Nigerbreen (limestone) Fro. The formation occurs only in the southern part of Luciakammen and at Fiskcknatten in the north but appears to wedge out between. It is defined in Sorkapp Land where it is 80 m thick but is probably less in Wedel Jarlsberg Land where it hardly shows on the map (Birkenmajer 1978, fig. 2). Dusken (limestone) Fro, 100m. This thin-bedded, grey, black-laminated limestones with yellow laminae and with black cherts is defined in Wedel Jarlsberg Land. It is thinner in Sorkapp Land (20-30m). It crops out through most of the length of Luciakammen. No fossils have been recorded from the formation.

SOUTHWESTERN AND SOUTHERN SPITSBERGEN

Luciapynten (dolostone) Fm, 400 m. The formation is made of dolostone, calcareous - massive or thick-bedded with black or blue chert intercalations with sponge-like (stromatolitic) structures. It is defined in Wedel Jarlsberg Land at Luciapynten and is exposed through the southern part of Luciakammen, the lower strata being mostly covered by ice. Wiederfjeilet (quartzite) Fro, 150m. This arenaceous, quartzite and dolomitic formation is defined in Sorkapp Land, but extends north into Wedel Jarlsberg Land where an extensive outlier of the lower member rests directly on Sofiekammen Group rocks (Cambrian) at Nordstetinden. Goi~sbreen Mbr (very limited occurrence) in the Sofiekammen range was noted by Birkenmajer and no outcrop is seen on his map (fig. 2). It is of dark grey calcareous shales and thin blue quartzite layers. Paierlbreen Mbr, 150m of dolomitic sandstone with fragments of the underlying Nordstetinden (dolostone) Fro. Sofiekammen Gp, 635-850m (Birkenmajer 1958, 1978) Nordstetinden (dolostone) Fro, 150m (Birkenmayer 1958, 1978) Nordstebreen Mbr, 150m (Birkenmajer 1978), of platy dark grey-black (yellow-weathering) dolostone in three layers, 1-10cm, alternating with yellow mainly dolostone 1-2 cm layers. Hansbreen Mbr, 100m (Birkenmajer 1978) of light or dark grey to bluish (yellow weathering) massive or poorly bedded dolostone. Grey dolostone sometimes alternates with black bituminous dolostone. Gnfilberget (marble) Fro, 250-300m (Birkenmajer 1959, 1978). Massive limestone marble with pink calcite or red jasper veins; no fossils were recorded. Slaklidalen (limestone) Fro, 25-120 m (Birkenmajer 1975, 1978). Black to grey limestone is sometimes dolomitic, bituminous or arenaceous and often thin-bedded; correlated with the richly fossiliferous Slakli Subgp of Late Early Cambrian age (Major & Winsnes 1955), but fossils in Wedel Jarlsberg Land were not specified. Vardepiggen Fro, 110-130 m Flogtoppane Mbr, 30-40 m, yellow dolostone or grey limestone pass down into black to grey graphitic shales often with sedimentary breccias. Midifjellet Mbr, 5 - 5 5 m , black to dark grey limestone, often shaly or phyllite with indeterminate trilobite fragments. Olenellusbreen Mbr, 44-65 m (Birkenmajer 1978) of green to black shale with sedimentary breccias with flattened imprints and exoskeletal fragments of olenellids and anemone burrows Dolopichnus. A late Early Cambrian age was suggested. Blfistertoppen (dolostone) Fro, 100-150m. Blue-black, yellow weathering arenaceous dolomitic rocks passing into pure dolostone or dolomitic limestone. No fossils are recorded from Wedel Jarlsberg Land. A basal conglomerate is said to rest with angular unconformity on the Bogstranda unit which is correlated with the Ggtshamna phyllite Fm (south of Hornsund); but the section at Islova-Lovetanna (Birkenmajer 1978, p. 14) shows a concordant relationship. Sofiebogen Gp. This is part of the Precambrian succession and was described by Birkenmajer (1958 et seq.), as at the beginning of this section, for the whole of south Spitsbergen. However, other names have been introduced here (e.g. from Harland 1978) for this terrane (east of Hansbreen and north of Hornsund) to facilitate discussion of correlation between the terranes. They are distinguished by asterisks. The sequence appears to be continuous and demonstrably younging to the east so that the rocks have been overturned with a steep westerly dip. *Bogstranda unit, 2.0km. This unit has been correlated with the Gfishamna Fm south of Hornsund and a separate formal name may not be necessary except for the purpose of discussion so as not at first to assume identity. The rocks are better developed here and their relation to the older beds is well exposed. The strata are very largely pelitic, intercalated with seven quartzite shale horizons (up to 60m) in the lower 1000 m where some dolostone beds occur up to 5 m. A limestone bed occurs above the quartzite beds. The pelites are phyllites in many shades of green and black. The former probably indicate a volcanic component and the latter a biogenic input in the absence of volcanic material. The quartzite shale horizons, the quartzitic sandstones and/or quartzites are white to rusty brown weathering. Some chert fragments occur at their soles and the associated pelites may be graphitic. At Bogstranda the dolostones may contain silicified ooids. The limestones are reminiscent of Cambrian facies. Although the thickness south of Hornsund may total more than 3 km the lower contact there is faulted and the missing beds there may be represented by the phyllites with some of the seven quartzite horizons at the base of the Bogstranda unit. On the other hand the upper Bogstranda contact is faulted and may have cut out a substantial thickness of relatively uninterrupted phyllites.

195

*Fannytoppen Fm, c. 120m Harland (1978); Harland, Hambrey & Waddams (1993). This unit has always been correlated by Birkenmajer (1958-1972) with the H6ferpynten Fm south of Hornsund, so making the older strata pre-H6ferpynten. This correlation has been questioned (Harland 1978-1985, Harland et al. 1993). Pisolific mbr, 0 - 2 4 m dolostone with fine oncolitic texture. Radwanski & Birkenmajer (1977) described and correlated it with the H6ferpynten Formation south of Hornsund. Dolostone mbr, 14m in which stromatolites were observed with T. S. Winsnes (Harland et al. 1993). Limestone mbr, 80m. This is Birkenmajer's Fannytoppen Mbr of the H6ferpynten Fm of Major & Winsnes (1955) to the south. *Fannypynten Fm (about 500m). The Fannypynten Fm is a polymict reddish diamictite with a great range of stone sizes up to boulder size, and of composition of stones (quartzite 60%, feldspathites (granitoids) 20%, dolostones 15%, limestone 5%). They are either dispersed or in contact. Harland (1978) and Harland et al. (1993) concluded from the thickness, poorly sorted nature, high stone content, remnant lamination that the formation developed in a proximal glaciomarine environment or as waterlain till. This unit is sheared so that many stones and boulders are elongated and flattened. *Unnamed division (about 300 m). A break in the exposure (at the gravel tombolo spit west from Fannytoppen) suggests that less resistant rocks, possibly phyllites, may intervene. Hansvika Fm (about 500 m). Occupying the rocky promontary at the end of the tombolo is a polymict diamictite of tilloid appearance and greyish colour with dispersed dolostone, limestone and quartzite and no feldspathic rocks. The colour contrast with the Fannypynten Formation was commented on by Birkenmajer who referred to both formations as the Slyngfjellet conglomerate at the base of his Sofiebogen Group. His two members upper and lower were, however, probably described from Slyngfjellet, because his upper member was described without feldspathic clasts which are so conspicuous from their colour at Fannypynten. The type Slyngfjellet conglomerate might correlate with the Hansvika but not with the Fannypynten Fm. Harland (1978) and Harland et al. (1993) concluded a similar mode of formation as the Fannypynten Fm. It was referred to informally as the Hansbreen unit (Harland 1978) but Hansbreen Mbr of the Norstetinden Fm was used formally by Birkenmajer (1978a). To avoid confusion, Harland, Hambrey & Waddams (1993) used the only other name available, and Hansvika is appropriate.

10.7.3

Comparison of stratal schemes for southwest Wedel Jarlsberg Land

F i g u r e 10.6 c o m p a r e s five different s t r a t i g r a p h i c schemes. F o u r m a y be culled f r o m the literature a n d were p r o p o s e d at a b o u t the s a m e time a n d t h e fifth is t h a t w h i c h c u r r e n t l y fits the a u t h o r ' s field i m p r e s s i o n s in the light o f recent p u b l i c a t i o n s i n c l u d i n g the i s o t o p i c age d a t a o f B a l a s h o v et al. (1995). E a c h p o s i t i o n c h a n g e s w i t h evolving investigations so n o single p u b l i c a t i o n e n c a p s u l a t e s essential viewpoints. I n o r d e r n o t to a t t r i b u t e an o p i n i o n unfairly to a n y a u t h o r , f o u r initials are u s e d for the i n t e r p r e t a t i o n s s c h e m a t i z e d for their distinctive differences. B refers to an i n t e r p r e t a t i o n o f B i r k e n m a j e r ' s c o n t r i b u t i o n (1958-1993, especially 1992) a n d his 1990 m a p . C refers to his colleagues C z e r n e y et al. (1993) a n d is based o n their detailed m a p o f a critical b u t m u c h smaller area. O refers to the N o r s k P o l a r i n s t i t u t t m a p s , especially to O h t a & D a l l m a n n (1996) B 1 2 G sheet. O h t a has b e e n m o r e c o n c e r n e d w i t h the o l d e r r o c k s t h a n D a l l m a n n . H1 refers to H a r l a n d (1978), H 2 to H a r l a n d , H a m b r e y & W a d d a m s (1993) a n d H3 evolving to this w o r k . B, C & O adopted relatively fixist palaeogeology whereas H invoked significant displacement (e.g. along the Hansbreen Fault. Different traces for this were assumed in H1, H2, and H3. B, C, O & H all agree that the Isbjornhamna Gp is the oldest and with Paleoproterozoic, then Mesoproterozoic isotopic ages. O and H follow the C map as the best authority as to the outcrops of the many lithic units in this small but key area, and which supersedes the pioneer maps of B. But all differ in the interpreted sequence of strata.

196

CHAPTER 10

B

H1-2

Birkenmajer 1992

O

H3

Ohta & Dallmann 1992/1993

This work

C

Harland et al. 1993

Czerny et al. 1993

,

Sorkapp Land Group

S~rkapp Land Group

Sofiekammen Group

Sofiekammen Group

Sofiekammen Group

Sofiebogen Group G&shamna phyllite Fm

G&shamna phyllite Fm

H6ferpynten dst. Fm

Fannytoppen Ist Fm

Slyngf]ellet cgl. Fm

Fannypynten tUloid Fm Hansvika tilloid Fm

A

Deilegga Group Bergskardet Fm

E. of Hansbreen

Bergnova Fm Tonedalen Fm Eimfjellet Group Vimsodden Subgroup Jens Erikfjellet Fm Elveflya Fm

S~rkapp Land Group

Sofiekammnen Group 23-27

Sofiekammnen Group

Elveflya Fm (with dropstones)

G6shamna Fm (inc. 28 Dunderdalen Fm etc)

G~shamna Fm (incl. Tonedalen Fm)

H6ferpynten Fm 29-30

Fannytoppen Fm

Slyngfjellet Fm 31

Fannypynten Fm A

H6ferpynten Fm Jens Erikfjellet Fm

W. o f " - Hansbreen "--

Sorkapp Land Group

Hansvika Fm Jens Erikfjellet Fm 32

Slyngfjellet Fm

Slyngfjellet cgl. units Deilegga Subgroup Vimsodden Subgroup (Elveflya early tillite) A

Nottinghambukta Fm

[Bergskardet and Bergnova Fm] Eimfjellet Group Pytthomen Fm

Sk61fiellet Subgroup 33-38 Vimsodden Subgroup 39-45

Deilegga Group 55-57

E. of Hansbreen

Aust Torellbreen Group" \

Slyngfjellet units and Deilegga Fm

Elveflya Fm

A

Sk~l~ellet Fm

Sk&l~ellet Subgroup

?Dunoyane Fm ?Sk~lfjellet Subgroup

Steinvikskardet Fm Gulliksenfjellet

``

Jens Erikfjellet Fm

Gulliksen~ellet Fm Brattegggalen Fm

A

\ ` ` Magnethegda Group W. of `` Hansbreen

Deilegga Group Werenskioldbreen Group"- ...

G~shamna Fm

Eimfjellbreane Fm Skjerstranda Fm

Magnethegda Group 51

Eimfjellet Group

?Steinvikskardet Fm

Pytthomen Fm

Gulliksenf]ellet Fm

Gulliksen~ellet Fm Bratteggdalen Fm Sk&l~ellet Fm Eimfjellbreane Fm Skjerstranda Fm

Isbjernhamna Group

Isbjernhamna Group

Isbjernhamna Group

Isbjernhamna Group 52-54

Isbj~rnhamna Group

Revdalen Fm

Revdalen Fm

Revdalen Fm

Revdalen Fm

Revdalen Fm

Ariekammen Fm

Ariekammen Fm

Ariekammen Fm

Ariekammen Fm

Ariekammen Fm

Skodde~ellet

Skoddef]ellet

Skoddefjellet

Skoddefjellet

Skoddefjellet

Fig. 10.6. Comparison of stratigraphic schemes for southwest Spitsbergen as discussed in Section 10.9.1.

C maps a critical WNW-ESE nearly straight boundary line between their Isbjornhamna and their Eimfjellet Gp to the south and their Deilegga and younger groups to the north. This is the Vimsodden-Kosibapasset Fault (VKF) accepted by Balashov et al. (1995). It divides the Vimsodden Subgp of B whose lower units are included in the revised Eimfjellet Gp of C. The newly defined Eimfjellet Gp is accepted by H3. Thus C and H3 agree on the basement being Eimfjellet and Isbjornhamna groups. C interprets the (VKF) boundary between the Eimfjellet and Deilegga groups as a northward directed thrust, which it may well be; but H3 considers it also to mark a major unconformity. Overlying it H follows B in taking the oldest unit above the boundary to be formations of the Vimsodden Subgroup followed by the Deilgegga Gp into the Slyngfjellet Fm. H differs from B not as to the sequence but as to the age. H accepts the original Vimsodden tilloid (the Vimsa member of the Elveflya Fm of B) as Early Varanger tillite and most of the succeeding succession as Early Varanger including the Deilegga and Slyngfjellet units. This would break up the Eimfjellet Gp of B, and H3 proposes an Aust Torellbreen group to include this complex. Whereas H (and possibly B) consider the G~shamna F m (east of the Hansbreen Fault) as being late Vendian, C and O correlate it with the lower Deilegga unit and thence north to the Dunderbukta Fm which H is reasonably certain is intertillite, i.e. Early Varanger (Early Vendian) in age. This may be partly because O followed B in correlating the late or post tillite

Fannytoppen Formation as extending the H6ferpynten Fm. Thus O tend to assume that all pelites are GSshamna equivalents. On the other hand Krasil'shchikov (in Gramberg et al. 1990) would appear to support H in this respect. Referring to the Dunderbukta Formation of Krasil'shchikov & Kovoleva 1976 (which is the equivalent of the Dunderdalen Fm) he noted that the Deilegga Fm was a possible equivalent of this unit. B and O are agreed in making much of the Vendian succession of H much older. O follows C in arguing from the Slyngfjellet unconformity above the Deilegga rocks. O follows B in taking the Slyngfjellet Fm as preH6ferpynten Fm (which is probably Sturtian). From this it follows that the Deilegga and Vimsodden rocks would all probably be Mesoproterozoic. H would point out that the Slyngfjellet conglomerates occur also in mid Deilegga succession and could be a conglomeratic facies, nearly coeval. W i t h i n the area c o n c e r n e d (east o f H a n s b r e e n a n d s o u t h o f A u s t Torellbreen) the c u r r e n t l y available evidence is i n d e t e r m i n a t e . Nevertheless in this w o r k the s o l u t i o n here (H3) is suggested as the best fit to available d a t a a n d s t r e n g t h e n e d greatly by c o n s i d e r a t i o n s o f c o r r e l a t i o n elsewhere in Spitsbergen. W i t h o u t f u r t h e r discussion it is a d o p t e d in the c o r r e l a t i o n o f r o c k s t r e a t e d in this c h a p t e r in Fig. 10.7.

SOUTHWESTERN AND SOUTHERN SPITSBERGEN

Nordensk61dkysten

N.W. Wedel Jarlsberg S.W. Wedel Jarlsberg Land Land

Serkapp Land Group Sofiekammen Group Bogstranda Fm Fannytoppen Fm A Fannypynten Fm

o -s ?Ediacara Late Varanger

II III IIIII II III IIIIIIIII IIII Ill l Kapp Lyell Group A

Kapp Linn6 Fm 9 Linn~fjella unit

Konglomeratfjellet Group Aust Torellbreen Group Dunderbukta Fm Slyngfjellet and Deilegga fms Chamberlindalen Fm (B Gaimardtoppen Fm Jens Erikfjellet Fm (B) Fleykalven Fm / ~ Elveflya Fm Thiisfjellet Fm

Malmberget unit Early Varanger

L~gneset Fm (B) Gravsjeen Fm /~ L&gnesrabbane Fm Kapp Martin Fm

IIIIIIIIIII

E. Wedel Jarlsberg Land

III

Sturtian

MesoProterozoic

?Paleoproterozoic

q)

Duneyane Fm

Nordbukta Group Dordalen Fm Thiisdalen Fm Trinutane Fm Seljehaugfjellet Fm Botnedalen Fm Peder Kokkfjellet Fm Evafjellet Fm Kapp Berg Fm

Eimfjellet Group Pyttholmen Fm Gulliksenfjellet Fm Bratteggdalen Fm SkNfjellet Fm Eimfjellbreane Fm Skjerstranda Fm Isbjernhamna Group Revdalen Fm Ariekammen Fm Skoddefjellet Fm

197 S~rkapp Land Serkapp Land Group Sofiekammen Group G&shamna Fm

(unexposed unit)

Hansvika fm / ~

H6ferpynten Fm Quartzite Mbr Oolitic Ist Mbr Wurmbrandegga Mbr Andvika Mbr Kviveodden Mbr

J

Sigfredbogen Fm Magneth~gda Group

J Mefonntoppane units

IIII III Illlllllll

Lyngebreen sequence

ILIIIILIILIJlIILIIhll

Fig. 10.7. Correlation of Pre-Devonian units in southwest Spitsbergen as discussed in Section 10.9.1. Triangles are tillites; B indicates basic rocks; oblique slashes separate unconnected successions.

10.7.4

Mineralization

The only recorded occurrence of sulphide or other metallic minerals in Wedel Jarlsberg Land according to Flood et al. (1969) is at Revdalen where, within the Isbjernhamna and Eimfjellet Groups, Birkenmajer (1960) and Smulikowski (1965) recorded sulphidebearing quartz ankerite veins within amphibolite facies. Wojciechowski (1964) pointed out the sporadic occurrence of sulphides within the veins. The main minerals in Revdalen are pyrite, chalcopyrite, galena, sphalerite and pyrrhotite. Further details were given by Flood. However, the map of Czerny et al. 1992 plots a great number and variety of mineral occurrences between Torellbreen and Hansbreen in almost all formations. The occurrences include disseminated mineralization, concordant ore veins, discordant ore veins, laminated ores, nests and lenses of metasomatic ores, magmatic ultrmafic cummulate ores and pegmatite veins with the occurrence of minerals, each from the following list: pyrite, chalcopyrite, marcasite, sphalerite, galena, magnetite, hematite, imenite, pyrrotite, arsenopyrite, marcasite, cubanite, bornite, tetrahedrite, bournonite, boulangerite, bismuth, bismuthinite, proustite, antimonite, meckinawite, ankerite, dolomite, calcite, siderite, barite, fluorite, microcline, chlorite, epidote, actinolite, tourmaline and stilpnomelane. The problems of these and other mineralizations is addressed as a whole in the Appendix, because it cannot be assumed that they are Proterozoic, Paleozoic or Cenozoic.

10.8

Early Paleozoic and Proterozoic strata of Sorkapp Land

Sorkapp Land is a distinct geographical entity accessible mainly from Hornsund. Geological work has been largely achieved by the Norsk Polarinstitutt culminating in their 1 : 100 000 geological map C 13G (Winsnes, Birkenmajer, Dallmann, Hjelle & Salvigsen 1992) which conveniently covers just this area. The map description accompanying it by Dallmann, Birkenmajer, Hjelle, Merk, Ohta, Salvigsen & Winsnes (1993) is the definitive text. With a dominantly N N W - S S E strike the strata are arranged in broad belts with Van Mijenfjorden and Adventdalen groups in the east, Kapp Toscana and Sassendalen groups in a narrow strip down the centre flanked by Tempelfjorden, Gipsdalen and Billefjorden groups. Then a narrow strip of Precambrian rocks of unknown relationship. The western part of Sorkapp Land comprises a broad belt of 'Hecla Hoek' rock, in this case of Ordovician, Cambrian, and Neoproterozoic rocks flanked on the east by narrow outcrops of Devonian and on the west by flat-lying Early Carboniferous and Triassic strata.

10.8.1

Early Paleozoic strata

A break-through in Hecla Hoek stratigraphy was made by Winsnes (1955) in Major & Winsnes (1955) who established a carbonate

198

C H A P T E R 10

sequence w i t h the first r e c o r d e d O r d o v i c i a n a n d C a m b r i a n fossil finds in m a i n l a n d Spitsbergen. I n all 16 fossil localities were described f r o m scattered o u t c r o p s in c o m p l e x f o l d e d structures. This sequence, a p p r o x i m a t e l y overlying Late P r o t e r o z o i c rocks, was described as below, b u t is n o t seen in a n y o n e succession. W i t h the benefit o f w o r k i n g first n o r t h o f H o r n s u n d a n d later in S o r k a p p L a n d , B i r k e n m a j e r r e a r r a n g e d the s t r a t i g r a p h i c s c h e m e in t w o g r o u p s s e p a r a t e d by u n c o n f o r m i t i e s between, a b o v e a n d below. T h e S o r k a p p L a n d G r o u p was said to be O r d o v i c i a n a n d the S o f i e k a m m e n G r o u p C a m b r i a n . His scheme was t h u s unified for s o u t h Spitsbergen, i.e. for W e d e l Jarlsberg L a n d as well as for S o r k a p p L a n d . W e follow it here w i t h m i n o r m o d i f i c a t i o n s b u t d i s t i n g u i s h only the rocks f o u n d in S o r k a p p L a n d . T h e G r ~ k a l l e n Series o f M a j o r & W i n s n e s (1955) c o m b i n e d Tsjebysjovfjellet, R a s s t u p e t , N i g e r b r e e n a n d H o r n s t u l l o d d e n units as described b e l o w a n d n o t u s e d in this scheme.

Hornsund Supergp Sorkapp Land Gp, 1400+ m (Birkenmajer 1978) Arkfjellet sequence, 200+m. The formation underlies the Devonian unconformity, its base is not seen and its relationship to other units of the group is not clear. In places the succession was inverted before Devonian deposition. The succession appears to be: 70 m at the top of hard, black, quartzite and clayey shales, black oolitic limestone with fossil debris (brachiopods and corals) and grey limestone with laminated algal structures; 55 m dark shaly limestones and calcareous shales; thin conglomerate; 200+ m of folded and crenulated weathered silty shales with phyllitic textures, thin quartzite bands and 'uneven lumps of quartz'. An Ordovician age or younger is indicated by the poorly preserved fossil material. It therefore overlies the other formations of the Sorkapp Land Group or is equivalent to some. Birkenmajer suggested a possible correlation with some Hornstulloden subgp strata. Hornsundtind (limestone) Fm, 500m (Birkenmajer 1978) (relationship not clear). Sjdanovfjellet (limestone) Unit was described by Major & Winsnes with a Late Canadian fauna: g a s t r o p o d s - Hormotoma, Maclurea and Straparollina; nautiloids: Onetoceras loculosum, Beekmantoceras priscum, Bathmoceras, Polygrammoceras. It may be the equivalent of the upper part of the Tsjebysjovfjellet Mbr or a third higher member. Tsjebysjovfjellet (limestone) Mbr, 4 0 0 + m of light grey to black slightly bituminous limestone with some dolomitisation or silicification. Both members may show fine lamination or phyllitization. Rasstupet (limestone) Mbr, 80 m of pinkish- or brownish grey thick bedded limestone. With Late Canadian fauna including gastropod: Maclurea; brachiopod, Diaphelasma; sponge, Receptaculites; nautiloids, Protocycloceras cf. lamarki, Vaginoceras. Nigerbreen (limestone) Fm 80 to 120m of black or grey banded limestone with black chert lenses and dolomitization and a Canadian fauna: gastropods, Ceratopea and Maclurea; nautiloid; Vaginoceras cf. longissimurn Hornstullodden Subgp. This unit, originally a formation, is retained from Major & Winsnes (1955) with three limestone divisions) which, (1) to (3), approximate to Birkenmajer's three formations and none with recorded fossils. (3) Dusken (limestone) Fro, 20 30 m (name from Wedel Jarlsberg Land, (Birkenmajer 1978) is of thin-bedded laminated limestones, grey to black alternating with yellowish laminae and puncuated by irregular cherts. (2) Luciapynten (dolostone) Fro, 100m of varied coloured dolostone passing into dolomitic sandstone and with occasional breccias. (1) Wiederfjellet (quartzite) Fro, 300m is best developed in Wedel Jarlsberg Land with two members. Goi~sbreen Mbr, 270m is the upper member best developed in Sorkapp Land. It is of dark grey to black arenaceous carbonates alternating with sedimentary breccias. Paierlbreeen Mbr appears to be limited to Wedel Jarlsberg Land. The Wiederfjellet Fm oversteps unconformably different units of the underlying Sofiekammen Group. Sofiekammen Gp (max 935 m) in Wedel Jarlsberg Land. The name (Birkenmajer 1958, 1978) is taken from the mountain in Wedel Jarlsberg Land. The Group is predominantly dolostone and limestone with shale and sandstone lower down and of variable facies. The thickness is somewhat less in Sorkapp Land. Nordstetinden (dolostone) Fm (Birkenmajer 1958, 1978) 150m in Wedel Jarlsberg Land with two members.

Nordstebreen Mbr, 50 m of platy dark grey or black dolostone in bands 1 to 10 cm thick alternating with yellow mainly dolostone. Lingulellaferringinea has been recorded.

Hansbreen Mbr, 100m of light or dark grey to bluish massive dolostone, sometimes laminated, with black chert or alternates with dark bituminous laminated dolostone. No fossils were recorded. Gn~lberget (marble) Fro, 200 m (Birkenmajer 1959). This is a massive calcmarble, limestone, and dolomitic limestone with some pink calcite and red jasper veins. No fossils were recorded. It mainly occurs in Wedel Jarlsberg Land with minor occurrences only in Sorkapp Land. Slaldi Subgp. Major & Winsnes (1955) introduced the name Slakli Series for the rocks described below as the Slaklidalen and Vardepiggen formations. This name, familiar in the literature, may be worth preserving as a subgroup. Slaklidalen (limestone) Fro, to 120 m (Birkenmajer 1978). This is unit (1) of Major & Winsnes Slakli Series. It is black to grey limestone, sometimes dolomitic, bituminous or arenaceous with Olenellus cf. thompsoni, Senodiscus bellimarginatus, S. cf. speciosus, Calodiscus lobatus, Pagetia, Hyolithellus cf micans, Hyolythes, Platyceras primaevum, Obolella cf. atlantica. ( : BonniaOlenellus zone of Fritz 1972) of late but not latest Early Cambrian age. Vardepiggen Fro, 420-450 m in Sorkapp Land (formation and member names are from Wedel Jarlsberg Land (Birkenmajer 1978). Flogtoppane Mbr, 10m is of black to grey, often graphitic shales, some sedimentary breccias. Midifjellet Mbr, 20m is similar to Slaklidalen Limestone (no recorded fossils) Olenellusbreen Mbr, 300-350 m is of green to black shale with sedimentary breccias 2 10 m thick with clasts of dolostone, limestone and (G~tshamnatype) phyllite; Olenellid trubolites Nevadella sp., Olenellus svalbardensis. This is the 'Olenellus shale' in the lower part of the Slakli Series of Major & Winsnes (1955). Blfistertoppen (dolostoue) Fro, 95+ m Russepasset Mbr, 25+ m is of black or blue, yellow weathered arenaceous dolostone. Flakfjellet Mbr, 35m of black shale with thin grey limestone and concretions, with Olenellus svalbardenis, O. sculptilis G~sbreen Mbr, 35m is of pure dolostone and dolomitic limestone above yellow arenaceous dolostone below. The basal unconformity was said to be in angular contact with the GAshamna phyllite Formation (see below). However, the section at Slaklidalen to Wiederfjellet (Birkenmajer 1978, fig 15, p. 20) suggests a concordant relationship.

10.8.2

Neoproterozoic strata

Sofiebogen Gp G~shamna Fro, 1.5 km (Winsnes 1955), c. 3 km (Birkenmajer 1992). As described above the lithologies of the Bogstranda unit are similar with dominant green to black (some graphitic) phyllites with intercalated quartzite shale units which may cut through 2kin to the south at Slaklidalen, the top being truncated by Cambrian strata suggesting that an upper 1 km of phyllites may be missing there. Beds of dolostone but not limestone occur. Interbeds are generally persistent over a km or more. Upper division, c. 500 m is of black shales and phyllites exposed near shore. Middle division crops out south of G~sbreen. Lower division is variable with green and grey slate and phyllite; probably equivalent to the lower part of the Bogstranda Fm. The lower boundary is tectonic as first pointed out by Winsnes (1965) and confirmed by CSE in 1977 Hiiferpynten Fm (Winsnes 1955). The formation is superbly well exposed at the eponymous promontory and is divided as below. Winsnes (1955) showed the unit to be thrust over the G~shamna Fm and not in a sedimentary succession. He described it in three parts (3) quartzites, (2) limestone with oolites and (1) dolostones with cherts. It is now divided into six members (Birkenmajer 1972). (6) Quartzite Mbr, 300+ m three prominent ribs of quartzite surounded by phyllite (at sea level) appeared to be conformable with the older strata to the author (Harland 1978) as to Winsnes whereas Birkenmajer has included these rocks in the G~tshamna Formation. Exposure is poor to the east. (5) Oofific Limestone Mbr, 40 m with a conspicuous stromatolite bed at the top. Grey limestone with oolite (Winsnes 1955) and pale-weathering dolomitic oolite and pisolite (Birkenmajer 1972, 1977 and named his Dunoyane Mbr).

SOUTHWESTERN AND SOUTHERN SPITSBERGEN (4) Wurmbrandegga Mbr, 300 m is a massive grey dolostone with occasional current bedding, lacking cherts. (3) Andvika Mbr, 300 m is the lower part of Winsnes' dolostone: it contains grey chert layers which are more continuous near the top. (2) KvivoddenMbr: Upper division, (20 m), is a complex of grey-greenish and yellowish dolostone, distinguished by Birkenmajer as his Fannytoppen Mbr. (1) KvivoddenMbr: Lower division, (10 m), is of deformed lenticular yellow and reddish quartzite pebbles and boulders (2 to 20 cm) within a matrix of deformed quartzite phyllite and interpreted as a silicified intraformational conglomerate, possibly first dolomitized. Harland 0978) incorrectly thought that this was mapped by Birkenmajer (1960) as the Slyngfjellet Conglomerate which unit was identified with apologies as the Sigfredbogen Fm (Harland, Hambrey & Waddams 1993). Sigfredbogen Fro, >300m. This unit was named (Harland et al. 1993) for the highly sheared quartzite-metapsammite forma~tion. It is exposed along the shore west of H6ferpynten and striking N-S with about 10m of metaconglomerate at the eastern end of the outcrop exposed in a small onshore depression. It was concluded that the the psephite and the psammite were joined in a continuous unit, the conglomerate being a local development of the quartzose rock. The psephite was referred to by Birkenmajer (1960, 1972) as his Slyngfjellet Conglomerate (at the eastern end), the psammite as the Bergskardet Fm of the Deilegga Group. However, both facies seemed to differ from those two formations north of Hornsund in both composition and in their higher metamorphic grade. This correlation is doubted and, on the evidence available, no other correlation is offered. If the postulated Kongsfjorden-Hansbreen Fault Zone (Harland, Hambrey & Waddams 1993) is a terrane boundary then the Sigfredbogen Formation would lie to the west of it and so belong to the Western Terrane. The correlation might thus be sought within the Isbjornhamna Group e.g. the Ariekammen Fm. But, because it is probably bounded by faults on east and west sides, and if these are N-S splays of the fault zone, then the Sigfredbogen Fm could have moved to its present position relative to the Isbjornhamna Group from further south.

Other older rocks of Sorkapp Land. There is a strip of older rocks extending south east of Samarinv~gen in Hornsund to Kistefjellet at the southern tip of Sorkapp Land. They were less metamorphosed and tightly folded beneath the Devonian and Carboniferous strata. The 1:100 000 map, C13G (Winsnes e t al. 1992) shows five rock types (map units 34-38). Although in one single belt extending 40 km N - S and 1-7 k m across the outcrops appear as two distinct associations. The northern two thirds of the outcrop belt is occupied by two facies mainly quartzite and garnet schist (map unit 38) in contact (without marked faults) with marble (unit 37), with unit 37 apparantly above unit 38. Each formation is probably at least 1 km thick. These are referred to as Mefonntoppene rocks. Dallmann et al. (1993, p. 18) compared the garnet mica schists with the Skoddefjellet Fm and the marbles with the Ariekammen Fm both of the Isbjornhamna Group north of Hornsund and thought to be at least 970 Ma old (Birkenmajer 1993) or older (Balashov et al. 1995). In addition to the above correlations similarities between some Mefonntoppane rocks and the Gulliksenfjellet and Steinvikskardet fms above the Isbjornhamna Group were suggested. The southern outcrop is less obscured by ice and shows a consistent sequence on the map around the flanks of Kistefjellet referred to here as the Lyngebreen sequence as below: carbonate (unit 34), 1+ km, quartzite (unit 36), 100-200 m phyllite and mica schist with garnets (unit 35) phyllite and mica schist (unit 35), c. 2 km. The carbonate, unit 34, appears in an isolated nunatak (Breskilknausen) between the Mefonntoppene rocks and those at Kistefjellet where the same unit is well developed. Birkenmajer (1993) compared this with the H6ferpynten Formation. These appear in a pre-Triassic anticline plunging NNW. Both rock groups are covered mainly by Triassic strata except at one locality in the centre where Adriabukta rocks (Early Carboniferous) intervene. Long N-S thrust faults bound the strip on each side. To the west the Sorkapp Land Group (Ordovician) strata down to the Hrferpynten Formation (? Late Riphean) are generally uncovered except by Marietoppen (Devonian) strata in the northeast, by scattered Triassic strata generally and by Early Carboniferous rocks in the west.

10.8.3

199

Minerafization around Andvika

Wojciechowski (1964), Birkenmajer & Wojciechowski (1964) and Flood (1969) reported sulphide occurrences at Andvika which are opposite the extensive occurrences north of Hornsund. They are associated with faults and associated sheared breccia zones within the dolomitic facies of the H6ferpynten Formation and have never tempted exploitation. Ankerite and siderite occur as general impregnations whereas the distinctive veins with quartz gangue and geodes are characterized by the sulphides, pyrite, arsenopyrite, sphalerite, galena and chalcopyrite.

10.9

Correlation of pre-Devonian through S W Spitsbergen

With the exception of the Early Cambrian and Early Ordovician strata of eastern Wedel Jarlsberg Land and Sorkapp Land the extensive Precambrian rocks have not yielded determinable fossils to aid correlation. The only significant isotopic ages from the sector are those from the Eimfjellet and Isbjornhamna groups which identify these as Mesoproterozoic. A major correlation tool for Proterozoic correlation has been the two Varanger glacial horizons and the presence of associated basic volcanics with the earlier one. Otherwise we are left with the uncertainties of lithological correlation in a terrane which has undergone at least two orogenic episodes. The difficulties in establishing an agreed sequence have been demonstrated for southwest Wedel Jarlsberg Land (Section 10.7.3). This work attempts to give at least one coherent solution (Fig. 10.7). A major terrane boundary is postulated to trend through Recherchefjorden, Recherchebreen and south to Hansbreen with a possible splay out through Torellbreen (the KHFZ).

Western terranes.

To the west of this postulated KongsfjordenHansbreen Fault are the western terranes which, south of Isfjorden, are entirely Precambrian with one possible exception. The major outcrop area of this has been argued to be of Varanger age i.e. including the two tillite horizons and the strata between. The tillites may be distinguished by their stone content, the later one being characterized by extra-basinal crystalline rocks often distinguished by colour. The earlier tillite is dominated by intrabasinal clasts (stones and matrix) generally softer and less conspicuous. The earlier Varanger rocks are typically associated with basic volcanics. The whole Varanger sequence reflects a tectonically mobile environment with erosion of tills forming conglomerates, with strong current indicators and thicknesses commonly around 10 kin. In Fig. 10.7 columns 1-3 are western terranes. In northwestern Wedel Jarlsberg Land are the (lower) Varanger Konglomeratodden Group and the (upper) Kapp Lyell Group; in the southwest only the equivalent of the lower group is represented by the (newly designated) Aust Torellbreen Group. Where the succession beneath the lower tillite is exposed in each case only thin strata are seen above a major unconformity. In northwestern Wedel Jarlsberg Land this truncates recumbently folded formations of the N o r d b u k t a Group. In the southwest Wedel Jarlsberg Land a faulted unconformity truncates an apparently concordant sequence of Eimfjellet overlying Isbjornhamna Group formations. Both these groups have yielded isotopic ages with a thermal event at c. 950 Ma with igneous strata 1100-1200 Ma old and with indications of some rocks being up to 2200 or 2500 Ma (Balashov e t al. 1995, 1996b). These two half windows show what must be a complex proto-basement in which the exposures have little in common. Possibly between the Vendian and proto-basement would be the Dunoyane Formation (?Sturtian) exposed in offshore islands. The western terranes are all associated with mineralization.

Central terranes.

East of the K H F Z the strata range downwards through Early Ordovician, Early Cambrian, probably Ediacaran phyllites (up to 2500m) and two Varanger glacials (totalling

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1500 m), no volcanics, and minimal mineralization. The K H F Z not only truncates the lower tilloid north of Hornsund, but also the H6ferpynten Formation to the south which, with its characteristic stromatolite and oolitic facies, could be Sturtian in age. To the north of Wedel Jarlsberg Land and east of the postulated fault at Recherchefjorden is the Magnethogda gneissic unit which would seem to be a further and distinct proto-basement unit. The Magnethogda sequence was mapped as units 49 down to 55 in Sheet B11G (Dallmann et al. 1990). However, as they now realise from mapping of the adjacent sheet B12G (Ohta & Dallmann) to the south, that the Ggtshamna Formation (unit 28) to the south overlaps with unit 55 to the north, which at least inverts the sequence to the north - the Magnethogda rocks being undoubtedly older. Thus units 53 and 55, and possibly also 52, could be Vendian, whereas 49 and probably 50 are almost certainly pre-Vendian. A problem remains with the interpretation of the mountain tract between Aust and Vest Torellbreen which has only been reconnoitred. Birkenmajer et al. (1992) reported at Krakkow 'anthracite' similar to the meta-bituminous vugs in the H6ferpynten Formation. Ohta (pers. comm.) reported a possible Cambrian fossil. This sub-terrane may be displaced by faults. Apart from the Magnethogda rocks, mineralization is minimal. Whereas Silurian Caledonian deformation has not been established in the western terranes it is evident as the main episode deforming the Precambrian strata in the inner Hornsund region. The Kongsfjorden-Hansbreen Fault, as a major postulated lineament, possibly an outcome of Caledonian tectonism with sinistral strike-slip completed in Late Devonian time, is generally obscured by ice, water or post-Devonian strata. Sinistral shear structures are seen just west of Hansvika, at least two fault splays are mappable just west to H6ferpynten and south of Magnethogda a mylonitic gneiss is mapped along the possible fault trace. However, there may well be one or more splays out to sea via Torellbreen (as was first thought by Harland & Wright, 1997). In conclusion, there are difficulties yet to be resolved with the above hypothesis. Some could be decisive enough to require a reformulation. Other hypotheses, or nul hypotheses without major strike-slip displacements, seem to the author to encounter greater difficulties. Time will tell and this work is to advance understanding by formulating fallible hypotheses as a challenge.

10.10

Structure of western Nordenski61d Land

Nordenski61d Land exposes the main body of the Central Basin with its Paleogene coalfields. Its western margin comprises two distinct terranes which are parts of the West Spitsbergen Orogen where it is relatively narrow. Bordering the western edge of the Central Basin with relatively flat-lying strata is an abrupt transition to the distinctive fold and thrust belt which deforms Carboniferous through Early Paleocene strata. This is a mountainous zone of visibly complex structures. West of it is the other terrane of Proterozoic basement. It is a low-lying area of slight relief forming an extensive strandflat known as Nordenski61dkysten. To interpret the structure of the basement, whose outcrops are seen mainly in plan, depends on a knowledge of the stratal succession and this has received relatively little attention. The two 1:100 000 map sheets (B9G, Ohta et al. 1992 and B10G, Hjelle et al. 1986) gave one stratigraphic interpretation. Another by Harland et al. (1993) postulated the whole succession from the upper tillite in the north to the lower tillites in the south to be of Varanger age. Narrow faulted inliers of Carboniferous conglomerates and sandstones are conspicuous. Less evident, perhaps is a postulated thrust to the N E trending N W - S E as shown on the map by Harland et al. Clearly many other structures remain to be elucidated. The eastern boundary is well marked by the pale-coloured conglomerates of the cover rocks above the basal Carboniferous unconformity. The unconformity generally dips E in the foothills and demonstrates that the low-lying basement had risen to at least a similar height as the fold belt and appeared to have provided the impetus for the eastward compressive thrusts and folds.

Croxton & Pickton (1976) reported that the extreme western limb of the Paleogene basin with a N W - S E axis is bounded by the fold and thrust belts of the West Spitsbergen Orogen (trends NNW-SSE). Paleogene strata dip steeply to the E and NE, but shallow rapidly eastwards. Around Kolfjellet the strike swings from N N W - S S E to N W - S E with dips up to 20 ~ Their structure contour map of the base of the Firkanten Formation shows this swing and minor normal faults also throw strata down to the east. The underlying Carolinefjellet Formation is not so easy to map structurally, but the Helvetiafjellet Formation below is concordant with the Paleogene structures above. The fold belt is conspicuous and has long been known especially from its E - W cliff sections which truncate the north and south of the belt where cut by Isfjorden and Bellsund respectively. It is also easily accessible from Gronfjorden in the east. The northern cliffs have been described many times most notably in the classic Festningen profile of Hoel & Orvin (1937) where, with steep dips and strikes broadly perpendicular to cliff sections, the standard succession of cover rocks was established with detailed measurements and descriptions (Fig. 4.1.1). With the regular succession in mind the structure was first visualized as a monocline forming the steep to vertical western limb of the Paleogene syncline of the Central Basin (Orvin 1940). However with greater appreciation of the West Spitsbergen Orogen, and this a key part of it, thrusts were identified with other complications in the structure. As part of the CSE programme of E - W traverses a first indication of the nature of the fold belt was evident in A. Challinor's serial sections (made between 1960 and 1969) - a selection of which, through the entire orogen, are first published in this volume in Chapter 20, and include the Nordenski61d Land sector. The structures have invited much attention in recent years. They are easily seen in the mountain cliffs by the lithologies of the strata of the cover rocks notably the Permian Kapp Starostin, palecoloured resistant and competent, marker horizon contrasting with the overlying dark, soft, incompetent siltstones and shales of the Sassendalen Group. The first comprehensive map with cross-sections for the whole belt between Isfjorden and Bellsund was by Maher, Ringset & Dallmann (1989) with eight serial W S W - E N E cross sections, superficially endorsing Orvin's monocline, but with many complications. The section depicted the observed structure in the mountains. A more sophisticated study of the same belt by Braathen, Bergh & Maher (1995) extrapolated the structural logic to the great depth and height (Fig. 10.8). They also attempted a N - S section which is equally complex. This shows a consistent northerly vergence of the thrusts which is consistent with the dextral transpression hypothesis. An interpretation of the required deformation stages was attempted (five at Festningen and four at Bellsund) to result in the postulated structure. A study of Kongressdalen in 1996 showed a SW verging thrust (D. Paton pers. comm.) Most of the details that follow are based on those two papers. It may, however, be generalized that all the structures interpreted by all parties endorse thick- rather than thin-skinned tectonics. This contrasts with the much wider belt north of Isfjorden where the deeper thrusting in thicker strata in the west pushes the strata on d6collement zones into the typical thin-skinned structures over the Nordfjorden Block. At this latitude the Central Basin takes the place of the Nordfjorden Block, the d6collement thrusting passed beneath the mildly folded Paleogene strata and probably occupies the same d6collement zones so as to surface in the older N - S fault zones still further east.

10.10.1

Eastern margin of the fold belt

In the north the transition between the fold belt and the Central Basin is obscured by Gronfjorden. The fjord appears to be eroded into a broad symmetrical anticline with a core of less resistant Jurassic-Cretaceous shales. To the west at Festningen the vertical Cretaceous sandstones with a sliver of Palaeocene Firkanten

SOUTHWESTERN AND SOUTHERN SPITSBERGEN

201

Formation are folded into a tight syncline seen in the northwest coast of Gronfjorden. The eastern flank of the anticline on the east coast of Gronfjorden is of generally easterly dipping Cretaceous sandstones overlain by the coal-bearing Firkanten Formation, mined at Barentsburg. This zone of softer Triassic, Jurassic and Cretaceous strata continues south and divides. In the west is the low-lying glacial cover of Gronfjordenbreane and into Fridtjovbreen and the large natural harbour of Fridtjovhamna. East of this is a ridge of steeply folded Triassic through to the low ground of Berzeliusdalen (with its deep well) underlain by Cretaceous strata and into the low easterly dips at the west of the Central Basin at an old coal working in the Firkanten Formation at Camp Morton.

The structures on Midterhuken can be attributed to the development of a foreland prograding fold- and thrust-belt characterized by east-vergent thrusting in Late Eocene time (Maher et al. 1986, 1988; Ringset 1988). The undeformed strata in the Midterhuken foreland dip 20 ~ towards the east as part of the west limb of the broad Central Spitsbergen Basin. Basement rocks become involved in Tertiary deformation about 8 km to the west even though about 3 km of platform strata are involved. In contrast to most fold-and-thrust belts, stratigraphic repetition occurs along only one Midterhuken fault. In addition, there is little evidence for typical ramp-flat staircase thrust geometry (Maher et al. 1986). Mann (CASP) from eigenvector analysis of the Janusfjellet folds suggested a dextral shear in a N-S-oriented shear zone.

10.10.2

10.12

Main fold belt

The high mountains identify the main fold belt of stratal thickness of about 3 km with the steepest dips. It varies in width from 4 km E-W in the south to 7 km in the north with a N-S length of 40 km. Easterly dips increase from 30 ~ in the W to vertical in the centre and east. Later than Challinor's foray in the early 1960s is the work of Maher et al. (1989), Braathen & Bergh (1995) and Braathen, Bergh & Maher (1995) (Fig. 10.8), Ohta (1988), Kimura, Ohta & Nakamura (1990) and other studies included in the synthesis by Dallmann, Andresen et al. (1993). In the Festningen section Permian to mid-Triassic formations dip east at about 30~ to 50 ~ and later Triassic to Paleocene strata dip 70 ~ to 90 ~ Balanced cross-sections from work by CSE/CASP Townsend & Mann indicated an E-W shortening of 3.25-3.5 km. In addition to truncation of strata by thrusts, Challinor noted that the top of the Vegardfjella Formation and the lowest units of the Gipsdalen Group have been cut out only by a basal Permian unconformity, so that Wordiekammen Formation lies directly on Billefjorden Group clastics. These Permian strata are folded into a series of inclined folds with wave lengths 250 500 m and verging westwards. In the Bellsund sections Botneheia shales, with minor N N W SSE-trending folds, transect cleavages indicating a dextral shear sense. The Janusfjellet Formation forms a detachment and accommodation zone between the Kapp Toscana sandstones and the Helvetiafjellet sandstones. Cambridge geologists including WBH have reconnoitred the area but their results do not contradict what has been published. The structure of this segment of the fold belt is illustrated in Fig. 10.8. The structure is well displayed by the conspicuous outcrops of the competent Kapp Starostin Formation, which underlies the incompetent Sassendalen Group strata, and in turn by the competent Kapp Toscana Group strata. Recent seismic and structural studies (Faleide et al. 1988; Andresen et al. 1988; Bergh et al. 1988; Haremo & Andresen 1988) imply that basement overthrusts occur in the subsurface of Nordenski61d Land (e.g. Ohta 1988). These structures would be necessary for the lateral continuity of the thrust system further east.

10.11

The Structure of western Nathorst Land

Midterhuken is the western tip of Nathorst Land where the two fjords Van Mijenfjorden and Van Keulenfjorden converge to form the wide fjord of Bellsund. To the north is the long straight N-S island, Akseloya, which almost connects the Kapp Starostin Formation with Nordenski61d Land to the north. The structure can be seen well in the cliffs from the sea and is one of the most photographed structural features in Svalbard. It was described by Maher et al. (1986) with seven structural zones west to east (ST 1-7). They are based on the differences in structural response by the various stratigraphic units, in addition to the major fault surfaces. They are illustrated in Fig. 10.9.

The structure of Wedel Jarlsberg Land

Wedel jarlsberg Land is intermediate between the lands to the north and those to the south geologically as well as geographically. From east to west four zones are recognized: (a) the Central Basin Paleogene and Cretaceous outcrops narrow southwards with a western margin which trends NW-SE to NNW-SSE; (b) the West Spitsbergen Orogen Fold belt to the west runs parallel from western Van Keulenfjorden to inner Hornsund; (c) the Hornsund-Sorkapp Basement extends east of Recherchefjorden in the north and Hansbreen; (d) west to the coast is the western basement (Coastal Horst of Harland 1989). The boundary between (a) and (b) is transitional westwards into more intense folding which is certainly of Paleogene age. The boundary between (b) and (c) is less easy to assess. Almost certainly the (Marietoppen Formation) Devonian strata with eastward verging folds and thrusts belong to the Paleogene fold belt (Fig. 10.10). The Hornsund-Sorkapp Basement (c) to the west a basement high exhibits Late Proterozoic to Ordovician strata dipping steeply west and younging eastwards. It is clear from similar structures south of Hornsund that they are pre-Triassic and typically Caledonian from which Devonian conglomerates derived possibly along a boundary fault zone (Gjelberg & Steel 1981). These were admirably depicted in the profiles north and south of Hornsund by Birkenmajer (1960) (redrawn in Fig. 10.10). Within this complex to the north is a probable Proterozoic Basement unit in the Magnehogda rocks. These are highly deformed metamorphosed gneisses in close proximity to metamorphosed CambrianOrdovician strata. It has yet to be isotopically investigated. The Coastal Horst (d) in Wedel Jarlsberg Land has no Phanerozoic strata to constrain the age of deformation excepting the Calypsobyen half graben of Late Eocene to Early Oligocene strata which help little because the main West Spitsbergen Orogeny climaxed in mid-Eocene time. However, the Coastal Horst contains two major structural units which may well be related structurally if not by age. They are (i) the proto-basement of the Nordbukta Group, deformed in recumbent folds and incontravertably unconformably overlain by (Early Varanger) tilloids and (ii) the proto-basement of the Isbjornhamna and Eimfjellet (sensu Czerny et al. 1992) groups with a postulated unconformable tilloid cover, as argued in Section 10.9 above, and with a Paleo- to Neoproterozoic thermal record. It is suggested here that the whole Coastal Horst (proto-basement and Vendian cover) may have suffered some ?Ordovician tectonothermal event, but was mainly a western zone of the Paleogene orogeny.

10.12.1

Structure of the West Spitsbergen Orogen

The latest (Paleogene) Spitsbergian deformation structures are the most conspicuous. The northern transect' south of Van Keulenfjorden has been investigated in some detail (the work of R6zycki 1959, Dallmann 1988a, b and Dallmann et al. 1993). The middle of Wedel Jarlsberg Land to a less extent and the southern outcrops were reconnoitered, but not subjected to similar analysis.

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Fig. 10.8. Structural map and representative cross-sections of Nordenski61d Land, illustrating the structure of Carboniferous to Cretaceous units. Simplified and redrawn from figures in Braathen, Bergh & Maher (1995), with permission. The dotted line markes the ice-rock boundary.

SOUTHWESTERN AND SOUTHERN SPITSBERGEN

203

Fig. 10.9. Simplified structural profile across the Midterhuken Peninsula (after Maher, Craddock & Maher 1986). The northern transect. T h e Berzeliustinden area is located at the o u t c r o p b o u n d a r y between the largely m e t a m o r p h i c H o r s u n d S o r k a p p Basement sequences and the overlying cover sediments o f C a r b o n i f e r o u s to Tertiary age. To the west of this b o u n d a r y , cover rocks preserved on the d o w n - f a u l t e d block at R e i n o d d e n and at R e n a r d o d d e n show that C a r b o n i f e r o u s - P e r m i a n strata extended further west prior to extension in this area ( D a l l m a n n 1988a, 1989). The structure of the Berzeliustinden area has been discussed by a n u m b e r of authors (R6zycki 1959; D a l l m a n n 1988a, b 1989). A lithological a n d stratigraphic s u m m a r y for the late Paleozoic to Cretaceous successions in the area was given by R6zycki (1959). The extensional structures in the area post-date the West Spitsbergen O r o g e n y ( H a r l a n d 1969, 1985; B i r k e n m a j e r 1972).

Dallmann (1988a, b, 1990) divided the area into two main structural units separated by the Berzeliustinden Thrust Fault (BTF), which has an approximate ENE vergence and displacement of about 800 m. The amount of displacement along the BTF has been estimated to be 2 km by Hauser (1982), which approximates with the value obtained if the displacement accommodated by folding in both the upper and lower

tectonic unit is added to the displacement of 800 m along the BTF, projected into the true plane of displacement, giving a total displacement of 1.5 km (Dallmann 1988b). Dallmann (1988a, b) showed that movement on the Foldaksla Thrust Fault (FTF) and d~collement zone caused repetition of part of the succession without stratigraphical inversion. On a west to east profile, sandstones of the Wilhelmoya Formation and Brentskardhaugen Bed are overlain by black shales of the Botneheia Formation; both the Botneheia Formation and the Kapp Toscana Group are structurally repeated and interpreted as a backthrust in front of the Berzeliustinden thrust unit. Formation of the Berzeliustinden structure. Dallmann (1988a, b) inferred a sequence of events for the development of the Berzeliustinden structure based on a thrust wedge propagation model. (1) Uplift of the basement antiform to the west followed by mechanical failure and eastward thrusting along the Berzeliustinden Thrust Fault. The fault may initially have continued into the Botneheia Formation black shale. (2) The development of a backthrust cutting the Botneheia Formation sandstone and the Kapp Toscana Group, giving rise to a ramp structure from the lower Botneheia to the upper Janusfjellet black shale formation.

Fig. 10.10. Schematic structural profiles of northern Sorkapp Land and of southern Wedel Jarlsberg Land (adapted from Birkenmajer 1960 so that both profiles are drawn as interpreted from the south).

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(3) A d6collement zone developed within the Botneheia Formation shale causing the formation of detachment folds in the repeated sequence between the shale formations. The interaction of backthrusting and gravity glide may have provided a mechanism for the generation of eastward and west-vergent structures. (4) The regional folding of the whole area initially generated the basement antiform, but may have continued during or subsequent to the main thrusting event. The low angle of the BTF and the steep orientation of the backthrusts implies eastward rotation and may be explained by regional folding. The geometrical configuration, resulting from the regional folding, permitted further propagation of the thrust wedge. (5) Subsequent thrusting along the BTF was accommodated by faultpropagation folds (i.e. tip-line structures) in the strata in front of the former wedge. Thin-skinned deformation within the Janusfjellet black shales, aided by low shear strength, formed east-vergent thrust systems in the continuation of the BTF and a backthrust at the boundary to the overlying Helvetiafjellet sandstones. The estimated displacement on the BTF of almost 1.5 km is partly accommodated by deformation in the overlying sedimentary cover.

conglomerates and basic volcanics. The terrane to the west is locally rich in a variety of sulphide minerals in contrast to the east. In line with the supposed boundary a N - S mylonitic outcrop is mapped (Ohta & Dallmann 1992) across north of Profilbreen. At Baranowskiodden, immediately west of the glacier cliffs of Hansbreen, which is postulated to conceal the KongsfjordenHansbreen Fault Zone, are clear indications of sinistral shear in a N - S direction. To the east of the promentory are indicators of strata with sinistral strike-slip faults and deformatiom. To the west in the Steinsvikskardet Formation, Birkenmajer (1992, p. 21) depicted a complex of tight folds cut by N - S sinistral faults, similarly at Wilkczeodden, southwest of Isbjornhamna. These structures could represent an initial strike-slip (transpression zone) in the Silurian Caledonian Orogen and end with final Late Devonian docking of the central with the western province.

10.12.3 A middle transect: the structure of the Supanberget area. The Supanberget area is located in the interior of Wedel Jarlsberg Land about 20 km to the south of Van Keulenfjorden, and forms part of the central NW-SE-trending ridge that separates the pre-Carboniferous basement in the southwest from the Late Paleozoic strata in the northeast. The stratigraphic succession of the area is based on the work of R6zycki (1959), Bjornerud (1990), Steel & Worsley (1984) and Nys~ether (1977), and the basement sequences have been reviewed by Harland (1978), Flood et al., Sheet 1G (1971) and more recently by Bjornerud (1987, 1990). Within the Supanberget area, the pre-Carboniferous basement, referred to as Caledonian basement by Dallmann & Maher (1989a, b), comprises the Magnethogda sequence or group (Harland 1978, 1985; Bj ornerud 1990) of possible Mid-Proterozoic age (Flood et al. 1971). The Supanberget Thrust System can be divided into a western zone characterized by significant basement involvement, and an eastern (foreland) zone characterized by high level tectonism (Dallmann & Maher 1989a, b). The minimum estimate of shortening within the Zittelberget--Engadinerberget area, determined using the shortening accommodated by the fold structures above the thrust, is about 500 750 m and must represent the sum of the transport along thrusts and also the shortening by drag folds beneath the thrust. The presence of bedding-parallel thrusts (i.e. detachments) or backthrusts in the foreland area, particularly in the northern part, suggests a much greater amount of shortening especially if such thrusts occurred at deeper levels (Dallmann 1988a, b). In the area between Supanberget and Stanislawskikammen the shortening by thrusting is estimated to be about 1 km with an additional amount accommodated by drag folding.

10.12.2

Postulated Silurian-Devonian strike-slip faulting

The boundary between central and western provinces of Svalbard of Harland & Wright (1979) followed a trace through Recherchefjorden, Recherchebreen in the north and through Hansbreen in the south ofWedel Jarlsberg Land as revised by Harland, Hambrey & Waddams (1993). The terrane boundary has been argued on evidence outside this land, but only evidence from Wedel Jarlsberg Land will be noted here. Correlation of the formations in the eastern and western limbs of the Kapp Lyell syncline is secure by mapping. However, the underlying proto-basement (the Nordbukta Group), which is relatively unmetamorphosed, contrasts with the Magnethogda gneisses to the east of the supposed boundary. The post-proto-basement strata succession to the east of Hansbreen is argued to be of thin lower and upper Varanger tillites about 1.5 km thick (minimum) followed by phyllites (?late Vendian) followed by fossiliferous Early Cambrian and Early Ordovician strata mainly carbonates with no evident metamorphism. To the west the post-proto-basement succession is interpreted as a thick Varanger sequence of mobile facies with tilloids,

Caledonian structures

As already remarked, the Hornsund Sorkapp Basement, zone (c) as defined at the beginning of this chapter, exposes in Hornsund, Ordovician, Cambrian and Vendian strata overturned and dipping steeply west. The structure is easterly verging with associated green-schist facies metamorphism and is truncated by an unconformity overlain by flat-lying Triassic strata to the south. The Marietoppen (Mid-Devonian) strata rest unconformably on the eastern margin of the Hornsund-Sorkapp Basement (Murashov 1976) and so constrain its deformation as probably Silurian (Caledonian). At Van Keulenfjorden Dallmann (1988b) has referred to structures in the same basement as Caledonian The lithological layering in the metamorphic basement is folded in a different style and orientation from cover rocks, and is inferred to relate to a mid-Paleozoic Caledonian deformation (Dallmann & Maher 1989a, b). In addition, folds within the basement are truncated by a Caledonian unconformity in the Supanberget area, with similar relationships defined elsewhere. Dallmann & Maher (1989a, b) suggested that the basement rocks were largely deformed by fracturing, slip along foliation and faulting during the West Spitsbergen Orogeny. The massive dolostones that are present in the basement have a strong controlling effect on the deformation of the adjacent cover rocks. Where the dolostones underlie the unconformity, the cover rocks are gently folded into large open flexures, and may be cut by a single brittle thrust fault. Similar geometries and relationships are defined further to the north of Berzeliustinden (Dallmann 1988b). Where the banded phyllite/quartzite sequence underlies the unconformity, the foliation either controls the thrust direction or is rotated into the transport direction, with tight and overturned folds in the overlying strata. The contrast between the degree of basement anisotropy (phyllite/quartzite versus dolostones) and fabric orientation controls the deformation style in the overlying cover strata. Those areas with strongly developed basement anisotropies (phyllite/ quartzite successions) are likely to show more complex deformation in the cover strata (Dallmann & Maher 1989a, b). However, the contrast in metamorphic facies between the Magnethogda gneisses and Cambro-Ordovician strata within a few kilometres and on the same strike implies that the Magnethogda rocks suffered a pre-Caledonian metamorphism.

10.12.4

Jarlsbergian diastrophism

Birkenmajer argued for a diastrophic episode between his Gfishamna (?Vendian) phyllites and the Early Cambrian carbonates and quartzites. There is little evidence of systematic discordance to produce an unconformity with marked overstep. The contrast in composition from phyllites to carbonates raises a further question.

SOUTHWESTERN AND SOUTHERN SPITSBERGEN Nevertheless, this is a possible unconformity with only one clear exposure reported at Slaklidalen in Sorkapp Land. Therefore some warping rather than tectonism may mark the Jarlsbergian Diastrophism.

10.12.5

Proto-basement deformation

The Nordbukta, Isbjornhamna-Eimfjellet, and Magnethogda rocks have already been referred to. They cannot yet be correlated between them stratigraphically or structurally. However the isotopic ages from the Isbjornhamna Group suggest a c. 2.5 Ga age and from the Eimfjellet Group 930 Ma which may reflect a widespread 950Ma event referred to as Grenvillian. Other ages have been claimed such as 594 and 1130, 1135 and 1200Ma. Work is in progress.

10.12.6

Post-proto-basement deformation of Precambrian rocks

This question refers to the age of manifest deformation of mainly Vendian strata, west of the Kongsfjorden-Hansbreen Fault Zone (i.e. the western terranes and in the Section the Coast Horst). The considerations above leave open several possibilities for deformation episodes affecting the pre-Carboniferous and especially the Proterozoic terranes. In the Vimsodden area of the coastal basement basic dykes are displaced by faulting which Birkenmajer (1986) attributed to post-Cretaceous deformation on the presumed basis of their Cretaceous age. The gently northward plunging wide open symmetric syncline in the Varanger strata of northwestern Wedel Jarlsberg Land could be Early Cambrian (Jarlsbergen), Ordovician or Silurian (e.g. Dallmann et al. 1990) or Paleogene. In that western provinces to the north there is no firm evidence of other than mid-Ordovician and Paleogene deformation. In these circumstances Paleogene deformation seems the most likely with thick-skinned structures. Similarly Birkenmajer (1986) attributed crenulation fabric and spaced fracture cleavage in phyllites of the Nottinghambukta Formation to Paleogene deformation, but that could be part of the Czerny et al. (1992) Eimfjellet Group and so be a possible pre-Vendian effect. On the other hand the complex fold and thrust structures in the later Vimsodden and Deilegga rocks have the imprint of Paleogene tectonics. This question has not been faced squarely partly because so much depends on the disputed Precambrian stratal sequence. According to the interpretation here it follows that the Late Varanger succession comprises more competent strata than the Early Varanger strata. This would account for the contrast in the wide open plunging syncline in the north and the exceedingly complex structures in the south where incompetent Deilegga pelites predominate.

10.13

Structure of Sorkapp Land

Sorkapp Land (and Tokrossoya), the southernmost area of Spitsbergen while continuing the structure as seen to the north, at the same time reveals more evidence of late Paleozoic diastrophism which is consistent with a position nearer to Europe with its Hercynian tectonism which Svalbard otherwise largely escaped.

10.13.1

205

outcrop nearly 20km E W . The basin is warped into similarly trending anticlines and synclines, five or six pairs, with wavelength averaging 2 km and amplitudes of about 500 m. This demonstrates a less abrupt eastern margin to the Central Fold Belt. (b) The main fold belt deforming Devonian through Jurassic strata is well exposed on both sides of inner Hornsund. (c) The Hornsund Sorkapp Basement is delineated by N N W SSE-trending faults obscured by similarly trending glaciers. It comprises Late Proterozoic, Cambrian and Ordovician strata, dipping steeply to the west, younging generally to the east, and with thrusts and folds verging eastwards as shown in the profiles N and W of Hornsund (Birkenmajer et al. 1960). These structures are truncated by relatively flat-lying unconformable Triassic strata so defining the main structures as Caledonian. This became the Hornsund High during Carboniferous through Triassic time. To the east, in Samarinbreen and Samarinv~gen, these older rocks are unconformably overlain by middle Devonian Marietoppen Formation strata involved in the Paleogene fold belt. (d) To the west is a terrane of flat-lying Billefjorden and Sassendalen Group strata with a late Carboniferous and Permian hiatus. This would appear to correspond to the Coastal Basement west of the Hansbreen Fault zone in Wedel Jarlsberg Land. It also contains the uncorrelated Sigfredbogen rocks and a slice of the H6ferpynten Formation. (e) In the southernmost tip in Southwest Sorkapp Land and in Tokrossoya is a further NNW-SSE-trending fold belt deforming Permian and Triassic strata and projecting offshore to the N W and subparallel to the coast. (f) Two further Paleogene outcrops occur with the Oyrlandet plain and hill top east of Sorkappfonna and Vasilievbreen. The northern outcrops referred to in (e) and (f) above together with the Proterozoic through Cretaceous-Paleogene extension of the fold belt are separated by wide ice cover from the Sorkapp Land outcrops to the south. This raises questions as to whether there is lateral displacement between north and south. On reflection such a model is rejected, with the consequence that the fold belt, the Hornsund-Sorkapp Basement, and the coastal basement have all been narrowed southward to less than half the width at the latitude of Hornsund. The definitive map of Sorkapp Land sheet C13G of Dallmann et al. (1993) maps five major faults some of which, being straight, must be suspect strike-slip fault zones. The westernmost of these appears to be the southern continuation of the KongsfjordenHansbreen Fault Zone and throws down to the west. The next zone to the east within the Sorkapp Basement appears as a series of thrusts pushing Cambro-Ordovician rocks eastwards over G~shamna phyllites. A fault, or pair of faults, appears to cut the length of the Cambro-Ordovician strata without noticeable effect on the outcrop pattern. Then the main Samarinbreen Fault, hardly constrained because it is within the glacier, divides folded Devonian on Cambro-Ordovician outcrop to the west through its length from a strip of Proterozoic, Devonian and Carboniferous strata to the east, which is separated from Carboniferous strata through Cretaceous strata by a well-constrained thrust fault. The Samarinbreen Fault is shown approximately in line with the fault to the south separating the Oyrlandet Basin to the west from the Proterozoic Basement covered by Triassic strata. This has structural affinity with the Hornsund Basement except that the Proterozoic rocks appear to have more affinity with those (at Mefonntoppane) east of Samarinbreen.

The structural units 10.13.2

The structural zones of Wedel Jarlsberg Land pass across Hornsund south into Sorkapp Land and with some interesting variations. From east to west they are as follows. (a) The southern tip of the Central Basin may be represented in a Paleogene outlier at the extreme east of Sorkapp Land and underlain by Early Cretaceous strata gently undulating and occupying an

Proterozoic structures

Proterozoic outcrops appear almost entirely within the zone of intense (probably) Silurian deformation. The arguments for intraProterozoic tectonism depend more on stratigraphic correlation elsewhere (e.g. whether the H6ferpynten Formation is protobasement). The main consideration here, as in Wedel Jarlsberg

206

CHAPTER 10

L a n d , concerns Birkenmajer's (1960, 1991) Jarlsbergen diastrophism which should be evidenced in s u b - C a m b r i a n structures. Certainly the G~tshamna phyllites are n o t m a t c h e d in the overlying C a m b r o Ordovician succession w h i c h is m a i n l y carbonate. However, most, if n o t all contacts are f a u l t e d - a result of c o m p e t e n c e contrast. Nevertheless, the m a i n thrust faults are m i n o r c o m p a r e d with stratal thicknesses, a n d everywhere the earliest C a m b r i a n strata follow the G ~ s h a m n a phyllite so that a m a j o r u n c o n f o r m i t y is unlikely.

10.13.3

Paleozoic structures

Birkenmajer's (1975) H o r n s u n d i a n diastrophism separates the (Early C a m b r i a n ) S o f i e k a m m e n a n d (Early Ordovician) Sorkapp L a n d Groups. There is evidence of a gentle tilt to the north, so the hiatus widens s o u t h w a r d . But the hiatus is a widespread p h e n o m e n o n a n d not altogether a tectonic one, with a similar hiatus elsewhere in Svalbard, East G r e e n l a n d a n d in Scotland. There is little d o u b t a b o u t the (Silurian) m a i n C a l e d o n i a n tectonism with its resulting eastward-verging overfolding a n d thrusting. This is responsible for the thick o v e r t u r n e d Proterozoic limb, but also for the detailed structure affecting the thinner Early Paleozoic units. The individual structures, evident in the m o u n t a i n s south of middle H o r n s u n d , are well d o c u m e n t e d by Birkenmajer (1978a, b). The resulting structure forms the H o r n s u n d - S o r k a p p Basement on w h i c h the D e v o n i a n ( M a r i e t o p p e n ) F o r m a t i o n rests u n c o n f o r m a b l y . The C a l e d o n i a n diastrophism could have continued into Early D e v o n i a n time. A c o m p l i c a t i o n is that the later Paleogene tectonism is also eastverging a n d p r o b a b l y c o n t i n u e d some of the C a l e d o n i a n thrust surfaces so that at first sight there is continuity of structures f r o m Proterozoic eastwards t h r o u g h Cretaceous. The G~shamna Formation has been thrust upon a sliver of the Cambrian limestones of the Slaklidalen Formation, which were subsequently thrust upon Sorkapp Land Group limestones; the two thrusts formed a fault zone of interconnecting splays. The Sorkapp Land Group to the east is deformed by more thrusts with a similar strike, but has shallower dips. At Rasstupet, the Hornsundtind and Nigerbreen formations are deformed into tight recumbent folds above a shallow westward-dipping thrust fault. To the east of Samarinbreen, the Ggtshamna Formation is deformed by west-vergent folds, which may be related to a backthrust. Along the eastern margin of the Hornsund-Sorkapp High, the contact between the Sorkapp Land Group limestones and the Devonian and younger rocks of the fold belt is unconformable, with a steep eastward and almost vertical orientation (Townsend & Mann CASP). Late Devonian (Svalbardian) tectonism is evident in Spitsbergen to the north. The youngest Devonian deposits in the Hornsund area, based on marine bivalves, are of Emsian to Eifelian age (Birkenmajer 1964). The Adriabukta Formation unconformably overlies the Devonian sediments and is thought to be of Visean age on the basis of palynomorphs (Birkenmajer & Turnau 1962), although in the type area at Adriabukta the upper part of the formation may be divided by an unconformity. But, there is no evidence at Adriabukta for an angular unconformity (Dallmann 1990, 1992). The Adriabukta Formation unconformably overlies Precambrian basement to the east of Samarinbreen and Olsokbreen. In the southern part of PSskefjella, Devonian sediments are attenuated between two adjacent ridges, which may be explained by the formation of an angular unconformity of at least 8~ or by faulting prior to the onset of Carboniferous sedimentation; this is the only evidence in the area of tectonism at the end of Devonian time. Further evidence of Svalbardian tectonics in the Sorkapp Land area is not known. Although not supported by evidence in Sorkapp Land, the postulated strike-slip fault between the central and western provinces would be at latest Late Devonian and probably initiated in Silurian time. Other relatively straight NNW-SSE faults might have the same early history, Sinistral strike-slip displacement may have led to the contrast west of the Hansbreen Fault suggesting subsidence of the West Sorkapp Land Basin.

Early Carboniferous basin development.

The northeastern part of

the West S o r k a p p L a n d Basin is characterized by extensional

structures that trend parallel to the principal N N W - S S E basinb o u n d i n g faults. There is limited evidence for localized early N a m u r i a n deformation, for example small-scale syn-sedimentary faults are identified in the H o r n s u n d n e s e t F o r m a t i o n on K u l m stranda. Evidence for larger-scale d e f o r m a t i o n in the younger, Early Triassic, rocks is not k n o w n here. Associated with the NNW-SSE and NE-SW-trending faults are a number of roll-over anticlines that suggest that some of the extensional faults may have a listric geometry at depth (Mann, CASP). The largest rollover structure identified is related to a NE-SW fault that cuts the whole of the cover sequence on the northwestern part of Sergeijevfjellet, with the closure extending 2 km northwestwards towards Hohenlohefjellet.

Adriabukta tectonic event.

B i r k e n m a j e r (1964, 1975) defined the ' A d r i a b u k t a Phase' on the basis of an angular u n c o n f o r m i t y between the A d r i a b u k t a a n d overlying Hyrnefjellet formations ( S e r p u k h o v i a n - B a s h k i r i a n ) . H o w e v e r , strong folding of the Adriab u k t a F o r m a t i o n , and (3) the thrusting of basement rocks and overlying A d r i a b u k t a F o r m a t i o n strata west onto the A d r i a b u k t a F o r m a t i o n overlying D e v o n i a n rocks require p o s t - A d r i a b u k t a tectonism. Dallmann (1990, 1992) from the interior of Sorkapp Land, at the nunataks of Lebedevfjellet, RokensAta, Smerudknausen and Eggetoppen suggested that the folding and thrusting may be related to the West Spitsbergen Orogen, although there is uncertainty about the presence of an angular unconformity. Devonian strata are tightly folded and are unconformably overlain by shallow-dipping (about 10~ Triassic strata. Dallmann (1992), concluded that the Samarinbreen Syncline is of post-Visean but pre-Triassic age, with the angular unconformity at Adriabukta indicating a mid-Carboniferous age limit (Birkenmajer 1964). At Haitanna the geometrical relationship of the two angular unconformities (Adriabukta and Hornsundneset formations over Caledonian basement) suggests that the Hornsundneset Formation also unconformably overlies the Samarinbreen Syncline. This further constrains the Adriabukta tectonic event to Serpukhovian. The total areal extent of the Adriabukta deformation is unknown. Dallmann (1992) suggested that strain was concentrated along the Samarinbreen Syncline and thrust faults; other deformed zones to the east or west may have developed but are not exposed. Mann (1989, CSE) found evidence of early Carboniferous compression associated with lower green-schist facies metamorphism in Adriabukta.

Carboniferous block faulting.

The N-S trending faults within the Sorkapp b a s e m e n t cut the u n c o n f o r m a b l y overlying Triassic strata, with the relative displacement of the Carboniferous base being greater than that of the Triassic base. Faults within Carboniferous strata m a y be overlain by u n d e f o r m e d Triassic strata (Steel & Worsley 1984; D a l l m a n n 1990, 1992). The age of the faults c a n n o t be constrained closer than p o s t - S e r p u k h o v i a n and pre-Triassic (Steel & Worsley 1984). The sedimentary facies of the Carboniferous strata and their lateral distribution indicate that the fold belt was affected by syn-sedimentary faulting during Carboniferous time. The localised appearance of a thick, proximal delta or alluvial fan facies of the Adriabukta Formation (Haitanna Member) suggests that the assumed boundary fault to the Adriabukta Formation graben (Steel & Worsley 1984) was active during sedimentation. The Hornsundneset Formation (Namurian) is eroded in many areas as a result of faulting in late or post-Namurian time (Dallmann 1990, 1992). The Bladegga conglomerate represents a local facies within the Middle Carboniferous Hyrnefjellet Formation and has been interpreted as an alluvial fan facies related to an active basin margin (Gjelberg & Steel 1981). Deposition of the Bladegga conglomerate was rapid (Birkenmajer 1964), with a transport direction towards the ENE. The local cut-out of the Late Carboniferous-Early Permian Treskelodden Formation at Bautaen suggests the possible continuation of minor fault activity into Permian time (Dallmann 1992). The Late Permian Kapp Starostin Formation shows a thin unit of nearshore facies (about 6 m) in parts of the fold belt (e.g. Austjokeltinden) that may thicken eastwards; the increase in thickness may be related to activity along the Inner Hornsund Fault Zone during Triassic time (Mork et al. 1982; Dallmann 1992).

SOUTHWESTERN AND SOUTHERN SPITSBERGEN

10.13.4

Mesozoic structures

The H o r n s u n d - S o r k a p p High was covered by a relatively condensed sequence of early Triassic sediments by Dienerian (Early Nammalian) time compared with other areas of Spitsbergen (Worsley & M o r k 1978), e.g. the westward thickening of Triassic sediments offshore (Eiken & Austegard 1987). Evidence for minor tectonic instability during early Triassic time is seen along the eastern margin of the West Sorkapp Land Basin at Kovalevskifjellet and Savitsjtoppen, where the base Triassic unconformity is displaced by several extensional faults, and is overlain by AnisianLadinian (Botneheia Formation) sediments. The tectonic instability occurred before the late Triassic (post-Ladinian) phase of extensional faulting that affects the Sassendalen Group in Van Keulenfjorden (Mann CASP).

10.13.5

Paleogene structures

The West Spitsbergen Orogeny resulted in conspicuous tectogenesis not paralleled since Caledonian events in Svalbard. Probably with an Eocene climax it is reasonable to attribute any major deformation of Carboniferous through Paleocene strata to this event.

Post-Jurassic tectonics in the west. A series of relatively open NNE-SSW-trending folds deform both the Triassic sediments at Lidelva and the Triassic and Jurassic sequence at Roysneset, where a well-developed cleavage is associated with the folds. Offshore seismic data provide some evidence for the compressional reactivation of an extensional fault (e.g. Eiken & Austegard 1987) along which Carboniferous and Mesozoic sediments have been uplifted (Mann, CASP). The fold axes at Roysneset show an anticlockwise transection by cleavage surfaces suggesting that a component of dextral strike-slip may have been involved in the development of these folds. This may reflect localised deformation rather than regional tectonics. F r o m paleostress tensors the Wurmbrandegga Fault was considered to have a dextral offset by Lepvrier, Le Parmentier & Seland (1988) and to be related (reactivatedly) to the West Spitsbergen Orogeny. The Central Fold Belt in Sorkapp Land. The fold belt in Sorkapp Land forms a prominent NNW-SSE-trending lineament, though it is considerably less pronounced when compared with areas further north. The Fold Belt comprises a zone, 5-10 km wide, of folded and thrust Late Paleozoic to Mesozoic strata, with fold trends broadly parallel to the N N W - S S E trend of the lineament. The principal source of information regarding the structure of the fold belt in this area is that of Challinor who mapped an area between Inner Hornsund and Storfjorden at a scale of 1: 25 000. A 1: 100 000 scale map of Hornsund, Sorkapp Land and part of Wedel Jarlsberg Land was compiled by Challinor (CSE) using both published and unpublished data (R6zycki 1959; Birkenmajer 1959, 1960a,b, 1964; Birkenmajer & Narebski 1963; Major & Winsnes 1955; Siedlecki 1960; Nagy 1966) and was partly updated by the structural work of Mann (CASP). The absence of significant compressional structures in this area indicates that the fold belt in Sorkapp Land, in contrast to areas further north, is structurally relatively simple. Challinor constructed a series of cross-sections through Wedel Jarlsberg Land and Sorkapp Land (Fig. 20.8) that illustrate the principal features. He interpreted these cross-sections assuming that the development of folded thrust fault trajectories was the result of competence differences between layers of previously folded strata. Using later techniques, it is found that thrusts were folded subsequent to initial thrust displacement, and that thrust trajectories can be modelled according to ramp and fiat geometries. The original cross-sections of Challinor cannot be balanced, but do contain the elements for producing a balanced cross-section, i.e. ramps, fiats and equal length cut-offs in the hangingwalls and footwalls to thrust faults (Townsend & Mann, CASP). The structural inversion produced east-verging folds and minor thrusts, but without significant stratigraphic repetition (Mann & Townsend 1989).

207

Shortening estimates, based on restored cross-sections for this area compiled from Challinor (1968, CASP), indicate between 4 and 6 km of ENE-WSW shortening. Surface structures that define the fold belt have been mapped for 30 km to the south of Hornsund. In the Sorkapp Land segment, there is a distinct lack of compressional structures along strike (Major & Winsnes 1955; Flood et al. 1971; Orvin 1940; Livshits 1973). Welland (CSE) similarly failed to recognise compressional structures along the projected fold belt line. However, at Oyrlandet in southwest Sorkapp Land, Permian strata exhibit steep to vertical bedding. Assuming that the steep dips at Oyrlandet are the result of Cenozoic compression, and that the fold belt may not be offset by E W or NE-SW dextral strike-slip faults.The explanation may be that some shortening associated with the orogeny transferred from an east to a west zone of folding. Birkenmajer's (1964) section illustrates a sequence ofkilometre-scaletight folds, which are in part overturned. The Kvalfangarbreen Thrust, a westdipping structure beneath Hyrnefjellet, cuts through this folded sequence, with evidence in the eastern part of later extensional reactivation. Dallmann (1988a, b, 1990) suggested a model to explain the Inner Hornsund structure as a result of continuous compressional deformation. The Kvalfangarbreen Thrust was originally a westward-directed backthrust developed above an implied eastward-directed basement-involved thrust at depth, i.e. a wedge type geometry (cf. Dallmann 1988a). The backthrust ramps upward from Carboniferous to Cretaceous strata and is inferred to accommodate a minimum shortening of about 3 km. The backthrust, to the south of Hornsund, is structurally similar to the Berzeliustinden Thrust in Wedel Jarlsberg Land (Dallmann 1988a, b). The Hyrnefjellet section provides a m i n i m u m shortening estimate of about 7 km, or about 10 km if shortening amounts to the west or east of the section are included. Near Sorkapp, 40 k m further south, there is no significant shortening at Keilhaufjellet, though it is unlikely that the fold belt entirely disappears, but rather the shortening is transferred to the west. The root zone of the fold belt appears to follow the Inner Hornsund Fault Zone, with the western area of the Hornsund-Sorkapp High behaving as a stable block. Dallmann (1990) suggested that there is tectonic repetition of Mesozoic strata in the suggested thrust structure at Lidfjellet, forming an east-vergent thrust system that would necessitate another root zone offshore to the west. Down-faulted Late Paleozoic and Triassic strata on Oyrlandet and Sorkappoya show many folds with a similar trend to those of the central fold belt, though again, there is no clear evidence for the age of this deformation.

The fold-and-thrust belt in central Sorkapp Land. The southern part of the Tertiary fold-and-thrust belt structurally overprints the eastern part of the Samarinbreen Syncline and adjacent areas to the east as seen within a distance of 10kin to the north and south of Hornsund where detailed mapping has been concentrated (Birkenmajer 1990; Dallmann 1990, 1992). The following structures are critical to the development of a kinematic model. (i) The east-vergent Braemfjellet Thrust emplaces Vendian basement and overturned Devonian rocks on overturned Triassic strata. (ii) The east-vergent Kvalfangarbreen Thrust emplaces highly deformed Cretaceous and Jurassic rocks on overturned Triassic and Permian strata; the thrust is refolded. (iii) The Hyrnefjellet Antiform and adjacent synform deform both Late Paleozoic and Early Triassic rocks. (iv) The west-vergent Mariekammen Thrust emplaces basement with overlying Lower Carboniferous strata on Lower Carboniferous overlying Devonian strata; the thrust is sub-vertical (Birkenmajer 1964). (v) West-vergent structures and hanging-wall cutoffs in Late Paleozoic strata. (vi) The eastward overturned Strykjernet-Isryggen Fold deforms Cretaceous strata. (vii) The P/~skefjella Thrust emplaces basement on highly deformed Lower Carboniferous strata; this may relate to the Adriabukta tectonic event. The model, favoured by Dallmann (1992), explains the development of the principal structures by continuous compression, incorporating

208

CHAPTER 10

back-thrusting and wedge insertion. Shortening estimates are as follows: (1) the Braemfjellet Thrust (about 500m), (2) recumbent fold (4.5km), and (3) Kvalfangarbreen Thrust (about 3kin) (Birkenmajer 1964, 1977; Dallmann 1992).The minimum amount of total shortening, assuming a back-thrusting model, is 8 km across the structure to the north of Hornsund. The total amount of shortening across the fold belt at Hornsund is about 10-12km or possibly greater assuming further displacements are accommodated further east (Dallmann 1992). The area to the south of Hornsund may represent a lower structural level, where the basal detachment of the tectonic wedge is exposed. Tertiary deformation diminishes to the south through the orogen. In the area around Haitanna, there is probably only a regional flexure which decreases southwards to Keilhaufjellet where only a simple monocline dipping towards the Central Spitsbergen Basin is identified (Dallmann 1990, 1992). At Keilhaufjellet in the south, shortening is estimated at 200-300 m and was caused by minor folding of the Central Spitsbergen Basin strata. Measurements at Haitanna suggest that approximately 700 m of shortening was accommodated by regional flexuring of the Triassic strata; similar estimates indicate a minimum of 1.8km across the southern part of P~skefjella.

area, and are considered to relate to the development of the western Svalbard continental margin during Oligocene time (Dallmann 1990). Some faults may have developed during an Early to MidPaleocene extensional/transtensional phase (Steel & Worsley 1984). Deformed Triassic strata in the H6ferpynten area suggest that the faults formed prior to the main Late Paleocene-Eocene compressional phase (Dallmann 1992). Paleogene reactivation of earlier faults is evident in the H6ferpynten area where the displacement of Early Carboniferous strata is greater than that of Triassic strata. Many of these faults are cross-cut by compressional structures, as evident in the Oyrlandet Graben, Lidfjellet-Oyrlandsodden Fold Zone and the Fold Belt (Dallmann 1992). A major NNW-SSE-trending fault through Inner Hornsund has a maximum downthrow to the northeast of about 1.5 km at Condevintoppen/ Firlingane (Dallmann 1992). At Tsjernajafjellet, south of Hornsund, the displacement is reduced to about 100 m; the lateral extent is not known due to extensive ice cover (Dallmann 1990, 1992).

The Lidfjellet-Oyrlandsodden fold zone. The Paleocene strata on Oyrlandet are down-faulted, but in the limited exposures these strata appear otherwise undeformed. Seismic studies of the Central Spitsbergen Basin indicate that deformation occurred within preTertiary strata, while Tertiary and some Cretaceous strata were uplifted and remained apparently undeformed (Faleide, Myhre & Eldholm 1988). The Lidfjeilet Oyrlandsodden Fault Zone extends south through Sorkappoya from the southernmost point of the main fold-and-thrust belt; however, the lateral extent of this fold zone is not known. This may be an en echelon arrangement of the two fold belt zones (Dallmann 1992). Within the Lidfjellet-Oyrlandsodden Fault Zone, at Lidfjellet, the minimum offset of the Triassic base suggests a minimum thrust displacement of 1.8 km.

Evidence of strike-slip. There is local evidence for strike-slip motion within the fold-and-thrust belt of Sorkapp Land. From an analysis of fold axis rotations Dallmann (1992) proposed that the two motions were decoupled (e.g. Maher & Craddock 1988) with a phase of strike-slip motion along pre-existent ENE-WSW-dipping fault planes. In the area where the Hornsund Sorkapp mobile zone and of Lidfjellet-Oyrlandsodden Fold Zone a further indication of dextral transpressional motion may be the oblique arrangement of several normal faults. It is unclear whether this transtension is of Tertiary or Late Paleozoic age, since the Tertiary movements may simply have reactivated pre-existent structures. Near the Eastern Hornsund Fault at Tsjernajafjellet, large-scale drag folds and faults which show dextral strike-slip and a downthrow to the east occur in strata of Triassic age; the oblique slip is inferred to be of Tertiary age (Dallmann 1992).

Tertiary extensional faulting. Normal faults trending N N W - S S E cross-cut the central and western parts of the Hornsund-Sorkapp

A synthesis of the West Spitsbergen Orogeny is attempted in Chapter 20.

Chapter 11 Southern Svalbard: Bjornoya and submarine geology W. B R I A N 11.1 11.2 11.3 11.3.1 11.3.2 11.4 11.4.1

HARLAND

with contributions with ISOBEL

Early work, 210 Geological frame of Bjornoya, 212 Triassic strata of Bjornoya, 212

The Skuld Formation, 213 The Urd Formation, 213 Late Paleozoic strata of Bjornoya (W.B.H. & I.G.), 213

Miseryfjellet Formation (Tempelfjorde Group), 213 Hambergfjellet Formation (group undecided), 214 Kapp Dun~r Formation (Gipsdalen Group), 214 Kapp Hanna Formation (Gipsdalen Group), 215 11.4.5 Kapp Kfire Formation (Gipsdalen Group), 215 11.4.6 Landnordingsvika Formation (Gipsdalen Group), 216 11.4.7 Nordkapp Formation (Billefjorden Group), 216 11.4.8 Roedvika Formation (Billefjorden Group), 217 Pre-Devonian strata of Bjornoya, 218 11.5 11.4.2 11.4.3 11.4.4

The area south of Spitsbergen (about 76~ to latitude 74~ and between longitudes 10~ and 35~ by which Svalbard was first defined, contains the small island of Bjornoya (Bear Island, B/iren Insel) and the rest is sea (Fig. 11.1). The 500 m isobath conveniently separates the edge of the Barents shelf from the Norwegian Sea Basin which runs south from Spitsbergen between 14 ~ and 16~ To the east, the large shallow area, Spitsbergenbanken, less than 100m deep, supports Bjornoya at its southwestern end, extends northeast to Hopen and joins Edgeoya. It is separated from Spitsbergen to the north by the Storfjordyrenna and to the east by Hopendjupet. These submarine valleys appear to drain westwards into the ocean deep with deltaic fronts convex westwards.

11.5.1 11.5.2 11.6 11.6.1 11.6.2 11.6.3 11.6.4 11.7 11.8 11.8.1 11.8.2 11.8.3 11.8.4 11.8.5

GEDDES

& PAUL.

A. D O U B L E D A Y

Ymerdalen Group, 218 Bjornoya Group, 219 Structural sequence of Bjnrnoya, 219

The basement, 219 The cover sequence, 220 The platform sequence, 222 Post-platform structure, 222 Submarine outcrops, 222 Submarine structure (W.B.H. & PA.D.), 222

Continental margin: Knipovich Ridge to the Hornsund Fault Zone, 222 Vestbakken Volcanic Province, 223 Stappen High, 224 Sorkapp Basin, 224 Crustal structure and a possible Iapetus suture, 224

This chapter focuses first on Bjornoya which though small is a key outcrop in the Barents Sea and distinct in m a n y respects from Spitsbergen being about 250 km distant. The chapter then surveys a little of what is known of the surrounding sub-sea area. Bjornoya (20 km N-S and 15 km E W), as the southern outpost of Svalbard, has long been a key to Svalbard geology since it is generally free all year from tight sea ice. But though its location is convenient, its cliffs generally bar access. Indeed there are very few places where landing by other than inflatable dinghy are feasible. After the island had been claimed by a Norwegian syndicate in 1915 mining of Tournaisian coal began in 1916 and exported over 116 000 tonnes before the work ceased for economic reasons in 1925. The coal was loaded directly off an exposed cliff into the boat's hold.

Fig. 11.1. Bathymetric map of the western Barents Sea around southern Svalbard, with principal bathymetric features named, based on 1 : 2 M bathymetry chart of the Western Barents Sea, Norsk Polarinstitutt, Oslo 1989, compiled by Kristoffersen, Sand, Beskow & Ohta.

210

CHAPTER 11

NATHORST1910 partly from i ANDERSSON 1900 14 i Myophoria 20m * i Sandstein

13

~

i

HOLTEDAHL 19201HORN & ORVIN 1928 i i -I

Schiefer

C

11 i Korallensandst. i 10 i Fusulinenkalk

8

i

io

i i

~ Sandstein ohne Fossilien

Ambigua kalk

i !

i i

i :i i i

Cora Limestone

(1)

HARLAND et al. 1993" S M I T H & ARMSTRONG 1996 1SKS 1996

Skuld Fm

Miseryfjellet

i Alfredfjellet Fm

~: Hambergfjellet

Fm Fm

i

No group designated SKS

i

Yellow Sandstone Ambigua Limestone

Kapp Duner Fm

Kapp Dun6r Fm

I Kapp Hanna Fm

Kapp Hanna Fm

i

Kobbebukta Fm

................................

Red Conglomerate Nordkapp

Fm

i

Ursa

~

Sandstone

i Tetradium Lst 1 i (Black River) 240 i Younger dolomite 1" (Canadian) 400m ~ g

& 1976

LaksvatnetFm

i

O < O -"

iDarkred& greenish grey (2) Slate Light grey quartzite Sandstone (3) grey & red dolomite Tetradium limestone (4)

TEMPELFJORDEN GP

Spirifer Limestone

WORSLEY EDWARDS

Verdande Bed Urd Fm

L~arK tiSSile snaies

Fusuline Limestone

S. :,

Sandstein

1

i i

i

iS" i F ~o

Ursa

2

g

A i

6

3

SkuldFm

i

L Diskordanz

4

i

a' { ~" i z A

7

5

i

i

i

Diskordanz

_

MyophoriaSandstone

.......................................................... Dunke dunsch eft ge cn i . . . . . . g

12 i Spiriferenkalk

9

i i

CUTBILL & K R A S I L ' S H C H I K O V CHALL NOR[ & i 1965 i[ LIVSHITS 1974 ......................... i-

m

r--r- Nordkapp Fm m

Soed-~; vika Fm

I I i I kandnordingsvika Fm

m z

I I

(Uzankian) 400m

3~

Landnerdingsvika Fm Nordkapp Fm

i

i

Slate quartzite "l175m Older dolomite l-

Bogevika Mbr

i

i Ymerdalen Fm t

Kobbebukta Mbr. SKS

Efuglvika Mbr

iIi

i Sorhamna Fm Russehamna Fm

Antarcticfjellet 1 i Fm i YMERDALEN Perleporten 1" ! GROUP Fm i Sorhamna Fm i BJORNOYA* ', GROUP Russehamna Fm

B

Fig. 11.2. Summary of stratigraphic schemes for Bjornoya.

Later the settlement was abandoned and the meteorological and radio station moved to the north coast where there is a better direct landing facility to which supplies are ferried by small boat and raft from vessels standing out to sea. There is no airstrip but long distance helicopters supplement the occasional visits by ship. Sulphide mineralization affected the Ymerdalen Group and possibly older rocks. Galena was mined on a trial scale. A Caledonian age seems likely. For a source of metallic-bearing fluids it is noted later in this chapter that Bjornoya may have long been part of eastern North Greenland. The other mineralization in Svalbard (especially southwest Spitsbergen) which, while probably not Caledonian, nevertheless was associated with basement terrane also closely related to the North Greenland shield (Horn & Orvin 1928; Flood 1969).

11.1

Early work

Bjornoya was noted for its coal from 1609. The first recorded geological visit was by the Norwegian Keilhau in 1827 (1831). The next was probably by Nordenski61d in 1864 (Duner & Nordensk i n d 1867) and in 1868. Material collected on those expeditions continued to provide for paleobotanical studies especially by Heer (1872). Further Swedish expeditions in 1898 and 1899 resulted in several key publications (Lindstr6m 1899 and Andersson 1900) on the older rocks, B6hm on the Triassic rocks (1899, 1903), and Wiman on Late Paleozoic brachiopods (1914). At the same time

reports on the coal potential were made (e.g. M611man 1900). These and other results were synthesised in Nathorst's (1910) monograph. The mining facilitated further Norwegian work with Holtedahl's investigations in 1918 (1920b) of the older rocks. This led to his making a geological map of the whole island (e.g. 1926). A topographical survey to a scale of 1:10000 followed in 1922 and 1923 and, no doubt prompted by the diminishing coal prospects, Horn and Orvin surveyed the whole island in 1924 and 1925 resulting in a report (1928) with a geological map to a scale of 1 : 25 000. This remained the definitive geological monograph on the island until sheet D20G, 1:50000 (Dallmann & Krasil'shchikov 1996). Indeed most subsequent work had used the map units and their boundaries directly from the map of Horn & Orvin with one exception. Krasil'shchikov & Livshits (1974) reported on systematic work on most parts of the island by their Leningrad team. Their map still largely followed that of Horn & Orvin, with a few changes in the boundaries and these have been incorporated in the 1996 map (see Fig. 11.3). In addition, to the mainly structural study of Krasil'shchikov & Livshits a number of investigations have been published specialising especially in further biostratigraphic and sedimentological interpretations. These will be mentioned in the following pages. During these studies contemporary nomenclature has been introduced step by step. The remarkable fact is that the map units resulting from Swedish work and summarized by Nathorst (1910) and refined somewhat by Horn & Orvin (1928) have stood the test of time. Changes in nomenclature are depicted in Fig. 11.2.

Fig. 11.3. Geological map with sections of Bjornoya derived from the map of Horn & Orvin (1928) and using contemporary names for their rock units. Principal lakes identified (numbers in circles): (1) Djunvatnet; (2) Hobethvatnet; (3) Holmvatnet; (4) Kalven; (5) Krokvatnet; (6) Lomvatnet; (7) Lygna; (8) Lysingen; (9) Oyangen; (10) Snelvatnet; (11) Stevatnet; (12) Vomma.

S O U T H E R N SVALBARD: BJORNOYA A N D S U B M A R I N E G E O L O G Y

211

212

11.2

CHAPTER 11

Geological frame of Bjornoya

The geological m a p (Fig. 11.3) based on that of H o r n & Orvin (1928) shows the outcrops of the principal f o r m a t i o n s modified where the m a p of K r a s i l ' s h c h i k o v & Livshits (1974) differs. Figure 11.4 summarizes the seismic and porosity characteristics o f the principal B j e r n o y a formations. In the Sections 11.3 to 11.4 the Triassic, Late Paleozoic and pre-Silurian f o r m a t i o n s respectively are outlined f r o m the top down. The structure o f B j o r n o y a is then treated in Section 11.5 where a different grouping related to the tectonic history is employed n a m e l y basement, cover and p l a t f o r m sequences. A s u m m a r y o f the stratigraphic sequence follows, with early n a m e s in parentheses:

Kapp Toseana Gp Skuld Fro, 140+m (map unit 14) Shales and siltstones.

?Ladinian and Carnian

AGE ~

Tempelfjorden Group Miseryfjellet Fm (Spirifer Limestone), 115-120m (map unit 12). Sandy and partly silicified highly fossiliferous (biosparite) limestone with sandstone at base. KunguriamUfimian UNCONFORMITY [Group not assigned] Hambergfjellet Fm (Cora Limestone), 0.50 m (map unit 11). Limited to SW Bjornoya Limestones and sandstones. Artinskian-Sakmarian UNCONFORMITY

Billefjorden Gp Nordkapp Fm (upper Ursa Sandstone or Cuhn), l l0m in S to 230m subsurface in N (unit 6). Cross-bedded, grey sandstones with occasional conglomerates, shales and thin coals. Visean Tournaisian Roedvika Fm (lower Ursa Sandstone), 100 m in SW to 36 m at Tunheim in NE (unit 5). Sandstones, shales and coals. Famennian Early Tournaisian Tunheim Mbr, 80m grey sandstones, shales, local conglomerates and coal seams (mined at Tunheim). Tournaisian Kapp Levin Mbr, 80 m mainly sandstone. Veselstranda Mbr, 200 m, grey and purple sandstones and shales. Famennian ANGULAR UNCONFORMITY Ymerdalen Gp, 560 57 m Antarcticfjellet Fm (*Tetradium Limestone), 93-240m (unit 4), grey linestones (rich on fossils). Latest Llanvirn-Early Caradoc Perleporten Fm (Younger Dolomite Series), 250 400+ m (unit 3), pale grey dolostones (poor in fossils). ?Canadian UNCONFORMITY (not younger than latest Llanvirn to Early Caradoc)

Bjernoya Gp Sorhamna Fm (Slate Quartzite Series), 175+ m (map unit 2), green and red shales with quartzitic sandstones. Russehamna Fm (Older Dolomite Series), 400+ m (map unit 1). Variegated massive dolostones, partly oolitic, arenaceous in upper part.

10% 20% I

lOO

-

-

MINIMAL NET SUBSIDENCE RATE (mm y )

I

0.01 Miseryfjellet

0.01

Kapp Duner

0.02

-

500

Kapp Hanna -

O i.u u_

Kapp K~re

O

_Landnordingsvika

< O

_

1000

>~ 13

i

\

I

q

0.03

l-/_

\

]

1-

_Nordkapp

0.02

0.03

0.006

0.015

Roedvika

_

u_ _

1500 o

Antarcticfjellet

0~

0.017 O

Gipsdalen Gp Kapp Dun~r Fm (Fusuline Limestone), 75+ m (map unit 10). In western Bjornoya Mainly dolostones and dark limestones with fusulines. Asselian Gzelian Kapp Hanna Fm (Yellow-Sandstone), 150m (map unit 9) in western Bjornoya extending north to south. Is mainly of yellowish calcareous sandstones with shales, limestones, dolostones and conglomerates at base. Kasimovian Moscovian DISCONFORMITY Kapp Kfire Fm (Ambigua Limestone), (map unit 8). Mainly of grey limestone with the brachiopod Composita ambigua. Moscovian Bashkirian. Kobbebukta Mbr (SKS 1996), 8-45m. Carbonate and chert debris flows, conglomerate and marine limestones. Efuglvika Mbr, 80 m, cherty biomicrites. Bogevika Mmbr, 90m limestones, dolostones, sandstones and shales. Landnordingsvika Fm (Red Conglomerate), 145 m in SW and 120+ m in N (unit 7). Red sandstones and conglomerates. Bashkirian

POROSITY

_o

Sassendalen Gp Urd Fm, 65m (map unit 13) Verdande Bed (at top) a conglomeratic remani~ bed of phosphatic concretions. The body of the formation is of dark fissile shale with clay ironstone concretions and thin limestone and interbedded silstones with sandstones at base. Early Triassic (Scythian) to Early Ladinian

FORMATION

SEISMIC VELOCITY (kms') 4 5

~ o

Perleporten _

200C Sorhamna

0.037

R u s s e h a m n a

0.05

250( -

-

i

Fig. I 1.4. Summary plot of seismic velocity, porosity and estimated minimal subsidence rate adapted (except for right-hand column) from Gronlie, Elverhoi & Kristoffersen (1980) who also remarked, with growth of quartz and clay minerals, that silica cementation increases upwards and there is also some calcite dolomite mineralization. They discussed the problem of why at greater depth Roedvika sandstones show much greater porosity. Differential accumulation of core strata may have given lower than expected overburden in Bjornoya. The 1500 m of post-Silurian strata were formed during no more than 150 million years, a net subsidence rate of 0.01 m m a -1. The right-hand column attempts to compare subsidence rates for each lbrmation making crude assumptions. Even so the overall subsidence rate is consistent with a secular contraction of the mantle through cooling (cf. Harland 1969). (Reproduced with kind permission of Elsevier Science, Amsterdam.)

11.3

Triassic strata of Bjornoya

Triassic rocks are the youngest pre-Pleistocene strata in Bjornoya. They occupy the top of the highest m o u n t a i n , Miseryfjellet, on w h i c h three peaks, Skuld, V e r d a n d e a n d U r d have been used for the principal n a m e d Triassic units. The u p p e r f o r m a t i o n (Skuld) belongs to the K a p p T o s c a n a G r o u p of Spitsbergen and the lower f o r m a t i o n (Urd) to the Sassendalen G r o u p on the basis of similar lithologies (as well as age). The V e r d a n d e Bed is a conglomerate at the top of the U r d F o r m a t i o n . The Triassic fauna was first investigated by B o h m (1899, 1903), palynology by M o r k , Vigran &

SOUTHERN SVALBARD: BJORNOYA AND SUBMARINE GEOLOGY

213

Hochuli (1990) and geochemical studies were reported by Bjoroy, Mork, Vigran (1980, 1983, 1987).

A summary of the sequence is given in Section 11.2. Much of the following detail, especially the sedimentology, is from Worsley & Edwards (1976) and Gjelberg & Steel (1981).

11.3.1

11.4.1

The Skuld Formation (>140m)

The Formation was named by Krasil'shchikov & Livshits (1974) and further defined (but not mapped) on Miseryfjellet by Mork, Knarud & Worsley (1982). It is the upper part of the Triassic sequence (above the Verdande Bed) and the lateral equivalent of the lower part of the Kapp Toscana Group, i.e. the Tschermakfjellet and lower De Geerdalen Formation elsewhere on Svalbard. Dark grey shales with red-weathering siderite nodules (cf. the Tschermakfjellet Formation) rest on the phosphatic conglomerates of Verdande Bed at the top of the Sassendalen Group. The top has been removed by recent erosion. There is an upward-coarsening sequence similar to that seen elsewhere with the c o m m o n thin siltstones, becoming thicker, and fine-grained sandstones appearing at the top of the unit (at the highest level preserved) where there are 20 m of plane-laminated sandy siltstones. Marine fossils are present t h r o u g h o u t - bivalves, brachiopods and ammonites, especially in the upper half, while plant fragments appear at the highest levels present. These indicate a Late Ladinian (sutherlandi zone) to Early Carnian age (Pchelina 1972; Tozer 1967; Tozer & Parker 1968). A labyrinthordont was found high up in this succession (Lowy 1949).

11.3.2

The Urd Formation (65 m)

The formation was named by Krasil'shchikov & Livshits (1974) and defined more closely by Mork, Knarud & Worsley (1982) with a section on the southern slope of Urd, the highest peak of Miseryfjellet. It is approximately equivalent to all other units of the Sassendalen Group elsewhere. The Verdande Bed, 20 cm, at the top, is the condensed lateral equivalent of the Botneheia Formation. It is a conglomerate composed of eroded grey phosphate (carbonate-apatite) nodules 2.5 6cm in diameter. It is glauconitic. Phosphate nodules are distinctive constituents of the Middle Triassic throughout Svalbard (in the Botneheia Formation) which are here condensed into the remani~ bed which forms a good marker horizon on Bjornoya. Below are 62 m of alternating thinly bedded grey siltstones and silty shales. Carbonate-rich lenses and minor yellow-weathering dolomitic limestones appear in the upper part. The basal 3 m of the formation consists of fine sandstones which rest with sharp, locally unconformable, contact on Permian limestones. A variety of marine fossils including ammonoids suggests an ?Induan (not proven) Smithian age for the strata below the Verdande Bed (Pchelina 1972). In addition, sponge spicules, echinoderm fragments, fish vertebrae, bivalves and gastropods have been reported, some of which may be derived from the Permian beds below. The Verdande Bed contains various fossil remains of dubious identity and in view of the faunas above and below seems to represent Mid-Triassic (Anisian-Early Ladinian) time. There may be a time gap below the Verdande Bed (as might be expected from its nature), with the top of the Smithian and Spathian substages unrepresented. Arctoceras blomstrandi of Early Smithian age occurs just below the Verdande Bed.

11.4

Late Paleozoic rocks of Byjornoya (I.G. a n d W . B . H . )

Late Paleozoic rocks in Bjornoya occur throughout most of the island (Fig. 11.3). As elsewhere in Svalbard, with one possible exception they are contained within the three groups: Tempelfjorden, Gipsdalen and Billefjorden. The groups (defined in Spitsbergen) we represented in Bjornoya by eight formations as follows.

Miseryfjellet Formation (Tempelfjorden Group)

This formation, 115 m, consists almost entirely of limestone except for sandstones at the base. The latter infills karst structures in underlying limestones, and hence represents a transgression. The limestones represent high energy shallow marine environments, with shoreface, littoral and barrier deposits. The formation is of Kugurian, Ufimian and possibly Wordian age.

Definition. The Miseryfjellet Fm of the Tempelfjorden Group is the youngest late Paleozoic unit of Bjornoya. It was the 'Spirifer Limestone' of Nathorst (1910) and of Horn & Orvin (1928) owing to the abundant brachiopod fauna. Soviet geologists named it the Laksvatnet Formation (Pchelina 1972; Krasil'shchikov & Livshits 1974). Siedlecka (1975) described the petrography. Worsely & Edwards (1976) renamed the unit the Miseryfjellet Fro, as the only complete sections through the formation are on the slopes of Miseryfjellet, where there are approximately 115m of limestones and sandstones. However, the type sections occur at Brettingsdalen and Herwigshamna (Hellem in the IKU 1987 Excursion Guide to Bjornoya). The upper boundary is seen only on Miseryfjellet, where the formation disconformably underlies Triassic shales. The lower boundary is an unconformity, with a local basal conglomerate and calcareous sandstones overlying various older units (successively older units of the Early Carboniferous Nordkapp Fm in the north; Permian and pre-Devonian sequence in the south). Lithologies. Limestones, with a rich brachiopod fauna and partially silicified, make up 90% of the succession in which biosparites and biorudites, generally arenaceous, predominate. They are irregularly bedded, dark grey, highly fossiliferous and commonly partly silicified. Arenites make up about 10% of the sequence. In general, the sandstones are fossiliferous, with calcite, quartz or (rarely) dolomite cement. Porosity and permeability are both low. Some beds of cherty siltstone form the base of the formation, where they are usually 1-3 m thick and locally pebbly to conglomeratic. Medium to fine-grained quartzitic and calcareous sandstones occur in a 12 m bed, 20 m above the base on Miseryfjellet. This bed coarsens upwards and has tabular and lower-angle cross-bedding, directed southeastwards, at the top. On the north coast at the top of the formation, wedgelike sand bodies also appear. At the base are sandstones. Locally they infill 8-10m deep karstic features in the underlying Kapp Dun6r and Kapp K~re fms. In the basal sandstones, marine burrows extend down into the underlying Carboniferous rocks in some localities and Siedlecka (1975) noted moderate to good sorting with a distinctly bimodal size distribution. Conglomerates occur at the base of the formation in places, and also capping the 12 m sandstone on Miseryfjellet described above. The basal conglomerate clasts are derived from the underlying units. Quartz pebbles up to 11 cm in diameter show no preferred orientation. Palaeontology and age. Brachiopods, bivalves, crinoids, bryozoans and some corals occur, with Skolithos burrows in the sandstones (Holtedahl, 1925). Gobbett (1963) described seventeen brachiopod species from the formation, all of which also occur in the Kapp Starostin Fm. There is little doubt that the two formations correlate. Nakrem (1988) began a study of the conspicuous bryozoan element in the Tempelfjorden Group and later monographed the work in (1994). Ustritskiy (1971) and Ustritskiy & Cernjak (1973) assigned the youngest beds to the Ufimian stage, but continue the North American-Arctic sequence into Wordian time. Examination of CSE brachiopod collections (J.B. Waterhouse pets. comm.) suggested a Wordian or Late Kungurian age, though there are no definite Wordian indices. Nakrem (1991) on the basis of conodonts suggested a Kungurian-Ufimian age. The Miseryfjellet Fm is therefore of Kungurian, Ufimian and possibly Wordian age. The basal unconformity is comparable with that at the base of the Kapp Starostin Fm in Spitsbergen, and the fossiliferous biosparites are comparable with those of its Voringen Mbr. 11.4.2

Hambergfjellet Formation (group undecided)

This unit, 100 m is also dominated by limestone except for sandstones at the base. It is characterized by evidence of periods of

214

CHAPTER 11

e m e r g e n c e a n d erosion; its base is an u n c o n f o r m i t y a n d karstification structures (infilled by sandstone), calcretes a n d rootlet horizons are present at several levels t h r o u g h o u t . It is t h e r e f o r e a s h a l l o w - m a r i n e unit but one t h a t was subject to rapid changes in relative sea-levels. It is o f A r t i n s k i a n to ? S a k m a r i a n age based on fusulinid a n d b r a c h i o p o d assemblages.

Definition. The Hambergfjellet Formation is mainly a carbonate sequence between two unconformities. It is confined to the southwest of the island. The formation was named the Cora Limestone by early workers because of the occurrence of the brachiopod Linoproductus dorotheevi, identified then as Productus cora (Anderson 1900). This name was used by Horn & Orvin (1928) and Cutbill & Challinor (1965). It was renamed the Alfredfjellet Formation by Krasil'shchikov & Livshits (1974) and then the Hambergfjellet Formation by Worsley & Edwards (1976). There is no single type section defined, but exposures from two localities, Alfredfjellet and Hambergfjellet, cover the whole section from base to top. The upper boundary is marked by the low angular unconformity at the base of the Miseryfjellet Formation which oversteps it to the south and east. The top is partly silicified and has a micro-karstic surface. The lower boundary is at a clear unconformity representing a period of extensive uplift and erosion. The formation overlies Precambrian, Devonian and Carboniferous strata and at Alfredfjellet it overlies the earlier Permian Kapp Dun& Formation. The Hambergfjellet Formation is currently not included in either the Tempelfjorden or the Gipsdalen group, not primarily because it could be either, but because its submarine extension suggests a much larger development, which might merit its own group if more than one formation is defined. Lithologies. Limestones make up the bulk of the formation (95%). Medium-bedded biomicrites dominate at the top, which contain shaley and sandy partings or interbeds and a diverse brachiopod-crinoid-fusulinid fauna. These are underlain by red-weathering rubbly limestones with brachiopods. Below, the limestones are micritic and sandy, containing transported corals, brachiopods, crinoids, and fusulinids. Lower down there are several horizons with karst features infilled with coarse sandstone (terra rossa). In-situ Microcodium, possible root horizons, laminated stromatolitic limestone, calcrete, fenestrae and chicken-wire structure havc been noted. Here the fauna is poor and restricted with algae, ostracodes and small foraminifers. The sandy limestones pass downwards into homogeneous fine sandstone of variable thickness (up to 30 m). It appears to be unfossiliferous except for well developed root horizons in the middle of the unit. There is a pebbly, dark sandstone at the base of the formation. The thickness variations are possibly a result of the infilling of pre-Hambergfjellet Formation relief. Palaeontology and age. Anderson (1900) listed brachiopods from the upper part of the formation. Horn & Orvin (1928) recorded corals in the lower limestones which show an affinity with those of the Treskelodden Formation (B. T. Simonsen in the 1987 IKU Excursion Guide to Bjornoya ) and a rich brachiopod fauna was described by Gobbett (1963). Simonsen had mentioned the presence of crinoids and fusulinids in the upper beds and a restricted fauna of algae, ostracods and small foraminifera in the lower carbonates as well as root horizons in the basal sandstones. A variety of ages has been assigned to this formation. Fusulinids found in the upper part belong to the Sehwagerinajenkinsi zone which is Early-Middle Artinskian in age (Simonsen). Gobbett recorded a Sakmarian age on the basis of brachiopods, though he compared one brachiopod with an Artinskian species; and Bjoroy, Mork & Vigran (1980) stated that the brachiopod fauna suggests a Late Sakmarian or possibly Artinskian age. After a recent examination of the CSE collection, J.B. Waterhouse concluded that the upper beds contained very late Artinskian or Kungurian brachiopods, while the presence of Arculina in the basal part of the formation suggested an Artinskian or Sakmarian age at the oldest. Nakrem (1991) cofirmed an Artinskian age for the upper part of the formation from his study of conodonts.

1 !.4.3

Kapp Dun6r Formation (Gipsdalen Group)

The K a p p D u n & F o r m a t i o n , 75 m, consists m a i n l y o f dolostones a n d fusulinid-rich limestones. Sandstones a n d c o n g l o m e r a t e s f o r m m i n o r c o m p o n e n t s . In the lower p a r t o f the f o r m a t i o n , dolomitized palaeoaplysinid build-ups c o n t a i n i n g large b r y o z o a n colonies occur. In some places, the limestones show karst structures infilled by

r o o t - b e a r i n g c o n g l o m e r a t e , indicating periods o f sub-aerial erosion. Asselian deposition o f the f o r m a t i o n o c c u r r e d o n a m a r i n e shelf with open to restricted e n v i r o n m e n t s , p u n c t u a t e d by periods o f emergence.

Definition. The Kapp Dun6r Formation is a sequence of dolomites, it crops out on the west coast of the island and offshore to the west. It was described briefly by Horn & Orvin (1928) as the 'Fusuline Limestone'; they also listed the fossil identifications made by Anderson (1900). The term 'Kapp Dun& Formation' was introduced by Krasil'shchikov & Livshits (1974) and was used by Worsley & Edwards (1976). The detailed petrography of these sediments has been described by Folk & Siedlecka (1974) and systematically by Siedlecka (1975). There is no single type section. Several sections have been measured along the coast (Mork 1987), where the unit is up to 75 m thick. Both the upper and lower boundaries are present in a condensed section on Alfredfjellet. The formation lies stratigraphically below the Hambergfjellet Formation and this upper boundary, which is a strong unconformity, is exposed on Alfredfjellet where a condensed sequence of the Kapp Dun6r Formation crops out. The conformable base is taken at the transition from massive dolomites to the arenaceous deposits of the underlying Kapp Hanna Formation (Carboniferous). Lithologies. Massive to well-bedded dolostones with interbedded limestones are typical of this formation. Massive buff-weathering dolostones form 90% of the sequence. The upper part is dominated by dolomitized mudstones and two fusulinid-rich limestones, each with a distinctive fauna which makes them useful marker horizons (Simonsen in 1987, IKU Excursion Guide). Thin sandstone horizons occur in the middle part of the formation, associated with some sandy limestone, forming 4% of the formation. One sandstone is pebbly and upward-fining, lying on a microkarstic surface. Conglomerates are also a minor feature of the sequence. On Alfredfjellet, a coarse conglomerate overlies a karst surface and contains clasts of the underlying limestone which has a rich fauna dominated by fusulinids very similar to that of the upper fusulinid-rich limestone mentioned above. Both conglomerate and limestone contain abundant Microcodium. Three massive lenticular dolostones dominate the lower part of the formation, which are dolomitized palaeoaplysinid build-ups. In describing these reefs as frameworks Lonoy (1988) noted not only their wide extent but that they were related to karst features suggesting that they were at times subaerial. Dolomitization has left only ghosts of the original palaeoaplysinid framework. They contain large coral colonies, bryozoan 'thickets', stromotactic structures and local intraformationa] conglomerates. Stemmerik & Larssen (1993) shared the opinion of fluctuating sea levels with diagenesis leading to high porosity. Another conglomerate, half a metre thick, but wedging out laterally, occurs just above an infilled hollow in a build-up, containing roots. It is composed of a coarse sandy matrix and well-rounded pebbles as well as angular clasts derived from the build-up (Simonsen in IKU 1987). The carbonate build-ups are composite with superimposed structures. They have been sub-aerially exposed at several levels and show vugs and hollows infilled with laminated sediment containing root structures, karst and eroded surfaces. They pass laterally and upward into mudstones (lagoonal) which locally contain mudcrack horizons. At the top of the lower dolomite is a fusulinid-rich limestone with a distinct fauna, different from those of the upper two fusulinid-rich limestones (Simonsen in IKU 1987). Individual thin, highly bituminous beds occur with the porous biohermal structures (Bjoroy, Mork & Vigran 1983), comparable with the Brucebyen Beds of Spitsbergen. Interbedded with the dolostones are thin beds of biomicrite, partly dolomitized, which also appear higher in the section (forming 6% of the formation). They are a distinctive grey and contain fusulinids, corals, brachiopods and gastropods. Karst surfaces and marginal marine clastics are also present at some levels. The formation contains authigenic silica, replacing cement and/or fossils and forming nodules which occur as clusters resembling the chicken-wire fabric of evaporite nodules. In thin section they have a fibrous texture and contain ubiquitous minute sulphate inclusions which indicate that the silica has replaced sulphate (Folk & Siedlecka 1974). Palaeontology and age. Although the formation contains a moderately abundant fauna, including corals, brachiopods, gastropods, echinoderms and fusulinids, very few species have been described. Fusulinids have been useful in dating the formation (Simonsen in IKU 1987): Sphaeroschwagerina vulgaris?, which defined the Permian boundary in Russia and east Asia, is found in the uppermost part of the underlying Kapp Hanna Formation. Fusulinids from the lower fusulinid-rich limestones belong to the

SOUTHERN SVALBARD: BJORNOYA AND S U B M A R I N E GEOLOGY

Schwagerina arctica/Schwagerina (Daixina) sokensis zone. On the Russian platform, this zone is either late Gzelian or lowermost Asselian in age. The upper part of the formation contains distinct horizons with Sphaeroschwagerina mollieri and S. sphaerica, which are characteristic of the Late Asselian stage. The two upper fusulinid-rich limestones belong to the Asselian Schwagerina nathorsti/Schwagerina zone. Some fusulinids in the upper fusulinid-rich limestone indicate a close relationship with Early Sakmarian faunas, but a clear boundary between Asselian and Sakmarian faunas is not evident. Nakrem (1991) from conodonts concluded an Asselian age. The fusulinid-rich limestones at the top of the lower palaeoaplysinid dolomite contains a nearly identical faunas to that of the Brucebyen Beds on Spitsbergen with which it is correlated (Simonsen 1987).

11.4.4

Kapp Hanna Formation (Gipsdalen Group)

In c o n t r a s t to the overlying f o r m a t i o n s , the K a p p H a n n a F o r m a t i o n is a p r e d o m i n a n t l y a r e n a c e o u s unit. S a n d s t o n e s f o r m the b u l k o f the sequence, with smaller a m o u n t s o f i n t e r b e d d e d c o n g l o m e r a t e , d o l o s t o n e a n d shale. S a n d s t o n e s a n d c o n g l o m e r a t e s c o n t a i n rew o r k e d clasts d u e to e r o s i o n o f the u n d e r l y i n g u n i t as well as f r o m older sources. T h e s e d i m e n t o l o g y o f the f o r m a t i o n is c o m p l e x , w i t h variable facies. Overall, it represents m a r i n e , n e a r - s h o r e a n d floodplain e n v i r o n m e n t s , d e p o s i t e d o n an alluvial fan p r o g r a d i n g into a m a r i n e basin. It c o n t a i n s a varied f a u n a , w h i c h defines a K a s i m o v i a n - G z e l i a n age.

Definition. This is a distinctive arenaceous unit, previously known as the Yellow Sandstone (Horn & Orvin 1928; Cutbill & Challinor 1965). The present name was used by Krasil'shchikov & Livshits (1974) followed by Worsley & Edwards (1976). The formation crops out on the north and west coasts of the island, but no single section is typical because of faulting. The formation lies conformably below the massive dolostones of the Kapp Dun6r Fm. The base is erosional and is defined below a coarse conglomerate which marks a slight unconformity, beneath which lie carbonates and clastics of the Kapp Kgtre Fro. Lithologies. The formation consists of laterally variable alternations of conglomerates, sandstones, shales and dolostones. Sandstones form 75% of the sequence. They contain interbedded conglomerates (10%), micritic dolomites (10%) and thin, dark fossiliferous shales (5%). There is a general upward fining and a gradation through interbedded thin sandstone and dolomitic mudstone into the overlying carbonate-dominated Kapp Dun6r Fm. The sandstones are medium-grained, well-sorted, yellow-brown, and calcareous and commonly cross-bedded. Calcite, dolomite and celestine cements occur, generally giving the rocks a low porosity (Fig. 11.4). There is an 8-10 m basal conglomerate, red-brown in colour with clasts of vein quartz derived from pre-Devonian rocks, as well as cherts which are probably from the underlying Kapp KSre Formation. Conglomerates reappear interbedded with the sandstones. Analysis of sandstone mineralogy and conglomerate clast composition shows a well-developed inverse stratigraphy, reflecting progressive erosion of previously deposited sediments (Agdestein 1987). There is a dominance of pre-Devonian clasts in the southwest and Early Carboniferous clasts in northwestern exposures. The succession contains intraformational, erosional unconformities, of up to 5 degrees angular discordance. In addition, they may contain ravinelike channels up to 20 m deep, which are eroded into marine dolostone/shale sequences. These channels are filled with interbedded conglomerates and sandstones, which are partially cross-bedded and commonly have desiccation cracks on the bedding planes. Fissures filled with clastic material are another feature (Worsley et al. 1987). Palaeontology and age. Corals and crinoid stems were found by Holtedahl (1920) while Gobbett (1963) noted Linoproductus 6'19.Federowski (1975) described corals Worsley & Edwards (1976) reported corals, brachiopods and plants, but gave no further details. Agdestein (1987) mentioned corals, brachiopods, bivalves, fusulinids, crinoid fragments, trace fossils and plant debris. Corals in the lowermost conglomerates are the same as in the underlying Kapp Kfire Fm and are probably redeposited. Fusulinids from both parts of the Waeringella usvae zone have been reported by Cutbill and Challinor (pers. comm.) that indicate a KasimovianGzelian age. The Kasimovian-Gzelian age is supported by an Asselian estimate of the age of the overlying Kapp Dun6r Fm and by the underlying Late Moscovian Kapp Kfire Fm.

11.4.5

215

Kapp K~tre Formation (Gipsdalen Group)

T h e K a p p Kfire F o r m a t i o n is a c a r b o n a t e - d o m i n a t e d unit up to 1 7 0 m thick. T h e limestones are pale grey biomicrites, in places d o l o m i t i c a n d cherty. S o m e grey a n d red s a n d s t o n e beds a n d shales are i n t e r b e d d e d in the lower part. T h r e e m e m b e r s h a v e been defined. T h e (upper) Kobbebukta Member c o n t a i n s limestone, chert a n d cong l o m e r a t e c o n t a i n i n g c h a n n e l structures a n d small s y n - s e d i m e n t a r y faults. T h e Efuglvika M e m b e r consists o f c h e r t y biomicrites, a n d c o n t a i n s n u m e r o u s k a r s t surfaces a n d small, a n g u l a r u n c o n f o r m i ties, T h e (lower) Bogevika M e m b e r also s h o w s evidence o f sub-aerial erosion. It c o n t a i n s l i m e s t o n e s with d o l o s t o n e s , s a n d s t o n e s a n d shales. T h e overall d e p o s i t i o n a l setting o f the f o r m a t i o n was tidally influenced m a r g i n a l m a r i n e , affected by very variable relative sealevel c h a n g e s d u e to deltaic p r o g r a d a t i o n a n d subsidence, p r o b a b l y c o n t r o l l e d by local tectonics. Corals, b r a c h i o p o d s , fusulinids a n d o t h e r species m a k e up a rich a n d varied f a u n a a n d t h a t indicates a m a i n l y M o s c o v i a n age, a l t h o u g h a slightly wider t i m e - s p a n is possible as m a n y elements are n o t very age-diagnostic.

Definition. The Kapp Kfire Fm is a thick sequence of carbonates occurring in a fairly wide N-S belt in western Bjornoya. It is about 170m thick. It was originally described as the 'Ambigua Limestone' by Andersson (1900) and Horn & Orvin (1928). It was renamed the Kobbebukta Fm by Krasil'shchikov & Livshits (1974) with the Kapp Kgtre section as a type section, the Kobbebukta section being obscured by faulting. The upper boundary is taken at the thick extraformational conglomerate at the base of the overlying Kapp Hanna Fm which marks a slight unconformity above the intraformational conglomerates of the Kapp Kgtre Fm. The lower conformable boundary is marked by the underlying thick massive conglomerates of the Landnordingsvika Fm which contrasts with the carbonates (with thin intraformational conglomerates) of the Kapp KSre Fro. The formation consists mainly of limestones (85%), which are generally pale grey biomicrites. In the lower part grey and red sandstones and shales are interbedded. Corals and brachiopods are locally abundant and there are several oncolitic horizons. The limestones are dolomitic in places and are commonly cherty, especially towards the top of the formation. Two members were distinguished by Worsley & Edwards (1976), the upper Efuglvika Member and the lower Bogevika Mbr. Bjoroy et al. (1980), following the work of Kirkemo & Mork (1987), divided the Efuglvika Mbr into the Kobbebukta Mbr (upper-most) and Efuglvika Mbr. The Kobbebnkta Mbr thickens from 8 m at Kapp Kgtre in the southwest to about 45 m at the type section in the north. Erosion of the top, at the unconformity with the Kapp Hanna Fm, has caused this variation. It consists of limestones interbedded with massive intraformational conglomerates, containing chert and carbonate clasts. The latter often have channelled bases and show abrupt facies changes laterally. Small-scale syn-sedimentary faulting (along a WSW-ENE-trending scarp) has been observed, draped by the intraformational conglomerates. On the downthrown side, there is a sequence of shales and turbidites, the latter deposited by westward-flowing currents (Worsley et al. 1987). The Efug|vika Mbr is fully exposed at Efuglvika, where it reaches its maximum thickness of 80m, around Kapp KSre (70m) and also at Kobbebukta. It is dominated by thinly to massively bedded cherty biomicrites with an open marine fauna. The abundant chert occurs as nodules and 'dykes' and is of diagenetic origin. There are abundant karst and discontinuity surfaces and local small angular unconformities. Thin biomicrites are associated with the erosion surfaces. The karstic features seem to follow clear NE-SW trending zones of deformation and prominent large chert 'dykes' show the same general trend. The Bogevika Mbr lies conformably below, and in the type section at Landnordingsvika consists of about 90 m of limestones, interbedded with dolostones, sandstones and thin shales. Beds are generally greyish-red and greyish-green in colour, becoming paler and more grey towards the top, with more common biomicrite, in a transition to the overlying member. There are well-developed upward-coarsening rhythmic sequences from limestones to shale and sandstone in 3 - 8 m units. These typically show an upward transition from limestones and shales with a normal marine fauna of corals and brachiopods, to shales containing a more restricted fauna of bivalves, gastropods, ostracodes and plants. The upper contacts are typically sharp and may show either desiccation cracks, calcrete horizons or an erosional surface beneath the limestone or shale of the overlying cycle. Marked karstic and discontinuity surfaces are also relatively common within the limestones. Sandstones become less common upwards.

216

CHAPTER 11

Palaeontology and age. The limestones contain a rich fauna, of which brachiopods, corals and fusulinids have been described. Bivalves, gastropods, including Bellerophon (Anderson 1990), ostracodes and plants have been reported from the shales, but no details are available. Gobbett (1963) suggested, on the basis of brachiopods, a correlation with the Bashkirian/ Moscovian of the Moscow Basin. The fusulinids belong to the Wedekindellina zone implying a late Moscovian age (Cutbill & Challinor 1965). Work on corals from the formation (Fedorowski 1975) suggested that the fauna is transitional between Moscovian and Kasimovian.

11.4.6

Landnordingsvika Formation (Gipsdalen Group)

T h e L a n d n o r d i n g s v i k a F o r m a t i o n , 145-200 m is the lowest p a r t o f the G i p s d a l e n G r o u p in B j o r n o y a , a n d as elsewhere it is m a r k e d a n d i n d e e d characterized by the a p p e a r a n c e o f red-beds. It consists o f m a i n l y c o n g l o m e r a t e a n d s a n d s t o n e w i t h m i n o r m u d s t o n e s , in sequences. M o s t lithologies are r e d d e n e d , except for s o m e grey l i m e s t o n e s in u p p e r parts o f the sequence. T h e limestones c o n t a i n k a r s t surfaces a n d s o l u t i o n breccias, a n d a l o n g with d o l o s t o n e , chert a n d s a n d s t o n e they also a p p e a r as clasts w i t h i n the c o n g l o m e r a t e s . T h e s a n d s t o n e beds c o m m o n l y have erosive bases, a n d are crossb e d d e d a n d b i o t u r b a t e d . M u d s t o n e s o c c u r a b o v e the s a n d s t o n e s , especially lower in the f o r m a t i o n , a n d c o n t a i n desiccation cracks a n d rootlets indicating terrestrial d e p o s i t i o n . H o w e v e r , m a r i n e fossils o c c u r n e a r the t o p o f the f o r m a t i o n . This a n d o t h e r inform a t i o n indicates d e p o s i t i o n in a coastal setting, b u t m a i n l y o n an alluvial plain in semi-arid c o n d i t i o n s . F l o o d p l a i n , tidal-flat, coastal l a g o o n a n d offshore c a r b o n a t e facies are all represented. T h e f o r m a t i o n does n o t c o n t a i n a rich f a u n a a n d forms p r e s e n t d o n o t distinguish it f r o m the overlying f o r m a t i o n , suggesting an Early M o s c o v i a n a n d possibly B a s h k i r i a n age.

Definition. The Landnordingsvika Fm is a conglomeratic sequence up to 200 m thick occurring at the base of the Gipsdalen Gp in Bjornoya. It was named the "Red Conglomerate' by early workers (e.g. Anderson 1900; Holtedahl 1920; Horn & Orvin 1928), the present name being introduced by Krasil'shchikov & Livshits (1974) and adopted by Worsley & Edwards (1976). The type section is at Landnordingsvika. The upper boundary is conformable and transitional to the Kapp Khre Fm above. It is taken at the top of the uppermost distinct conglomerate below the carbonate-bearing sequence of the Kapp Kfire Fm. Carbonates appear almost immediately above. The base of the formation is taken at the boundary between the red beds and the underlying grey sandstones and conglomerates of the Nordkapp Formation (Billefjorden Group). The boundary is concordant but sharp in some localities (e.g. Krasil'shchikov & Livshits 1974), while at Kobbebukta there is a gradual passage over 10 20 m from coarse-grained sandstones of the Nordkapp Formation to finer red beds of the Landnordingsvika Formation. Similarly at Landnordingsvika, there is a transition to red beds over more than 60m (Horn & Orvin 1928). Lithologies. The formation consists of red conglomerates, drab sandstones and red mudstones, normally arranged in upward-fining cycles. Conglomerates form 50% of the section. They first appear about 40 m from the base and are most widespread in the middle part of the formation. They are generally red, of fine pebble to fine cobble grade. Sorting is variable, with a range from poorly sorted, matrix-supported conglomerates to well-sorted and grain-sorted conglomerates. Some show low-angle cross-bedding. Clasts consist of dolomite, limestone, chert and sandstone. The beds are cyclically arranged, commonly lenticular, with erosive bases. They tend to become finer upwards, passing into sandstones and red mudstones. Thick conglomerates are absent in the north. Red sandstones make up 40% of the sequence. Beds up to several metres thick occur throughout the formation in upward-fining cycles. Some beds in the lower part have erosive bases with intraformational conglomerates. The sandstones are moderately sorted, of coarse to very fine grain size and may show planar or cross-bedding. Flaser and lenticular bedding and bioturbation are found in some sequences. Towards the top of the formation, calcareous sandstone beds yield marine fossils. Grey bioclastic and micritic limestones appear also at higher levels, showing herring-bone cross-bedding and shallow channels with lag conglomerates. Karst surfaces with local solution breccias occur at the top of one of the carbonate sequences and the limestone has been strongly recrystallized, probably due to freshwater diagenesis (Gjelberg & Steel 1983).

Blocky, red and in places green mudstones make up 10% of the formation, occurring at the top of the sandstone in the upward-fining cycles, especially in the lower part of the formation, where they are dominant. Concretions, desiccation cracks and plant roots occur in places and marine fossils are absent in this facies. Palaeontology and age. A few fossils are found towards the top of the formation: brachiopods (Composita ambigua and Lingula), bivalve, crinoid and echinoid fragments, foraminifera and trace fossils of the Skolithos assemblage and ?Thalassinoides. These are indistinguishable from those found in the overlying Kapp Kfire Fm (Worsley & Edwards 1976). This fact, and the gradational contact between the two, suggests that the Landnordingsvika Fm is only slightly older, probably of Early Moscovian age, possibly extending to Bashkirian time (Gjelberg & Steel 1981).

11.4.7

Nordkapp Formation (Billefjorden Group)

T h e N o r d k a p p F o r m a t i o n , 2 3 0 m , is the u p p e r m o s t unit o f t h e Billefjorden G r o u p on B j o r n o y a , a n d is generally c o r r e l a t e d with the M u m i e n (Svenbreen) F o r m a t i o n o f the Billefjorden T r o u g h . N o f o r m a l subdivision o f the u n i t exists, but it can be split into an u p p e r a n d a lower unit. T h e u p p e r unit c o n t a i n s i n t e r b e d d e d c o n g l o m e r a t e , s a n d s t o n e a n d coaly shales. A t least three coal seams are also present, b u t they are laterally impersistent. Clasts in the coarser lithologies are quartzite, chert a n d quartzitic s a n d s t o n e . T h e lower unit c o n t a i n s thick c r o s s - b e d d e d s a n d s t o n e s with s u b o r d i n a t e m u d s t o n e a n d siltstone. T h e sandstones f o r m lenticular bodies a n d c o n t a i n s o f t - s e d i m e n t d e f o r m a tion features. It represents a b r a i d e d stream e n v i r o n m e n t within a n alluvial fan in p r o x i m i t y to an active fault. F i n e r - g r a i n e d units o f the u p p e r u n i t indicate the presence o f flood basins a n d lakes w i t h i n the fan. N o m a r i n e m a c r o f a u n a occur in the f o r m a t i o n ; a V i s e a n B a s h k i r i a n age is i n d i c a t e d by fusulinids. H o w e v e r , large depositional b r e a k s p r o b a b l y occurred, particularly at the b o u n d a r y b e t w e e n the u p p e r and lower parts.

Definition. This is the upper unit of the 'Ursa Sandstone' which was discovered when plant fossils of'Culm' (Early Carboniferous) age were found (Antevs & Nathorst 1917), which contrasted with the supposedly Devonian floras of the rest of the succession. It forms a quite distinct lithostratigraphic unit. Cutbill & Challinor (1965) gave the 'Culm' formational status, renaming it the Nordkapp Fm. They correlated it with the Svenbreen (Mumien) Fm in the Billefjorden Gp of Spitsbergen. No complete section exists, but Landnordingsvika provides a type section 120m thick; this increases to 230 m in the north. The formation dips to the west at 10-20 degrees, but in central and northern areas there is complex faulting. The upper boundary with the Landnordingvika Fm is conformable and, in some localities, transitional. It is marked by the upwards appearance of red beds. At Landnordingsvika, Worsley & Edwards (1976) defined the boundary as lying between the grey sandstones and conglomerates of the Nordkapp F m and the overlying red siltstones characteristic of the Landnordingvika Fm. However, Horn & Orvin (1928) and Gjelberg (1981) noted a more gradual passage at Kobbebukta. The lower contact with the Roedvika Fm is concordant, but Gjelberg (1987) noted that faults in the Roedvika Fm are truncated and overlapped by the sandstones of the Nordkapp Fro, which indicates a stratigraphic break. The massive sandstones of the Nordkapp F m can be distinguished and mapped separately from the sandstones with interbedded shales and coals of the Roedvika Fro. The formation consists of cross-bedded grey sandstones with subordinate conglomerates, rare shales and thin coals, which Gjelberg & Steel (1981) divided into two units, the upper containing more conglomerate and mudstone than the lower unit. The upper unit is exposed in the south at Landnordingsvika, where it is 65m thick. Thickness increases towards the northeast (Gjelberg 1981). It consists of intercalated conglomerates, fine- to coarse-grained sandstones and black coaly shales. The conglomerates are mostly matrix-supported and unsorted. Bedding structures are complex, with lenticular bedding, largescale planar trough cross-stratification and low-angle, almost horizontal stratification. Basal erosion surfaces are rare. Clasts are predominantly quartzite (45%), chert (35%) and red and grey quartzitic sandstone (20%). Red beds interfinger in the upper part in a transition to the Landnordingsvika Fro. Coal seams, 10-60cm thick, occur 15-40m below the

SOUTHERN SVALBARD: BJORNOYA A N D SUBMARINE GEOLOGY top, in a sequence of carbonaceous black shales with plant remains and rare pyrite nodules. They are thin and laterally impersistent. The transported plant remains and the absence of true seat-earths suggest that the coals are allochthonous. The lower unit is best exposed at Landnordingsvika in the south. It is dominated by monotonous cross-bedded sandstones with thin interbeds of mudstone and siltstone (1.6%). Sandstones are grey and white and quartzitic, with chert ctasts (more common than in the Roedvika Fm below). Heavy minerals include muscovite, biotite, pyrite, magnetite and ruffle. Ferruginous cement is common. Beds are lenticular, bounded by erosion surfaces and show large-scale, high-angle planar cross-stratification, trough cross-stratification and sub-horizontal stratification. Soft-sediment deformation features are common. Irregular beds and lenses of pebbly sandstone and conglomerate can be found in places. Palaeontology and age. Marine fossils have not been recorded, but the flora has been well documented. Several of the species present occur in, or are allied to, species in the Billefjorden Group of west and central Spitsbergen. They date the Nordkapp Formation as Early Carboniferous. There are six species and fifteen genera in common with the Aurita assemblage of Spitsbergen (Playford 1962, 1963) although some of the common genera, such as Densosporites, are rather wide ranging. Playford's original age-correlation for the Aurita assemblage was Visean and possibly Early Serpukhovian. On the basis of the known distribution of Diatomozonotriletes saetosus in Britain (Smith & Butterworth 1967), which may perhaps be restricted to Late Visean, Kaiser (1971) gave a Late Visean age for his assemblage, also found in the upper part of the formation. The lower part of the formation may span the Tournaisian/Visean boundary as a Late Tournaisian age coal seam crops out south of Ellasjoen, which probably belongs to this formation, though Kaiser (1970) suggested it belonged to the Roedvika Formation. Lack of biostratigraphical control makes age correlations difficult, and the presence of conglomerates may conceal one or more disconformities. Gjelberg (1981) considered that there was a dramatic change in deposition between upper and lower units, which may well reflect a break. As there is a transition to the Moscovian (and possibly Bashkirian) Landnordingsvika Formation above, the Nordkapp Formation may span Visean-Bashkirian time. Worsley & Edwards (1976) suggested a break in deposition at the top of the formation, following Krasil'shchikov & Livshits (1974) in considering the junction to mark an abrupt change in lithology. This seems unlikely in view of the transitional nature of the boundary elsewhere.

11.4.8

217

The upper boundary is concordant with the overlying Nordkapp Fm, but Gjelberg (1987) suggested that the boundary probably represents an unconformity, as Early Carboniferous faults are apparently truncated and overlapped by the Nordkapp Fm. The junction can be mapped at the base of the massive Nordkapp Fm sandstones which overlie interbedded shales, sandstones and coals of the Roedvika Fm. The base is unconformable, lying on metasediments of Late Precambrian to midOrdovician age (Fig. 11.5). The formation consists of shales, sandstones and conglomerates in varying proportions. The thicker northeastern development has been divided into three members (Worsley & Edwards 1976); the upper and lower are coal-bearing and separated by a middle more sandy member. (3) The Tunheim Mbr, 80 m has no complete section exposed, it consists of grey sandstones and shales, with local conglomerates and coals. The sandstones are quartzitic, cross-stratified and flat-bedded. Upward-fining cycles, with sandstones 5 25 m thick are clearly present. Plant fossils, which are abundant, have been reduced to coaly shale and ferrous minerals; underclays are developed. The top of the member is predominantly shale, which contrasts with the base of the Norkapp Formation. Coal-bearing shales appear about 20 30m below the top with three main seams. The lower 'A' seam is the thickest, varying from 90 to 150 cm. The 'B' and 'C' coals are much thinner (40-50 cm) and less persistent than the 'A' seam and may be eroded laterally by channelling at the base of the overlying sandstones. This is especially the case with the 'C' seam. These beds are underlain by a variable sequence of sandstones and shales. The upper shales of this unit thicken northwards and there is visible splitting of the coal seams. The lower 30 m are composed of three or four sandstone sequences, each eroding into the base of the one below. The Rifleodden Conglomerate Bed is a locally developed unit which occurs within approximately 20 m of the base of the member. It makes a useful marker. (2) The Kapp Levin Member, 80 m is of grey cross-stratified sandstones and conglomerates. Shales are rare except for a 10m shale sequence that forms the top of the unit. There are no well-developed coals seams. (1) The Vesalstranda Member, 200 m marks the occurrence of the finegrained lithologies. At the top, the member consists of 6 0 - 8 0 m of black shales and commonly coals, with some sandstone horizons (the Misery Series of Horn & Orvin 1928). The lower 180 200 m consists predominantly of grey and purple sandstones and shales in units up to 25m thick. The shales contain abundant plant fossils, and underclays are developed.

Roedvika Formation (Billefjorden Group)

A t the base o f the Billfjorden G r o u p o n B j o r n o y a , the R o e d v i k a F o r m a t i o n , 360 m, is a clastic sequence. T h e base, a n d possibly also the top, are u n c o n f o r m a b l e ; it rests o n P r e c a m b r i a n a n d O r d o v i c i a n b a s e m e n t , it has b e e n divided into three m e m b e r s , consisting o f s a n d s t o n e s , shales a n d c o n g l o m e r a t e s , w i t h m i n o r coal seams. T h e u p p e r ( T u n h e i m ) a n d m i d d l e ( K a p p Levin) m e m b e r s consist m a i n l y o f c r o s s - b e d d e d s a n d s t o n e s a n d c o n g l o m e r a t e s , a l t h o u g h the u p p e r m e m b e r also c o n t a i n s coal. T h e lower (Vesalstranda) m e m b e r is m a i n l y fine-grained, c o n t a i n i n g coal, a b u n d a n t p l a n t debris a n d also fish scales. T h e f o r m a t i o n was d e p o s i t e d in lacustrine, deltaic a n d fluvial e n v i r o n m e n t s , w i t h channel, crevasse splay, lev6e, f l o o d p l a i n a n d m o u t h - b a r deposits all represented. T h e overall u p w a r d c o a r s e n i n g , at least in the lower h a l f o f the f o r m a t i o n , suggests infilling o f a basin d u e to alluvial fan p r o g r a d a t i o n . P l a n t fossils at the base o f the f o r m a t i o n , t o g e t h e r with m i o s p o r e s , are c o n s i d e r e d typical o f D e v o n i a n flora, a n d d a t e the V e s a l s t r a n d a a n d lower K a p p Levin m e m b e r s as F a m e n n i a n . This is c o n f i r m e d by fish scales p r e s e n t in t h o s e units. T h e rest o f the f o r m a t i o n is o f T o u r n a i s i a n age.

Definition. The lower part of the 'Ursa Sandstone' of Horn & Orvin (1928) was defined as the Roedvika Fm by Cutbill & Challinor (1965), who included it in the Billefjorden Gp. It includes the Tunheim Series, the Flozleere Sandstone Series and the Misery Series of Horn & Orvin (1928) which have been redefined as the Tunheim, Kapp Levin and Vesalstranda mbrs respectively (Worsley & Edwards 1976). It crops out mainly in the east of Bjornoya and is about 360 m thick in total, but there is a general thinning to the south and southwest to only 100 m (which is also seen in the overlying Nordkapp Fro).

Fig. 11.5. Structure contour map of the base of the Roedvika Formation, with diagrammatic profile (from CSE observations),

218

CHAPTER 11

Boulder conglomerates of variable thickness occur locally at the base, which is unconformable on the pre-Devonian basement. Gjelberg (1978) reported a facies analysis of the coal bearing strata. Palaeontology and age. The plant fossils from the Roedvika Formation have been regarded as the typical flora of Late Devonian time. Nathorst (1902) correlated it with the Late Devonian rocks of Ireland and Belgium on the basis, particularly, of the occurrence of Archaeopteris, Roemeriana and Cyclostigma (Bothrodendron) kiltorkense which occur in the Tunheim Member. Sen (1958) reported on Nathorst's Late Devonian megaspores. In a study of the distribution of lycophyte species, Schweitzer (1969) also considered Cyclostigma kiltorkense to be Devonian, but he observed a 'floral break' between the Vesalstranda Member and the Tunheim Member. This is reflected in the detailed studies of miospore assemblages by Kaiser (1970, 1971) which suggest that the Vesalstranda Member and lower Kapp Levin Member are Famennian in age and the upper Kapp Levin and Tunheim Members are Tournaisian. Kaiser (1971) distinguished three distinct, though transitional, microfloral assemblages in the Vesalstranda and Kapp Levin members. He considered these three assemblages to be distinctive, contrasting with the assemblages characterising the overlying Tunheim Member and Nordkapp Formation. By comparisons with North American, Russian and Belgian sections, he showed that they have a Late Famennian age. The Famennian-Tournaisian boundary must be in the unfossiliferous upper part of the Kapp Levin Member. Thus the Kapp Levin Mbr seems to span the Devonian-Carboniferous boundary. Kaiser (1971) recognized three other distinct assemblages of Early Tournaisian, Late Tournaisian and Late Visean age. The two Tournaisian assemblages occur in the Tunheim Mbr and the Visean one occurs in the overlying Norkapp Fm (see above). The only fauna found is from the basal conglomerates of the Vesalstranda Member. It consists of fish scales of Holyptychius nobilissimus AG, H. giganteus AG and H. sp. ~f americanus Leidy, and one form belonging to the Asterolepidae (Holtedahl 1920). The occurrence of Holoptychius indicates a Late Devonian age.

11.5

Pre-Devonian strata of Bjornoya

In the south of the island older rocks are exposed beneath Late D e v o n i a n - E a r l y C a r b o n i f e r o u s cover. They were first noted by Nordenski61d in 1864 (Dun~r & Nordenski61d 1867) w h o correlated the dolostones and limestones with those at M t Hecla. On Nathorst's 1898 expedition Andersson found fossils identified as Ordovician (Lindstrom 1899) who described three members: (3) red and green slates, (2) dolomite and quartzite sandstone, (1) dark limestone with Tetradium. Holtedahl (1920) found Ordovician fossils in the dolostones underlying the Tetradium Limestone and his succession was quoted by Horn and Orvin (1928) thus: (4) Tetradium Limestone (340 m) Ordovician (3) Younger Dolomite Series (2) Slate Quartzite Series. (1) Older Dolomite Series, the upper parts being more arenaceous and lower with oolites, pisolites and stromatolites. In spite of the conspicuous thrusts, the upper (sandy) part of the Older Dolomite Series was reported as transitional to the overlying Slate Quartzite Series. Krasil'shchikov & Mil'shtein (1975) redescribed with 'suite' (formational) names as follows: Ymerdalen Fm Limestone Mbr (mid-Ordovician) Dolomite Mbr (Canadian) TECTONIC CONTACT Sorhamna Fm: Slate Quartzite Series UNCONFORMITY Russehamna Fm: Older Dolomite Series Harland, Hambrey & Waddams (1993) from CSE 1986 and 1987 in particular noted the relations of Sorhamna and Russehamna formations and combined them in a new Bjornoya Group. Armstrong & Smith (in press) from CSE fieldwork in 1986 and based on investigations of conodonts in the Ymerdalen Formation formalized the two original units with new names thus:

Antarcticfjellet Formation (= Tetradium Limestone) Perleporten Formation (= Younger Dolomites) and consequently the Ymerdalen Formation was raised to group rank. The formal classification of p r e - D e v o n i a n strata currently stands as follows.

Ymerdalen Group (Krasil'shchkov Livshits 1974) Antaretiefjellet Formation (Holtedahl 1920; Armstrong & Smith in press) Perleporten Formation (Holtedahl 1920; Smith & Armstrong in press) Bjornoya Group (Harland, Hambrey & Waddams 1993) Sorhamna Formation (Holtedahl 1920; Krasil'shchikov & Livshits 1974) Russehamna Formation (Holtedahl 1920; Krasil'shchikov & Livshits 1974).

11.5.1

Ymerdalen Group

Antareticfjellet Formation ( : T e t r a d i u m Limestone), 93 to 180m. This unit occupies the central part of the outcrops of older rocks and forms the rugged barrier of the blackish hills of Antarcticfjellet. H o r n & Orvin (1928) described the rock as d a r k grey with thin and white calcite veins. Large masses of Iceland spar are f o u n d near faults and east o f Ellasjoen in a vein with barite. The limestone is fine-grained 0.005 to 0.01 ram, and the larger calcite crystals m a y attain a d i a m e t e r of 10cm. The calcite crystals are interlocked. A r m s t r o n g & Smith (in press) n o t e d b u r r o w - m o t t l i n g in the grey fine m u d s t o n e s a n d wackestones. The middle part is thicker bedded, d a r k weathering and rich in crinoid ossicles and gastropods. Fossils are common about 120 m up from the base where Holtedahl (1920) reported a middle Ordovician (Black River) fauna. Tetradium cf. syringoporoides Ulrich, several species of bryozoans, crinoid ossicles, Rafinesquina sp., Maclurites sp., Orthoceras (Kionoceras?) sp., Endoceras (Vaginoceras?) sp., Endoceras? sp., Actinoceras bigsbyi Bronn (= A. tenuifilum Hall?), Gonioceras (occidentale Hall?) sp., Gonioceras nathhorsti u.sp. Armstrong & Smith (in press) added conodont records of low abundance but high diversity and including many unnamed taxa previously known only from Greenland and the Canadian Arctic. The macro- and micro-fauna together indicate that the base of the formation is of earliest Black Riveran (or latest Whiterockian) age and the youngest dated horizon is no younger than Black Riveran (latest Llanvirn or early to mid-Caradoc (Armstrong & Smith in press). The Antarcticfjellet (limestone) Formation appears to pass down conformably into the Perleporten (dolostone) Formation. Precise correlation with sections in N o r t h Greenland, is possible and shows that the f o r m a t i o n is equivalent to the B o r g u m River F o r m a t i o n (M. P. Smith in press). The estimated age of the base of the f o r m a t i o n is earliest Black River (or latest Whiterockian) and the youngest dated horizon is no y o u n g e r than Black River, i.e. latest Llanvirn or early to m i d - C a r a d o c .

Perleporten Formation ( : Y o u n g e r Dolomite), 250 to 400 m. Was described by H o r n & Orvin (1928) as a m o n o t o n o u s sequence of grey dolostone, weathering yellowish and forming steep sea cliffs. Generally it rests horizontally except near overthrusts where dips steepen. It is sandy, in the basal part where it u n c o n f o r m a b l y overlies the S o r h a m n a F o r m a t i o n . The new name is from the opening in the steep cliffs west of the anchorage at Sorhamna; no through section is available (Armstrong & Smith, in press). The upper part contains structureless bedded (1 20 cm) lime mudstones and dolostones. The middle part is poorly exposed. The base of the unit is of buff-weathering sandy dolostones with quartz sandstone beds about a metre thick, with cross lamination. Armstrong & Smith reported dolomicrite rip-up clasts, some being imbricated. Some thicker beds show dewatering structures and the overlying dolostones are not sandy, they contain black chert nodules. Holtedahl found fossils 250 m below the overlying Tetradium limestone including: Calathium, Archaeoscyphia and Piloceras and Ceratopea which date the horizon as Canadian (Early Ordovician). Armstrong & Smith (in press) reported that conodonts were few; only one sample, 60 m from the top, yielded identifiable forms: Paraprioniodus

SOUTHERN SVALBARD: BJORNOYA AND SUBMARINE GEOLOGY (Mound) and 'New Genus 4' of Ethington & Clark (1982, fig. 6), 'indicative of the holodentata-harrisi biozones (latest Early-Middle Whiterockian)' i.e. late Arenig to early Llanvirn. costatus

11.5.2

Bjornoya Group

Sarhamna Formation. This formation contrasts with the competent carbonate units above and below, consisting of red and green slates, often folded with well-developed cleavage, with beds of quartzitic sandstone. The sandstones which are only a minor constituent, are fine-grained (quartz 0.1-0.2mm) some with magnetite cement with cores of pyrite and accessory tourmaline, zircon and rutile. Others show interlocking grains with feldspar, pyrite, apatite, zircon and sericitic mica. (Horn & Orvin 1928). Harland & Wilson (1956) had suggested that the two older formations (Sorhamna and Russehamna) might be correlated respectively with the Polarisbreen and Akademikerbreen groups of Ny Friesland, thus making the Sorhamna Formation Vendian. Harland, Hambrey & Waddams (1993) confirmed that there need be no unconformity beneath the Sorhamna Formation which crops out at Sorhamna, Kvalrossbukta and Roedvika on the coast and inland where it overlies the Russhamna Formation and is unconformably overlain by the Late Devonian Roedvika Formation. They also concluded that the Perleporten Formation (Ymerdalen Group) lies unconformably on the Sorhamna Formation along the poorly exposed contact inland west of Russehamna. The basal Perleporten strata were recorded by A. P. Heafford and P. Smith as sandy and containing large clasts of dolostone. W. B. H noted, on the north cliff of Russelva a large fissure with the overlying formation sediments penetrating the Sorhamna Formation. The southern outcrop has clean wave-worked cliffs at Sorhamna and Kvalrossbukta and in each locality angular carbonate lonestones of 1-2 cm diameter occur within a slaty matrix. The slates are green and patchily red and grey. They could represent marine muds with an ice-rafted component in the grey facies. The red facies are similar to distal turbidites with lamination and load structures.

Russehamna Formation. Holtedahl (1920) had correlated this 'Older Dolomite Series' with the Porsanger Dolomite of northern Norway which, he thought to be Ozarkian or late Cambrian to Early Ordovician. It is a distinctive, somewhat variable unit with five members as described by Krasil'shchikov & Mil'stein (1975). Species of the assemblages are listed in Section 13.3.4 under the heading Vendian biotas. Member (5), 10-20m grey massive sandy dolostone with relict phytolithic texture, in isolated outcrops to the NE (west of Roedvika). Member (4), 150-200 m light grey dolostone with quartz sandstone laminae; transitional to member (3). At the bottom is assemblage IIIa of microphytoliths. Member (3), 80-120m grey fine-grained dolostone with up to 5% quartz grains near top with 'conglomerate texture'. Member (2), 50-80 m alternating units (4 6 m) grey massive dolostone and finely laminated dolostone with iron-stained partings. The bottom 15-20 m is a distinctive marker-bed with assemblage II: Member (1), 150m grey medium-grained dolostone with assemblage I near top. Assemblage IIIb compares with Yudoma assemblages i.e. Vendian and a less identifiable assemblage in Member (5) could be similar. Krasil'shchikov & Mil'shtein argued that assemblages II and IIIa are similar to each other in age and to the upper Riphean of Zhuralev (?Sturtian) and that assemblage I is probably older. Thus the upper part of Member 3 and Members 4 and 5 are probably Vendian. The unconformity postulated above Member 5 would suggest that the Sorhamna rocks are significantly younger, but that break has not been confirmed. On the other hand correlations on such a biota are not accepted as reliable by some authorities (e.g.N. Butterfield pers. comm.).

11.6

219

Structural sequence of Bjarnoya

The sequence of Bjornoya strata divides naturally into three and these three divisions are labelled, for convenience in this section only, as basement, cover and platform. The following discussion is arranged accordingly. Within each of the three sequences are disconformaties and even a marked angular unconformity. In brief: the Platform resting unconformably on a peneplane is hardly deformed being only tilted and cut by minor faults; the cover sequence within it records some mobility in sedimentary environments and is itself folded and cut by faults which appear to be truncated by the Platform unconformity; the basement was folded and thrust-faulted by a more intense (Caledonian) tectonism. These strata are mostly truncated by the cover and exceptionally by the platform sequence. Lepvrier, Leparmentier & Seland (1989) discussed the fault regimes of Bjornoya in relation to those of Svalbard generally.

11.6.1

The basement

Within the basement succession it appears that the Russehamna and Sorhamna strata may be conformable and even transitional. An unconformity is locally evident between the Sorhamna and Perleporten formations but most contacts are tectonic so its nature cannot be established. There would appear to be a Cambrian hiatus. On the other hand, the basement formations were together subject to intense tectonism between early Caradoc and Late Famennian so spanning part of Late Ordovician, all of Silurian and most of Devonian time. By analogy with Spitsbergen, this would exclude affinity with the west Spitsbergen terranes where significant midOrdovician tectonism is evident, but would fit the central and eastern terranes and so may broadly be classed as Caledonian. However, the lack of Cambrian strata as well as the distinctive biotas would appear to distance Bjornoya from the other Svalbard terranes. At the same time the close affinity with successions in eastern North Greenland (Smith & Armstrong 1997) are more promising. The dominant feature of these basement structures is of overthrusting to the west or W N W . This contrasts with the opposite vergence seen in the Hornsund region of south Spitsbergen in the Central Terrane. Since Holtedahl's early work and the geological survey of Bjornoya by H o r n & Orvin (1928) (Fig. 11.6)it is evident that the Older Dolostone Series dip 35 ~ to 40~ at Russehamna, more steeply at Sorhamna and even vertical in M~keholmen, the island marking the eastern barrier to Sorhamna. Seen from the south, the cliff sections show that these more competent older rocks thrust westwards over the younger rocks facilated by the incompetent Sorhamna slates which received their more acute folding and cleavage in this process (Fig. 11.7). Indeed the western boundary of the Russehamna dolostone is generally faulted. The dolostone is traversed by reverse faults that tend to strike N W - S E to N N W - S S E . The Perleporten dolostones are relatively flat-lying except for some folding adjacent to the above overriding thrust masses. Some further structures are listed below. (1) Strong cleavage is noticeable close to the thrust surfaces. The dolostones and limestones have been deformed by numerous fractures and several reverse faults that repeat the sequence. (2) The thrust faults exposed in the Sorhamna and Kvalrossbukta area dip eastwards. One such thrust can be traced from Sorhamna northwards to Kvalrossbukta where it is folded and the dip decreases from 45~ to 20~ consequently the thrust has a sinuous outcrop pattern. (3) Thrust faults have also been recognized in Ymerdalen, deforming the Ymerdalen Formation, and repeating the strata. Although these thrusts are not exposed their eastward dip had been determined on the basis of topographical constraints, but the amount of dip is indeterminable from our present knowledge. Even though the thrusts have a straight mappable trace this does not necessarily indicate a steep dip because of their position in the valley bottom. Other thrust faults are exposed or can be inferred by stratigraphic repetitions where there is good exposure in the river valleys, in particular along Russelva and Orvella.

220

CHAPTER 11 I 18~

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Because only the basement is mineralized it could be argued to be a concomitant effect of the E - W compression with corresponding N - S extension. Alternatively a sinistral Svalbardian strike-slip phase within the same tectonic interval could be responsible. Even Tertiary dextral strike-slip cannot be ruled out. At least one factor must be the composition of the deeper basement which appears to favour an eastern North Greenland connexion.

11.6.2

74"25' __

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Late DevonianEarly Permian strata Pre-Devonian faults

STRUCTURAL MAP OF BJORNOYA (Simplified from G. Horn & A.K. Orvin, 1928)

Pre-Devonian strata

Fig. 11.6. Schematic structural map of Bjornoya (simplified from Horn & Orvin 1928). (4) The strata generally have a N-S strike and the bedding generally dips eastwards (except where steeply folded). Greater dips (30~ I:: ~ ' ~ . - -~ Ir, l ,-I ,o ~ .-J

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LATER VENDIAN

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248

CHAPTER 13

Deilegga formations as younger than the lower tillite and approximately coeval with the Chamberlindalen and Dunderdalen formations to the north. This much is controversial. Although differing from land to land there is a similarity between them and a contrast with the more easterly successions. Seeking a single unifying name, Harland (1978) suggested the name Holtedahl Geosyncline from his early work in the key area of Oscar II Land. The Aavatsmarkbreen phyllites and schists regarded by Harland, Hambrey & Waddams (1993) as Vendian, may be Ordovician or at least have an Ordovician (Eidembreen) overprint (Ohta et al. 1996).

13.3 Vendian biotas Investigation of biotas from beneath and above the two tillite horizons confirms their Vendian age.

13.3.1

Siphonophycus inornatun, Zhang; Siphonophycus sp.; Myxococcoides spp.; Obruchevella Reitlinger 1959; ?Obruchevella sp. Poorly preserved acritarchs include leiosphaerid-like vesicles with an outward layer of hollow processes as have been described from late Riphean and Vendian strata are similar to Vandalosphaeridium from the Doushantuo Formation of China and Cymatiosphaeroides from the Pertatateka Formation of central Australia; these forms being of latest Proterozoic age. This is discussed more fully by Knoll (1992). From the known ranges of the other taxa 'the most likely age for the BCP beds is Late V e n d i a n - i.e. post-tilloid but preCambrian in age' (Knoll & Ohta 1988). That is an Ediacara age (Harland et al. 1990). Knoll & Butterfield (1989) tentatively suggested that large ornamented acritarchs, such as those in the Scotia Group, disappeared more or less coincidentally with the rise of the Ediacara faunas. Harland et al. (1979) had already placed the Scotia Group as later than the late Varanger tillite and pre-Ordovician or Silurian (the speculative age of the overlying Grampian Group).

Biotas from underlying rocks

Stromatolites and oncolites underlying glacigenic strata in Svalbard had already suggested a Vendian age for tillite deposition (Krasil'shchikov 1970, 1973; Raaben & Zabrodin 1969). Subsequently preliminary results from Precambrian microfossils confirmed this impression of the age of the Ny Friesland tillites (Knoll 1982a). Samples collected immediately below the tillite on Sore Russoya in Murchisonfjorden contained 'Bavlinella faveolata (Shepeleva)' Vidal (a pseudofossil), Trachysphaeridium timofeevi Vidal and Stictosphaeridium sp. in an assemblage nearly identical to that found by Vidal (1979) in shales from the Vendian tillite group in East Greenland. The tillites in East Greenland and northeast Svalbard are similar in many other respects (Knoll 1982). The above results, are consistent with the assumed age of the tillites of northeast Svalbard.

13.3.4

Harland & Wilson (1956) had suggested that the Polarisbreen tillite-bearing rocks might correlate with the Slate Quartzite Series, between the Younger and Older Dolomite Series, of Holtedahl (1920). Krasil'shchikov & Mil'shtein (1975) renamed the unit as the Sorhamna Formation beneath the Ymerdalen Formation (Ordovician) and overlying the Russehamna Formation. Harland, Hambrey and Waddams (1993) described the Sorhamna Formation as bearing small lone-stones (probably drop-stones) so increasing confidence in the 1956 correlation. Moreover, Krasil'shchikov & Mil'shtein (1975) described the underlying Russehamna Formation in five units thus: (5) (4)

13.3.2

Biotas from the Gotia (Polarisbreen) Group in Nordaustlandet, northeast Svalbard

The siliciclastic Backaberget Formation in Nordaustlandet overlies the Rysso dolostone Formation and underlies the Sveanor tillite. It has been correlated with the Elbobreen Formation (which contains the early tillite) in Ny Friesland. Indeed it appears also to contain elements of the early tillite in the (probably coeval) Langgrunneset succession to the north (Harland, Hambrey & Waddams 1993). In the shales Knoll (1982a) identified: Protosphaeridium sp., Trachysphaeridium spp. f stictosphaeridium sp. and Bavlinella the psuedo fossil. These are consistent with a Varanger age, i.e. midVendian sensu Vidal (1979a). Oncolite species Osagia svalbardica and the catagraph Vermiculites irregularis (ex Harland & Wright 1979) also suggested a Vendian age. But these may not be chronostratigraphically significant.

13.3.3

Biotas from the Scotia Group in western Svalbard

Whereas the Neoproterozoic sequence in northeast Svalbard is rich in microfossils and stromatolites, only one Proterozoic biota has been discovered in the west. This is not surprising considering the metamorphic grade of most of the rocks. However, in the Scotia Group of Prins Karls Forland, Knoll & Ohta (1988) and Knoll (1992) reported microbial fossils from chert nodules in a 'Black Carbonate Pelite' BCP which probably corresponds to the lowest of the three formations (i.e. Baklia Formation of Harland et al. 1979). The whole (tectonized incompetent) Scotia Group is in need of revision. The following taxa were described and figured: Eomycetopsis robusta, Schopf emend, Knoll & Golubic (1979); Eomycetopsis sp.;

Biotas from Bjornoya

10-20m grey massive sandy dolostone with relict phytolithic texture. 150-200m light grey dolostone with quartz sandstone laminae; transitional to (3).

At the top of unit (4) is their assemblage IIIB: Asterosphaeroides (?) ruminatus. Zabr.; Vesicularites lobatus, Reite.; V. compositus, Z. Zhur.; V. aft. botrydioformis, (Krasnop.): V. elongatus, Zabr.; V. enigmatus, Zabr.; V. vapolensis, Zabr.; V. Parvus, Zabr. At the bottom is assemblage IIIA of microphytoliths: Osagia maculata, Zabr; O. milsteini, Zabr.; O. pullata Zabr.; Vesicularites elongatus, Zabr.; V. raabenae, Zabre. (3)

80-120 m grey-fine grained dolostone with up to 5% quartz grains near top with 'Coagulation texture'.

(2) 50-80m alternating units (4-6m) grey massive dolostone and finely laminated dolostone with iron-stained partings. The bottom 15-20m is a distinctive marker bed with assemblage II: Osagia crispa, Z. Zhur; O. medwezhiella, Milst. and probably Radiosus aculeatus, Z. Zhur. are associated. (1) 150m grey medium-grained dolostone with assemblage 1 near top: Vesicularites lobatus, Reite. and Nubecularites, Masl. Krasil'shchikov & Mil'shtein argued that assemblages II and IIIA are similar to each other and to the Upper Riphean of Zhuravleva (?Sturtian) and that assemblage I is probably older. Assemblage IIIB compares with Yudoma assemblages, i.e. Vendian, and the less identifiable assemblage in unit 5 could be similar. Thus the upper part of unit 3 and units 4 and 5 are probably Vendian with downward transition. Harland, Hambrey & Waddams (1993) reported that the Ymerdalen Formation rests unconformably on the Sorhamna Formation. They concluded that the Sorhamna Formation is Vendian (Varanger) and that the underlying Russehamna Formation passed down into earlier Varanger, and then to Sturtian age. The biostratigraphic age conclusions from the above biotas, however, may not meet more stringent later criteria.

VENDIAN HISTORY 13.4

Vendian environments

Marine, climatic, glacial, volcanic and tectonic environments are selected for consideration.

13.4.1

249

scale in every case is from - 8 to +8 plotted against thicknesses. The positive values in theory might indicate loss of the lighter isotope to land-based ice. In practice they correspond reasonably to wellknown tillites and so presumably yield a climatic signature. In due course this promises a powerful correlation tool especially in Precambrian successions.

Marine environments

It is virtually certain that strata accumulated in prevailing marine environments rather than in isolated basins. This was on the basis both of the Hecla Hoek sequence in the northeast, which continued with little break for even hundreds of millions of years, and on the lack of near-shore sedimentary patterns (e.g. Harland & Herod 1975). This opinion was later confirmed by the finding that the salinity of the ambient water in which glacigenic sediments formed was similar to that of present-day oceans. High salinities are indicated by local occurrence of anhydrite relicts as in carbonate members of the Elbobreen Formation. High carbonate concentrations are evident from the rock flour derived from thick preceding carbonate formations exposed in a great area of shallow seas (Fairchild 1983). The northeastern Vendian outcrops reflect relatively shallow water with changing sea levels in response to Varanger glacial episodes. The western outcrops give evidence of deeper marine environments. Carbon isotope ratios in marine deposits also yield information on global climatic changes to be discussed (e.g. Knoll et al. 1986; Kaufman & Knoll 1995). Kaufman & Knoll made systematic comparisons of C-isotope values in a number of key Neoproterozoic sections worldwide. This work has already been referred to in the pre-Vendian successions. In each case Svalbard provided significant 613C data which are abstracted here in Fig. 13.4. The

~'~ C

f,f, o

l

100

-

200

-

-

300

-

-

400

-

-

500

-

,-?,;2 I

,0, ,2 , i , ~,, ,8

l

Oracoiserl

- 600 -

-

7oo

-

-

800

-

-

9OO

-

Wilsonbreen

Elbobreen

-lOOO

-

11oo

-

12oo

-

13oo

-

14oo

..~

..~

- 1500 .~ B a c k l u n d t o p p e n

-

1600

-

-

1700

-

-

1800

-

-

1900

-

-

2000

-

-

2100

-

-

2200

-

-

2300

-

-

2400

-

-

25oo

-

-

2800

Draken

S v a n b e r g ~ e l l e t

//

Grusdievbreen

Fig. 13.4. Secular variation in (~13C plotted against stratigraphic depth (m) for the Varanger and Sturtian succession of Spitsbergen (simplified from Kaufman & Knoll 1993 with permission of Elsevier Science, Amsterdam).

13.4.2

Vendian climates

Most palaeolatitudinal studies placed northeast Svalbard in Cambrian time in a near equatorial position as, indeed, applies also to coeval sequences in Central East Greenland, and probably also in northern Norway (e.g Harland & Bidgood 1959; Bidgood & Harland 1961; Harland 1964b). This is consistent with the thick pre- and post-Vendian carbonate sequences. Nevertheless dolostones may have formed in both warm and cold waters (Fairchild & Hambrey 1984). At the same time, the main Vendian outcrops all expose two distinct glacial horizons, named from the original Finnmark succession: Smfilfjord and Mortensnes combined in the Varanger Epoch (Harland & Herod 1975). Such an apparent anomaly led some to doubt the glacial nature of the tilloid deposits and others to doubt their tropical location as by rapid polar wandering. However, the hypothesis of two epochs of severe tropical, nearequatorial marine glacial deposits (Harland 1964a, b) has since been generally acknowledged (e.g. Frakes 1979; Chumakov & Elston 1989; Kirschvink in 1964, 1992). This carries with it the implication of at least two global glacial epochs, but it does not follow that tropical glaciation was synchronous with polar glaciation, especially if the main continental distribution at the time was in low latitudes. An independent isotopic assessment for Svalbard (Fairchild & Spiro 1987) suggested that oxygen isotopes may constrain palaeolatitudes of the Late Proterozoic glaciation. Pleistocene and Late Paleozoic glacials known to be polar give a known measure of 6180 on the basis that modern snow, glacier ice and meltwaters in high latitude are depleted therein. The isotopic compositions of ambient glacial seawater-meltwater maximum has unexpectedly heavy oxygen for a polar environment (Harland, Hambrey & Waddams 1993). Sufficient criteria are now generally accepted for identifying tilloids as truly glacial (formed in a variety of environments). Such tillites are often good marker horizons and may be distinguished even after severe tectonization and metamorphism. However, several other Neoproterozoic glacial horizons are known so that, it is essential to estimate the age proximally by lithocorrelation and distally by biocorrelation. Fortunately in Svalbard both these may be achieved. Moreover, the two tillite horizons in Svalbard may be distinguished by their stone content. The earlier is typically composed of intrabasinal clasts and the later by additional crystalline, often pink granitic, stones along with intrabasinal clasts. It so happens that Svalbard exposes extensive Vendian strata, often largely identified by tillites and tilloids. The correlation principle being that such extreme climatic excursions could not have been local, they must have been regional at least, and most probably global. Therefore correlation by these two glacial episodes does not imply original proximity.

13.4.3

Glacial environments

Svalbard Varanger deposits, especially in the northeast, present a remarkable opportunity to interpret glacial environments (Fig. 13.5). The facies are conspicuously different in the eastern and western outcrops. The latter are more difficult to interpret because of two subsequent tectonic episodes.

250

CHAPTER 13

Early Cambrian

strata. They were consolidated before erosion. Continuous glacial cover is suggested from lack of supraglacial debris. (iii) 'Interglacial' sediments. First a rise of sealevel (MacDonaldryggen Member E3) with offshore sedimentation and then a fall (Slangen Member, E4) are indicated. Oolitic and intraclastic grain stones, teepee structures, with fenestrae and anhydrite inclusions in chert, were observed. Breccia-filled wedges occur at the top.

TokammaneFm.

/ / / / / /'

Dracoisen Fm.

/ / / D6. / / / / / /. / / / / / / / / / .I I .

~

Shallowmarine l .~Emergent

~

Shallowmarine

D5 ~ D4

Ediacara

1Emergent

(iv) Sedimentation during second glacial (Mortensnes) (Wilsonbreen Formation, W1-3). A second major regression marks the onset

~l~Emergent ~ 1 ~ Shallowmarine

--

D3 -

9

1

Warm

Offshore

D2 D1

t Shallowmarine

il~

W3

Proximalglaciornarine ~ 1 ~ Groundedice

t

Proximalglaciomarine Grounded ice Proximalglaciomarine

t

q'ffO. Wilsonbreen Fm. w?~ o

~ e

w~ t ' ; . " 9

~

.

Glacial Fluvioglacial Proximalglaciomarine ~ 1 ~ Emergent-fluvioglacial-periglacial

Glacial

Emergent

~

Lagoonal

Warm

Varanger E3 "

"

~ Offshore

Elbobreen Fm, E~-.g.~,~-~

J

~ , /, El

Late Riphean

Backlundtoppen Fm.

I--I --I - II I

I--I / /

"qt-~" Distalglaciomarine Proximal glaciomarine ~1 Shallowmarine

} Glacial

] Tidal

, Warm

j

,/

Fig. 13.5. Interpretation of Vendian environments from the successions of Ny Friesland (northeastern Spitsbergen), based on data from Harland, Hambrey & Waddams (1993, table 20).

Eastern outcrops.

of glaciation (W1). The Wilsonbreen Formation exhibits all the glacial features of the first stage, but the scale and intensity were much greater. This formation cannot be overlooked because of the conspicuous exotic stones, often pink granitoids and many other lithologies in contrast to the strictly intrabasinal stones of the lower tillite. Chumakov (1968) described a glacial pavement within the boulder-rich diamictite succession. The Middle Carbonate Member (W2) with stromatolites and rhythmic limestones, interpreted as periglacial, divides the typical till facies into two (Wl and W3). (v) Post-glacial sedimentation (Dracoisen Formation, D). A trangressive succession follows beginning with a basal conglomerate. A surf zone discontinuity followed by shallow, sublittoral wavedominated fine-grained dolostones, D1, fine upwards into offshore mudstones D2 and D3. This is followed by regression with ephemeral lakes, desiccation cracks, silicified anhydrite nodules and halite pseudomorphs. A return to marine conditions is shown by dark shales with acritarchs below the sub-Cambrian discontinuity (A.H. Knoll in Fairchild & Spiro 1987). It is noteworthy that an almost identical sequence occurs in East Greenland (Fairchild & Hambrey 1995).

The evolution of the evolving environment is summarized in Fig. 13.5 based on studies by Hambrey (1982), Fairchild & Hambrey (1984) and Fairchild & Spiro (1987). It was a period of deposition of fine-grained sediment in a slowly subsiding basin or shell punctuated by the influx of coarse material by glacial transport from a distant source. There is no record of tectonic instability nor of volcanic activity. The sequence of events may be summarized in the following five stages (Harland, Hambrey & Waddams 1993) redescribed in sequence stratigraphic terminology by Fairchild & Hambrey (1995). (i) Pre-glacial sedimentation (Elbobreen Formation, El). Through Sturtian to early Vendian time limestones and dolostones predominate and are interbedded with sandstones and mudstones. Stromatolites, dolostones, oolites, pisolites and limestones with shrinkage cracks are widespread.There may then be a hiatus representing Vidal's (1985) early Vendian microflora and the lack of negative 513C values. (ii) Sedimentation during first glacial (Sm~ffjord) stage (Petrovbreen Member E2). Lodgement and waterlain tillites predominate with material mainly from the upper Backlundtoppen Formation and above. A fall in base-level is interpreted to provide erosion of local strata. Features include: glacio-lacustrine rhythmites with dropstones; periglacial wedge fillings; fluvioglacial and debris flow conglomerates; dolostones of rock-flour. Provenance from SE to SW sectors suggests uplift of rocks similar to underlying

Western outcrops.

Although largely tectonized the same two tillite horizons in the sequences, but an order of magnitude thicker, may be distinguished as in the east. The upper one is conspicuous, resistant and often with exotic stones. The lower tillite with stones of calcareous composition similar to the matrix may be overlooked. Nevertheless occasional critical sedimentary structures are preserved to confirm a glacial origin: dropstones at Kapp Martin and Vimsodden; original shapes of lone-stones; fine extensive laminations; outsize stones are dispersed therein; great thickness and extent (Harland, Herod & Krinsley 1966). The stones form a smaller proportion of the total clasts, typically 1-5%, but up to 50%. There are no abraded rock surfaces (as in Ny Friesland). The environment suggests ice rafting into highly mobile distal turbidite facies often with flame structures. Uplift and reworking of till material concentrates and results in fluvial conglomerates. Steep submarine slopes enabled transport of cobbles, the oolitic matrix coming from a shallow marine environment. Study of sediments, as above, may suggest local environments. A regional or global study of coeval strata may give some clue as to the global influences affecting the local environment. A Varanger global glaciation has already been suggested which would most likely require i.a. a reduction in atmospheric CO2. Of alternative and contributing mechanisms Young (1995), while not denying that the Varanger glacials (at about 600 Ma) could be global as indeed also the Sturtian glacials (at about 750 Ma), suggested that the best development of the Varanger glacials occurs along the North Atlantic-Arctic seaboards whereas the Sturtian glacials dominated the western margin of Laurentia and neighbouring Australia as juxtaposed in the SWEAT hypothesis. He argued a break-up of the SWEAT supercontinent in two stages. The earlier assembly (named Kanatia by him) was separated at about 750 Ma by fission between Laurentia and Australia and Antarctica. The later assembly (Rodinia) at about 600 Ma separated Baltica and Amazonia from Laurentia (with Greenland). He suggested that the initial rifting first splitting Kanatia and then Rodinia localised the glacials. He pointed out the long-observed double glacial episodes in each case

VENDIAN HISTORY as though there might be similar tectonic causation which he discussed. His actual maps of Kanatia and Rodinia, however, would not accommodate the palinspastic relationships developed in this work.

13.4.4

Volcanic environments

We have no record of volcanism during the formation of the Polarisbreen Group rocks of northeast Svalbard. Volcanic stones (e.g. amygdaloidal basalt) of unknown age were reported in the Sveanor tillite of Nordaustlandet. On the other hand the west coast successions are conspicuous by their basic igneous component. Orvin (1940) referred i.a. to outcrops of gabbro, along the west coast south of Isfjorden, which on investigation, in spite of later tectonism, could be shown in most instances to be contemporaneous within the succession. All the main outcrop areas of Vendian rocks in the west have a significant volcanic content as follows (e.g. Kovaleva 1983; Turchenko et al. 1983).

Oscar II Land. Within the St Jonsfjorden Group, i.e. well beneath the upper tillite, are two formations with basic components. In the lower part of the Lovliebreen Formation is the conspicuous basic amygdaloidal lava formation. On Gunnar-Knudsenfjella foliated dark brown, green and purple rocks are exposed and also occur extensively in the neighbouring moraine and, indeed, through southern Oscar II Land (Harland et al. 1979). Ohta (1985) referred to these as Trollheimen volcanics, describing their lavas as up to 15 m thick with calcite amygdales, possible pillow structures, and associated with interbedded pyroclastics at Trollslotten in upper Eidembreen. Chemically these rocks are calc-alkaline and Ohta suggested a non-oceanic type, possibly formed in a shallow marine setting in association with shelf-edge sediments. Some pyroclastic rocks are reddened suggesting contemporaneous weathering. Some of the finer metasediments within the formation, typically phyllite, appear to have some basic content. The overlying Alkhorn Formation has a less conspicuous igneous aspect; but contains distinctively Na-alkaline basites, also with pillow structures (Ohta 1985). North of St Jonsfjorden are near-coastal exposures of the Aavatsmarkbreen Formation, at the top of the Comfortlessbreen Group and well above the upper (Haaken) tillite. Between its upper and lower divisions, of grey-black phyllite and marbles, is an incompetent middle division of up to 100 m of dark grey, green and black slate and light green fibrous serpentinite. At Snippen soft, light green and purple banded shales may be seen. A distinctive volcanic component thus characterizes this formation also to some extent in the lower division (Harland, Hambrey & Waddams 1993). Subsequently, Ohta et al. (1995) have shown this to be part of the newly identified Kaffioyra Complex of Ordovician metamorphism and Paleogene shearing, but the correlation here of the protolith as Early Varanger still holds. With such extensive volcanic rocks in the St Jonsfjorden Group it is not unlikely that the Vestg6tabreen Complex represents a Vendian protolith. It is a tectonic slice of blue-schist facies, intensively studied because of the high pressure mineral assemblage. Demonstrated biostratigraphically as pre-Caradoc and isotopically as mid-Paleozoic, it is now suggested that of the pre-Vendian strata known in the west none have been reported with a volcanic component. Therefore it must be considered that the complex may have been (?subducted) rocks of the St Jonsfjorden Group. This could be tested geochemically (contra Harland, Hambrey & Waddams 1993). Prins Karls Forland. The oldest rocks are the up-thrusted metamorphic complex of the Pinkie Formation. The age is uncertain but a case was made for it to correlate with the St Jonsfjorden and equivalent groups further south, not least because of the metavolcanic component (Harland, Hambrey & Waddams 1993).

251

The Alasdairhornet Formation, consisting of banded and welded tufts and some basic lava flows, belongs to the Peachflya Group which is well above the Ferrier Group (with distinctive diamictite, probably Late Varanger). These rocks are difficult to correlate in detail with the Vendian succession in Oscar II Land just across the water. The Kaggeu Formation of the Scotia Group, already distinguished by its Ediacara fossils, is the middle formation, conspicuous for its grey, green-purple and striped slates and phyllites which reflect a fine-grained volcanic component. It was correlated with the Aavatsmarkbreen Formation across Forlandsundet.

Nordenski6ldkysten. The stratigraphic succession in this strandflat has been variously interpreted, e.g. by Turchenko et al. (1983), Hjelle et al. B10G (1986) and Harland, Hambrey & Waddams (1993). Regardless of the succession the older maps show the promontories Diabaspynten and Gronsteinodden on the southwest coast. These are closely associated (interstratified) with tilloids. Whereas Turchenko et al. and Hjelle et al. considered them to belong to the top of the succession, Harland, Hambrey & Waddams, distinguishing two tillite horizons, argued these to be of Early Varanger age. On the second hypothesis they could correlate with the St Jonsfjorden volcanics; but in any case they are of Varanger age. Hjelle (1962) noted the similarity of the basites in Nordenski61d Land and in Chamberlindalen to the south, in northern Wedel Jarlsberg Land. Turchenko et al. (1983a, b) remarked on the geochemical similarity of the same rocks with metabasites at Vimsodden and still further south. They described green schists with basic volcanic derivation, intrusive and extensive gabbro, andesite and andesite-basalt. Harland, Hambrey & Waddams (1993) further noted a similarity with the Lovliebreen rocks to the north in Oscar II Land.

Northwest Wedel Jarlsberg Land. Of the two groups of formations accessible from the coasts east and west of Kapp Lyell the Kapp Lyell Group (Late Varanger) has little or no volcanic component, whereas the underlying Konglomeratfjellet Group includes the Chamberlindalen Formation whose (lower) Asbestodden Member is dominated by basic igneous rocks, including pyroclastics, lavas (some pillow) and small intrusions. Pelites and carbonates are interbedded with the volcanic rocks. The middle and upper members also have a similar though proportionately less conspicuous volcanic component. Turchenko et al. (1983b) described: 1300-1500 m schistose andesite-basalts and tufts; 500-1800 m andesite-basalts and picrites with sills of gabbro and peridotite, and dolostone; 150-200 m marbles with basalt and andesite basalts, transformed into green schists. Also diabase, gabbro and peridotite dykes; some pillow structures. The Chamberlindalen Formation is part of the eastern limb of a northerly gently plunging syncline. Where the strata reappear at the surface to the west they are not so well exposed and have been given a different name (Dunderdalen Formation). Some elements may have been cut out; but more likely (as seen further south) there are sharp east-west changes of facies in a highly mobile environment.

Southwestern Wedel Jarlsberg Land (south of Austre Torellbreen). The considerable differences between authors as to the succession, outlined in Chapter 10, will not be repeated here. The questions are unresolved. Naturally this account follows the conclusion of Harland, Hambrey & Waddams (1993) with some modifications. However, it is possible if desired using the following nomenclature to transpose the rocks described to the different implied time scales. The effect of these differences is that whereas the bulk of the basites described below are taken here as of Early Varanger age, other authors would make them mostly pre-Vendian.

252

CHAPTER 13

The Elveflya (Vimsodden) Formation is rich in green schists, interpreted as tufts and lavas, interbedded with diamictite. They were described by Smulikowski (1968) with further notes by Birkenmajer (1991) and Harland, Hambrey & Waddams (1993). The formation appears to pass upwards (northeastwards) into the Jens Erikfjellet (volcanic) Formation (map unit 32 B12G in Ohta & Dallmann 1991). The SkSlfjellet Formation (subgroup) is made up largely of basic igneous material (Smulikowski 1968). It had been regarded as an eastern lateral equivalent. It is now established as a Mesoproterozoic unit in the Eimfjellet Group of Czerny et al. (1992). Harland, Hambrey & Waddams (1993a) grouped all these rocks together with the overlying Deilegga and Slyngfjellet rocks in a thick and complex Werenski61d Group. On this basis it would be equivalent to the Konglomeratfjellet Group to the north. To avoid confusion, a new name, Austre Torellbreen Group, is preferred here. It may be recalled that the Scotia Group of Prins Karls Forland is of established Ediacara age and is also associated with purple as well as black slates.

strata, even though there may be some hiatus or non sequence. The changes in facies appear to reflect mainly sea level and climatic changes. These circumstances make it reasonable to postulate that the close similarities between the Ny Friesland and East Greenland successions are indeed the result of glacio-eustatic changes keyed in by the ubiquitous double Varanger glacial epochs with their concommitant changes in 613C compositions (e.g. Fairchild & Hambrey 1995). In the west of Svalbard, the contemporary mobility with turbiditic resedimented conglomerates (Waddams 1983) has already been stressed. In northwestern Wedel Jarlsberg Land a Late Varanger sequence of at least 3 km and about 3 km of Early Varanger strata rest with strong angular unconformity on an overfolded sequence. The impression of most observers (e.g. Bjornerud 1990) is that provenance of western deposits was in the east (not then in present-day Svalbard). In Southwest Wedel Jarlsberg Land the Early Varanger strata exceed 7 km in thickness and reflect volcanic facies. It also appears that normal tillites occur in the western outcrops as in the Elveflya Formation, but that only approximately coeval conglomerates (of similar composition) occur in the eastern outcrops and at a higher stratigraphic level. Therefore it would seem that still further to the east the early tills or tillites were uplifted, eroded and transported to be exposed now in the eastern outcrops. The Vendian outcrops east of Hansbreen give the impression of a relatively stable sedimentary environment; but they are not extensive enough to determine a direction of provenance. Thus rapid subsidence (and volcanism) characterises the western terranes in contrast to those in the centre and east.

Sorkapp Land. Winsnes (1955) described the GSshamna (phyllite) Formation as having a volcanic component. It lies beneath fossiliferous Cambrian strata and stratigraphically (with a tectonic break) above the H6ferpynten Formation. The latter is probably pre-Vendian. Harland et al. (1993) agree with Birkenmajer (1960 et seq.) in correlating G5shamna with their Bogstranda Formation to the north which they place above the Fannytoppen and Fannypynten formations (of Late Varanger age). On balance they regarded the GSshamna phyllites as most probably Late Vendian (Ediacara).

13.5

Bjorneya. The green and purple colour of some of the Sorhamna (?Vendian) Formation suggests a small volcanic component.

13.4.5

The Vendian Period is exceptionally well represented in its earlier (Varanger) epoch which reflects the two major glaciations. These enable international correlation, being distinguished from other Neoproterozoic glacial epochs by sufficient biostratigraphic control. Figure 13.6 shows approximate correlations between the various lands surrounding Svalbard. Of these all show a somewhat

Tectonic environments

In the northeast of Svalbard, the Vendian strata reflect a stable tectonic environment, and so do the preceding and succeeding

SPITSBERGEN 1

Vendian international correlation

GREENLAND

FINNMARKEN

, KOLA PENINSULA4 Western

East2

Northeastern

North 3

Paraut~176

(Sredniy Peninsula) i

BULLBREEN

OSLOBREEN

CAMBROORDOVICIAN

5

]

-J

Dracoisen

Spiral Creek Canyon

Wilsonbreen

Storeelv

Region 6

'

Portfjeld

,

CambroOrdovician

~

~

'

Brelvik . . . .

u~ Aavatsmarkbreen

AREA

SOUTHERN NORWAy7

Barents Sea

Berlev~g ." ~

Stappogledde

r

.,,.-~,

WESTERN SCOTLAND 8

Jura Quartzite

~AGE CAMBRIANSILURIAN

Vangsgs

,,,,, Illll

Ekre

Annabreen

Bonahaven Dolomite

O<
10% was by feldspar volume as shown in Fig. 15.6 taken from Hjelle (1966) so defining 8 rock species: 1, trondhjemite; 2, Na-granite; 3, normal granodiorite; 4, K-granite; 5, granosyenite; 6, quartz monzonite; 7, granodiorite; 8, quartz diorite (Fig. 15.6). His detailed mineralogical and chemical results are not repeated here. Hjelle (1966) recognized three main types of granites. (i) Medium-grained grey granite to quartz diorite in northwest Spitsbergen, often occurring as dyke rocks in the migmatites. These are the syntectonic layered granites of most authors. They are generally younger than the migmatites and older than the massive pink unfoliated granites. (ii) Coarse, often porphyritic, mainly quartz monzonites. They generally occur as batholiths in N W Spitsbergen and central Ny Friesland. (iii) Medium-grained granites of the Nordkapp area of northernmost west Nordaustlandet and of Laponiahalvoya and Rijpfjorden-Rijpdalen, in northwestern and central Nordaustlandet respectively.

An

An

\

Ab

15.4.3

281

25

45

65

K feldspar

Migmatites

'When the degree of feldspathisation and mobilisation increases in the layered gneiss, the granitic material begins to penetrate discordantly the layers and the axial planes of the small folds discordantly,

Fig. 15.6. Quantitative petrographical classification of granitic rocks in Svalbard. Quartz >10vol%, Feldspars >30vo1% (as used by Hjelle 1966).

282

CHAPTER 15

(iv) To the above three classes of Hjelle, the 'feldspathites' of N y Friesland are distinguished. They were so designated because of their p r o b l e m a t i c history and genesis in western N y Friesland ( H a r l a n d , Wallis & G a y e r 1966). To anticipate the following discussion (i) and (ii) above are confirmed as Paleozoic a n d related to the C a l e d o n i a n o r o g e n y whereas (iii) and (iv) are n o w confirmed as originally Proterozoic but modified by mid-Paleozoic t e c t o n o - t h e r m a l influence.

15.4.5

Syntectonic (grey) granites

Grey, often foliated, granites are typical of the extreme n o r t h w e s t e r n and n o r t h e a s t e r n terranes of Svalbard. They are typically closely associated with migmatites. F r o m the northwest, e.g. in V a s a h a l v o y a the w o r k of O h t a a n d of Gjelsvik was described by Hjelle (1979) a n d integrated with that of Gee (Gee & Hjelle 1966). Marginal contacts are gradational, but some truncate earlier structures. Some contain shadowy metasters with the implication that the granitic magmas represented a more advanced stage in the process of migmatization. That is to say that they are dominantly metatect with only occasional ghost metaster relicts. All grey granites adjoin migmatite areas. The composition (typically monzo-granite to quartz diorite) corresponds to the bulk composition of the migmatites. Structurally the granitic rocks conform to the flow structures of the open folding of the migmatites rather than the older tight isoclinal folding of the gneisses. Associated with these occurrences are grey-granitic dyke rocks of two generations. The earlier intrusive relationships reflect an early stage in the penetration of the metaster, i.e. early to pre-migmatite. Later more common dykes cut across the migmatites (with sharp contacts). They often follow the jointing. These dykes also include aplitic and pegmatitic facies, the latter are generally younger and narrower (only 10% > 0.5 m). Again the composition is typically monzo-granite to granodiorite. The migmatites and then the granites represent the Early through Late Smeerenburgian phases. Indeed Hjelle (1966) recognized two main periods of intrusion. (1) One earlier, relatively deep-seated and related to the migmatization; the structures were folded in the orogeny and discussed in Section 15.4.3 above. (2) The second which is Hjelle's class (i) cuts the migmatite gneisses and metasediments as dykes. The dyke widths are typically less than I m but may range up to 2 km east of Krossfjorden. As a result of assimilation the compositions are variable with quartz monzonite, granodiorite and quartz diorite predominating. In Nordaustlandet, the grey granite-red granite contrast was noted by Sandford (1926), but at a time when migmatization was not a familiar concept, although the term migmatite is an old one. Silurian or Devonian tectono-thermal overprint on demonstrably Proterozoic original granites (as well as the host rocks) as have been identified by age determinations of zircons. To what extent a Silurian-Devonian rejuvenation of a Proterozoic magmatic terrane was general remains to be elucidated. Isotopic age determination of these grey granites are few but they must be older than the late tectonic plutons referred to below.

15.4.6

Late tectonic plutons

Late tectonic batholiths are distinctive bodies generally of pink porphyritic granite lacking any foliation. The H o r n e m a n n t o p p e n Batholith occupies the n o r t h w e s t e r n Spitsbergen terrane. In eastern N y Friesland are two m a i n batholiths, C h y d e n i u s b r e e n and Nordenski61dbreen. Their names imply relatively p o o r exposure. In N o r d a u s t l a n d e t there are m o r e plutons of less regular o u t c r o p pattern, which is itself obscured by ice or sea. They m a y not all be large e n o u g h to qualify as batholiths. The occurrences were m a p p e d at I : I M (Winsnes 1986) b o t h east a n d west of L a p o n i a h a l v o y a and M a r t e n s o y a , east and south of Rijpfjorden, a n d three units in a n d near D u v e f j o r d e n . H o w e v e r , the N o r d a u s tlandet plutons are m o r e p r o b a b l y N e o p r o t e r o z o i c , nevertheless they a p p e a r to have been reheated in Silurian to D e v o n i a n time f r o m K - A r age determinations.

Northwest Spitsbergen. The Hornemantoppen Batholith (Hjelle 1979) occurs within the migmatite terrane and covers 150km 2. Of the varied facies is a coarse to medium grained red monzo-granite grading with equal proportions of potash and plagioclase feldspars (c. 60%), the former reaching 2cm in porphyritic varieties. Then after quartz (c. 30%), biotite constitutes 4-8% with some chlorite and plagioclase tending to sericite, accessories are titanite, apatite, pyrite and magnetite. The latter is more abundant than in the migmatites and is sufficiently abundant to cause a magnetic anomaly which may suggest a basic facies lower in the pluton. The granite is cut by aplites and pegmatites and contains small xenoliths. Marginal foliation suggests a batholithic shape as does a relief of 700 m. The granite contacts are unsheared, intrusive and truncate the migmatite structures which entirely surround it. No hornfelsing was observed. Part of the roof zone in the north may be seen with roof pendants and larger xenoliths. The batholith may either have been emplaced in a pre-existing antiform or, more likely, to have itself arched the country rock structures (Hjelle 1979). Hjelle reported a whole rock Rb-Sr age of 414Ma (approximately Late Silurian to Early Devonian). The composition given by Hjelle (1966) is of quartz-monzonite. Balashov et al. (1996)obtained a Rb-Sr age of 413 + 5 Ma. Ny Friesland. The Chydeniusbreen Granite Batholith. The Chydeniusbreen Granite occurs entirely within the middle Hecla Hoek strata of the Lomfjorden Supergroup. They are folded but not obviously metamorphosed except for a one km wide zone of hornfels. Most of the main outcrop is covered by ice but the granite supports Newtontoppen the highest (ice) peak of Svalbard at 1717m. The batholith appears as a diapiric emplacement having shouldered its way through the country rock when its margins at least were already solidified. It is difficult to say whether the marked attenuation of steeply dipping strata, especially on the west side, was the result of the emplacement or of simultaneous or late E-W compression of the orogen. Both may have operated. The rock is described briefly in Chapter 7.4 (Harland 1959). It averaged granite-adamellite and varies locally, partly according to border (xenolithic contamination) facies. Hjelle (1966) remarked on the uniform composition classifying it as quartz monzonite to granosyenite. K-Ar ages of the granite biotite yielded 391,395 and 414 Ma, say 400 Ma, at or later than the Silurian Devonian boundary (Hamilton et al. 1962). A further small outcrop the Raudfjorden granite crops out to the north east and appears to be an apophysis of the main body. Indeed there may well be a connexion between these granites at no great depth (Harland 1959). These granites have been described in much greater detail (Teben'kov et al. 1996), but with little change to the above conclusions (Section 7.4.1) and concluded an age of 432 + 10 Ma. The Nordenskiiildbreen Batholith. Tyrrell (1922) described a syenitic suite from morainic samples. These were derived from what appears to be an extensive subglacial outcrop seen in the cliffs of the nunataks of Terrierfjellet and Ferrierfjellet. These nunataks show that the unconformable Carboniferous cover would project beneath the surface of the ice field of Lomonosovfanna and the syenitic rocks evident in the marginal exposures may not be typical of the whole batholith. The samples described held more quartz and less augite than a typical syenite Hjelle (1966). It was suggested ( H a r l a n d 1971) that the c o m b i n e d effect of tectonic thickening with increased o v e r b u r d e n of the lower rocks, c o m b i n e d with the shear friction in the neighbouring zone of transpression increased the t e m p e r a t u r e so as to generate m a g m a from the lower Hecla H o e k rocks. That the m a g m a penetrated the overlying strata to the side o f the m a i n orthotectonic zone might be due to the lack of the space in the pervasive transpressive regime in contrast to the contiguous unsheared c o m p e t e n t terrane which could have generated space for the initial diapirs by the adjacent N - S extensive regime.

The Nordaustlandet granite plutons.

S a n d f o r d (1926) perhaps first suggested a C a l e d o n i a n age for the granites of N o r d a u s t l a n d e t as confirmed subsequently. The various outcrops m a y be grouped into two principal areas (Hjelle in F l o o d e t al. 1969). (i) In the northwest at L a p o n i a h a l v o y a and (ii) R i j p f j o r d e n - R i j p d a l e n , further east. The m o s t frequently observed mineralogical association in the granites is q u a r t z - m i c r o c l i n e - p l a g i o c l a s e (albiteoligoclase)-biotite-muscovite. This suggest a m o r e alkaline and less calcic and r e m i t c o m p o s i t i o n t h a n that of N y Friesland.

SILURIAN HISTORY Hjelle (1966) remarked that the two principal granites of Nordaustlandet (i) and (ii) below are similar not only in composition, but in many other respects (refer to Section 6.4 for details). They are medium-grained, leucocratic, muscovite granites. However, it is now virtually certain that in spite of Phanerozoic ages the Laponiahalvoya granites are at least Neoproterozoic and by analogy also those further east. The following summarizes the isotopic age data, discussed in Section 6.4, for the Nordaustlandet granites. (i) The Laponianhalvoya granites show a variation in isotopic ages, with K - A r dating suggesting an age range of Mid-Silurian to Early Devonian (Krasil'shchikov et al. 1964). However, zircon ages from the Kontaktberget and Laponiafjellet granites gave ages of 939 • 8 and 961 + 17 Ma respectively (Gee et al. 1995). The Nordkapp granite has only one Rb-Sr date of 537 Ma (Hamilton & Sandford 1964), and its significance is open to interpretation. (ii) The Rijpfjorden-Rijpdalen granites also appear to show definite Silurian-Devonian ages (Krasil'shchikov et al. 1964), although Gee & Teben'kov (1996) suggest a 'Grenvillian' age based on a zircon date.

15.4.7

15.4.8

283

Feldspathic (augen) schists

Ny Friesland. Whereas many of the stratiform feldspathites exhibit feldspar augen textures, it is the Planetfjella Group schists that are especially noteworthy in this respect. This distinctive facies extends the entire length of Ny Friesland west of the Veteranen Line. Harland & Wilson (1956, p.275) described these Planetfjella schists with 'conspicuous pink feldspar augen set in a dark schistose matrix'. Bayly (1957, p.387) wrote 'the dominant textural feature is a lozenge-shaped feldspar clot, but this is usually not a true auge: that is to say, there is no central crystal which has forced an opening in the foliation and produced vacancies on either side of it'. The clots are homogenous aggregates. The other minerals evident are biotite, garnet, tourmaline, clinozoisite and occasional fluorite and allanite. Wallis (1966) described the stratigraphy and petrology of the group in more detail. The feldspathic lithology is best seen in the F1Aen Formation (the lower of the two in the group) divisions (4), (6), (7) and (8) contain the feldspar megacrysts. They were interpreted as derivatives of acid pyroclastics or arkoses but the exact genesis was not clear (Harland et al. 1966). The intense shearing is however consistent with the sinistral transpression structure of the whole of western Ny Friesland (Harland 1971) (see model in Fig. 15.4).

Stratiform feldspathites

Ny Friesland. It was primarily because of the puzzling nature of these granitoid rocks that the classification of feldspathites having >50% feldspar was applied (Wallis et al. 1968, 1969). The principal such unit occurs in the Harkerbreen Group as the Bangenhuk Formation, a granite gneiss in the north correlated with the original Camryggen gneiss in the south of western Ny Friesland (Bayly 1957; Harland, Wallis & Gayer 1966; Harland et al. 1992). Structurally this unit is exposed as a stratiform body at least 120 km N-S, up to 20 km E - W and up to 2 km thick. It occurs in a consistent sequental relationship to meta-strata above and below. Some margins show graded compositions with growth of feldspar phenoblasts in adjacent metasediments. In south Spitsbergen a thinner Bottfjellet band, stratigraphically a little higher than the Camryggen gneiss shows similar transitional margins. These characteristics led Harland et al. (1966) to account also for its typical granitic composition and occasional intrusive contacts by suggesting that it was formed as arkose or more likely as ignimbite sheets. Later tectogenesis would produce its spindle-shaped gneissose texture and thermal metamorphism, and would melt it locally so as to produce the intrusive effects. Others have argued that the rock body is a typical granite of magmatic origin in which case a sill or a laccolith may be envisaged. This opinion is strongly supported by the primary nature of the zircon crystals whose ages approximate 1750 Ma (Gee et al. 1992; Johansson et al. 1995; Chapter 12). The other two of the metasedimentary units into which the granite was supposed to have intruded turned out to be much younger so in these cases the granite was reinterpreted as basement, leaving one host formation which might be older (Gee 1996). Whatever the origin of the Bangenhuk granitoid it could not have been emplaced except tectonically within large nappes or thrust sheets. In any case intense Caledonian tectonism has modified its original nature, shearing it to spindle-form gneissose texture. The magmatic contacts could then be either relicts of its original nature or the effect of subsequent melting. Because of its remarkable nature the rock body has attracted considerable attention structurally, isotopically and geochemically. It retains through Ny Friesland a consistent stratigraphic position. There is no doubt about the mid-Silurian age of its deformation and metamorphism. However, the zircon studies of Johansson et al. (1995) made it certain that there was a late Paleoproterozoic magmatic origin or zircon component. The problem remains as to how this thin extended sheet would appear on a large scale map. A somewhat similar granitic feldspathite has been mapped in northernmost Ny Friesland at a lower level, introducing a new (Instrumentberget) unit at the base of the Harkerbreen Group (Johansson et al. 1995). The same considerations may apply.

15.4.9

Shear zones and mylonites

Ny Friesland. The upper (Vildadalen) formation of the Planetfjella Group is largely a chlorite-biotite sub-pelite and its (upper) Ros6nfjella Member, 1500m suffered intense two-phase deformation with minor folds in the hinges of earlier folds. The finegrained psammitic interlayers recrystallized as quartz lenses which are a distinctive feature of the pelitic facies of the Planetfjella Group (Wallis 1966). This facies, often with near-vertical N-S, foliation forms what Manby & Lyberis (1995) have referred to as the Eolusletta Shear Zone. Within it are mylonitic zones as noted by Manby (1990) Mylonites, concordant with the general foliation, are evident on the northwestern coast of Ny Friesland within the Harkerbreen Group as a 'zone of retrograde greenschist facies rocks, mylonites and related ductile-brittle shearing phenomena, indicating a long history of sinistral displacement in the Hecla Hoek parallel to the Billefjorden Fault Zone (Manby & Harland unpublished paper)' (Manby 1990, p. 132). At the southwest margin of Ny Friesland, where Hecla Hoek rocks adjoin the Billefjorden Fault Zone on land and overthrust the Devonian rocks to the west, is a 2-3 km wide chlorite zone (the Cambridgebreen Sheer Zone) almost certainly retrograded from Harkerbreen Group amphibolites. The brittle fracture in this zone indicates shear under a shallower overburden and is taken to represent much of the Devonian strike-slip component. This is a shear zone of mafic rather than feldspathic rocks and thus relates to the following subsection.

15.4.10

Mafites

Ny Friesland. In the tectonic environments of the Silurian orogeny amphibolites are the typical mafic facies. In Ny Friesland it had been concluded (Harland 1959; Harland, Wallis & Gayer 1966; Harland et al. 1992) that the basic layers which are common within the Harkerbreen Group, but not in the overlying Planetfjella Group, and rare in the underlying Smutsbreen Formation of the Finnlandveggen Group, were mainly contemporaneous or penecontemporaneous with the associated strata. The principal lithology is of amphibolite schists and gneiss. Excluded from this immediate discussion are some massive basites with preserved igneous (ophitic) texture. The opinion for a penecontemporaneous origin was that not only do amphibolites occur, most conspicuously as concordant black

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CHAPTER 15

layers within pale coloured quartzite, but that black bands only a few m m thick extend systematically over considerable distances. The boundaries are seen to be sometimes sharp and sometimes transitional. The interpretation is that basic volcanic activity was prevalent with both lava and pyroclastic eruptions. In such a volcanic environment some transgressive sills and feeder dykes might be expected. Indeed, some cross-cutting bodies are observed. Different viewpoints had also been expressed. Harland (1941) suggested lit-par-lit intrusions. Manby (1990) argued that the amphibolites were not contemporaneous nor penecontemporaneous but were later igneous bodies. These alternative ideas would need to be accommodated according to the evident extreme transpression in the stratification in which nearly all originally discordant structures would now appear to be concordant, and the thin bands would originally have been thicker. In the less extreme alteration, however, the competent amphibolite bands are commonly boudinaged within the quartz-rich strata, always extending N-S. The basic rocks with igneous texture range from quartz-dolerites to quartz augite macro-norites (Manby 1990) and some with primary biotite and hornblende and olivine hypersthene dolerites were reported (Gayer 1969). Manby (1990) gave detailed mineral and chemical details which confirm that they derived from basaltic rocks with marginal calc-alkaline to tholeiite compositions in a related magmatic suite which would be consistent with a variety of tectonic environments. The critical point for Silurian history is that if the mafic rocks formed only at one time it would have been in a contemporary Proterozoic episode. But if the intrusive basites were later that event could be Proterozoic or Paleozoic, and if the latter most probably connected with the Silurian Ny Friesland Orogeny. The model for such a Silurian event might be a temporary transtensional phase during the main orogenic compression rather than a reversal from compression to extension. A Proterozoic origin for most sheets is virtually certain. A Silurian origin for some bodies remains to be established.

15.5 15.5.1

Silurian terranes, provinces and palinspastics Grouping of terranes by province

The foregoing discussions are now reviewed according to the hypothetical model of allochthonous terranes in which those with affinities are grouped together as parts of four original provinces. These were provinces on the margins of Laurentia. Three were dismembered largely through Silurian displacements. The fourth (southern) Bjornoya Terrane was probably deformed east of the westward-verging North Greenland Caledonides and may have remained attached to Eastern North Greenland until severed from it by Paleogene dextral faulting to form part of the composite Svalbard terrane and indeed part of the Barents shelf at the northeast corner of Eurasia (Smith in press). The evidence for the original (provincial) relationship of the terranes belongs mainly to late Proterozoic and early Paleozoic stratigraphy and tectonics. The final juxtaposition or docking of the displaced terranes to form the composite terrane of most of Svalbard was completed in Devonian time. The Silurian story of tectogenesis is the reflection of the active displacement of these terranes following the closing of the Iapetus Ocean (mainly in Ordovician time); the initial collision tectonics was followed by large zones of transpression as some Svalbard terranes moved north with respect to Greenland. In turn transpression changed to transcurrence as the strike-slip component replaced the convergent motion between the newly consolidating Caledonides on the margins of a Barents Craton and Baltica. The terranes and their present bounding fault zones are listed below as introduced in Chapter 3. What is observed today in each terrane is a distinct tectonostratigraphic sequence and configuration through Neoproterozoic, Cambrian and Ordovician time, with Silurian (and later) tectogenesis superimposed.

The western terranes contrast with the others in that sedimentation reflects a mobile tectonic environment which persisted at least Vendian through Silurian time with a marked Early to midOrdovician (Eidembreen) tectonic episode. The Central and Eastern terranes were relatively stable until the Early Silurian Caledonian Orogeny, with stable sedimentary environments where sediments may be exceptionally preserved. Because of a possible confusion between the individual descriptive terranes, each in the singular, and their hypothetical grouping into Eastern, Central, Western and Bjornoya terranes the term province, as first used by Harland & Wright (1979), is employed to distinguish the palinspastic interpretation from the descriptive units. Thus, the eastern terranes: (a) i-vi below, are referred to as the Eastern Province and derived from the Central East Greenland Province.

(a) The Eastern Province of Svalbard. Much has been already made of the affinity of the east Svalbard pre-Devonian successions and those of Central East Greenland and it is taken here that these East Svalbard Terranes once formed part of the East Greenland Province.

(i) Nordaustlandet Eastern Terrane (NAET). Originally thought to be a Precambrian metamorphic terrane it was then reinterpreted as part of the Caledonian orogen in which the Precambrian metasedimentary strata and underlying migmatites would be the result of Silurian tectonothermal events. Isotopic ages now throw doubt on either model in its simple form. Late Precambrian values around 600 Ma and older zircons indicate earlier events of unknown age because later values ranging from 438 to 373 Ma indicate Llandovery through Mid-Devonian ages. In this terrane, the meta-sedimentary succession is relatively flat-lying implying that the Phanerozoic events were dominantly thermal rather than tectogenic. The later thermal influence was mainly Devonian. It is discussed in the next chapter as part of the 'Lomonosov conjecture'. NAET may be accepted, as long advocated by Russian geologists, as part of the Barents Craton (north of Iapetus) and the eastern foreland of the Ny Friesland Orogen. (ii) Nordaustlandet Western Terrane (NAWT). This terrane west of Rijpfjorden is better known and has a distinct Precambrian Hecla Hoek stratal succession with magmatic events around 970 Ma from zircons but also with Silurian-Devonian ages. The latter are related to the Ny Friesland (Caledonian) orogeny which folded the strata in a broad southwardplunging anticline with axes on the Laponianhalvoya granites. Further west in the Murchisonfjorden region the Neoproterozoic strata (which young westwards) are steeply folded on N-S axes forming the eastern limb of the Hinlopenstretet Synclinorium. No major fault or shear zone has been established separating these terranes within Nordaustlandet or in Hinlopenstretet even though the whole area is traversed by faults. NAWT is thus a continuation of NFET. (iii) Ny Friesland Eastern Terrane (NFET). This terrane constitutes the western limb of the Hinlopenstretet Synclinorium exposing the youngest Hecla Hoek strata (Llanvirn) on the eastern coastline and the oldest of the middle Hecla Hoek Veteranen strata at the Veteranen Line on the west. The strata are penetrated by three late tectonic batholiths with (limited) age data spanning the Silurian-Devonian boundary. The strata are strongly deformed in upright folds and with pinched synclines of low competence (Vendian) strata to the east all with N-S axes and with a regional dip to the east. The folding, defining the Ny Friesland orogeny, is demonstrably postLlanvirn and pre-Devonian, presumed to be mainly Silurian. Metamorphism to chlorite grade is evident in the north especially within the Vendian pelites, whereas most strata are competent carbonates, quartzites or psammites and the style indicates a deep fold structure. The only evidence for N-S stretching evident in the east might be the emplacement of the batholiths. (iv) Ny Friesland Western Terrane (NFWT). West of the Veteranen Line and the east of the Billefjorden Fault Zone is the Lower Hecla Hoek complex (Stubendorffbreen Supergroup) of three groups of rocks, all intensely metamorphosed. The tectogenesis is all clearly part of the same Ny Friesland Orogeny. Thanks to the metamorphism the age of the principal tectonothermal events was reported in 1966 spanning the Silurian Period and then, with more sophisticated determinations, was reported in 1994 (Gee & Page) as mid-Silurian. The data all confirm that this Ny Friesland orogeny was a major Silurian (Caledonian) event.

SILURIAN HISTORY The highly tectonized western Ny Friesland structure exhibits westward verging, recumbent folding that was sheared sinistrally with N S lineation and extension along the fold axes. Deformation phases may be recognized with isoclinal shear folds and boudinage marking N-S extension superimposed on E-W nappe extension in a continuous transition from compression through transpression. In earlier terminology b-lineation follows a-lineation. WittNilsson et al. (1997) estimated a 200% E W shortening. This would be a minimum value. There was little or no migmatization, even in the rocks which were stratigraphically 18 km down. Folding thickened the sial in spite of syntectonic erosion. The Veteranen Line marks the eastern boundary of a shear zone that approximates to the boundary between the Kortfjellet and Vildadalen formations at the top of the succession in west Ny Friesland. This was probably active during Silurian time within the steeply dipping Planetfjella Group strata to move the Ny Friesland Western Terrane at say 50 to 100 km north with respect to the adjacent Eastern Terrane. The Billefjorden Fault Zone separates the Lower Hecla Hoek rocks from the Devonian strata to the west. As a fundamental fault with a long history, its Silurian sinistral transpression extended through the Ny Friesland Western Terrane but was concentrated near the fault zone as seen by mylonite zones as well as extreme elongation in the neighbouring rocks. The 2-3 km Cambridgebreen Shear Zone, east of the fault of chloritic rocks with some brittle fracture was sheared under greatly reduced load and this was probably mainly during Devonian time. (vi) South Eastern Svalbard Terrane (SEST). Older rocks, as found in North Eastern Svalbard, must underlie the platform cover in southeastern Svalbard and can only be known directly by deep drilling. Two wells in Edgeoya do not penetrate the basement. (b) The Central Province of Svalbard originated in a province comprising basins extending from N o r t h East G r e e n l a n d . The terranes are m o s t obviously distinguished from b o t h eastern terranes by the presence of D e v o n i a n a n d possibly latest Silurian strata. They also include fossiliferous Early C a m b r i a n a n d Early Ordovician c a r b o n a t e strata with different faunas f r o m those of the Eastern Province. T o g e t h e r with the Late Proterozoic rocks they were subjected to Silurian t e c t o n o - t h e r m a l o r o g e n y as part of the East G r e e n l a n d Caledonides. (i) The Andr& Land-Dickson Land Terrane (ADLT) is bounded to the east by the Billefjorden Fault Zone and in the west by the Breibogen Fault Zone. It is entirely covered by the Early to Mid-Devonian Andr& Land Group so that no Silurian events can be detected at the surface. (ii) The Biskayerfonna-Holtedahlfonna Terrane (BHFT) comprises the Precambrian Horst and the Old Red Sandstone Graben and is bounded on the east by the Breibogen Fault Zone and on the west by the Raudfjorden Fault Zone. These N-S faults and the intervening Hannabreen Fault appear to have been sinistrally active from late Silurian through early Devonian time generating conglomerates from their moving fault scarps. How much of the Siktefjellet Group's history is Silurian is not known. But it is likely that these major fault zones became established before Devonian time. This sedimentary story, a response to tectonics, is treated in the next chapter. Within the BHFT is a belt of pre-Devonian and Silurian metamorphosed Proterozoic rocks, i.e. the Krossfjorden Group. (iii) The Western Northwest Terrane of Spitsbergen (WNWT) comprises metamorphosed Precambrian strata bounded on the east by the Raudfjorden Fault Zone and on the southwest by the Kongsfjorden (Hansbreen) Fault Zone and to the southeast by a cover of younger strata. This may be regarded as a simple orthotectonic (Silurian) Caledonian structure. It is constrained in age by Early Devonian sediments resting unconformably on top of a sequence comprising three Precambrian formations in the Krossfjorden Group all folded, the lower strata being altered to layered gneiss. These rocks were then subject to migmatic invasion and melting (the Smeerenburgian Event) which in part resulted in grey foliated granite. A last event was the diapiric emplacement of the Hornemantoppen Batholith, cooling ages of which are latest Silurian to Devonian. Many early determinations of the metamorphic and igneous ages have been recorded with a spread from Late Ordovician through early Devonian with a concentration of Silurian ages. (iv) The Middle Hornsund Terrane (MHDT) in Wedel Jarlsberg Land and Sorkapp Land is bounded to the west by the (Kongsfjorden) Hansbreen Fault Zone and to the north and east by cover of later strata. The age of deformation is certainly post-Canadian and pre-Mississippian and so would be consistent with a Silurian orogeny.

285

To the east of Hornsund High is the southward continuation of the Fold and Thrust Belt of the Paleogene West Spitsbergen Orogen which, with similar vergence, deforms Early Devonian through Early Paleogene strata. There is some question (e.g. Dallmann et al. 1993 in C13G) as to whether the Arkfjellet strata are Early or Late Ordovician. If the latter then a Silurian tectonic episode is necessary. If not then the main Silurian tectonism is just not so well constrained. The Devonian strata define the later limit of the Silurian age of deformation in the zone between the two subterranes described above.

(c) The Western Province of Svalbard originated outside the Caledonides, being n o r t h o f N o r t h G r e e n l a n d and having affinities with both the N o r t h G r e e n l a n d F o l d Belt a n d P e a r y a o f n o r t h e r n Ellesmere Island. Because of similarities with Peary L a n d in N o r t h G r e e n l a n d and especially with Trettin's P e a r y a in Ellesmere Island it is n a m e d the North Greenland Pearya Province. The allochthonous terranes (Svalbard western terranes a n d Pearya) m a y have d o c k e d before or in early Silurian time having been involved in the earlier M ' C l i n t o c k O r o g e n y and then a b o u t to be subjected to D e v o n i a n Ellesmerian diastrophism. Indeed, this collection of terranes m a y have been within the same general province at least t h r o u g h o u t Paleozoic time. The Silurian story (of w h i c h little is r e c o r d e d f r o m Svalbard) is one of sedimentation within a tectonically unstable e n v i r o n m e n t . S o u t h of the N o r t h G r e e n l a n d F o l d Belt is a large terrane of Silurian strata deposited on the G r e e n l a n d c r a t o n a n d deriving m a i n l y from the e r o d i n g C a l e d o n i a n O r o g e n to the east. These western terranes, with a smaller o u t c r o p area than the central or eastern terranes, b o r d e r the west coast o f Spitsbergen f r o m K o n g s f j o r d e n to H o r n s u n d and include Prins Karls F o r l a n d . T h e y are b o u n d e d on the east by the postulated K o n g s f j o r d e n H a n s b r e e n F a u l t Z o n e that w o u l d be mostly obscured by postD e v o n i a n strata, ice or water. The later strata have been folded and thrust eastwards over m u c h of the trace o f the p o s t u l a t e d fault. The constituent terranes o f this Western Province are not so clearly distinguished except geographically. The p r e - C a r b o n i f e r o u s o u t c r o p s are largely V e n d i a n with p r e - V e n d i a n p r o t o - b a s e m e n t . H o w e v e r two areas o f p o s t - D e v o n i a n strata include fossiliferous Late Ordovician to Silurian sediments and other p r o b a b l y Silurian sediments. A l t h o u g h sedimentation reflects an unstable environm e n t its preservation indicates a lack of local orogenic activity, p r o b a b l y t h r o u g h o u t Silurian time in contrast to the intense tectonism of the Central a n d Eastern provinces and a n a l o g o u s to that o f the N o r t h G r e e n l a n d Silurian sedimentary response (Hurst e t al. 1983). Such tectonism, as m a y be distinguished from the Paleogene West Spitsbergen Orogeny, could be m i d - O r d o v i c i a n a n d / o r D e v o n i a n . Ordovician strata are k n o w n in both western Svalbard a n d N o r t h G r e e n l a n d , D e v o n i a n strata in neither. (i) Prins Karls Forland. Separated from Spitsbergen by the Forlandsundet Graben, the sequence passes from Late Varanger tillites through fossiliferous Late Vendian strata which pass up into the turbidite and quartzite Barents Formation (in the Grampian Group) with the Sutorfjella contemporaneous slumped conglomerate that could be Silurian by lithological correlation with the Holmsletfjella Formation in Oscar II Land. (ii) Oscar II Land between Kongsfjorden and Isfjorden. This terrane contains the only Silurian fossils yet recorded in Svalbard. Slumped shelf coral limestones overlie Ordovician strata and are followed by turbidites indicating a mobile Silurian depositional environment. This succeeds an early to mid-Ordovician tectonic phase evident in both Prins Karls Forland and Oscar II Land. Away from this constraining evidence, where two phases of Pre-Carboniferous deformation may be determined, it is difficult to distinguish Ordovician from any Late Silurian or Devonian diastrophism and often even from the ubiquitous Paleogene deformation. (iii) Nordenskiiildkysten between Isfjorden and Bellsund. There is local conformity in which Carboniferous rocks cover Vendian strata. It would seem that the metamorphism and more intense deformation would be Early Paleozoic and the evident faults and thrusts and outcrop patterns would be later. Silurian structure remains to be established. (iv) Northwestern Wedel Jarlsberg Land Terrane between Bellsund and Torellbreen, and west of the Recherchefjorden and Recherchebreen presumed

286

CHAPTER 15

fault, the entire succession is Vendian and pre-Vendian. The next youngest strata within the terrane are Late Eocene to Oligocene so that the evident post-Vendian deformation structure could be Paleozoic and/or early Paleogene except east of Recherchefjorden where they are seen to be preCarboniferous. The structures both east and west of Recherchefjorden were described by Craddock et al. (1985). Two pre-Carboniferous folding phases were determined. (i) Small isoclinal folds, sub-horizontal with axial planar foliation, ridge-groove lineation in foliation, and large recumbent folds were interpreted as strong NNW-SSE shortening with NNW transport. (ii) Later tight to isoclinal folds, axial planar foliation and younger folds, foliation, kink bands and crenulations were interpreted as NE-SE shortening and NE vergence. Although it is clear that these deformation effects are more severe than the later Paleogene structures a variety of attitudes were reported, but their localities were not always mentioned. It is only possible to be sure of a pre-Carboniferous age east of Recherchefjorden (in the Central Province) so that the strong phase (ii) NE vergence would belong to the Central Terranes and match the easterly vergence in middle Hornsund, probably Silurian. The phase (i) with strong NNW vergence of Craddock et al. could be Ordovician, especially if the data derived from west of Recherchefjorden. E.C. Hauser's unpublished K-Ar age determinations were quoted by Ohta (1992) whose map indicated a position of samples probably from the (Early Varanger) Chamberlindalen Formation or near to it. Values from biotite were 337, 347 and 358 Ma and from whole-rock 407 and 358 Ma and from whole-rock 407, 462, 472 and 48 l Ma. The younger values indicate a Carboniferous age and the older ones span Silurian and most of Ordovician time. This would appear to rule out the Paleogene Orogeny as the main tectonothermal event. The title of an abstract by Hauser (1991) reads 'Early Paleozoic deformation of a late Precambrian sequence in West Spitsbergen: a possible link between Svalbard, North Greenland and the Pearya orogen'. This may suggest that the mid-Ordovician ages were regarded as the most reliable (462 481Ma). (v) Southwestern Wedel Jarlsberg Land and Western Sorkapp Land south of Torellbreen. In western S~rkapp Land, west of the projection of the Hansbreen Fault Carboniferous and Triassic rocks constitute the main outcrop covering highly metamorphosed Proterozoic strata of uncertain affinity. This terrane escaped major Paleogene deformation except for some bedding thrusts in the younger strata. The Wedel Jarlsberg Land outcrops to the north of Hornsund and west of Hansbreen while their succession and age are much disputed, but nevertheless agreed by all to be Precambrian. The evident deformation of the rocks may be a product of Paleozoic and/or Cenozoic tectonism. However, combining the reports by Craddock et al. (1985) and Hauser's data in Ohta (1992), the preference would be for Ordovician rather than Silurian tectonism. It is concluded here that there is no evidence in the Western Terranes for Silurian tectonism, the lack of which would fit their position west of the Caledonian front.

(d) The Bjarnaya Terrane. Only one outcrop area of pre-Silurian strata is available. Bjornoya with its neighbouring submarine rocks is a distinct terrane separated from the main archipelago. Its nearest affinity may be with eastern North Greenland and possibly north of the Central Svalbard Province. The affinity of conodonts from the Antarcticfjellet Formation of Bjornoya with those in the coeval Caradocian (Black River) formation of kronprins Christian Land of easternmost north Greenland suggest an attachment of the two areas (Armstrong & Smith in press). Moreover, the Caradoc age of the strata noted by Holtedahl and confirmed by Smith is later than that of the Canadian strata of the Central and Eastern Province of Spitsbergen. Bjornoya might therefore have occupied a position north of the Central Province and towards the northern end of the East Greenland Caledonides. Late Proterozoic and Early to Mid-Ordovician carbonate strata show no evidence of contemporary tectonism which contrasts with the western Svalbard terranes. The structures show westward thrusting of the competent beds and more intense folding and

thrusting of the incompetent (Vendian) slates. The structures are covered unconformably by latest Devonian continental clastics. Thus the deformation can be constrained only as post-early Caradoc (Late Ordovician) and pre-latest Devonian and so is consistent with the main Caledonian events of the Eastern and Central terranes and with a presumption that the main tectogenesis was Silurian; but Late Ordovician and Late Devonian (Svalbardian) components cannot be ruled out.

15.5.2

Silurian fault and shear motions

Having considered the characteristics of the many Svalbard terranes outlined above, and their postulated original locations in the Greenland and Canadian provinces, it remains to be considered how the three Spitsbergen Provinces travelled to dock in latest Devonian time to form the single composite terrane of Svalbard that has remained largely intact from its Carboniferous to Cretaceous location north of Greenland and its Cenozoic translation to the present configuration. For the present purpose the Silurian displacements need to be identified. Starting from their Early Ordovician position in the three Greenland provinces it has been argued that the Iapetus Ocean was closing during Ordovician time, not least from the evidence of converging faunas (McKerrow & Cocks 1976) which suggests that the main sinistral strike-slip motion necessary to achieve the composite terrane had not then begun. The main Silurian Caledonian Orogeny appears to have begun with the final closure of Iapetus. The collisional tectonic phase causing folding, nappe formation, thrusting along the eastern margin of Greenland was recorded in the structures of the Eastern and Central terranes of Svalbard and the thrust structures of Baltica. The motions between Laurentia and Barentsia plus Baltica, having exhausted a compressive phase, began to move sinistrally with oblique compression (i.e. transpression). The Eastern Svalbard Province had the greatest distance to travel (say 1000 to 1200km) and the transpressive structures are most evident in western Ny Friesland. Perhaps 50 to a maximum of 100 km sinistral displacement was effected within the two or three km of strata just west of the Veteranen Line. Possibly a further 200km was distributed within the main body of the rock, and possibly another 100 or 200km was effected in shear and mylonite zones east of the Billefjorden Fault (see Fig. 16.10). Already in Late Silurian time the main transpressive motions were transforming to simple strike-slip transcurrent displacement which uses less energy. Thus the second part of the 1000-1200 km travel was more likely by transcurrent faulting. East of the main Billefjorden Fault is the N-S Cambridgebreen Shear Zone, 2-3 km wide, of chlorite schists retrograded from amphibolite. This is evidence of a substantial shear under a much reduced tectonic overburden. Arguments from Devonian sedimentation suggest that not less than 200km of sinistral motion was likely along the Billefjorden Fault Zone and probably more. So that, for example, if 300 km strike-slip were displaced along this fault zone, most of it in Late Devonian time, some might have begun in Silurian and continued through Mid-Devonian time. On the other hand the Central Province had a much shorter distance to travel before docking north of Greenland. There is evidence of strike-slip within the central terranes in the north (as in the Breibogen and Raudfjorden faults) and at the western margin as at Hansbreen. Therefore a component of say 1000-1200kin transport for the Eastern Province may have been taken up within and beside the Central Province. Moreover, there is evidence of some sinistral transpression and strike-slip in the Western Province at the margins of the Forlandsundet Graben. This argument is resumed and completed at the end of the Devonian story (Chapter 16) with a conceivable plot of the net contribution of each transpression and fault zone at different times to achieve a final docking from the initial positions within the

SILURIAN HISTORY

TKF, was said to have come from near west Spitsbergen in spite of major stratigraphic differences, when west Spitsbergen affinities relate to Pearya. On the other hand the East Spitsbergen Terranes, with marked similarities to Central East Greenland, were apparently always north of the TKF system.

~,Melville>"~'~ Pearya /

~,~(and Bat~h~uFst~R)' gnes~

~-~, x ~

Western

Svalbard Terranes

15.5.3 ENGP

~/~; ~j I

e,~\

Central Svalbard

II Terranes

EG

_42,,

o o GP

I

Eastern

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Svalbard Terranes

T I A,e25 "-~/

/

i//I// //////

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287

/~ Fold vergence

/

Fig. 15.7. Schematic illustration of terranes surrounding Greenland at approximately the beginning of Silurian time, with the closure of the Iapetus Ocean. The four provinces relating to Svalbard terraces are indicated by the dashed circles: EGP, East Greenland Province; NEGP, Northeast Greenland Province; ENGP, Eastern North Greenland Province; and NGPP, North Greenland Pearya Province with Western Svalbard Terranes. Small arrows indicate approximate directions of Silurian tectonic vergence. The Caledonian front is defined in a broad sense. Parts of Norway and Scotland are included only to show schematically their approximate relative positions. A more precise palinspastic map would require further research than was available for this project.

Greenland provinces. The equation is necessarily speculative and with very many options; but each should somehow add up to a total of say 1000-1500 km. A qualitative diagram to indicate the relative positions of the terranes through Silurian time is shown in Fig. 15.7. In conclusion, it would greatly weaken the case for major sinistral strike-slip components in Svalbard if such displacements were not recognized in the projected zones to the south. Indeed Svalbard may have led somewhat in this respect. However, quite independent evidence has appeared for such sinistral motions in Greenland, Scotland and Newfoundland at least. One of many is the paper 'Sinistral transpression and the Silurian closure of Iapetus' (Soper et al. 1992). Holdsworth & Strachan (1991) concluded similarly for Northeast Greenland. The Trollfjord-Komagelv Fault in Finnmark (Johnson, Levell & Siedlecki 1978) was said to have dextral motion on palaeomagnetic evidence Max & Ohta (1988), by inspection of mapped fault lines in northern Norway and offshore western Spitsbergen in particular, argued that Cenozoic faulting was controlled by basement faults, some possibly going back to Precambrian time. The thrust of their thesis is that the TrollfjordenKomagelv Fault (TKF) in Finnmark and some faults in southwest Spitsbergen were segments of the same system which parallels some Cenozoic faults. However, they noted that the early movement was sinistral in Spitsbergen and dextral in Norway. Little or no evidence was provided or cited as to the age of the critical early movements, and evidence as to stratigraphic affinity was ignored so that the Barents Sea Group, north of the

Baltica, Barentsia and lapetus

A major consequence of the strike-slip hypothesis developed in this work is that Baltica moved north at least as much as the East Svalbard Province with respect to Greenland. Indeed northern Norway on this hypothesis could have been opposite southern East Greenland when Iapetus closed between them, whereas the East Svalbard Province was already adjacent to central or northern East Greenland and on the same side of Iapetus. Therefore the collisional histories of the two segments of the orogen would be different. A similar situation may apply as between the Central Svalbard Province and Northeast Greenland. The southern segment of the Caledonian orogen would result from collision between opposing lithosphere plates with the development of the great thrust sheets in the Scandinavian Caledonides. Barker & Gayer (1985) offered a Scandinavian perspective of the same event. The northern segment, involving eastern and central Svalbard terranes exhibits less extensive nappe transport. The folding, with minor thrusting resulted from the compression of Barentsia against Greenland. Barentsia is a postulated extension of Laurentia situated to the east of Ny Friesland and exposed in eastern Nordaustlandet. Russian geologists have long regarded this as a continental foreland. Harland & Gayer (1972) introducing the name Iapetus and delineating its approximate suture, suggested that the Hecla H o e k geosyncline developed between Greenland and the Barents Craton in a Proto-Iapetus trough or basin. This might be regarded as an offshoot of Iapetus, i.e an aulacogen which never became an ocean. It preceded the opening of Iapetus by about 400 My and developed on a gently subsiding (?thin) continental basement on a cooling mantle (Harland 1969) (Fig. 15.8).

Late

A

(a)

Ordovician - Early Silurian (c. 440 Ma) Glaciogenic deposits

(b)

Mid-Silurian (c. 425 Ma)

SOUTHCHINA

~LAURENT\I

~

GONDWANA /

Fig. 15.8. (a) Late Ordovician to Early Silurian global palinspastic reconstruction, with glacigenic deposits indicated by black triangles. (b) (A Mid-Silurian palinspastic reconstruction (adapted from Torsvik et al. 1996 with permission of Elsevier Science, Amsterdam.).

288

CHAPTER 15

Gee (1989) and Gee, Johansson et al. (1995) have emphasized the abundance of zircon ages in Svalbard approximating 950 Ma as Grenvillian and that the Grenvillian Orogen might have caused the opening of the Iapetus Ocean, in spite of a delay of 400 million years. On the other hand the Proto-Iapetus trough might well have been a more immediate response. This idea might be supported by the beginning of the post-Harkerbreen, post-Brennevinsfjorden successions with magmatism and volcanism around 950-900 Ma in the Planetfjella Group. This is speculative, but not unlikely because further south along the margin of Greenland there are the Moinian, Dalradian and Torridonian sequences of Laurentian Scotland. Indeed, a major part of the Caledonian Orogen is Precambrian, i.e. mostly pre-Iapetus.

15.6

Sequence of Silurian (main Caledonian) events

The very limited control of Silurian history from Svalbard stratigraphy corresponds to the Caledonian orogenic events that are recorded in the older rocks throughout the Central, Eastern, and Bjornoya Provinces. The only sure Silurian strata belong to the Western Svalbard Province which north of Greenland was well to the west of the Caledonian front. This North Greenland Pearya Province had already undergone Early to Mid-Ordovician tectogenesis. North Greenland, however, preserves the debris transported westwards from the Caledonian Orogen and the sediments are latest Ordovician and Early Silurian turbidites. The eroding nappes advanced over the Ordovician carbonates. These events appear to predate the main Caledonian thrusting of Scandinavia and the East Greenland Caledonides (Hurst et al. 1983). Away from this region, west of the Caledonides and including the Western Svalbard Province there is a biostratigraphic hiatus from about Llanvirn through probably latest Silurian time. That is a maximum of 15-20 million years of Late Ordovician time and about 25-30 million years of Silurian time, probably about 40 million years. The closing of the Iapetus Ocean, generally taken as an Ordovician process partly because of convergence of faunas was not so clearly documented as shown by Zalasiewics, Rushton & Owen (1995) who argued that environmental changes, not least from the late Ordovician ice age, may have influenced the faunas more than the increasing proximity of Laurasia and Baltica. The following model, while poorly constrained, is at least consistent with the above and other known data. (1) During Ordovician time the Iapetus Ocean was closing. (2) Uplift from collision of Barentsia and Baltica and Laurentia (with most of the Svalbard terranes) may have begun in later Ordovician time and possibly earliest in North Greenland. This is consistent with the lack of Late Ordovician deposits in the Eastern or Central Provinces of Spitsbergen and in East Greenland.

(3) The main Silurian collision generated westward-vergent recumbent folds, nappes and thrust sheets in East Greenland and in eastern Svalbard. Some boudinage developed in the extending recumbent limbs (a lineation). From Scandinavian evidence Baltica may have underthrust Laurentia (Gayer 1989) with evident eastern vergence in Norway. (4) In the Central Svalbard Province the compressive vergence was probably eastward. In inner Hornsund the thrusting verges E and south of Bellsund NE as also in northwest Spitsbergen. (5) The convergent regime between Baltica and Laurentia (with Barentsia) transformed slowly into the oblique compression which is so well exemplified in the (type) transpressive structures of western Ny Friesland. The result was a sinistral shearing of the early compressive structures leading to N-S elongation. This interpretation replaced (Harland 1971) the more symmetrical indentor model of Harland & Bayly (1958) and Harland (1959). Boudinage, mineral lineation and N-S extension of psephite stones mark this stage (b-lineation). The rocks now exposing these structures were at a depth of about 20 km deforming a pile with a stratal overburden of about 12 km. The metamorphic climax was mid-Silurian. (6) Oblique motion changed from transpression with a dominant compressive component to one with a dominant strike-slip component so developing the marked shear and mylonite zones in western Ny Friesland. The sinistral shear was not so marked in Nordaustlandet to the east nor indeed in eastern Ny Friesland. Thus, in the Eastern Province transpressive deformation was concentrated in western Ny Friesland. East of the Veteranen Line there was compression with little noticeable shear, so forming relatively open upright folds. In northwest Svalbard, in the terrane that travelled a much shorter distance than the Eastern Province, sinistral shear is nevertheless evident both in deformation structures and in the en 6chelon granite lenses within metasediments of the Kongsfjorden Group. However, the last resulting shear at increasing depth may have generated localised granitic magmas. In any case the shear stresses transmitted across the Veteranen Line may have opened the way for diapiric intrusion of the Ny Friesland batholiths. No analogy need be sought for the batholiths of Nordaustlandet which appear to have originated in Proterozoic time. On the other hand the Hornemantoppen Batholith in the northwest formed in a demonstrable, yet modest, sinistral regime allowing for local pull-apart intrusion. (7) In the final Silurian episode strike-slip (transcurrent) displacement was probably focused in relatively distinct fault zones (see Fig. 15.4). (8) Transcurrence continued into Devonian time with rapid erosion of the orogen and resulting in shear structures with brittle fracture. The batholiths, emplaced at about the Silurian-Devonian boundary, continued to cool in Devonian time. In Gondwanaland global perspective, the Cambro-Ordovician assembly of Unrug (1996) set the starting point for the SilurianDevonian translation of Svalbard's fragments to their Pangea resting place.

Chapter 16 Devonian history W. B R I A N 16.1 16.1.1 16.1.2 16.1.3 16.2 16.3 16.3.1 16.3.2 16.3.3 16.3.4 16.4 16.4.1 16.4.2 16.4.3 16.4.4 16.5 16.5.1 16.5.2 16.5.3 16.5.4 16.5.5

HARLAND 16.5.6 16.5.7 16.5.8 16.6

Devonian time scale and correlation, 289 International time scale, 289 Biostratigraphic correlation, 289 Devonian Isotopic ages (c. 410-360Ma), 291 Devonian succession, 291 Devonian biotas, 291 Fossil fish, 291 The record of fossil fish in Svalbard, 292 Devonian invertebrates of Svalbard, 293 Devonian plants of Svalbard, 294 ?Silurian and Devonian sedimentation, 296 Siktefjellet and Red Bay groups sedimentation (Friend et al. 1997), 296 Wood Bay Formation sedimentation (Pragian and Emsian) Late Early Devonian, 298 Mid-Devonian sedimentation, 299 Late Devonian-Famennian sedimentation, 299 Devonian tectonics, 299 Albert I Land High, 299 Mitrahalvoya, 300 Blomstrandhalvoya-Lov6noyane Basin, 300 Raudfjorden Fault (RFF), 300 Biskayerfonna-Holtedahlfonna Terrane, 300

16.6.t 16.6.2 16.6.3 16.6.4 16.6.5 16.6.6 16.6.7 16.7 16.7.1 16.7.2 16.7.3 16.7.4 16.7.5 16.7.6 16.7.7 16.7.8 16.7.9 16.8

Svalbard is part of the Old Red Sandstone province with affinities in East Greenland, Norway, Appalachian N o r t h America and, of course, the British Isles where the Devonian Period was defined. This allows Devonian history in this region, controlled by Caledonian events, to form a neat and natural chapter, though not necessarily a global one. Old Red Sandstone environments in each area were already becoming established in Late Silurian time. Olaf Holtedahl was the prime author of both Caledonian tectogenesis in Svalbard and the Old Red Sandstone aftermath. Of the many and varied biotas of Svalbard the fossil fish have made remarkable and classic contributions to Spitsbergen geology. The earliest 'Old Red Sandstone' Spitsbergen strata have yet to yield evidence of age and so may be latest Silurian (Siktefjellet Group). But the earliest Devonian strata to be identified biostratigraphically begin with the Red Bay Group. Similarly the (major) Ny Friesland Orogeny and the various late orogenic granite emplacements, while initially Silurian, continued at least to cool in Devonian time. For convenience the orogenic events that may

continue as early Devonian are treated in the Silurian chapter and the sedimentary events that may be Silurian are treated here. Devonian successions in Svalbard are known only from terranes which are postulated to have originated from the North East Greenland Province. No record has yet been established for Devonian strata in Svalbard either from the eastern terranes (East Greenland Province) or from the western terranes (North Greenland-Pearya Province). Moreover, the East Greenland succession lacks Svalbard's Early Devonian record. The main Devonian outcrop is confined to what has commonly been referred to as a graben or half graben because of its sharp eastern boundary against the N y Friesland Orogen (Fig. 16.1). It is argued later that the sedimentary basin extended further to the east and that the Ny Friesland orogen only became juxtaposed in Late Devonian time by strike-slip rather than being in the present relationship but beneath the basin.

16.1

Table 16.1. Divisions of the Devonian with ages (Ma) from (1) Harland et al. 1990) and (2) Tucker & McKerrow (1995) Epoch

Stage

(1)

(2)

Tournaisian 363 Famennian Late Devonian

367 Frasnian 377 Givetian

Mid Devonian

381 Eifelian 386

391

390

400

396

412

4O9

417

Emsian Early Devonian

Pragian (Siegenian) Lochkovian (Gedinnian)

Breibogen Fault (BBF), 301 Andr6e Land-Dickson Land Terrane, 301 Billefjorden Fault Zone (BFZ), 301 The question of sinistral Paleozoie strike-slip faulting, transpression and transtension, 303 A controversial hypothesis, 303 Billefjorden Fault Zone (BFZ), 303 Postulated Kongsfjorden-Hansbreen Fault Zone (KHFZ), 305 Fault zones in northwest Spitsbergen, 305 Other Fault zones within Svalbard, 305 Ellesmere Island and North Greenland, 306 Some of geotectonic conclusions, 306 Sequence of events through Devonian time, 306 Latest Silurian-Early Devonian events (i.e. pre-Lochkovian), 306 Haakonian faulting and sedimentation, 307 Lochkovian (Red Bay Group) sedimentation, 308 Postulated Late Lochkovian to Early Pragian movements, 308 Pragian to Emsian, i.e. mid- to late Early Devonian, 308 Eifelian-Givetian (mid-Devonian), 308 Mimer Valley Phase (early Svalbardian), 309 Frasnian-Famennian (Late Devonian) events, 309 Late Famennian events, 309 A Lomonosov conjecture, 309

16.1.1

Devonian time scale and correlation International time scale

The international divisions shown in Table 16.1 are used with approximate ages (Harland et al. 1990) and as updated by Tucker & McKerrow (1995). The divisions are based on marine faunas: ammonoids and graptolites and (recently and more precisely) conodonts for correlation purposes both within Svalbard and in international correlation, especially within the standard Anglo-Welsh Borderland sequence. These index fossils are unsuited to non-marine facies of Old Red Sandstone type and so a major Devonian biostratigraphic preoccupation has been to correlate the standard marine zonation with the vertebrate (fish) faunas. In this the Spitsbergen contribution has been outstanding. At the same time advances in palynology have provided a new lever especially in later Devonian floras.

16.1.2

Biostratigraphic correlation

Early Devonian correlation. Perhaps the most authoritative account of Early Devonian biostratigraphy in Svalbard was by

290

CHAPTER 16 /12 ~

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312

CHAPTER 17

Gee et al.

1953 F o r b e s et al. 1 9 5 8 Upper

Nathorst 1910

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Middle

PRODUCTUSFOHRENDE KIESELGESTEINE

BRACHIOPOD CHERTS

Lower

KAPP STAROSTIN FM

Svenskeega Mbr

D a l l m a n n et a / . 1 9 9 6 adopted here

Z

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3 members in central Spitsbergen

KAPP STAROSTIN FM

V~ringen Mbr

Limestone A

SPIRIFERENKALK

SKS

Cutbill & C h a l l i n o r 1 9 6 5

I--

UPPER GYPSIFEROUSSERIES Limestone B

gesteine

Brucebyen Beds

Lower

CYATHOPHYLLUMKALK

Black Crag

(.9 CO

~,o

~CO

....... Black Crag

Cadellfjellet Mbr

Passage Beds

Z I.IJ

UNTERER GIPSSTUFE

Tyrrellqellet Mbr

{

Tyrrellfjellet Mbr LL

Mid

_i Pyramiden 1 C~176 I LOWER GYPSIFEROUS SERIES

I

~)

GIPSHUKEN FM

Finlayfjellet Beds

"Limestone B"

Upper WORDIEKAMMEN LIMESTONES

Fusuline

2 members in central Spitsbergen

GIPSHUKEN FM

Pyramiden Beds Minkinf]ellet Mbr

z LU LU n"

~0 n"

q

z

O z iJ.l n, O z

WORDIE- DICKSON LAND KAMMEN SUBGROUP FM

Brucebyen Beds

Cadellf]ellet Mbr tu a Black Crag beds o9 13MINKINFJELLET FM 3 members

i.' Carronelva Beds

CAMPBELLRYGGEN SUBGROUP

EBBADALEN FM 3 members

EBBADALEN FM i

KULM SANDSTEIN

BILLEFJORDEN SANDSTON ES

Hultberget Mbr Sporehogda Mbr Hoelbreen Mbr Triungen Mbr

SVENBREEN FM H~RBYEBREEN FM

HULBERGET FM .B.Birger,Johnson.f]ellet Mbr MUMIEN FM bporenogaa M~r HoelbreenMbr HORBYEBREEN -~CO Triungen Mbr ~ FM ~ 3I

Fig. 17.2. Chart illustrating successive classifications of rock units in Spitsbergen.

Kulling (Nordaustlandet); Stensi6, Hoel & Lyutkevich (central Spitsbergen); Nathorst, Holtedahl, Hoel & Orvin (western Spitsbergen). Freebold (1936, 1937) investigated the rich Permian brachiopod fauna. M u c h of this work was summarized by Orvin (1940). Since 1940, Norwegian, British, Soviet, Polish and German groups have contributed to geological knowledge: There was a resurgence of Norwegian work in the late eighties and nineties; e.g. by Stemmerik & Worsley (1989, 1995). Perhaps most significantly the rationalization of Carboniferous and Permian stratigraphic units was completed by SKS (Dallmann et al. 1996). The Norsk Polarinstitutt had fostered in Norway an interest in these rocks (e.g. Major & Winsnes 1955; Winsnes 1966, 1979; Flood et al. 1966; Lauritzen & Worsley 1975; Worsley & Edwards 1976; Lauritzen 1977, 1981, 1983; Gjelberg 1981, 1987; Gjelberg & Steel 1979, 1981, 1983; Nysaether 1977; Winsnes & Worsley 1981; Skaug et al. 1982; Mork 1987; Johannessen & Steel 1992) including the publication of the series of 1:500 000 geological maps (Flood, Nagy & Winsnes 1971; Hjelle & Lauritzen 1982; Lauritzen & Ohta 1984; Steel &Worsley 1984). British expeditions, in particular the Scottish Spitsbergen Syndicate (SSS) around 1920 and then the Cambridge Spitsbergen Expeditions (CSE), were concerned with the Late Paleozoic strata beginning in 1938 (Harland in McCabe 1939). As a result, a new stratigraphic scheme was proposed (Gee, Harland & McWhae 1953; McWhae 1953; Forbes, Harland & Hughes 1958; Forbes 1960). A series of expeditions from Birmingham in 1948, 1951, 1954 and 1958 added to the knowledge of Late Paleozoic rocks in western Spitsbergen (e.g. Baker, Forbes & Holland 1952; Weiss 1953; Dineley 1958; Bates & Schwarzacher 1958). Playford (1962, 1963) undertook extensive palynological work and Gobbett (1963) monographed the brachiopods. Between 1961 and 1965, Cutbill, Challinor, and later Holliday, worked extensively on Carboniferous and Permian stratigraphy. Cutbill's work enabled a detailed revision of the stratigraphy based on fusulinid zones comparable with those of the Russian Platform (Cutbill & Challinor 1965). These contributions are marked in the stratigraphic schemes shown in Fig. 17.2 including subsequent modifications in the light of Worsley & Edwards (1976) and this work.

Russian geologists have paid attention especially to the Permian sequence (e.g. Livshits 1960; Ustritsky 1962, 1967, 1979, 1980; Burov et al. 1964, 1965; Klobov 1965; Sosipatrova 1967, 1969; Stepanov 1936, 1937, 1957; Pchelina 1977; Sosipatrova 1967a,b, 1969) established foraminiferal zones over the whole carbonate sequence (Gipsdalen and Tempelfjorden Groups) which are, however, not sufficiently widely recognizable throughout Svalbard to be a useful tool for internal correlations. Work on Bjornoya was brought forward by Krasil'shchikov & Livshits (1974). Polish geological expeditions, based in southern Spitsbergen, have resulted in many publications on aspects of stratigraphy, structure and palaeontology (e.g. Biernat & Birkenmajer 1981; Birkenmajer 1959b, 1960a, 1964a, 1979b, c, 1984d; Birkenmajer & Czarnieki 1960; Birkenmajer & Turnau 1962; Czarnieki 1966, 1969; Fedorowski 1964, 1965, 1967, 1975, 1982; Rozycki, 1959; Siedlecka 1968, 1970, 1972 & Siedlecki 1960, 1964, 1970; Siedlecki & Turnau 1964; Malecki 1968, 1973, 1977). From German expeditions to Bjornoya in 1964 and 1967 Schweitzer (1967a, b, 1969) monographed the macroflora and Kaiser (1970, 1971, 1974) recognized several useful microfloral assemblages. French contributions to coal data, include Michelsen & Khorasani (1991).

17.2

Stratigraphic flame: B/insow Land Supergroup

The Bfinsow L a n d Supergroup conveniently combines the three groups of Carboniferous and Permian formations including some latest D e v o n i a n strata. The supergroup thus approximates the C a r b o n i f e r o u s - P e r m i a n chapter in Svalbard history. The position of the initial Carboniferous and Permian boundaries are only approximately k n o w n in the strata, but the supergroup as a whole is readily distinguished by late D e v o n i a n and Late Permian unconformities each with biostratigraphic hiatus.

CARBONIFEROUS AND PERMIAN HISTORY OF SVALBARD

Approximate age

I Trll

Approximate Location Hornsund Bjerneya Serkapp Land

Bellsund

Isfjorden

Nordfjorden

Nordensk61dLd

W.J. Ld

OscarllLd

Billefjorden DicksonLd

313

Tempelfjorden

Hinlopenstretet

B0nsowLd OlavVLd

Nordaustlandet

Griesbachian Lopingian Revtanna Hovtinden Mbr Mbr ...................................................... KAPP STAROSTIN Svenskeegga ............................

Capitanian |

Wordian Ufimian

GROUPS SASSEN-DALEN GROUP

MISERY-FJELLET FM

TOKROSSOYA FM

veringen

Stensi6fjt Mbr

i Selanderneset Mbr i ~-15aia-n~Jer-bu-kta .................... L. . . . . . . . M--br-

FM Mbr Mbr

~ m ~ ~ m ~ ~) ~D (:2

m c: Z

Kungurian

Artinskian

O

HAMBERG -FJELLET FM

GIPSHUKEN Kloten Mbr

Vengeberget

Mbr

FM

O --~

Zeipelodden Mbr

i "o

Sakmarian

Pl I

Asselian Gzelian

2 g

KAPP DUNER FM

Kasimovian

KAPP HANNA FM

Moscovian

KAPP[ 3 KARE IMbrs FMI

Bashkirian

r'-

Z

LANDNORDINGSVIKAFM

Tyrrellfjellet Mbr

TRESKEL-

WORDIEKAMMEN

-ODDEN FM

_

-,~ ~

FM

..................... Merebreen Mbr

Brattberget Mbr

TARNKANTEN FM PETRELLSKARET FM

SCHETELIGFJT FM BROGGERTIN-DEN FM

z 2> t-" m z

~Kapitol Mbr

Cadellfjellet Mbr

co

c

CHARLESBREEN SUBGROUP

HYRNEFJT. FM Helmen Mbr

~ ,~.

~

MINKINFJT. FM 3 Mbrs

BRUNFJT. -RDBR-EEN FM c u~

EBBADALEN FM 3 Mbrs HULTBERGETFM

;u O

c::~l -o ~

c

I

-o m

-o

:;0 Serpukhovian

O Nordhamna Mbr

Visean

NORD-

Kapp -KAPP Harry FM Mbr

Tournaisian C1

ID31 Famennian

ROED- Tunheim Mbr ,-VIKA .K~-p -~ i FM Levln Mbr

SERGEIJEVFJELLET FM HORNSUNDNESET FM ADRIA- Meranfjt. Mbr -BUKTA FM

VEGARDFJELLA FM

ORUSTDALEN

Julhegda Mbr Haitanna Mbr

V~sal"~randaMbr

FM

Birger Joh nsonl~t, r MUMIEN FM Sporehegda Mbr HORBYE- Hoelbreen BREEN Mbr FM

Triungen Mbr

g

c

O o ;;0 O c "o ANDNEELANDGROUPm

Fig. 17.3. Lithostratigraphic scheme for Carboniferous and Permian formations of the Biinsow Land Supergroup. It plots the recommended relationships between the named units and the age estimates are only approximate.

As recently determined latest Devonian strata are exceptional to the Billefjorden Basin (Van Veen pers. comm.), they have long been known in Bjornoya. These share the typical continental grey clastic facies, rich in plant material and often-coal-bearing. This Billefjorden Group developed in separate basins throughout Svalbard. It is mainly of Tournaisian and Visean age. The overlying Gipsdalen Group spans Late Carboniferous (Pennsylvanian) through Early Permian (Rotliegendes) time with possible breaks around Serpukhovian and in Artinskian time. The lower (Campbellryggen) subgroup begins with red clastics and evaporites with an increasing carbonate content upwards. Variable basinal facies reflect a complex but decreasing diastrophism. The upper (Dickson Land) subgroup comprises widespread relatively uniform carbonate facies changing to evaporite and carbonate facies. The Tempelfjorden Group formations overlie the Gipsdalen Group with a recognizable break. The rocks are distinctively resistant typically of siliciclastics and cherts. They are the most easily recognizable strata in Svalbard reflecting a relatively uniform environment of deposition. It was the above lithological characteristics which led to the three-fold grouping of multifarious formations (Cutbill & Challinor 1965) at a time when the American lithostratigraphic code was becoming employed internationally. In an attempt to agree and systematise the developing lithostratigraphic nomenclature the Stratigraphisk Komite for Svalbard (SKS) achieved an early report which is followed here (Dallmann 1996). What follows is thus in conformity with those recommended conventions. The units already encountered in the regional chapters 4 5, 9 10 and 11 are listed below with reference to their definition and set out in Fig. 17.3 which shows their approximate distribution in time and space. It is

not, however, a time-correlation chart, but rather to show the formal relationship of the units and hence the stratigraphic framework of the rocks for discussion. Biinsow Land Supergp (new) Tempelfjorden Gp (Cutbill & Challinor 1965) with three formations: Kapp Starostin Fm (Cutbill & Challinor 1965) extends throughout northern Svalbard and with other names in the south. It is divided threefold into members, some yet to be formalized. Hovtinden Mbr (Cutbill & Challinor 1965) was the original upper division. Selanderneset Mbr (Burov et al. 1965) is the uppermost equivalent in Nordaustlandet. Palanderbukta Mbr (Lauritzen 1981) is below it in Nordaustlandet. Stensi6fjellet Mbr (SKS 1996) is an equivalent in north central Spitsbergen. Revtana Mbr (SKS 1996) is an equivalent in the Bellsund region. This upper division is often characterized by glauconitic sands Svenskeegga Mbr (Cutbill & Challinor 1965) is the middle division, not so distinctive and defined by the overlying and underlying members. The upper and middle divisions correspond to the Productus fOhrende Kieselgesteine of Nathorst (1910). Veringen Mbr (Cutbill & Challinor 1965) is the lower distinctive and widespread division of the formation. It has an extensive submarine development and corresponds to the Spiriferenkalk of Nathorst (1910). Tokrosseya Fm (Siedlecki 1964) is the correlative of the Kapp Starostin Fm in its eponymous island and in Sorkapp Land. Miseryfjellet Fm (Worsley & Edwards 1976) is an approximate equivalent of the lower part of the Kapp Starostin Formation in Bjornoya. Hambergfjellet Fm (Worsley & Edwards 1976) is not yet allocated to any group being intermediate between the overlying and underlying formations. It has a small outcrop on Bjornoya, but is reported to have an extensive submarine development.

314

CHAPTER 17

Gipsdalen Gp (Cutbill & Challinor 1965). In the type area of north central Svalbard the group was originally defined by three formations: Gipsdalen, Nordenski61dbreen, and Ebbadalen with further formations in South Spitsbergen and four formations in Bjorn~ya. However, to facilitate more convenient mapping units the Nordenski61dbreen and Svenbreen formations have been redivided and replaced using earlier names and one later name. Four subgroups have also been introduced to combine all except the Bjornoya formations. Diekson Land Subgp (SKS) is defined by two formations. Gipshuken Fm (Cutbill & Challinor 1965) is characterized by clastics evaporites and breccias with a number of informal members, three in the upper part and three in the lower part. Bredsdorffbergen Mbr (SKS 1996) to the northwest in Spitsbergen Templet Mbr (SKS 1996) to the northeast in Spitsbergen Sorfonna Mbr (SKS 1996) in Nordaustlandet. The three lower members alternate evaporites with, probably related, collapse breccias. Kloten (breccia) Mbr (Cutbill & Challinor 1965) Vengeberget (evaporite) Mbr (SKS 1996) Zeipelodden Mbr (Lauritzen 1981) Wordiekammen Fm (Gee, Harland & McWhae 1953) was reintroduced by SKS for the upper two members of the Nordenski61dbreen Fm as representing relatively uniform widespread carbonate facies especially the upper member. Tyrrellfjellet Mbr (Cutbill & Challinor 1965) extends from NE Spitsbergen to Bellsund in the south. It includes the Finlayfjellet Beds at the top (originally Limestone B) and the Brucebyen (fusuline) Beds near the bottom. Cadellfjellet Mbr (Cutbill & Challinor 1965) in central and NE Spitsbergen with three beds: Mathewbreen, Gerritbreen and Black Crag at the bottom which to the east may approximate the Pyefjellet Beds. Kapitol Mbr (Cutbill & Challinor 1965) occupies the Nordfjorden High. Morebreen Mbr is the equivalent in the northwestern outcrops: In the Nordaustlandet the whole Wordiekammen Fm is represented by the Idunfjellet Mbr. Campbellryggen Snbgp (Forbes, Harland & Hughes 1958) was reintroduced by SKS to comprise three formations in the Billefjorden trough and two formations one in NE Spitsbergen and one in Nordaustlandet. Unlike the Wordiekammen Fm these reflect separate basinal developments. Minkinfjellet Fm (Cutbill & Challinor 1965) is divided into three members. Fortet Mbr (Dallmann 1993) in the north centre Terrierfjellet Mbr (SKS 1996) Carronelva Mbr (Cutbill & Challinor 1965) Ebbadalen Fm (Cutbill & Challinor 1965) is also divided into three members Odellfjellet Mbr(Johannessen & Steel 1992) Trikolorfjellet Mbr(Holliday & Cutbill 1972) Ebbaelva Mbr (Johannessen & Steel 1992) Hultberget Fm (Cutbill & Challinor 1965) is the upper part of their Svenbreen Fm, now divided mainly in account of a mappable boundary between these red beds and what is now renamed below as the Mumien Fm. Malte Brunfjellet Fm (SKS 1996) is an equivalent in northeastern Spitsbergen of the Minkinfjellet Fm. H~irbardbreen Fm (Cutbill & Challinor 1965) is similarly a corresponding unit in NordaUsttandet. Charlesbreen Subgp (Dineley 1958; SKS 1996) is analogous to the Campellryggen Subgp to the west of the Nordfjorden High in the northwestern and western outcrop. It comprises four formations, two in the north at Broggerhalvoya. Seheteligfjellet Fm (Cutbill & Challinor 1965) Holtedahl (1913) described his Moscovian fauna from this unit. Broggertinden Fm (Cutbill & Challinor 1965). Further south are two formations along the west coast more or less equivalent to the two in the north. T~irnkanten Fm (Cutbill & Challinor 1965). Petrellskaret Fm (Cutbill & Challinor 1965). Treskelen Subgp (SKS 1996) was instituted by SKS to combine two formations in inner Hornsund. Treskelodden Fm (Birkenmajer 1959b). Hyrnefjellet Fm (Birkenmajer 1959b). Not combined into a subgroup are the four original units described by Andersson (1900) from Bjornoya. Kapp Dun~r Fm (Krasil'shchikov & Livshits 1974) is the original 'Fusulina Limestone'.

Kapp Hanna Fm (Krasil'shchikov & Livshits 1974) is the original 'Yellow Sandstone'. Kapp Kfire Fm (Worsley & Edwards 1976) is the original 'Ambigua Lst': it has three members. Kobbebukta Mbr (SKS 1996). Efuglvika Mbr (Worsley & Edwards 1976). Bogevika Mbr (Worsley & Edwards 1976). Landnordingsvika Fm (Krasil'shchikov & Livshits 1976) is the original 'Red Conglomerate'. Billefjorden Gp (Forbes, Harland & Hughes 1958) is the original Culm or Kulm of older authors and comprises sandstones formations with black plant remains and coals. It is not divided into subgroups but is represented by three pairs of formations and one threefold succession in each of four or five distinct basins or outcrops. In the Billefjorden trough are the: Mumien Fm (SKS 1996) comprising the Birger Johnsonfjellet Mbr (SKS 1996). Sporehogda Mbr (Cutbill & Challinor 1965). Horbyebreen Fm (Cutbill & Challinor 1965) comprising the Hoelbreen Mbr (Cutbill & Challinor 1965). Triungen Mbr (Cutbill & Challinor 1965). Along the west coast (west of the Nordfjorden High) from Broggerhalvoya to Bellsund are two formations. VegardfjeHa Fm (Dineley 1958). Orustdalen Fm (Cutbill & Challinor 1965). In Inner Hornsund and in Sorkapp Land are three formations. SergeijevfjeHet Fm (Siedlecki 1960). Hornsundneset Fm (Siedlecki 1960). The third and lower formation is restricted to inner Hornsund. Adriabukta Fm (Birkenmajer & Turnau 1962). This has been divided into three members. Meranfjellet Mbr (Dallmann e t al. 1993). Julhogda Mbr (Dallmann et al. 1993) Haitanna Mbr (Dalhnann e t al. 1993). In Bjornoya are two formations: Nordkapp Fm (Cutbill & Challinor 1965) with two members. Nordhamna Mbr (SKS 1966). Kapp Harry Mbr (SKS 1996). Roedvika Fm (Cutbill & Challinor 1965) with three members. Tunheim Mbr (Cutbill & Challinor 1965). Kapp Levin Mbr (Worsley & Edwards 1976). Vesaistranda Mbr (Worsley & Edwards 1976).

17.3

Structural frame

The u n c o n f o r m i t y surface on which the Bfinsow L a n d Supergroup strata rest is a major, perhaps the most significant, structural feature of Svalbard geology. The older (or basement) rocks below are characterized by complex geosynclinal and orogenic histories. The y o u n g e r (or cover) rocks have a coherence that unites t h e m into a basin and platform sequence beginning in latest F a m e n n i a n time. However, the complexity of the basement h a d a lasting effect on the differential deposition, erosion and d e f o r m a t i o n of the y o u n g e r rocks by providing an inherited terrane framework. Events o f later history derive primarily from thickness and facies variations which call for some explanation. The structural n o m e n c l a t u r e adopted here (Fig. 17.4) is intended to serve generally for p o s t - D e v o n i a n history. There is a general N N W - S S E trend o f principal features so that over most of Spitsbergen the terranes a n d b o u n d i n g zones can be identified in E W traverses. The cover rocks m a y be b r o a d l y divided into an Eastern Svalbard Platform and a Spitsbergen Basin. The latter, for C a r b o n i f e r o u s time in particular, m a y be divided into blocks and troughs as s h o w n in Fig. 17.4. Subsequently the distinction between the east a n d central (Spitsbergen) basins is not so m a r k e d and both m a y be s u b s u m e d in the Spitsbergen Basin. Late Paleozoic basins show trends similar to the earlier D e v o n i a n graben, reflecting the c o n t i n u i n g influence of the same m a j o r fault zones u p o n sedimentary patterns. The D e v o n i a n graben was inverted during Late D e v o n i a n time to p r o d u c e the N o r d f j o r d e n High, a positive feature t h r o u g h to mid-Triassic time. Three depositional

CARBONIFEROUS AND PERMIAN HISTORY OF SVALBARD

315

basins are recognized, within which Early Carboniferous rocks have been preserved in structural troughs. The basins are separated and bounded by positive tectonic blocks, defined by major northsouth lineations.

17.3.1

Basins and blocks

The Eastern (Svalbard) Platform. In Nordaustlandet, in the northeast of Svalbard, there is a complex sequence of mainly pre-Devonian rocks on which a condensed succession of later Carboniferous and Permian rocks rest unconformably. Isopachs and facies distribution point to the existence of a region of uplift and sediment source in the east throughout 'Middle' and Late Carboniferous time, which continued into Permian time. The western margin of the block is not clearly defined, but there appears to be a fault or axis of rapid attenuation in the region of Hinlopenstretet.

The East (Spitsbergen) Basin. This basin extends from Ny Friesland southwards, possibly onto the northern Barents Shelf. There are two distinct troughs, preserving Early Carboniferous sediments, separated by a weak axis of Bashkirian and later uplift in Ny Friesland. Later Carboniferous rocks are continuous across the basin, but thin to the east (Fig. 17.4). The Billefjorden Trough lies on the western edge of the basin and preserves the thickest sequence of Carboniferous rocks in Svalbard, over 1500 m. It was a site of decreasing subsidence throughout the Carboniferous Period. The Lomfjorden Trough, the easternmost of these troughs, underwent less subsidence. It has been accentuated by post-Permian uplift in central Ny Friesland.

The Nordfjorden Block. This block, bounded to the east by the Billefjorden Fault Zone and to the west by the Raudfjorden and the Kongsi]orden-Hansbreen Fault Zone, was in part a negative feature during Tournaisian and Visean time. However, in the Serpukhovian (Namurian) epoch this pattern was reversed and the block became strongly positive during Bashkirian-Moscovian time, when it was a sediment source, separating the East and West Spitsbergen Basins. It was overlapped by latest Moscovian strata, but continued to be positive, relative to the basins, until the end of the Carboniferous Period. Its effects decreased until hardly noticeable in Late Permian time. On the eastern margin of the block, there was a narrow axis of uplift in eastern Dickson Land, parallel to the Billefjorden Fault Zone and to some extent fault-bounded, which was the site of uplift and erosion during a Bashkirian/Moscovian episode. Gzelian strata show marked thinning across the axis.

Fig. 17.4. Schematic map of the structural framework mainly evident from Carboniferous and Early Permian time. Key to numbered faults: (1) postulated Palaeo-Hornsund Fault; (2) Kongsbreen-Hansbreen (part postulated) Fault; (3) Post-Carboniferous Pretender Fault; (4) Adriabukta Fault; (5) Inner Hornsund Fault; (6) Raudfjorden Fault; (7) Breibogen Fault; (8) Billefjorden Fault Zone; (9) Lomfjorden Fault Zone; (10) Storfjorden Fault Zone.

The West (Spitsbergen) Basin (St Jonsfjorden Trough). Thick Carboniferous sequences are preserved in scattered outcrops within the Paleogene orogenic belt of west Spitsbergen, which contrast in facies and thickness with those of the Nordfjorden Block. The rocks, which generally overlie pre-Devonian basement, are folded and thrust. In the west, they are sometimes highly deformed and somewhat metamorphosed. The apparent contrast between the West (Spitsbergen) Basin and its eastern neighbour may well be accentuated by the Paleogene eastward thrusting and folding of the platform sequence.

The Bjornoya Basin. Bjornoya lay on the southeastern margin of a NNW-SSE-trending rift or semi-graben from Famennian to Bashkirian time, bounded to the west by a major fault, the West Bjornoya Fault (Gjelberg & Steel 1983). This is probably an extension of the Palaeo-Hornsund Fault Zone (Fig. 17.4). This depositional basin may extend to the Barents Shelf between Bjornoya and Spitsbergen.

316

CHAPTER 17

The Inner Hornsund Trough postulated by Gjelberg & Steel (1981) shows a similar sequence and may be part of the Bjornoya Basin. The Sorkapp-Hornsund High developed on the western margin of the Inner Hornsund Trough in Bashkirian time on the site of a widespread shallow Early Carboniferous basin. This basinal inversion can be compared to that which occurred in Late Moscovian-Gzelian time, when there was uplift in eastern Bjornoya. Following latest Carboniferous uplift and erosion in southern Spitsbergen, the Permian Period was one of tectonic stability across much of Spitsbergen. The changing palaeogeographic regimes and transition to more stable platform environments probably reflects northward plate movement and the relocation of the tensional tectonic regimes that produced the major intracratonic rift structures. These dominated sedimentation during Carboniferous time, although there was continuing active uplift to the south. Four palaeo-tectonic elements thus can be recognized. (i) The Northern Platform is a hypothetical Permian land area to the north of Spitsbergen which may have been geomorphologically continuous with the Lomonosov Ridge of the present Arctic Basin. (ii) The Spitsbergen Basin was the main basin of deposition through Permian, Mesozoic and Paleogene time. (iii) The Sarkapp-Hornsund High was a positive ridge throughout Permian time in the south of Spitsbergen, the southern continuation of which is not known. The Tempelfjorden Group thins rapidly in southern Spitsbergen and the High separated the Permian sediments in south Sorkapp Land from the main development. Considerable amounts of clastic sediment were supplied as a result of this uplift during latest Carboniferous and Early Permian time (the Treskelodden, Hyrnefjellet and Reinodden formations), while over the rest of Spitsbergen, carbonates prevailed (in the Tyrrellfjellet Member and the Gipshuken Formation). (iv) The Bjornoya Basin. Bjornoya lay on the margin of a depositional basin. Shallow-marine shelf carbonate and clastic sedimentation was twice interrupted by tectonic upheavals, resulting in Early Sakmarian and Late Artinskian unconformities. Otherwise there are close stratigraphic parallels with the sequences of the Central Basin. The Tempelfjorden Group deposits on the southwest flank of the Hornsund High in Sorkapp Land may represent the deposits of the northern margin of this basin.

dividing the Dicksonfjorden and Ekmanfjorden areas. In the earlier publication a similar fault C is projected as the Pretender Lineament from a small fault trace which does not necessarily have a pre-Tertiary history, nor is it in line with the Raudfjorden Fault Zone. Authors addressing post-Devonian stratigraphic boundaries did not anticipate the Kongsfjorden-Hansbreen Fault Zone (KHFZ of Harland et al. 1993), or its predecessor the Central West Fault Zone (CWFZ of Harland & Wright 1979). They may be referred to together with the Pretender Lineament of Mork & Worsley as the (generic) 'West Spitsbergen Fault Zone'. They were postulated to bound the central and western provinces or terranes. This ancient fault zone, redrawn through Hansbreen in western Hornsund in 1993 (Harland, Hambrey & Waddams) fulfils the function of separating the West (Spitsbergen) Basin from the Nordfjorden High and from the Central Spitsbergen Basin further south. It also separates the Hornsund-Sorkapp High from the West Sorkapp Land Basin to the west.

17.3.2

For immediate practical use Mississippian is preferred to Early/'Lower' Carboniferous as being unambiguously Tournaisian+Visean+Serpukhovian. Mid-Carboniferous is unambiguously Russian and equals Bashkirian + Moscovian. Late Carboniferous is ambiguous being Kasimovian+Gzelian for the Russian usage, but more correctly should be Pennsylvanian (Bashkirian to Gzelian). Thus 'Middle' and 'Late' Carboniferous strata in Svalbard combine in Pennsylvanian. International stage or epoch names avoid these pitfalls.

Boundary faults

The terranes as outlined above are bounded by mainly preCarboniferous fault zones with a N N W - S S E trend. (i) Eastern (Svalbard) Platform. Lomfjorden Fault Zone (ii) East (Spitsbergen) Basin (including Billefjorden Trough) Billefjorden Fault Zone (iii) Nordfjorden Block. (a) Dicksonfjorden ?Breibogen Fault Zone (b) Ekmanfjorden Kongsfjorden-Hansbreen (postulated) Fault Zone (Fault C of Mork & Worsley 1979) approximates their Pretender Lineament in the north. (iv) West Spitsbergen Basin (including St Johnsfjorden Trough) ?Paleo Hornsund-West Bjornoya postulated Fault Zone (of Gjelberg & Steel 1983) The scheme above differs from those of Mork & Worsley (1979) and Steel & Worsley (1984). The southerly projections of their faults trend further to the southeast than those in Fig. 17.4. so that the two schemes cannot simply be translated. The more southerly trend of the Billefjorden Fault Zone in Fig. 17.4 is based on the subsurface section by Mann & Townsend (1989). In each case their fault C is projected SSE along the axis of the (Tertiary) Central Basin. In the later publication it extends the Breibogen Fault Zone, which had a Silurian to Early Devonian strike-slip history, but the only evidence from exposure would be in Ekmanfjorden so

17.4

Carboniferous and Permian time scale

Figure 17.5 is an attempt at an international geological scale. It is based on a study in 1989 (Harland et al. 1990) in which the stages/ epochs were nearing international agreement. At least three Carboniferous features are noteworthy, each of which arises from the different traditions in the Former Soviet Union (FSU), Western Europe, North America and Asia. Because Svalbard strata are generally easiest to correlate with the Arctic regions of the FSU the Russian tripartite division of Carboniferous time is commonly followed in which Mid-Carboniferous is understood as Bashkirian plus Moscovian. However 'Early Carboniferous' could refer (i) to pre-Bashkirian in the Russian sense; (ii) to Dinantian in the West European sense which includes only Tournaisian and Visean (Namurian being Serpukhovian and early Bashkirian as the earliest Silesian (late Carboniferous) epoch or (iii) Mississippian which is approximately Tournaisian through Serpukhovian. Harland et al. recommended Mississippian as having priority in this competition for a single international scale, but most writers on Svalbard geology simply refer to 'Lower' Carboniferous etc. from FSU usage. One distinction is that whereas coal measures in Western Europe tend to be Late Carboniferous in age (Silesian), the Dinantian being typified by Carboniferous limestone, the Svalbard sequence is the reverse with 'coal measures' the (original Kulm) being Tournaisian, Visean (& Serpukhovian).

Permian division also differs. In western Europe, where marine Permian strata are somewhat exceptional the Dyassic or two-fold division became established (and persists in the Chinese name for Permian) but the Permian System was set up by Murchison in the Russian Urals where a better marine sequence obtains and for long the Russian stages have been applied generally in Europe while dividing the period into West European Rotliegendes and Zechstein. However, the Zechstein (in Russia) passes upwards into continental red beds, which are difficult to correlate; so that Tatarian has little application and Kazanian not much more. On the other hand, the later Permian succession in North America is better based in marine strata so that Harland et al. adopted a Guadelupian epoch with Ufimian, Wordian and Capitanian stages. However, even in N o r t h America latest Permian time is not well represented and it turns out that in the eastern Tethys, and southern China in particular, richly fossiliferous marine faunas are younger than anything known in the west. This was the reason for introducing Lopingian for the Late Zechstein epoch because it can be well documented (Harland et al. 1990) but for the above reasons not easy to correlate elsewhere.

CARBONIFEROUS AND P E R M I A N HISTORY OF SVALBARD International

Some regional equivalents

I

w

Period

Stage

TRIASSIC I

Epoch / Stage

N

Spitsbergen

Russia EuropeIAmericaBj~rn~ya Fm

Griesbachian ? .~_

Gp

Age of boundary in Ma

Some index fossils Foraminifera 3rachiopod zonesI Palynomorphs

~,.,-vv , v ~ , . , ~

Changxingian

(Eastern Tethys)

o,

Longtanian

9t-

._~

Capitanian

"~.

.~

317

"o r

?

?

245 Paleofusulina -

~~o

~ =

Cap

~ ~_

(5)

Codonofusiella

- 250

cO iN

._~

~.

Wordian (.9

Ufimian

Wor

Kun

-~

"~ 0o

8

._~ =o

Artinskian

Sakmarian

(6)

Art

~

~

rY

Sak

~'~" I~-E Neoschwagerina Lissochonetes Cratianifera N. simplex Pseudosirena

o)

~.

E

=

-r"

.~ (5

,~

rY

Parafusulina

o

,~

Sowerbina Antignotunia Jakutoproductus

~* ~

%

Gzelian

.

~

o

~~o

~9

Kasimovian

(9)

(13)

Yakovlevia Q. ,~ PseudoTonuopsis ~ schwagerina Orlkotichia V e- Schwagerina Kichoproductus ? & ~ ' ~ ' .~~ T r i t i c i t e s ~

-6

Ass

-

282 (8)

T

- 290

I

(.o

256 (4)

~.~ - 269

Tornquistia Pseudofusulina Attenuatella

"~

-

- 260

=

Asselian

(13)

/

E ._~

"~ Yabeina O~ Lepidolina Verbikina

~ Ufil

~

Kungurian

~o ~

~

*~

303

Fusulina

~

Moscovian

(8)

g

c-

"g Atoken -

r

g n

Bashkirian

O

~

~

IM

(12) r ._

r

- 323

2 Serpukhovian

Z

(10)

..E

o El.

- 333 &

L Tournaisian

Fig. 17.& Carboniferous and Permian time scale and biostratigraphy, based mainly on Harland et al. (1990).

DEVONIAN

g

3=

Visean

_.1

Famennian

The above points are relevant in considering Svalbard correlation. The Templefjorden Group lacks diagnostic fusulines and ammonoids. Even in the more representative Arctic Canada the earliest Triassic faunas appear to follow Capitanian rocks with Cyclolobus. Western successions are affected successively by Variscan (Hercynian), Appalachian and Uralian orogenic episodes, the effects of which largely passed Svalbard by, as well as the North American Arctic. But the Lopingian epoch is still something of a mystery in the west (including Svalbard) and this lack of a historical frame vitiates much stratigraphic description. At the same time, if the calibration estimates are reliable, the latest Permian stages were of very short duration. A new question has arisen concerning the Lopingian division. It appears that it may overlap in time with the Early Scythian (Griesbachian stage). This may become clearer with conodont studies. This is a typical boundary problem where overlap or gap should now be settled by the 'golden spike' (GSSP) procedure. Once the Permian-Triassic boundary has been finally defined by GSSP the consequences will be automatic if the rocks can be correlated. Hitherto the North American succession has provided provincial GSSP for the period boundary. It is standard practice that the initial boundary of the later division shall ipsofacto be the terminal boundary of the earlier division in each case giving preference to the later division. However, until the matter is internationally agreed the question remains open.

:

311

Eofusulina

g g

g a E SZoo

z

g ~

(17)

o

350 Raritubereulatus

(13)

.M~

The reason for this digression is that Wignall & Twitchet (1996) have adopted the view that the earliest strata of the Sassendalen Group, traditionally Triassic, are Lopingian (Permian). This makes no difference to the geological interpretation and an international decision is awaited. Their significant contribution, however, is that the lower Sassendalen (Vardebukta) formation reflects anoxic conditions which might mark a Permo-Triassic biotic crises. This matter is discussed with the traditionally Triassic Vardebukta Formation in the next Chapter. Figure 17.5 lists the divisions that might be relevant for correlation of Svalbard rocks. There are seven epochs for the Carboniferous sequence which in Europe, at least, is divisible into 25 stages for effective correlation. International biostratigraphic correlation of Svalbard formations is n o t easy in spite o f the rich biotas. T h e Mississippian rocks are largely n o n - m a r i n e ; b u t rich p a l y n o l o g i c a l assemblages give r e a s o n a b l e ages t h o u g h n o t to stage level. E v a p o r i t e facies limit the possibilities o f precise B a s h k i r i a n age estimates. T h e r e a f t e r fusulines h a v e been reliable index fossils b u t are f o u n d in S v a l b a r d only u p to a b o u t S a k m a r i a n age. R u g o s e corals are also valuable, b u t are n o t precise indicators. T h e later rich b r a c h i p o d - b r y o z o a n - s p o n g e f a u n a s give little help. This distinctive T e m p e l f j o r d e n facies is nevertheless w i d e s p r e a d in the Soviet a n d C a n a d i a n Arctic. I n d e e d

318

CHAPTER 17

Stepanov (1937) proposed a Svalbardian Stage for it, of postArtinskian, possibly Kazanian age. It is a facies event difficult to date, and its age in terms of international stages has not been determined. Conodonts which are internationally valuable range only through to Bashkirian when Svalbard lacked suitable marine limestones. In an attempt to improve the correlation prospects for Svalbard's Permian strata, Mangerud & Konieczny (1991, 1993) made a thorough study of Svalbard palynomorphs. The facies were not appropriate and the material poor; nevertheless, the distribution of 95 species or forms through the representative sections resulted in the recognition of three Permian assemblages: Vittatina a s s e m b l a g e - latest Noginskian to mid-Asselian; Hamiapollenites tractiferinus a s s e m b l a g e - mid-Asselian to mid-Artinskian; Kraeuselisporites assemblage - mid-Artinskin to ?earliest Longtanian. Within the Billefjorden Group continental coal measure environments favoured vegetation and Playford (1962, 1963), from a study of 57 species distinguished two assemblages: Rarituberculatus (Tournaisian) and Aurita (Visean possibly to Serpukhovian). Thirteen species were c o m m o n to both and 21 and 23 species respectively characterized the two stages. The age of the Tempelfjorden Group, notably the Kapp Starostin Formation, has been a puzzle. The formation contains an abundant fauna, predominantly of silicified brachiopods, but also of bryozoans, bivalves, corals, sponge spicules, echinoderms, gastropods and foraminifers. Trace fossils abound, with Zoophycos, Teiehichnus and Chondrites. Szaniawski & Malkowski (1979) distinguished two time-equivalent fossil associations which represent different depths: the bioclastic limestone facies of near-shore, shallow-water, high-energy thicker-shelled species and an offshore, low-energy, deeper-water fauna dominated by sponges, with more fragile brachiopods and bryozoans, which occurs in the siliceous rocks associated with in-situ glauconite and pyrite. The brachiopod fauna is broadly comparable with the later Early Permian and Late Permian assemblages of the USSR (Tschernyschew 1898, 1902). However, many of the species have long time ranges and show considerable intraspecific variation which has caused confusion over correlation. Biernat & Birkenmajer (1981) found that at the base of the Kapp Starostin Formation in Torell Land, two brachiopod species were the same as those in Sakmarian-Early Kungurian rocks of Inner Isfjorden. Many species are closely related to the Artinskian or Kungurian species of the Former Soviet Union, but several genera characteristic of Late Permian also occur (Gobbett 1963). Ustritskiy (1962) and Burov et al. (1965) distinguished two separate faunas, both belonging to the Ufimian stage, in the 'Starostin Suite' (=Svenskeegga/Voringen Members) and 'Selander Suite' (=Hovtinden Member), the latter being distinguished by the presence of Cancrinelloides and Sowerbyna. These assemblages have not yet been recognized throughout Spitsbergen. A Kungurian age has been confirmed for the lower part of the formation (Nysaether 1977; Ustritskiy 1979) and a Ufimian age is indicated by the foraminifers for the small Permian inliers of Edgeoya, which represent a glauconitic chert facies (Pchelina 1977). The upper part contains brachiopods which extend into the Kazanian stage (Ustritskiy 1979) and Ustritskiy assigned the 'Starostin' (=the Voringen and Svenskeegga Members) and 'Selander' (--the Hovtinden Member) 'Formations' to Boreal stages (Paykhoyian and Early Novozeml'ian) which correlate with the Kungurian-Ufimian and Kazanian ?basal Tatarian respectively. Conodont assemblages also confirm a Kungurian-Ufimian age as they correspond stratigraphically to the Late Leonardian/Early Roadian of the USA (Szaniawskij & Malkowski 1979). As the formation is transgressive, lithological boundaries must be diachronous until open-sea cherty facies occur everywhere, i.e. at the top of the formation (Malkowski 1982). There is a stratigraphic gap in the Hornsund region, where the Voringen and Svenskeegga Members of the Isfjorden area absent. The possibility that Late Lopingian (i.e. Changxingian) might approximate the Early Scythian (Greisbachian) stage, as suggested by Wignall & Twitchett (1996), does not affect the age estimate of the youngest Tempelfjorden Group strata as discussed above. Therefore in any case the whole B/Jnsow Land Supergroup is latest Famennian, Carboniferous and Permian. The question remains as to the time span and the corresponding events of the interval between the Tempelfjorden Group (Kapp

Starostin Formation) and the Sassendalen Group (Vardebukta Formation). The base of the Vardebukta Formation, with the ammonoid Otoceras boreale, whether or not correlated with the conodont zone Hindeodus paroces, rests locally with disconformity on the Kapp Starostin Formation. Slight earth movement is evident locally. The corresponding hiatus might span later Capitanian and possibly Longtanian time.

17.5

Carboniferous and Permian sedimentary environments

The distribution in space and time of the rock units already introduced in their regional context in Chapters 4 5, 9 10 and 11 is shown in Fig. 17.3. Formational boundaries are not expected to coincide with standard chronostratigraphic boundaries, but for convenience of description they may be approximated as below. Lithological and biostratigraphic details appear in the regional formational descriptions. This section outlines environmental interpretations in time sequence. The conclusions of these interpretations is applied in Section 17.7 'Tectonic controls of sedimentation'.

17.5.1

Late Famennian-Tournaisian-Visean-Serpukhovian deposition (Billefjorden Group)

The Billefjorden Group is dominated by continental sediments of fluviatile swamp and lacustrine origin. Coal-bearing members indicate a humid climate. The only evidence of any marine influence is in Broggerhalvoya (Western Basin) and in southern Spitsbergen.

Horbyebreen Formation (Billefjorden Trough). The Horbyebreen Formation lies unconformably on Proterozoic basement rocks in Dickson Land and southern Ny Friesland. It is variable in thickness from 57 to 200m thinning to the west. The complete absence of marine fossils and the abundant plant remains indicate a continental environment. The formation was probably deposited in a small, elongate basin, partly fault-bounded in the east, as the formation is absent east of a line between Austfjorden and Billefjorden except for some possible outliers east of Austfjorden (Harland 1941). In Ebbadalen and on Terrierfjellet, the overlying Svenbreen Formation rests directly on Pre-Devonian (Hecla Hoek) basement. The eastward increase in clast size in conglomerates of the Triungen Member and in coarser lithologies in the Hoelbreen Member suggests a sediment source to the east, perhaps a result of upfaulting of the Ny Friesland region and its Hecla Hoek basement. However, palaeocurrent analysis suggests a second contemporaneous source area to the west and probably south (Gjelberg 1987). Gjelberg & Steel (1981) and Gjelberg (1987) suggested that the arenites and rudites of the Triungen Member represent braided stream with overbank deposits, whereas the mudstones may be lacustrine. The Hoelbreen Member, in contrast, appears to have been dominated by northward-flowing, high sinuosity meandering streams in a large, swampy, densely-vegetated floodplain environment where finegrained, organic-rich sediments accumulated (Abdullah et al. 1988). Channel fill, levee, crevasse channel and splay, point bar and flood basin deposits are all preserved within the sequence, but no distributary channel deposits have been identified. Plant debris appears to be concentrated in the east, probably nearer the source. Coal occurs as thin beds with seat-earths and rootlet beds, interbedded with shales and siltstones. They may represent the local development of coal-swamp conditions on the floodplain. The Hoelbreen coals are humic, low in ash and sulpher, and enriched in vitrinite. They are hydrogen-rich with up to 15% liptinites. Selaginella-rom megaspores and thick-walled spores are common (Michelsen & Khorasani 1991). The eastward increase in grain size and thickness, together with the lack of distributary channels, points to a faulted eastern basin margin. Downthrow may have encouraged flooding (Gjelberg & Steel 1981) and restricted the river system to near the basin margin, such that distributary channels are probably preserved to the east of present exposures, where subsidence was greatest (Gjelberg 1987). The general thinning to the west suggests a western margin in the region of Dicksonfjorden.

C A R B O N I F E R O U S A N D P E R M I A N HISTORY OF SVALBARD

Mumien Formation (Billefjorden Trough). The Mumien Formation is a terrigenous unit present in the Billefjorden area, with a thickness of up to 230 m. It contains two members: Sporehogda and Birger Johnsonfjellet. The Sporehegda Member contains massive coarse sandstones with minor shales and allochthonous coal, whereas the Birger Johnsonfjellet Member contains numerous coal seams within a predominantly shale and siltstone sequence. Deposition of this formation was mainly within a rather restricted elongate basin, with the thickest deposits along the line of the BiUefjorden Trough, where subsidence was greatest (Fig. 4.12). Pre-Bashkirian uplift and erosion has further restricted the formation, but the original basin may not have been more than 45 km across if both members are indeed recognizable in the thin sequence at Terrierfjellet (Fig. 4.10). There is no evidence of marine incursions, so the sediments must be of fresh or brackish-water origin, a conclusion backed up by the abundant plant debris. The sandstone units, with their signs of rapid deposition, such as cross-bedding, wash-outs and slump structures, and their rapid lateral thickness variations, are interpreted as the channel deposits of rivers. Meandering channel migration on a poorly drained floodplain with swamps and lakes would produce the cyclic sandstone/siltstone/shale sequences. The finer sediments, including the carbonaceous material, could settle out in quiet water with coals forming locally where plant material accumulated. The lack of seat-earths suggests that they are allochthonous. A lake origin for the upper coals is supported by organic petrological studies. There was a change in the mid-Birger Johnsonfjellet Member from a peat swamp environment to lacustrine conditions with deposition of rich cannel and boghead cannel facies upwards. This corresponds to the time of active normal faulting to the west of Pyramiden. (Abdullah et aL 1987; Michelsen & Khorasani 1991). The appearance of conglomerates locally in the upper member may also be due to movements along thc East Dickson Land Axis. No palaeocurrent directions are known from the fomaation, so the source area can only be guessed at. The general absence of conglomerates, suggests it was fairly distant. A source to the west would mark the onset of uplift of the Nordfjorden Block. However, the underlying formation has evidence of both eastern and western provenance (see above). Orustdalen Formation (Western Basin). Sandstones and shales are the predominant constituents of this formation, which varies in thickness up to several hundred metres. The lithology, abundance of plant remains and total absence of marine fossils indicates a continental, predominantly fluviatile environment in a humid climate. In Broggerhalvoya Fairchild (1982) recognized three facies. (i) A fluvial channel facies consisting of interbedded conglomerates and cross-bedded sandstones which he interpreted as a series of braided river channel deposits with flow directions to the south and west. (ii) An overbank facies of shales, which become more important upwards, containing some in situ, but mostly drifted plant remains. This facies is scarce in the section containing the third facies. (iii) A marine reworked sandstone facies occurs at several levels in one section only, grading up from the fluvial channel facies. Medium-coarsegrained, cross-stratified sandstones contain unimodal and bimodal current directions, which are indicative of reworking of the fluvial sandstones by waves or tides. Conglomerates are not known. In this area, Fairchild concluded that the sediments were deposited onto coastal alluvial fans derived from a fault scarp to the northeast, uplifting a siliceous Early Paleozoic source. The paucity of fine material is attributed to the nature of the source. Other source areas certainly included pre-Devonian basement on which the formation rests and there is evidence of Devonian elements in the conglomerates (Dineley 1958). Evidence from the Billefjorden Group around Billefjorden suggests that there was uplift of the Nordfjorden Block at this time. Although there are basal conglomerates locally, they have been reworked and sorted. The basement rocks have been channelled and thoroughly planed (Dineley 1958; Flood 1968). Vegardfjella Formation (Western Basin). The Vegardfjella Formation consists of sandstones with carbonaceous shales and subordinate conglomerate. The lithologies, with their total absence of marine fossils and abundant plant fragments, suggest a continental fluviatile/lacustrine environment, the shales representing the latter. Adriabukta Formation (South Spitsbergen). Unconformably overlying Devonian basement, the Adriabukta Formation consists of at least 500m of black, dark grey and green shales. The formation was deposited to the east of the Inner Hornsund Fault Zone, and overlaps underlying formations to the west and to the north. It is relatively thick and may have had quite a

319

considerable extent to the east and south. The local mid-Carboniferous erosion of the top of the formation was probably due to movements on this fault, which may also account for the sudden marine to continental environmental change between this and the overlying Hornsundneset Formation. As the bottom of the sections on Hyrnefjellet contain a recognizable benthonic fauna, as well as plant remains, it would seem that this part of the formation was deposited in a shallow, near-shore marine environment. A fairly high energy level is indicated by the abundant conglomerates and sandstones showing signs of cross-bedding. Crossbedding in the basal clastics suggests a relatively close sediment source to the east (Gjelberg & Steel 1981). The main shale sequence, in contrast, yielded no fauna and seems to represent a quite different environment of quiet, anaerobic conditions in a restricted basin. The thin, poorly sorted or graded sandstone beds and conglomerate lenses were probably brought from shallow, marginal areas by occasional mass-flow/turbidity currents. These were possibly triggered by movements on the boundary faults of this basin, the Inner Hornsund Fault and the extension of the Billefjorden Fault Zone. The main shale sequence is neither carbonaceous nor coal-bearing like other Billefjorden Group shales, a fact explicable if it represents a marine basin, in which the absence of fauna implies anaerobic or restricted conditions.

Hornsundneset Formation (South Spitsbergen). Up to 750 m thick, this is the thickest and most coarse-grained unit of the Billefjorden Group in southern Spitsbergen. Clasts are derived from Precambrian basement. Plant remains are common and thin coal seams are present in places. Birkenmajer (1979) considered that the rather polymodal cross-bedding directions point to meandering river-channel deposits. Gjelberg & Steel (1981), however, favoured braided streams associated with a widespread series of alluvial fan systems. The source was to the west and/or northwest. Most of the clastic material is derived from a distant source and not local to southern Spitsbergen. The only local material is in the pebble-lag conglomerates. The finer deposits, which are a minor component, represent alluvial-plain overbank sediments. Marine faunas and calcite cement are not recorded. Sergeijevfjellet Formation (South Spitsbergen). The Sergeijevfjellet Formation consists of approximately 180 m of shales with fine-grained sandstones and siltstones. The sandstones are cross-bedded in places, the shales contain abundant plant debris, and thin coals are common. They were clearly deposited in a fluvial environment with localized flood basins and swamps. Roedvika Formation (Famennian and Tournaisian of Bjornoya). At the base of the Billefjorden Group on Bjornoya, the Roedvika Formation is a elastic sequence up to 360 m thick. The base, and possibly also the top, are unconformable; it rests on Precambrian and Ordovician basement. It has been divided into three members. The lower and middle parts of the Roedvika Formation constitute a single upward-coarsening sequence from the coal-bearing Vesalstranda Member to the coarser Kapp Levin Member. Facies analyses by Worsley & Edwards (1976) and Gjelberg (1978, 1981) all concluded that lacustrine, deltaic and fluviatile environments prevailed. The lakes provided conditions suitable for coal formation. As no true seat-earths have been found, the coals are probably allochthonous. There is no evidence of marine influence in the Roedvika Formation. Cross-bedding shows a great diversity of flow directions, although a general palaeoslope to the north is indicated (Worsley & Edwards 1976; Gjelberg 1978). Calcrete or desiccation cracks have not been reported so it may be concluded that the climate was moist. The Vesalstranda Member (Late Famennian) consists largely of floodplain sediments and shows an overall progradational trend from lacustrine/ deltaic up to fluviatile environments, though the thinly developed basal conglomerate may represent braided streams. The lacustrine/deltaic association consists of crevasse, channel and mouth-bar sediments organised into small upward-coarsening sequences indicative of delta lobe progradation, presumably into lakes. Fluvial sediments become more common upwards, with upward-fining, meandering river/floodplain associations of sandstones, siltstones and mudstones, representing fluvial channel, levee/channel fill and floodplain facies. Palaeocurrent evidence suggests a source to the southeast. The Kapp Levin Member (Early Tournaisian) represents the culmination of this basin-filling episode, containing the coarser-grained deposits of lowsinuosity braided streams which probably flowed to the east or northeast. The overall change in depositional environment and palaeocurrents seen through this upward-coarsening sequence is probably related to the increasing dominance, with time, of lateral alluvial fan systems building out from the southwest margin of the basin over the northwestward-flowing axial fluvial channels (Worsley et al. 1987). The shales at the top of the

320

C H A P T E R 17

member mark an abrupt change in depositional environment. The entire basin may have been suddenly covered by a lake, perhaps because of a sudden lowering of the base level as a result of faulting. The Tnubeim Member (later Tournaisian) represents the re-establishment of floodplain environments and the start of a second depositional phase. Channel deposits predominate in the lower part, while finer overbank, coal-bearing shales are characteristic of the upper part. The visible splitting of the upper unit northwards suggests an increase in subsidence in this direction. The member contains the deposits of north- or northwest-flowing meandering rivers. Studies of the plant fossil Pseudobornia ursina, which occurs in this member, indicate the presence of bodies of water, along the shores of which the plants grew in rather pure stands (Schweitzer 1967). The lowermost coal seam shows a systematic increase in vitrinite content from floor to roof where the seam splits. Coals are commonly pyrite rich. The next lowest seam is thin and enriched in inertinites and all contain up to 5% meta-lipinites (i.e. Sporinite matured to near vitrinite. They are of prime coking rank (R0 = 1.34%)

Nordkapp Formation (Visean of Bjornoya).

The Nordkapp Formation is the uppermost unit of the Billefjorden Group on Bjornoya. It is up to 120 m thick. Gjelberg (1981) suggested that the lower sandstones represent braided stream deposits on the distal part of an alluvial fan system, with crossbedding indicating a sediment-source to the southwest. Soft-sediment deformation structures point to an active fault nearby (on the West Bjornoya Fault Zone?), perhaps producing an elevated area to the southwest. The features of the conglomerates of the upper unit are characteristic of debris-flow and stream-flood environments and may represent rejuvenation of the alluvial fan system, still prograding northeastwards. The conglomerates may mark the renewal of activity on the West Bjornoya Fault Zone (Gjelberg 1978), which then continued to be active into ?Bashkirian time. It is consistent with the sedimentological evolution postulated for the overlying Landnordingsvika Formation. The finer and carbonaceous sediments must represent flood-basin or lacustrine areas in this fan complex. The sequence was deposited in a relatively moist climate, with a high water table, resulting in reducing conditions and the development of coal and clay-ironstone horizons (Gjelberg & Steel 1981). The exposures of the north coast suggest that there was a transition to the red-beds of the Landnordingsvika Formation. This would impose such a long time span on the Nordkapp Formation that there may have been breaks in deposition, e.g. between the lower and upper parts of the formation (Gjelberg 1981).

17.5.2

B a s h k i r i a n - M o s c o v i a n - K a s i m o v i a n deposition (lower Gipsdalen Group)

By this t i m e the c l i m a t e was m o r e arid. R e d beds are c h a r a c t e r i s t i c o f the l o w e r G i p s d a l e n G r o u p , w i t h c o a s t a l m a r i n e facies c o n t a i n ing e v a p o r i t e s a n d c a r b o n a t e s . T h e e n v i r o n m e n t o f this interval was discussed b y L u d w i g (1989).

Campbeliryggen Subgroup Hultberget Formation (Billefjorden Trough). This unit marks the beginning of red facies in the trough. It is dominated by variable sandstones. Ebbadalen Formation (Billefjorden Trough).

The Ebbadalen Formation is one of the best known lithostratigraphic units of Svalbard. The total thickness of the formation is about 750 m but this decreases to the east away from the fault to zero. Described by Holliday & Cutbill (1972), Gjelberg & Steel (1981) and Johannessen & Steel (1992) the overall setting of the basin appears to have been one of a narrow basin, with deposition occurring in a half-graben against the Billefjorden Fault Zone. The Ebbaelva Member had a fluvial component, with braided stream, playa lake, lagoon, sabkha and barrier shoreline deposits represented. Marine conditions, indicated by marine fossils and sulphates, occur towards the top of the unit and represent occasional, sudden changes in relative sea level, within an overall transgressive regime. The Trikolorfjellet Member and the laterally equivalent Odellfjellet Member represent open-basin and alluvial fan deposits respectively building out from the Billefjorden Fault Zone. Close to the fault zone the red beds are conglomeratic, clasts being mainly composed of quartzose debris reworked from the Billefjorden Group. These alluvial fan deposits formed

in an arid marginal-marine environment. To the east, finer-grained and better-sorted sandstones in the Odellfjellet Member suggest fan-delta, shoreline and aeolian environments marking an arid alluvial plain with occasional marine incursions. Further away from the fault zone, the sandstones are transitional to shales with gypsum nodules, and then into the gypsum-anhydrite facies of the Trikolorfjellet Member. These deposits represent a change into warm to arid lagoon and sabkha environments. Eastwards, carbonates increase and become dominant over the evaporites which disappear entirely at the top, marking intertidal and open marine environments. This is especially so in the extreme east, where offshore skeletal limestones make up the whole of the highly attenuated section. Subsidence in the Billefjorden Trough was greatest near to the faulted western margin, decreasing gradually towards the eastern shelf sea area. Occasional marine transgressions, possibly as a result of fault movements, gave intervals of carbonate sedimentation over the entire basin. The alluvial fan sequences normally have a quartzitic beach-capping, which is in turn overlain by dolostone. Provenance of the formation is difficult to specify. Cross-stratification is varied, but indicates currents from the south. Clasts of Precambian biotite schist occur, probably also indicating a source to the south. Tournaisian and Visean spore assemblages found in shale clasts are probably derived from rocks of that age to the west, and may represent uplift on the East Dickson Land Axis. Hence, the source may have been to west and south.

Minkinfjellet Formation (Eastern Basin east of Billefjorden Fault Zone). The Minkinfjellet Formation is present in the Billefjorden area only. It is a variable unit with rapid lateral and vertical facies variations. It has a thickness of 300 400 m with its maximum adjacent to the Billefjorden Fault Zone, corresponding to the area of greatest subsidence. The deposition of the formation was largely controlled by subsidence within the Billefjorden Trough, bound to the west by contemporaneous faulting and flexuring along the Billefjorden Fault Zone. There are also prominent northsouth facies belts parallel to the trend of the fault zone. It is likely that the environment was similar to that for the underlying Ebbadalen Formation. Clastic sequences may represent continental fluvial fan deposits, but interbedded carbonates and evaporites indicate a marginal situation with frequent marine transgressions. The evaporite zone represents coastal sabkha environments, but pure sulphate is somewhat restricted and the sequence contains a higher proportion of lagoonal dolostone. Further east, the thinner carbonates represent more open marine conditions and marine sandstones become an important constituent eastwards. The breccias of the Fortet Member probably represent either seismically-induced in situ brecciation due to movement on the Billefjorden Fault zone, or local erosion of the fault scarp.

Hhrbardbreen Formation (Nordaustlandet). Unconformably overlyingPrecambrian basement, the Hhrbardbreen Formation is only 15 m thick, of which the bottom 8 m is a basal conglomerate. The remainder consists of lightcoloured quartz-rich cross-bedded sandstone with conglomerate layers. It is a shallow marine unit, probably deposited in the inter-tidal zone, and represents a transgression over basement. Charlesbreen Subgroup Broggertinden Formation (Northern Oscar II Land).

The Broggertinden Formation is a 350 m thick unit of sandstones and conglomerates that is correlated with the Ebbadalen Formation of the Billefjorden area. The cyclic nature of the deposits and their red colouration, the general absence of marine fossils and the rare occurrence of carbonates plus the presence of fish fragments suggest fluvial deposition. Current directions are variable. They are from the south and east at Scheteligfjellet, but the regional drainage pattern must have been towards the south if the Petrellskaret Formation is coeval. Stratigraphic relationships across the Kvadehuken Fault indicate that uplift occurred to the east of the fault during deposition.

Petrellskaret Formation (Southern Oscar II Land).

This formation consists mainly of shales and mudstones approximately 350 m thick. The generally fine character of the formation, the purple colour, calcareous nodules and rarity of marine fossils suggest deposition on a coastal alluvial plain with a dominance of overbank sediments, or perhaps an interdistributary bay. The sandstones, with their well-defined upward-fining and sharp bases could be crevasse-splay deposits. There was some marine influence at the base, where limestone and evaporites occur, and again near the top, so the area must have been marginal to the sea, allowing occasional marine incursions and deposition of limestones and evaporites. The dark shales at the top may be lacustrine or lagoonal.

CARBONIFEROUS AND P E R M I A N HISTORY OF SVALBARD

Scheteligfjellet Formation (Northern part of Western Basin). This formation consists of carbonates, calcareous sandstones and conglomerates forming sequences up to 150m thick. The formation must represent a marine transgression into the area. The absence of lime muds, the abundant coral growth and the frequent signs of local erosion are evidence of shallow agitated water (Holliday, 1968). A nearby landmass is indicated by the presence of sandy beds and pebbles in the limestones. The basal conglomerates could be littoral deposits. Holliday interpreted them as intertidal. Barbaroux (1968) recorded current directions from his 'Leinstranda Formation' from the northeast and southeast. This is not inconsistent with other evidence such as the general increase in clastic content to the southeast and the presumed lateral transition to the clastic deltaic T~rnkanten Formation to the south. In general, the formation represents a nearshore, marine environment with more normal offshore marine conditions to the north. T~rnkanten Formation (Southern Oscar II Land and Nordenski61d Land). The T~rnkanten Formation is up to 250 m of mainly quartz arenites with minor conglomerate, shale and limestone. The sedimentary features and red colour of the formation imply deposition in a coastal or intertidal environment. The cycles begin with deposition of channel sandstones and conglomerates with interbedded overbank or interdistributary shales. The overlying sandstones, conglomerates and shales show more evidence of marine influence, being calcareous and containing thin limestones and rolled fossils. An intertidal situation and a hot, dry climate would account for the contorted bedding, the mudcracks and the calcareous concretions. The period of deltaic build-out may have been terminated by widespread marine transgression, or simply channel-switching, allowing the deposition of fully marine fossiliferous limestones before a further clastic influx.

Treskelen Subgroup Hyrnefjellet Formation (inner Hornsund in south Spitsbergen). Exposed throughout the Hornsund area, the Hyrnefjellet Formation is variable in thickness from 30m to 500m. It is dominated by red-beds, mudstones, sandstones, conglomerates and breccias. The formation represents fastflowing alluvial-fan/fluvial sediments deposited under continental oxidising conditions in a warm, arid climate, on a pediment of deeply weathered and eroded Adriabukta Fm. The increase in rudites to the west and palaeocurrent measurements suggest that sediments were derived from an uplifted landmass in that direction (Gjelberg & Steel 1981; Birkenmajer 1984) which exposed pre-Devonian and possibly Devonian rocks. Lack of plant remains or coal point to a warm, arid climate. Such conditions favour accelerated diagenesis with migration of silica, and precipitation of iron oxide. Carbonates and sulphates were deposited as cement during early diagenesis, mainly in the upper part of the formation. This has a significance for correlation, as Bashkiria~Moscovian evaporites occur associated with redbed conglomerates in central Spitsbergen, in the Pyramiden Conglomerates (Ebbadalen Formation). In view of the contrasting intercalations of mature sandstone, and also the fact that littoral marine conditions prevailed in the overlying Treskelodden Fm, they were probably marginal to a shelf sea. The red colouration suggests a continental or marginal marine environments. Steel & Worsley (1984) regarded them as alluvial deposits which built out eastwards from the Hornsund High into a marine sedimentary basin, the Inner Hornsund Trough, which is largely concealed by younger rocks. The basal breccia-conglomerates probably represent debris-flow; the sandstone clasts appear to be intraformational, while the quartz pebbles are probably recycled. The sandstone-conglomerate cycles represent distributary channels and the siltstone-shale facies represents overbank deposits. A major distributary channel has been recognized at Urnefjellet (Birkenmajer 1984), characterized by the predominance of conglomerates over sandstones and overbank facies, the latter forming a substantial part of the sequence around Adriabukta and north of Hyrnefjellet. Each cycle was interpreted by Gjelberg & Steel (1981) in terms of gradual alluvial fan-gravel outbuilding over an alluvial coastal plain, followed by sudden marine transgression, which reworked the surface of the alluvial fan to form a thin quartzitic beach-capping. Birkenmajer (1984) interpreted the pale quartzitic sandstones as point-bar deposits. Clastic marine sediments increase in volume upwards towards the overlying Treskelodden Formation. The cyclicity is interpreted as sudden basin-floor lowering against the basin's boundary faults, resulting in marine transgression, with subsequent alluvial fan outbuilding. The mass flow conglomerates in the south suggest a fault line south of Adriabukta, probably part of the Adriabukta Fault Zone between the Inner Hornsund Trough and the Hornsund High.

Landnordingsvika Formation (Bjornoya). The formation is the lowest part of the Gipsdalen Group in Bjornoya, and as elsewhere it is marked and indeed

321

characterized by the appearance of red-beds up to 145 m thick. The red colouration and upward-fining cycles with calcrete and mudcrack development suggest deposition on an alluvial plain in semi-arid conditions. A coastal situation is indicated by the appearance of marine fossils and limestones towards the top. Analysis of cross-bedding indicates that the rivers were northward flowing and sinuous, giving a variety of current directions. Conglomeratic alluvial fans built out eastwards in the middle part of the formation, probably as a result of movements along the West Bjornoya Fault Zone. A source to the south is also suggested by the more distal nature of the sediments in the north. These are less conglomeratic and represent a prograding sandy shoreline, with tidal flat and lagoon deposits interdigitating in the upper part in a transition to the overlying Kapp K~re Formation. Gjelberg (1981) and Gjelberg & Steel (1983) showed the formation to consist of a variety of facies sequences ranging from floodplain facies which dominate in the lower part, through alluvial fanglomerates to tidal flat and coastal lagoonal sequences, followed by foreshore-shoreface and carbonate facies. One of the latter has been interpreted as lagoonal, protected behind a barrier, where solution and fresh-water diagenesis could occur (Gjelberg & Steel 1983).

Kapp K~re Formation (Bjornoya). The formation is a carbonate-dominated unit up to 170m thick. The formation was deposited in tidallyinfluenced marginal marine environments varying from lagoonal to open marine. The two lower members show the continuing effects of the regional transgression, heralded by the sequences in the upper parts of the Landnordingsvika Formation, with a transition from clastic to carbonatedominated sedimentation and a generally upward-fining trend, resulting from an ongoing regional rise in sea-level. The rhythmic sequences of the lower member, with their faunas indicative of a variation between marine and brackish water, may represent minor deltaic progradations. The good state of preservation of the corals implies little transport or reworking. The entire Bogevika Member reflects deposition in a marginal marine environment with repeated shoreline progradations and sub-aerial exposure. The abundant discontinuity surfaces suggest that the ryhthmicity may be due to the local tectonic activity. The few variable palaeocurrent measurements obtained may reflect both longshore and bimodally directed on/offshore tidal currents (Worsley et al. 1987). Microfacies and fauna suggest that the Efuglvika Member carbonates were deposited under more constant marine conditions, on a carbonate shelf of moderate depths, but intermittent periods of erosion and emergence, probably due to fault movements, must have occurred to produce the karst and discontinuity surfaces. The directional trends of the karst features and the chert dykes suggest that this tectonic activity was related to the new basinal pattern clearly seen in the overlying units. The intraformational conglomerates of the Kobbebukta Member have been interpreted as both sub-aerial and submarine debris-flows, triggered by syn-sedimentary faulting immediately to the east of the present exposures of the Kobbebukta and Efuglvika members (Bjoroy, Mork & Vigran 1983). This is considered to be a major new lineament through the east of the island, producing inversion of parts of the previous basins (Worsley 1985, 1988). Kapp Hanna Formation (Bjornoya). The Kapp Hanna Formation is a predominantly arenaceous unit. The unit represents marine, near-shore environments associated with coastal and floodplain deposits, which are the result of alluvial fan progradation into a marginal marine environment. The sedimentology is complex: marginal marine, tidal flat and lagoonal sequences were eroded by westward-flowing rivers which deposited alluvial fan and channel complexes of thick sandstones and conglomerates. These show debris-flow and braided river characteristics (Bjoroy et al. 1983; Agdestein 1987). Better-sorted intertidal and beach sediments contain clayclasts, desiccation cracks, marine fossils, bioturbation, lenticular and flaser bedding and have bimodal cross-bedding directions (Agdestein 1987). The fossils in the shales suggest deposition in brackish lagoons subject to periodic marine incursions. Fault movements both increased the clastic input and changed relative sea levels, causing either progradation (upward-coarsening) or marine transgression (upward-fining) on the NNE-SSW-trending shoreline, depending on which factor was dominant. Palaeocurrent data from the coastal alluvial clastics clearly indicate an eastern source area and Bjoroy et al. (1980) postulated uplift east of a NE-SW trending lineament intersecting the area, with erosion of Early Mississipian and older rocks. The mineralogy of the clastics suggests that the present day-exposure patterns of Carboniferous and earlier rocks on Bjornoya were largely established during the deposition of this formation, rather than in subsequent Permian tectonism. The existence

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C H A P T E R 17

of this upfaulted block in eastern Bjornoya was first recognized in the uppermost Kobbebukta Member of the underlying formation. The unconformities and erosion surface suggest that this movement continued sporadically during deposition of the Kapp Hanna Formation. The in filled fissures may be evidence of syndepositional earthquakes. Greater stability, coupled with decreasing elastic supply, resulted in an overall upward-fining trend and the establishment of a stable shelf environment.

17.5.3

Kasimovian-Gzelian-Asselian--Sakmarian deposition (middle Gipsdalen Group)

C a r b o n a t e s d o m i n a t e the m i d d l e o f the G i p s d a l e n G r o u p , deposited in w a r m shallow seas. In s o u t h e r n Spitsbergen, cyclic s a n d y deltaic facies are interspersed a n d locally s u l p h a t e s occur.

Dickson Land Subgroup Wordiekammen Formation.

The lower part of the formation comprises the laterally equivalent Cadellfjeilet Member (Billefjorden Trough), Kapitol Member, and Morebreeu Member (Oscar II Land) the former two being overlain by the Tyrrellfjellet Member in the central and western basins of Spitsbergen (Nordfjorden Block). The Cadellfjellet and Kapitol members consists of a sequence of Late Carboniferous limestones (locally dolomitic), occurring widely across Oscar II Land, James I Land, Dickson Land and Btinsow Land. It reaches 200m thickness in the Billefjorden area. The formation represents quiet, stable marine shelf conditions of normal salinity with the deposition of lime muds. Terrestrial influence increased to the east towards a presumed land area, where coarser-grained, recrystallized limestones occur and become sandy, passing into calcareous sandstones. Conditions of high salinity were locally reached in this region with gypsum deposition, perhaps in coastal sabkhas. Primary dolomite may have been formed locally. TyrrellfjeUet Member (Central and Western Basin of Spitsbergen), 160 m. The Tyrrellfjellet Member is a widely developed carbonate sequence of Early Permian (Gzelian-Asselian-Sakmarian) age, occurring at the top of the otherwise Carboniferous Wordiekammen Formation. There appears to have been minor uplift of the entire area around the Carboniferous-Permian transition, resulting in the widespread development of discontinuity surfaces and intraformational conglomerates, probably on reef margins. Renewed transgression led to the establishment of open marine environments with shelf carbonate deposition. Some restriction of circulation may have led to the deposition ofdolostones, especially in the upper part of the formation. In the northwest, there is much primary lagoonal dolomite, perhaps indicative of a nearby landmass. However, dolomitization is clearly secondary in many areas. To the east and north, increased sandstone content indicates terrestrial source areas. Although there are no significant thickness variations over the margins of the blocks which dominated Carboniferous palaeogeography, shoals and bioherm buildups still tended to develop at those sites suggesting continued subtle controls on sedimentation by downwarping along their boundary faults. The bioherms, which were described from the lower part by Skaug et al. (1982), extend from the eastern margins of the Nordfjorden Block, across the Biflefjorden Fault Zone and several kilometres out into the Billefjorden Trough. They formed an effective barrier to open marine conditions allowing lagoonal environments and dolomite deposition to develop behind them. Hardgrounds have been described at the base of each bioherm, showing signs of freshwater leaching and palaeosol development considered to have been formed in an intertidal environment. This environment is consistent with the presence of desiccation cracks and intraformational conglomerates elsewhere. They show regressive cycles with hardground development at the top prior to a transgressive biostrome build-up phase. Idunfjellet Formation (Nordaustlandet). Up to 150 m thick, the formation consists of limestones and dolostones with minor sandstones. The fossil content indicates an open marine, carbonate shelf environment with input of terrigenous quartz at both top and base. There is evidence of shallowing, with numerous erosive surfaces and intraformational conglomerates in the upper part. Diametrically opposed cross-bedding suggests a tidal influence. Dolomitization appears to be secondary. The chert nodules in the upper part could indicate an originally evaporitic environment, as they are similar to gypsum and anhydrite nodules which occur elsewhere in Svalbard (Lauritzen 1977). There is now no trace of sulphates, but the nodules may

indicate supratidal conditions. Gypsiferous layers also occur in the eastern outcrops of the Cadellfjellet Formation. Micritic and shaly beds point to low-energy, protected situations.

Treskelodden (Reinodden) Formation. Its thickness is variable and reaches 200 m in places. (a) Hornsund. Both marine and continental environments have been recognized in this 185cm thick formation (Birkenmajer 1979c, 1984d; Fedorowski 1982). The cyclic carbonates and elastics of the upper part, following the conglomeratic lower part, suggest a fan-delta system prograding into the sea, presumably from the margin of the Hornsund High (Kleinspehn et al. 1984; Birkenmajer 1984c; Steel & Worsley 1984), though Birkenmajer's current directions imply a predominantly easterly source. Birkenmajer recognized a basal unfossiliferous alluvial facies that is overlain by shallow marine facies. The former has distributary channel deposits (sandy conglomeratic channel bars and conglomeratic channel lags) containing wedge-shaped and planar cross-bedding and alluvial delta (overbank) deposits of clay, shale and siltstone with subordinate crevasse-splay sandstone. The succeeding subtidal to intertidal facies is fossiliferous and contains sandy offshore bars and a probably submerged delta, (cross-bedded and rippled), tidal channel fills (conglomerate and sandstone) and carbonate platform sediments (mainly subtidal calcarenites and arenaceous limestones). Interspersed are lagoonal facies deposits of carbonate-rich elastics and unfossiliferous carbonate (dolostones and dolomitic limestone), the fills of restricted basins, which may have been hypersaline. Above the first cycle, which is alluvial, are four cycles starting with tidal channel and shallow marine deposits (conglomerate and biogenic limestones) that cut into the top of the preceding cycle. These show more alluvial characteristics upwards with evidence of emergence at the tops of some cycles (mudcracks) which, associated with finer sediments, correspond to overbank and lagoonal deposits. There is an increasing marine influence higher in the sequence as the tectonic environment stabilized. There is evidence from the abundant coral fauna for warm, shallow seas. The fauna were redeposited under the high-energy conditions prevailing during deposition of the calcites, with submarine erosion and channelling by tidal currents. Palaeocurrent measurements are variable and indicate sources of alluvial elastics to be lying mainly to the east, but also to the west (Birkenmajer 1984c). The quartz conglomerate noted south of Hornsund at Bautaen was derived from the east (Gjelberg & Steel 1981) and may be a beach deposit. The major cycles could be eustatic, but could equally be a result of distributary channel switching. (b) Bellsund (e.g. at Reinodden). Nysaether (1977) concluded that the cyclic nature of the Reinodden Fm was probably due to fluctuations in sea level (cf. the palaeoaplysinid bioherm regressive sequences in the Tyrrellfjellet Fm to the north) rather than deltaic influence as there is no evidence of channels. Worsley (Aga et al. 1986) regarded fan-delta systems to be responsible for the elastic input, derived from the Hornsund High. Some sequences in the Bellsund area show cross-bedding which suggests input from the eastern margin of the basin. At Kopernikusfjellet, the thin, entirely conglomeratic sequence is interpreted as forming on top of the Hornsund High. The carbonates clearly indicate open shallow marine conditions, while the terrigenous elastics were probably deposited in a nearshore, paralic environment. Some beds may represent partly reworked fluvio-deltaic sediments. As the dolostones contain abundant corals in the middle unit, the dolomitisation was probably early diagenetic, following the regressive phase after the deposition of the carbonate, which may have created restricted lagoonal environments in the nearshore area, with deposition of sulphates before the advance of terrigenous deposits (Nysaether 1977). Northwards there is a progressive decrease in elastics with a transition to the Tyrrellfjellet Mbr. The conglomerates may be littoral.

Kapp Dun6r Formation (Bjornoya).

Consisting mainly of dolostones and fusulinid-rich limestones, sequences of the Kapp Duner Formation reach 75 m. The formation was deposited during a time of stabilisation and postrift subsidence, following Carboniferous tectonic activity. This resulted in the establishment of a marine shelf, containing open to restricted environments, allowing the deposition of carbonates characterized by bioherms, biostromes and patch reefs (Agdestein 1980). Several karst surfaces indicate periods of sub-aerial exposure which probably resulted from small fluctuations in sealevel. The dominantly dolomitic nature of the carbonates suggests deposition under conditions of high salinity for much of the formation. Folk & Siedlecka (1974) distinguished petrographic characteristics, such as very finely crystalline penecontemporaneous dolomite and replaced sulphate nodules with a fibrous texture, authigenic length-slow chalcedony and sulphate inclusions, which they interpreted as being indicative of a

CARBONIFEROUS A N D P E R M I A N HISTORY OF SVALBARD hypersaline evaporitic environment. Other petrographic evidence suggests the presence of fresh water during cementation and the diagenetic history of the lower part of the formation supports evidence of the schizohaline environments of fluctuating salinity as presented by Siedlecka (1972, 1975), Folk & Siedleck (1974) and Adgestein (1980). This may have developed by the periodic flooding of an evaporitic lagoon or sabkha by rain, or by diagenesis within a zone of fresh connate water. The occurrence of evaporites and length-slow chalcedony (typical of evaporite environments) indicates a hot dry climate and partial sub-aerial exposure. However, the palaeoaplysinid build-ups and the rich fossil content of many of the carbonate rocks indicate that normal marine conditions with shallow-water carbonate deposition was prevalent for some of the time, and that some of the dolomitisation, at least, is secondary. These reefoid structures have a markedly lenticular form, with long axes parallel to the temporary quiescent NE-SW-trending fault lineaments on Bjornoya which can be compared with the relationship of similar build-ups to the Billefjorden Fault, seen in the Tyrrellfjellet Member of central Spitsbergen (Aga et al. 1986). Faulting, flexuring and erosion followed, to produce a gentle anticlinal structure. This occurred contemporaneously with Early Permian regression and deposition of dolomites and sabkha evaporites elsewhere in Svalbard (Aga et al. 1986).

17.5.4

Sakmarian-Artinskian deposition (upper Gipsdalen Group)

C o a s t a l c a r b o n a t e s , e v a p o r i t e s a n d m i n o r s a n d s t o n e s are typical o f this interval in S p i t s b e r g e n a n d N o r d a u s t l a n d e t . In B j o r n o y a shallow m a r i n e limestones follow s a n d s t o n e s , transgressive o n e r o d e d limestones o f the u n d e r l y i n g K a p p D u n t r F o r m a t i o n .

Dickson Land Subgroup Gipshuken Formation (throughout Spitsbergen Basin and eastwards into Nordaustlandet). Present across much of western and central Spitsbergen, the Gipshuken Formation is 150-250 m thick, consisting mainly of carbonates and evaporites with minor quantities of sandstone. North of Isfjorden, in the Dicksonfjorden and Billefjorden area, stacked sabkha cycles occur, described by Holliday (1966, 1967, 1968a, b) and Lauritzen (1981). They suggested a coastal environment that was maintained for a considerable time with alternations of regressive periods of evaporite formation and periods of intertidal deposition, which allowed the deposition of a substantial thickness of evaporite-dominated sediments. It is evident from the succession that marine flooding took place, probably as a result of storms and relative sealevel changes, causing erosive surfaces, ripples, cross-bedding and oolites which are all indicative of stronger currents, and may represent tidal channels in the lagoon. The nodules and interbeds of evaporites which occur in the dolostones of the upper part in the Dicksonfjorden area, although not dominant, are considered by Lauritzen to represent shorter sabkha events in a more marine-influenced environment. Even though dolomitization is extensive throughout the succession, widespread algal lamination can still be seen, showing algae to be an important constituent of the dolomicrite. Early diagenetic dolomitization is characteristic of supratidal coastal sabkhas (Kinsman 1969). Once shoreline regression occurs, evaporitic minerals are deposited in the upper part of the marine wedge and dolomitization of the finegrained carbonate sediment takes place. In this process, calcium ions are released, causing the precipitation of more gypsum or anhydrite. The dolomicrite lithology suggests deposition mainly in lagoons, but more open marine carbonates with corals are also found. Grain-supported carbonates reflect deposition in agitated environments such as channels or areas bordering the lagoons. Replaced aragonite needles suggest lower intertidal or submarine cement (Lauritzen 1981). The cyclic, algal-laminated sediments seen in Nordaustlandet are also interpreted as representing a lagoonal environment, with the intraformational conglomerate beds representing tidal channel infills within this environment (Lauritzen 1981). These lagoonal environments pass upwards and laterally into a more open marine shelf carbonate zone, perhaps reflecting a marine transgression. Lauritzen (1981) discussed the origin of the sulphates and considered that at least some of them may have a diagenetic origin as sulphate crystals have commonly been observed growing at the cost of dolomite, though also vice versa. Gypsum is replaced by anhydrite at depth and was probably originally deposited as anhydrite (as there is no deformation of the host rock, which would occur on dehydration of gypsum) with its origin in brines produced by evaporation of sea water or ground water. Lauritzen concluded that the evaporites could have originated in three ways:

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(i)

primary precipitation from standing water (probably the case in the laminated and bedded anhydrites); (ii) precipitation within the vadose zone, which produces the chicken-wire structure found in the regular beds; (iii) as a later stage diagenetic product formed by solution of pre-existing rocks; (the Kloten Breccia may have provided a source, see below); the infilling of cracks, fissures and stylolites may be the result of such diagenetic mineralization. Arenaceous facies, which appear locally in northern Torell Land, probably indicate proximity to the Hornsund High. Brecciation may have occurred as a result of solution of evaporites interbedded with the dolomites, followed by collapse. The cellular type of breccia may have been formed by solution and the volume change on hydration of anhydrite, which does occur as interbeds in the lower twothirds of the formation. The brecciated sequences in western areas occur in close association with sabkhas and are thought to represent early to mesogenetic solution and collapse phenomena. At other localities, especially in thick sequences along the Billefjorden Fault Zone and in thinner, but characteristic, beds in eastern Svalbard, they may represent primary depositional features. Possible origins include downslope movement following early lithification on organic build-ups to form brecciated flank facies and/or debris flows associated with minor movements on lineaments. The Zeipelodden Member seems to represent intertidal to supratidal environments, characterized by the growth of algal crusts and mounds (Lauritzen 1981). The mixture of white chert and calcite found within is interpreted as remnants of sulphates representing periods of deposition of evaporites that were partly dissolved during periods of flooding, and which resulted in the formation of solution breccias. The pattern of dolomitization in the massive breccias indicates that some dolomite was present before brecciation and that dolomitization continued after brecciation. Before brecciation, these rocks probably consisted of unlithified, partially dolomitized limestone, but the presence of primary dolomite cannot be ruled out. Karstification was reported from Mathiesondalen by Salvigsen, Lauritzen & Mangerud (1983).

Hambergfjellet Formation (Bjornoya). As in the Miseryfjellet Formation, this unit is dominated by limestone except for sandstones at the base. The unit is approximately 100m thick. This thin, easterly onlapping clasticcarbonate wedge covered part of the now peneplaned anticlinal structure formed after the deposition of the Kapp Dun+r Formation. The arenaceous deposits at the base of the formation are typical of a marine transgression following a period of erosion. Periods of emergence are indicated by the root horizons, calcretes and karst surfaces. The overlying carbonates indicate a shallow-marine environment. This probably resulted from the same rise in sea level which produced the open marine carbonates at the top of the Gipshuken Formation in southern areas of Spitsbergen, east of the Hornsund High. Terrestrial influence is smallest at the top of the formation.

17.5.5

Kungurian-Guadelupian deposition (Tempeffjorden Group)

The Tempelfjorden Group clastics a n d c a r b o n a t e s .

is characterized by s h a l l o w - m a r i n e

Kapp Starostin Formation (throughout Spitsbergen except Sorkapp Land). The Kapp Starostin Formation is the main unit of the Tempelfjorden Group. The type section is at Kapp Starostin (Festningen), Nordenski61d Land, where the formation is up to 412m thick. The formation rests disconformably on carbonates, evaporites and siliciclastics of the Gipsdalen Group and is unconformably or disconformably overlain by the Vardebukta Formation of the Triassic Sassendalen Group. It comprises three principal members. The (basal) Voringen Member is a coarse, sandy bioclastic limestone. The (middle) Svenskeegga Member is a complex facies mosaic of mudstone, chert, glauconitic sandstone, silicified limestone and limestone. The (upper) Hovtinden Member includes mudstone, chert and glauconitic sandstone. Current investigation by CASP (D. I. M. Macdonald pers. comm.) postulates five major facies associations: (i) basal karst and associated facies; (ii) basal limestone facies association; (iii) black shale facies association; (iv) spiculite facies association; (v) sponge-bryozoan facies association. As this study is in progress and publication is not imminent, the following descriptions are based on available literature and checked for consistency by D. i. M. Macdonald. Ezaki, Kawamura & Nakamura (1991) made a detailed study of facies and

324

CHAPTER 17

fauna of the succession at Festningen, especially with regard to changing water depths and transgressive-regressive cycles. The formation was deposited in a broadly trangressive setting, although there are reversals of this trend. Nearshore to shallow-water marine facies characteristic of the base are replaced upwards by open marine facies, with a shift of sedimentary environments southwestwards with time as the Hornsund High became partly submerged due to deposition of the Hovtinden Member (Nysaether 1977). Glauconite is a distinctive constituent of the formation, except for the Voringen Member, and was found by Siedlecka (1970) in almost all the thinsections she examined, generally less than 3% in the mode, but occasionally up to 25 %. Much of this occurs as grains which could have been redeposited (some patchy distribution of quartz and glauconite grains suggests local accumulations), but some is undoubtedly authigenic (e.g. infilling sponge spicules) and the conditions of sedimentation must have been suitable for the formation of this mineral, which has the following specific requirements (Cloud 1955): marine environment of normal salinity; slightly reducing conditions (perhaps due to the decay of organic matter present); water temperature averaging 14-15~ rather slow sedimentation, in a depth of between 15 and 500m. The origin of the silica is probably the dissolution of sponge spicules, remnants of which are seen to be abundant in some thin sections, commonly forming up to 75% of the rock matrix (Nysaether 1977). It was precipitated in pore spaces except in those limestones which were cemented early on by calcite. The chert bands and nodules which occur in the fossiliferous biosparites are of diagenetic origin, while the massive chert interbedded with the shales represents deposition in a more basinal environment and has been regarded as the product of primary silica precipitation under semi-stagnant, slightly reducing conditions (Siedlecka 1970). However, much of the massive chert is calcareous, so may be diagenetic, replacing carbonate. The distribution of siliceous and calcareous sponges has been used in Permian basins of the USA as a bathymetric indicator (Worsley in Aga et al. 1986); siliceous sponges suggest water depths in excess of 200m. The abundance of these sponges indicates relatively cool, deep shelf environments. The massive chert bodies are interpreted as being sponge build-ups (Steel & Worsley, 1984). There are two facies associations (dominated by shale and chert) in the Hovtinden Member: (i) shale with sponges also corals, crinoids and bryozoans; (ii) shale and sandstone with Zoophycos and rare glauconite in the sandy beds (D. I. M. Macdonald pers. comm.). The Zoophycos was noted by Worsley (Aga et al. 1986) and the thin-shelled brachiopods and well-preserved sponges (Hurcewitz, 1982) indicate relatively quiet water, offshore, well below normal wave base, with low rates of sedimentation. An abundance of skeletal debris, some in life-position and burrows that penetrate the glauconitic sand, point to oxidizing conditions during deposition, though slightly reducing conditions, probably associated with organic matter, must have existed, perhaps just below the surface, for the glauconite to form. It was thus a deeper-water shelf facies which prevailed in the central part of the basin. However, the occurrence of thick, crossbedded, sandy units within the 'basinal' facies suggests shallower water. The Svenskeega Member breccia points to a local palaeoslope in the Tempelfjorden area which allowed a gravity slide to occur, possibly at the boundary between shallow and deeper water facies, and also to early silica diagenesis. The carbonate facies represents well-oxygenated water on shallower parts of the shelf. There is an abundance of large, broken fossil fragments which must have been redeposited locally, perhaps from attempts at early build-ups (Siedlecka 1970 referred to patch reefs). Shallow-marine conditions were widespread during deposition of the Voringen Member in Kungurian time. The bioclastic arenaceous facies is interpreted as representing a sublittoral shelf environment with terrigenous sediments, influenced by strong wave action and bottom currents. The sands represent shallow migrating shoals and banks. Benthic fossil fragments are generally large and angular, so have not been transported far. The sandstones of the northwest reflect relatively low rates of deposition in intermediate water depths. The southwestern basin margin shows a major upward-coarsening silt to sandstone sequence which thins rapidly westwards onto the Hornsund High. In the Hornsund region, a very thin sequence of open-marine and intermediate shallow-water siltstone facies is underlain by the transgressive basal conglomerates which lie on different units of the Treskelodden Formation, infilling karst surfaces in the limestones. At Austjokeltinden, the repeated occurrence of conglomerates and lag deposits of abraded phosphatic nodules suggest an extremely condensed sequence with a complex history of burial, exhumation and reworking of fossil shells. Other sections, although

only a few metres thick, contain fine-grained limestones with textures and ichnofossils that suggest deposition in low-energy environments. This area would thus seem to be near the eastern margin of the Hornsund High which seems to have been emergent until the Triassic Dienerian stage (Hellem & Worsley 1978), though facies patterns in adjacent areas may indicate that it was submerged in the transgression at the base of the Templefjorden Group then subsequently uplifted again (Worsley in Aga et al. 1986). Thus, shallow-marine conditions extended across the basin with deposition of transgressive deposits at first in Kungurian time, before a general deepening in the Isfjorden Basin, when the marginal facies became restricted to the north and south, nearer the land areas of the Northern Block and the Hornsund High. A regression led to the encroachment of glauconitic sandstone during the Ufimian stage, especially from the northwest, and latest Permian time is marked by an apparent hiatus, with the absence of identifiable Wordian, Capitanian or Lopingian strata, due either to marine regression or non-deposition. Across much of Spitsbergen, basal Triassic strata overlie Permian rocks without apparent unconformity, although there is a sharp change in lithology. No conglomerates are found in basal Triassic rocks, except in southern Spitsbergen, where there is a strong unconformity on the Hornsund High, indicating continued uplift of this area. Gruszczynski & Malkowski (1987) reported stable isotope records of the Kapp Starostin Formation which was discussed by Malkowski, Gruszczynski & Hoffman (1991). However, Mt~, Grossman & Yancey (1997) questioned part of their result as 'diagenetic artifacts' but concluded that a Kazanian-Tatarian 613C maximum of 7.5% is substantiated and represents the highest specified Phanerozoic values and probably correlates with a similar maximum in East Greenland and in northwestern Europe. The shift was thought to reflect global storage of organic carbon by Late Permian coal volume changes.

Tokrossoya Formation (Sorkapp Land).

In southwestern Sorkapp Land this formation replaces the Kapp Starostin Formation, with which it has many similarities. It is at least 400 m thick. In western Sorkapp Land there is a thick upward-coarsening sequence. Although the base is not exposed, spiculitic shales and siltstones grade upwards into sandstones interpeted as shallow-marine sand wave deposits (Worsley in Aga et al. 1986). The coarser units seem to thin southwestwards away from the Hornsund High. However, these exposures are highly tectonized and may not be in their original position in relation to the High. A fault separates them from the rest of the Permian outcrop. The Upper Member represents a shallowmarine marginal environment which points to the existence of land nearby whereas the Lower Member represents deeper, quieter basinal conditions. The facies are the same as those found further north, but there has been an increase in thickness in this area, possibly accommodated by a Late Permian fault bounding the Hornsund High to the northeast.

Miseryfjeilet Formation (Bjornoya). This formation is l15m at its type section, where it consists almost entirely of limestone except for sandstones at the base. It is evident that a mid-Permian transgression covered an uplifted and peneplaned surface, submerged after the cessation of earlier tectonic activity, but still a positive structure (Hellem 1987). The sedimentary environment of the unit has been discussed in detail by Siedlecka (1975) and Hellem (1987). In general, the arenaceous biosparites indicate a high energy basin margin environment under shallow marine conditions of lower shoreface and offshore shelf above wave base. The basal arenaceous strata are transgressive littoral and barrier deposits, and Siedlecka has inferred from the bimodality of some of these sands that they are reworked aeolian sands. The latter may have been reworked and incorporated, along with bioclastic debris into the carbonate sands of the shelf. The cross-bedded sandstone body on Miseryfjellet may be an offshore sandbank with cross-bedding directed shorewards i.e. to the southeast (Worsley & Edwards 1976). Hellem (1987) considered it to be a regressive sequence, representing shoreface and foreshore deposits. The formation may represent a southern marginal facies of an extension of the Spitsbergen Basin, beyond the Hornsund High, referred to as the Bjornoya Basin, where the rocks are in marked contrast to the spiculitic cherts which dominate the Templefjorden Group of the Spitsbergen Basin.

17.6

Carboniferous and Permian fossil record

T h e variety o f facies in S v a l b a r d at different times t h r o u g h this interval o f nearly 120 million years precludes a full r e c o r d o f t h e progress o f life. Nevertheless the fossil r e c o r d is rich as is e v i d e n t

CARBONIFEROUS AND PERMIAN HISTORY OF SVALBARD

325

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326

CHAPTER 17

from the selection of palaeontological studies noted in Fig. 17.6. Until recently, the conspicuous macrofossils and the routine micropalaeontological investigations have consumed resources to the exclusion of knowledge of other elements in the global biota, or perhaps the environments for life and preservation have in each case been sufficiently extreme for the fossil record to give a limited picture of life at that time and place. For example little, if anything, has been recorded concerning microbial life. Lacking distal marine shaly facies there is little record of vertebrates, ammonoids or other cephalopods. Trace fossils are rare except in some bioturbated Kapp Starostin facies (Zoophycos was mentioned by Worsley in Aga et al. 1986). Figure 17.6 gives an indication of the range of fossils recorded.

17.6.1

Plant life

After late Devonian colonization of continental environments by primitive land plants, Carboniferous vegetation quickly achieved a rich diversification. Svalbard records are limited to the deltaic environments of the Tournaisian through Serpukhovian epochs; but Svalbard has the advantage of preserving earliest Carboniferous floras following directly on latest Devonian, whereas in many parts of the world the typical 'coal measure' environments came later.

Maerofloras. The macroflora as described by Nathorst in several papers (e.g. 1900) is dominated by pteridophytes, with Equisetales, notably Calamites pith casts, and many arborescent lycopod genera including several species of Lepidodendron, also Bothrodendron, Cyclostigma, Lepidophloios, Archaeosigillaria, Sigiilaria and Stigmaria. There is a similar diversification of pteridosperms with fern-like fronds of Sphenopteridium, Sphenopteris, Cardiopteridium and several other genera. Seward (1931) pointed out that the Early Carboniferous foras (of which the Svalbard record was certainly the best known) has affinities in the southern hemisphere. This contrasts markedly with the widespread records of Late Carboniferous and Permian floras in which there is a reduction in the diversity of species coupled with a Tethyan barrier between the northern (Laurasian) flora and the distinct Glossopteris flora of Gondwana. Of these events Svalbard tells us little. Nathorst (1920) described three separate floras from the Orustdalen Formation of Bellsund (Billefjorden Group) Forbes, Harland & Hughes (1958), on the basis of correlation with Dinantian floras of Scotland (e.g. Cyclostigma and Lepidophloios scoticus) concluded that the Billefjorden Group spanned much of Russian Early Carboniferous time and did not correlate with the immediately preceding Devonian flora of Bjornoya. They noted the absence of the supposedly Devonian 'Ursa Flora' of Bjornoya, and the presence of some forms not known below earliest Namurian time elsewhere, such as Stigmaria rugulosa. This 'Ursa Flora' has been shown by Kaiser's work on spores (1970, 1971) to span the Devonian-Carboniferous boundary and on the basis of lycophyte species present, a floral break has been recognized by Schweitzer (1967, 1969) between the Vesalstranda Member and the Tunheim Member. The Vesalstranda Member alone contains ?Cyclostigma brevifolium and Sublepidodendron isachensii. Pseudolepidendropsis carneggianum is exclusive to the Tunheim Member. Cyclostigma kiltorkense occurs in the upper Vesalstranda Member and also in the Tunheim Member.

Microfloras. Inevitably the reproduction of the macroflora resulted in rich palynological material so that some Billefjorden Group rocks have proved productive. (a) Palynomorphs. Hughes & Playford (1961) and Playford (1962, 1963) recognized two distinct palynomorph assemblages defining the rarituberculatus and aurita zones. (i) The index species of the rarituberculatus assemblage, Lophozonotriletes rarituberculatus and others are characteristic of

Tournaisian strata in Russia. Playford quoted sixteen species which do not occur before the Tournaisian, and hence concluded an exclusively Tournaisian age for the assemblage. However, publication of Van Veen's evidence for a Late Famennian age of the lower H6rbyebreen Formation in Central Spitsbergen is awaited. (ii) The aurita assemblage is marked by a complete absence of specifically Tournaisian forms. It conforms closely with microfloras reported from Visean strata of the Russia, and in some respects can be correlated with the Lower-Middle Chesterian stage of Canada. Some Serpukhovian (Namurian) forms appear towards the top of the zone, and Playford concluded that the assemblage has a Visean age, possibly extending to Early Serpukhovian. (b) Spores. Bharadway & Venkatachala (1961) and Dettmann & Playford (1963) described spore assemblages from the Mississippian of Spitsbergen. Four spore assemblages have been recognized in the terrestrial Roedvika and Nordkapp Formations of Bjornoya as a result of the work of Kaiser (1970, 1971), which have proved more useful than the macroflora. A distinctive, purely Devonian, assemblage in the Vesalstranda and lower Kapp Levin members is of Late Famennian age and can be further subdivided into three, with microflora closely related to the Prolobites zone of the Russia. The second earliest Tournaisian assemblage is from the lower Tunheim Member and occurs with the 'Ursa' macro-flora described above. A Late Tournaisian assemblage occurs higher in the Tunheim Member and a Late Visean assemblage is found in the Nordkapp Formation. From less promising Permian strata Mangerud & Konieczny (1993) recognized three assemblages of palynomorphs. (1) Vittalina assemblage: latest Noginskian to mid-Asselian (2) Hammiapollenites tractiferinus assemblage: mid-Asselian to mid-Artinskian and (3) Kraeuselisporites assemblage: mid-Artinskian to ?earliest Longtanian. (c) Algae etc. Carbonate environments favoured calcareous algae. Within the Permian strata are reefs of Palaeoaplysina. They became interesting to industry because of their reefoid shape and porosity (Skaug et al. 1982). Palaeoaplysina is commonly regarded as a calcareous hydrozoan.

17.6.2

Foraminifers

Large foraminifers are easy to collect in the field and are valuable as age indicators, though correlation is difficult, because as bottom dwelling creatures they tend to be provincial. Of the potential international Pennsylvanian and Permian correlation, only Bashkirian to Early Sakmarian forms have been found in Svalbard. A zonal scheme for Svalbard was initiated by Forbes (Forbes et al. 1958) and worked out and applied by Cutbill (Cutbill & Challinor 1965). This work led to the recognition of seven fusulinid zones, five of which are Carboniferous, which were based on a very wide sampling of the group and have proved valuable for internal and external correlation. Some detail of these Carboniferous zones is given below (oldest to youngest). (1) Antiqua Zone. This zone occurs only in the upper part of the Ebbadalen Formation, where the distinctive assemblage includes Pseudostaffella antiqua and Pseudoendothyra spp. with Millerella, Eostaffella, Ozawainella and Profusulinella species occurring less commonly. Fusiform species are rare or absent. P. antiqua ranges from Namurian B to the Moscovian Vereiskiy horizon, but as fusiform species are abundant in the latter horizon, the zone probably correlates with the Bashkirian Stage. (2) Profusulinella Zone. An assemblage comprising Profusulinella prisca. P. cf. librovitchi. Waeringella eopulchra, Ozwainella mosquensis, Pseudostaffella antiqua, and P. sphaeroidea with Eostaffella, Pseudoenthyra and Eofusulina species is found in the lower Minkinfjellet and Scheteligfjellet formations. The fauna is very similar to that of the Moscovian Vereiskiy and Kashirskiy horizons. (3) WedekindeUina Zone. This zone contains a wide variety of genera, of which the typical species include Pseudostaffella

CARBONIFEROUS AND PERMIAN HISTORY OF SVALBARD

sphaeroidea., Waeringeila eopulchra, Ozawainella mosquensis, Beedeina rockymontana, Wedekindellina dutkevichi and Fusulinella boeki plus rare Quasifusulina and Schubertella species. The last three species suggest a correlation with the Moscovian Podol'skiy and Myachkovskiy horizons. This fauna is found in the upper part of the Minkinfjellet and Scheteligfjellet formations. The species Fusiella typica, Fusulina pankouensis and Waeringella usvae occur in the Jotunfonna Beds of the Kapitol Member and suggest a definite correlation with the Myachkovskiy horizon. (4) Waeringella usvae Zone. This zone is confined (by definition) to the Gerritbreen Beds. The lower part of these beds contains abundant Protriticites oratus, Waeringella usvae and Montiparus montiparus, and also Fusulina sp. The assemblage, plus Ozawaiconella, Quasifusulina and Schubertella species, indicates a correlation with the Kasimovian stage. Higher up, Montiparus unbonoplicarus, M. Paramontiparus, Tricetes rossicus and Tricetes sp. are found, which are more characteristic of the Klazminskiy horizon. Thus, the zone correlates with the Kasimovian and Gzelian stages and may be subdivisible. (5) Rugofusulina arctica Zone. The Mathewbreen Beds of the Billefjorden area are dominated by the species Rugofusulina arctica with rare Quasifusulina longissima and Schwagerina and Waeringella species. The fauna contrasts with the usvae zone beneath in being distinctly more advanced, and is correlated with the latest Carboniferous Noginskiy horizon of the Moscow Basin (formerly Orenburgian), which is now included in the top of the Gzelian stage. (6) Schwagerina anderssoni Zone. This zone, with only abundant S. andersonni, some Rugofusulinas and rare Pseudoschwagerina, was correlated with Asselian (and Early Wolfcampian). (7) Monodiexodina Zone. This has only Schwagerina in addition and is correlated with that Late Wolfcampian (Early Sakmarian) zone. The larger forams do not persist above the Tyrrelljellet Formation into the more saline Gipshuken Formation and they are thus limited to the Wordiekammen, Minkinfjellet and Ebbadalen formations. Solov'yeva (1969) described the genera Wedekindellina. Small foraminifers have received less study and are less reliable indicators of stratigraphic level. However, Soviet workers have recognized a total of twelve assemblages in Spitsbergen's Carboniferous and Permian rocks (Sosipatrova 1967). The seven Carboniferous assemblages, while not referred to any type sections do, however, confirm Cutbill's correlation with the Russian Platform. On the other hand her Permian zones extend beyond the range of the larger forams and provide an independent estimate of the age, especially of the Tempelfjorden Group, which she correlated with Russian stages. Her three latest zones correspond with the three members of the Kapp Starostin Formation thus: Hovtinden Member Frondicularia bajcurica (Early Ufmian) Svenskeegga Member Gerbelna komiensis (Late Kungurian) Voringen Member Nodosaria Longa (Early KungurianLate Artinskian). If reliable, these correlations would establish the late Permian hiatus in Svalbard as corresponding to most of the Zechstein subPeriod. Igo & Okimura (1992) made a further study of the Carboniferous-Permian foraminiferal succession. 17.6.3

Corals

Rugose corals are sufficiently conspicuous for the name 'Cyathophyllum Limestones' (Cyathophyllum Kalk of Nathorst 1910) as was used for the Tyrrellfjellet Member. Study of the coral faunas of Svalbard, possibly begun by Heritsch (1939), has indicated that this group of fossils may prove to be increasingly useful stratigraphically in the Arctic (Fedorowski 1964, 1967, 1975). However, at the present time, age correlations based on the coral assemblages must be considered as corroborative evidence only. Fedorowski concluded that both Carboniferous and

327

Permian faunas migrated to Svalbard and to the Canadian Arctic from the FSU to the southeast, where they evolved. A further study was reported by Ezaki & Kawamura (1992). Stromataporoids, of uncertain biological affinity, had the capacity to build reefs which are evident in the 'hydrozoan buildups' in early Permian strata on the Nordfjorden High and to the east (Worsley in Aga et al. 1986, p. 53).

17.6.4

Brachiopods

Brachiopods are amongst the most abundant and easy to collect of all Svalbard macrofossils and have been monographed by Wiman (1914), Stepanov (1936, 1937) and by Gobbett (1963) who reviewed the previous work and examined extensive international collections to describe 143 species of which 19 were new and many others have been recorded only in Svalbard. However, many appear to have long ranges so their correlation potential is limited. The following list gives an impression of the faunal composition. Atremata 2 spp.; Neotremata 2 spp.; Dalmanelloidea 2 spp.; Strophomenoidea 8 spp.; Productoidea 59 spp.; Chonetoidea 7 spp.; Rhynchonelloidea 10 spp.; Spiriferoidea 47 spp.; Terebretuloidea 6 spp.; of doubtful occurrence or uncertain systematic position 8 spp. Further studies have been reported by Nakamura, Kimura & Winsnes (1987) and Malkowski (1988). Most collections have come from the Spirifer Limestone and Brachiopod Chert (Kapp Starostin Formation) and this particularly rich brachiopod fauna is the most difficult to correlate. It was given the stage name Svalbardian by Stepanov (1957). Gobbett found this useful if only to label its unknown age. This uppermost Permian Formation has been characterized by its lithology and fossil content (Table 17.1) There is indeed a variety of facies within this group ranging from quiet marine with bioturbation to high-energy environments with robust spirifers. The productid beds are somewhat intermediate. Somewhat similar difficulties pertain in the Russian Arctic successions both east and west of the Urals; and Ustritskiy (1983) proposed a Permian faunal sequence: Sezymian (approximately Asselian and Sakmarian); Artinskian; Paykhoyian (approximately Kazanian and Ufimian) and Novazemlian (approximately Kazanian or Guadelupian). It is this latest that has most Svalbardian affinity. Below the Kapp Starostin Formation Gobbett distinguished two distinct brachiopod faunas within the Gipsdalen Group. The later one was in the Permian, Tyrrellfjellet Member of Btinsow Land and the Cora limestone of Bjornoya (Hambergfjellet Formation) and the fauna was consistent with the Sakmarian age concluded on the basis of fusulines. The earlier fauna was from the Minkinfjellet (Campbellryggen Subgroup), Scheteligfjellet, T~rnkanten and Kapp Khre (Ambigua Limestone) formations and is consistent with a BashkirianMoscovian age by correlation with the Moscow Basin.

17.6.5

Bryozoans

Lazutkina & Goryunova (1972) compared bryozoans of Spitsbergen and the Russia. From well-preserved silicified material in the Kapp Starostin Formation Nakrem & Spjeldn~es (1995) redescribed

Table 17.1. Subdivisions of the Kapp Starostin Fm Nathorst (1910)

Gee et al. (1952)

Cutbill & Challinor (1965)

Productus Ffihrende Kieselgesteine Spiriferenkalk

Brachiopod cherts-upper Brachiopod cherts-middle Brachiopod cherts-lower

Hovtinden Mbr SvenskeeggaMbr Voringen Mbr

328

CHAPTER 17

Toula's (1875) Spitsbergen Ramipora hochstetteri and reviewed the literature, especially from Permian Svalbard rocks, revising the taxonomy in some earlier records and concluding extensive synonymy. Nakrem (1994) monographed 41 species from the Voringen Member and concluded an Artinskian-Kungurian age, by correlation with the Sverdrup, Wandel Sea and Timan-Pechora basins.

17.6.6

Gastropods

Yochelson (1966) reported new Permian gastropods from Spitsbergen and Alaska.

17.6.7

Trilobites

Osmolska (1968) reported two new trilobites from the Treskelodden Formation of Hornsund and Kobayaski (1987) described a Permian trilobite from Spitsbergen.

17.7

northward motion of Laurasia through the global climatic zones. The most recent palaeomagnetic data shows that the palaeolatitude of Svalbard was between 14~ and 18~ N during the deposition of the Early Carboniferous Billefjorden Group (Watts 1985), while it was 35.5 ~ N in Late Paleozoic time (Vincenz & Jelenska 1985). Harland, Pickton & Wright (1976) had estimated a Carboniferous through Permian latitude from 15-25 ~ to 45 ~.

Carboniferous-Permian tectonic control of sedimentation

The Early Carboniferous succession is characterized by deposition in rather humid climates, with a high water-table resulting in reducing conditions and the development of coal and clayironstone horizons. In contrast, in latest Serpukhovian (Namurian), Bashkirian and Moscovian times, there were arid or semi-arid conditions. Finally Permian climates appear to have been humid and temperate. Lateral variations in Carboniferous stratigraphy are shown in a fence diagram (Fig. 17.7), from work by Cutbill & Challinor (1965). The cause of the climatic change, which has been recognized throughout Svalbard at this time, may have been the gradual

17.7.1

Tournaisian-Visean-Serpukhovian (Mississippian) events

This Tournaisian-Serpukhovian phase (Fig. 17.8) was characterized by fault-controlled terrestrial sedimentation of the Billefjorden Group, with the formation of thick continental sandstones, shales and coals; there was significant tectonic control at this time. The strata are of limited lateral extent, mostly deposited in elongate basins containing poorly drained floodplains, with lakes and swamps accumulating sediment brought by rivers draining a vegetated landscape. Tournaisian basal braided river conglomerates in the Horbyebreen Formation of Dickson Land were deposited from a horst area to the east of Ny Friesland. Hutchins (1962) found few metamorphic heavy minerals in these sediments so that the source could not have been western Ny Friesland, but to the east of Veteranen Line where the Veteranen Group (Precambrian) sediments are rich in quartz (contra Aga et al. 1986). They pass up into the finer coaly floodplain deposits of a northwardflowing meandering river. The periodic flooding may have been caused by tectonic downthrow (Gjelberg & Steel 1979). The Tournaisian member of the H6rbyebreen Formation tended to follow the pattern of Old Red Sandstone sedimentation with northward flowing streams as did the Adriabukta Formation in the south. By Visean time, similar environments were established in central Spitsbergen resulting in the fluviatile-deltaic deposits of the

Fig. 17.7. Fence diagram illustrating lateral variations and tectonic controls on the Carboniferous stratigraphy (redesigned by I. Geddes, using concept of Cutbill & Challinor 1965, but with contemporary nomenclature).

CARBONIFEROUS AND PERMIAN HISTORY OF SVALBARD

329

Fig. 17.8. Early Carboniferous lithofacies maps. (a) Famennian-Early Tournaisian, (b) Late Tournaisian-Visean, (c) effect of block-faulting on deposition of the Billefjorden Group in central Spitsbergen.

330

CHAPTER 17

Orustdalen Formation (Fairchild 1982). Meanwhile, in the Inner Hornsund Trough, there was a Tournaisian-Early Visean marine basin, if somewhat restricted, where clastics and shales of the Adriabukta Formation, which appears also to have had a source to the east, were being deposited. Further south, post-Svalbardian sedimentation had already begun in the Bjornoya Basin in Late Famennian time with the poorly drained floodplain deposits of the Roedvika Formation, from a southerly source. Its lowest (Vesalstranda) member consists largely of floodplain sediments deposited by northwestwardflowing meandering streams. The overlying and coarser Kapp Levin Member was deposited by east or northeastward-flowing braided streams. The uppermost Tunheim Member represents a return to meandering river conditions from the south or southeast which persisted throughout the Nordkapp Formation, with a return to eastward-flowing sandy braided streams. Alluvial fanglomerates in the upper part, may mark renewed uplift on the West Bjornoya Fault. This probable extension of the PalaeoHornsund Fault was reactivated intermittently during the Carboniferous Period, e.g. in the Landnordingsvika Formation above, with its similar alluvial fan deposits and which built out eastwards onto an alluvial plain. There was no marine influence until Late Bashkirian-Moscovian time. Marine conditions did not persist in the Inner Hornsund Trough, and alluvial fans and floodplain deposits spread into it, followed by the braided stream deposits of the Hornsundneset Formation and the fluvial sandstones and floodplain shales and coals of the Sergeijevfjellet Formation. They had a western source and covered a much wider area than the underlying Adriabukta Formation, which was probably restricted to a fault-bounded trough. Further north at this time, the Vegardfjella Formation's floodplain deposits continued the continental succession of western Spitsbergen, which may have been continuous eastwards with the similar Mumien Formation of the Billefjorden Trough. Like the laterally equivalent Sergeijevfjellet and Hornsundneset formations further south, the Mumien Formation covered a greater area than the fault-bounded Horbyebreen Formation below (Fig. 17.8). Thus, Visean alluvial fan sediments spread over a wider area. Dominance of a westerly rather than easterly source indicated increased tectonic activity along the western boundary faults. The first signs of uplift of the Nordfjorden Block were in Vis~an time. Large fan systems show 1.5km of braided stream sandstone sequences in the southwest and northwest basins of Spitsbergen. This may reflect major downwarping along the Palaeo-Hornsund Lineament as these clastic wedges thin eastwards (Aga et al. 1986). The Mumien Formation developed in a subsiding trough east of the Billefjorden Fault Zone. The Orustdalen, Vegardfjella and Hornsundneset formations occupied basins immediately to the west of the Kongsfjorden-Hansbreen Fault Zone (KHFZ). These two fault zones, originally separating the eastern, central and western terranes, thus continued to be active but with no demonstrable strike-slip. The isopach patterns of the Vegard and Orustdalen formations parallel almost exactly the KHFZ. They were drawn in ignorance of this hypothesis. Decreased subsidence rates by the end of Vis6an time are suggested by a widespread retreat of the braided fans and their replacement, in many areas, by fine-grained marsh and floodplain environments. Red beds first appeared at the top of the Vegardfjella Formation, a precursor of the red beds common in Bashkirian & Moscovian formations and indicative of a Serpukhovian/Early Bashkirian change from humid to arid conditions. This coincided with a regional rise in sea level bringing a transition from continental to marine sedimentation, that persisted into Early Permian time. The humid climatic facies of this alluvial fan and swamp/ floodbasin association show the following features which contrast with the more arid Bashkirian-Moscovian fan and playa/sabkha association. The mineralogy is more mature, with a dominance of quartz and quartzite, as is texture, with a smaller average grain size, more sorting and less clay matrix. This is because braided stream facies dominated the humid environments in contrast to the massflow and stream-flood facies prominent in the arid environments.

The subaqueous fans actually show little difference in the two associations. Sequences show little vertical organisation in the humid facies in contrast to the progradational upward-coarsening which is usual in the arid environment.

17.7.2

Bashkirian-Moseovian events

A general survey of this interval with climatic, tectonic and sea-level changes was provided by Gjelberg & Steel (1981) and updated for Bjornoya in 1983, with a further tectonic update by Gjelberg (1987). A Serpukhovian to Bashkirian break in deposition is marked by a pre-Gipsdalen Group unconformity or disconformity throughout Svalbard, indicative of uplift and instability, with a brief pause in sedimentation. Moderate deformation in this mid-Carboniferous interval has been recorded in the Billefjorden Group at Midterhuken, where there is a 25-30 ~ angular unconformity between Late and Early Carboniferous strata (Craddock et al. 1985). There was erosion on the East Dickson Land Axis and in the Billefjorden Fault Zone. In Oscar II Land, however, the basal Petrellskaret Formation appears to be conformable on the Vegardfjella Formation and an unconformity of this age is not so obvious on Bjornoya either. Possibly there were breaks within the Nordkapp Formation. Red beds and to some extent, evaporites, are characteristic of this time, with very rapid lateral facies variation. This reflects the strong tectonic control over sedimentation, resulting from uplift of the Nordfjorden Block, with syndepositional faulting at its eastern, and probably western margins. Within the red-bed successions, there is a repeated facies sequence which is especially clear where coarse-grained sediments are found in Inner Hornsund (Hyrnefjellet Formation) and in Billefjorden (Ebbadalen Formation). In the most proximal sequences, upward-coarsening red bed sequences are capped by a shallow-marine quartzitic sandstone. In more distal reaches, the marine sandstone is overlain by dolostone. This can be interpreted in terms of an overall lowering of base level and a marine transgression (demonstrably basin-wide in the case of the Billefjorden Trough at least), producing first a marine reworking of the alluvial surface and then carbonate sedimentation, followed more gradually by the progradation of the alluvial fans. The widespread coarse-grained nature of these sequences suggests that they were started by movement along the bounding faults of their basins. The scale of such sequences (up to 30 m) is consistent with the scale of fault scarps produced by rapidly repeated movements along fault lines in the Basin and Range Province (USA) in historic time. On Bjornoya, continued repetitive outbuilding of alluvial fans can also be recognized in the Landnordingsvika Formation. There the fan deposits are of a more distal nature (Gjelberg & Steel 1981). Clast content of sandstones and conglomerates implies a steady deepening of erosion on the Nordfjorden Block through midCarboniferous time, with successive exposure of Visean, Tournaisian, then Devonian rocks. Evaporites, formed in coastal sabkha environments, are most extensively developed within the Billefjorden Trough. They occur in the Ebbadalen Formation and Minkinfjellet Formation in a linear zone of nodular gypsum/anhydrite rocks between red beds to the west and shelf carbonates to the east. Thin gypsum beds and nodules are also found in the Petrellskaret Formation of western Spitsbergen which only became fully marine in the north in Moscovian time, with deposition of the sandy carbonates of the Scheteligfjellet Formation. In Bashkirian time (Fig. 17.9a), the Ebbadalen Formation was deposited in the East Spitsbergen Basin. Throughout the formation there was an overall upward-fining trend with gradual overlap of non-marine by marine facies, so that the upper part is largely marine. This reflects increasing stability and rising sea levels. Rhythmic intercalations of marine platform and alluvial fan deposits show a characteristic cyclicity which was again probably caused by fault movements lowering the basin floor. Palaeocurrents and facies

CARBONIFEROUS AND PERMIAN HISTORY OF SVALBARD Early

Bashkidan

lithofacies

I

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.

M A R G I N A L MARINE** COASTAL A R E A 9 I § / ~ § § +

331

which passed eastwards through a sabkha-evaporite zone, through lagoons to shallow marine carbonates. These sediments were thickest in the rapidly subsiding Billefjorden Trough. The Moscovian Minkinfjellet Formation shows the same facies variation and, at this time, carbonate deposition spread eastwards, becoming more arenaceous in that direction (Fig. 17.9b). This eastward spread of marine environments implies a transgression which resulted in submergence of the Nordaustlandet Block, an area which had not recorded deposition since the Caledonian Orogeny. Here the HArbardbreen Formation (Campbellryggen Subgroup) represents the transgressive deposits at the edge of the basin. These were followed by the sandy carbonates of the Idunfjellet Member. The Nordfjorden Block appears to have separated the East and West Spitsbergen Basins at this time. In the West Spitsbergen Basin, also, fluviatile conglomerates and sandstones in the north and west form the Broggertinden Formation, which passes southwards into marginal marine/lagoonal shales with sandstones of the Petrellskaret Formation. The latter was covered by Moscovian cyclic intertidal/deltaic red beds of the TArnkanten Formation, while further north, sandy marine carbonates of the Scheteligfjellet Formation represent a marine shelf environment. The extent of these basins into southern Spitsbergen is not clear, but the Hyrnefjellet Formation's cyclic alluvial fan red-beds and marine clastics were deposited at some stage throughout Late Carboniferous time, with a source on the Hornsund High to the west of the Inner Hornsund Trough, except for the enigmatic Bladegga conglomerates with their eastern source. The cyclicity here may also be tectonically related, due to sudden marine transgressions as a result of basin floor lowering against a boundary fault, as in Bjornoya where the environment of deposition was similar in the coastal plain red beds of the Bashkirian Landnordingsvika Formation. The lower part of this formation contains coastal fluvial red-bed sequences deposited by sinuous rivers which flowed from the south, there was caliche development in the overbank deposits. The middle part has red alluvial fanglomerates derived from the west (probably from a fault scarp). Marine clastics and later carbonates began to interdigitate towards the top, evidence of the onset of a transgressive regime which continued through the overlying Kapp K5re Formation. Here there was a gradual transition through the limestone, shale and sandstone cycles of the lower Bogevika Member to the limestone dominated Efuglvika Member. This mid-Moscovian establishment of carbonate shelf sedimentation was probably a result of submergence of source areas in the western fault block. The uppermost member catalogues the emergence of a new block in eastern Bjornoya bounded by a NW-SE-trending fault. The shallow marine/deltaic deposits of the Kapp KAre Formation contain evidence of this fault activity in the intraformational conglomerates and the karst and discontinuity surfaces which abound.

17.7.3

Kasimovian-Gzelian events

o

Fig. 17.9. (a) Early Bashkirian lithofacies. (1) Petrellskaret Fm; (2) Broggertinden Fm; (3) little or no uplift; (4) Ebbadalen Fm; (5) periodic uplift; (6) Hyrnefjellet Fm; (7) Landnordrungsvika Fm. (b) Moscovian lithofacies. (1) Tarnkanten Fm; (2) Scheteligfjellet Fm; (3) uplift; (4) Minkinfjellet Fro; (5) Malte Brunfjellet Fm; (6) Idunfjellet Fm; (7) High & Hyrnefjellet Fro; (8) Kapp K~re Fm.

patterns suggest that the trough formed an embayment which opened to normal marine environments in the north (Aga et al. 1986). Strong uplift of the Nordfjorden Block resulted in alluvial fan red beds being deposited adjacent to the Billefjorden Fault Zone,

The latest study of the Moscovian-Kasimovian stratigraphic framework was by Pickard et al. (1996). A late Moscovian transgression over the Nordfjorden Block led to the final phase of Carboniferous sedimentation, characterized by the spread of stable shallow-marine shelf carbonate deposits of the lower Wordiekammen Formation across much of Spitsbergen (Fig. 17.10). The major fault zones of northern Spitsbergen were overlapped as tectonic activity decreased and the Nordfjorden Block was submerged. It was covered by the Kapitol Member which passed laterally into the Cadellfjellet and Morebreen members respectively in the East and West Spitsbergen Basins. However, these basins continued to subside more rapidly. There was an eastward increase in sandstone content in the Cadellfjellet Member, which is replaced by the Idunfjellet Member in Nordaustlandet, indicating an eastern landmass. Dolostones and dolomitic limestones were widely developed, especially in the west (Morebreen

332

CHAPTER 17 Gzelian Iithofacies i

, ,

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TRIASSIC HISTORY

349

De Geerdalen Formation, 190m. The valley, De Geerdalen, is west of the type section at Botneheia. It consists of alternating grey-green sandstones and sandy shales: The base is marked by the first resistant sandstone above the Tschermakfjellet shales and the top, in most of Spitsbergen, below the 'Lias conglomerate'. Plant remains are fragmented and thin coal seams occur. The De Geerdalen Formation is the piece de rOsistance in Spitsbergen of the Kapp Toscana Group. It is dominanted by sandier non-marine facies whose sedimentary environment is treated in Section 18.6.4. The isopach map of the Kapp Toscana Group is largely a map of this formation. Wilhelmoya Formation Wilhelmoya and Hellwaldfjellet. The island of Wilhelmoya and the mainland section at Hellwaldfjellet, 40 km to the south, are of great interest in spanning the sequence. That is possibly from uppermost Sassendalen horizons at the base, through Tschermakfjellet and De Geerdalen Formations and the Wilhelmoya Formation where it was defined (Worsley 1973). It is followed by an uncertain succession through into Late Jurassic strata (Klubov 1965a) (Fig. 18.7). More detail is available in Chapter 5. Palynological ages were investigated by Smith (1975) and i.a. three preparations indicated a Norian age for the De Geerdalen Formation. Worsley named two members of the Wilhelmoya Formation:

T h e base of the K a p p T o s c a n a G r o u p is sharp, with a conformable shale unit overlying the h a r d e r cliff-forming p h o s p h a t i c shales at the top of the Sassendalen G r o u p . It appears to represent a stratigraphic break. The base is not seen in H o p e n , W i l h e l m o y a and K o n g Karls Land. The top is m a r k e d below the B a t h o n i a n p h o s p h o r i t e nodule bed (absent only in K o n g Karls L a n d ) a basal c o n g l o m e r a t e of the softer n o n - m a r i n e shales of the Jurassic A d v e n t d a l e n G r o u p (see C h a p t e r 19). The d o m i n a n t l y sandy D e Geerdalen F o r m a t i o n is the m a i n unit in the group. In some areas there is a basal shaly f o r m a t i o n , the Tschermakfjellet/Austjokelen F o r m a t i o n . W h e r e present, it grades up into the D e G e e r d a l e n F o r m a t i o n . Spitsbergen The Tsehermakfjellet Formation, 63m at Tschermakfjellet in South Dickson Land, is recognized only in the central and eastern terranes of the Central Basin; it has no sharp western margin. It is made of silty shales to fine-grained sandstones with distinctive small red-weathering cla~ironstone concretions and contains an ammonoid and bivalve fauna.

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Fig. 18.7. Localities and thickness of the Wilhelmoya Formation. Some thickness, including the Brentskardhaugen Bed were used in this compilation (by I. Geddes) so that the values on the map may need to be reduced by 1 m or a little more. The lower boundary in Spitsbergen is not everywhere easy to identify.

350

CHAPTER 18

Tumlingodden Member 60m clays and friable sandstones with coal lenses with lignite.

Bjornbogen Member, 59m clays and siltstones with conglomeratic phosphatic and limestone cherts at base. At the top of the 105 m section at Hellwaldfjellet, about 70 km to the SE, there is a conglomerate (suggested but not confirmed as the Brentskardhaugen Bed). The (lower) Bjornbogen Mbr of the Wilhehnoya Fm with its marine assemblage of bivalves and saurian (plesiosaur) bones correlates well with the Kapp Koberg Mbr in Kongsoya and the Flatsalen Fm of Hopen. Taken together the evidence suggests that these strata are most probably Rhaetian in age. The initial boundary probably being somewhere in the uppermost De Geerdalen Fm and the terminal boundary in the succeeding strata which for the most part are well established as Jurassic (Smith 1975; Smith et al. 1975, 1976; Worsley & Heintz 1977). Although not always easy to decide the boundary, the Wilhelmoya Formation extends widely in Svalbard. Moreover sedimentation continued from ?Norian, through Rhaetian into Liassic time. Mork et al. recognized two members in Spitsbergen: Knorringfjellet and Smalegga. The KnorringfjelletMember is, 20 m thick in the type section at Festningen, where it comprises shales, sandstones and carbonate with, at the base and top, thin polymict conglomerates. The Smalegga Member is 28 m thick in the type section in N. Sorkapp Land. Southwards it is predominantly bioturbated quartzitic sandstones with conglomerates, often phosphatic. Northwards it becomes more shaly and sideritic and merges with the Knorringfjellet Member. Barentsoya and Edgeoya. Lock et al.'s (1978) Kapp Toscana unit names (Edgeoya and Negerfjellet formations) are not applied here. Tschermakfjellet Formation serves as well for Falcon's Purple (Blue and Purple) shales and the De Geerdalen Formation for his Sandstone Group respectively. However, for detailed work sections are described as in that publication and correspond approximately to the fence diagram by Flood, Nagy & Winsnes (1971). The uppermost strata of Edgeoya (above Kvalpynten) could well be Jurassic, but no positive evidence to that effect has been adduced. (Rozycki 1959; Buchan et al. 1965; Winsnes & Worsley 1981; Steel & Worsley 1984). Indeed the Wilhelmoya Formation is not known in these islands. Kong Karis Land. In Svenskoya, Beds 1 and 2 (of Pomecknoi 1899, and of Nathorst (1901) were named by Smith et al. (1976) the Mohnhogda Member, 196+m underlain, but not in exposed contact with the Arnesodden Shale at sea level. In Western Kongsoya is the Sjogrenfjellet Member, 130-235m (Smith et al.). The Kapp Koberg Member was described below this at sea level (possibly obscured by ice in 1969) by Worsley & Heintz (1977). These units are Rhaetian and Rhaeto-Liassic and occur below the Jurassic and Cretaceous units which form the upper parts of the hills (Chapters 5 and 19). The Rhaetian unit is the Kapp Knberg Member of western Kongsoya. It is a marine shale passing up into a sandstone and noted for bones and a plesiosaur skeleton (Worsley & Heintz). Part may correspond to the Arnesodden shale at the bottom of the Svenskoya succession. The Mohnhogda and Sjogrenfjellet members have in common a coarse, loose, porous, multicoloured sand, with few cemented beds and lenses, with rare coal and ironstone horizons and containing fragments of petrified wood. It is almost entirely non-marine. Smith et al. (1976) and Bjaerke, (1977) listed 64 palynomorph forms and 12 dinoflagellates forms. From these studies it seems that ages range from ?Norian, Rhaetian up through Hettangian, Sinemurian and possibly younger. Lofaldli & Nagy (1980) found Early Jurassic foraminifera in the top part of the member.

Hopen. Described in Chapter 5 this linear island comprises the following succession: Kapp Toscana Gp Wilhelmoya Fm Lyngfjellet Mbr Fl~tsalen Mbr Iversenfjellet Formation. Notwithstanding the similarity of the Iversenfjellet Fm and the De Geerdalen Fm, Iversenfjellet is retained against the time when the subsurface succession is fully released for publication. Partly by the accident of exploration for hydrocarbons, Hopen has perhaps become better known biostratigraphically than coeval strata elsewhere in Svalbard and might provide one of the key sections globally for interpreting the Triassic-Jurassic transition. Rhaetian strata are preserved in sequence, and the fossils have been located in measured sections.

In summary, the Wilhelmoya Formation is a complex sedimentological unit, recording possibly latest Norian, certainly Rhaetian and Hettangian to Toarcian events. The Triassic-Jurassic boundary being indefinitely placed somewhere within the upper member where one can be distinguished. Smith et al. (1976), Worsley & Heintz (1977), Bjaerke & Manum (1977) agreed on the similarity of a marine Rhaetian shale facies followed by a continental sandstone passing from Rhaetian to Jurassic in all three areas examined by the same workers, i.e. Wilhelmoya (Worsley 1973; Smith 1975), Kongs Karls Land (Smith et al. 1976; Worsley & Heintz 1977) and Hopen (Worsley 1973; Smith et al. 1975). Combining surface and subsurface information (Hopen-2) the Kapp Toscana Group would amount to more than 1200 m in thickness.

Bjornoya. The Kapp Toscana Gp is represented in Bjornoya by the Skuld Fm which comprises the upper 135 m of the section in the mountain Urd and is characterised by several upward-coarsening sequences from dark grey shales with red-weathering siderite nodules to fine-grained sandstone. The lower 10m (just above the Verdande Bed) is of shale with small siderite nodules. Siltstones and then sandstones increase in abundance upwards in which current activity is indicated by ripples and on which plant debris is abundant. It would appear to be a regressive marine sequence of pro-delta deposits probably lateral to the delta distributaries. The siderite cement may indicate a proximal environment. About 50m up the formation was a 3m long Labyrinthodont amphibian P l a g i o s t e r n u m (first reported and covered for protection by a Cambridge party (Lowy 1949), and later removed to the Paleontological Museum in Oslo (Mork, Vigran & Hochuli 1990).

Barents Sea. Worsley e t al. (1988) outlined a newly defined stratigraphy in the Barents Sea. Because o f a feasible correlation with the Svalbard successions there has been a suggestion to r e n a m e some group and f o r m a t i o n names in Spitsbergen and classify t h e m according to the s u b m a r i n e units ( M o r k pers. comm.). In case such proposals should be developed the units from the H a m m e r f e s t Basin have been included in the stratigraphic glossary and index. If such a c o m b i n e d n o m e n c l a t u r e should be attempted the Svalbard names would generally have priority. At present m u c h of the i n f o r m a t i o n is unpublished.

18.4 18.4.1

Triassic time scale and international correlation The standard international scale

F e w controversial questions r e m a i n regarding an international chronostratic scale. Trias originated in the three-fold division in G e r m a n y following the two-fold P e r m i a n (Dyas). H o w e v e r being mainly o f red beds related to the Variscan orogeny there, it contributes little to international correlation. The m a r i n e sequence, especially in the N o r t h e r n Calcareous Alps of Austria b e c a m e the first marine s t a n d a r d with a z o n a t i o n based on a m m o n o i d s , but in complex tectonic relationships. However the argillaceous facies, especially o f the Arctic (and of British Columbia), p r o v e d to have the best a m m o n o i d sequence and has provided the world s t a n d a r d for correlation (Tozer 1967) unless it be in the I n d i a n subcontinent. Nevertheless, most of the Alpine stage names persisted, but were redefined in b o u n d a r y reference points mainly in the C a n a d i a n Arctic. The Alpine stage Scythian (i.e. Early or Eo-Trias) has been divided in two or three schemes as rich new material for this short interval became available. Russian geologists use I n d u a n and Olenekian. However, the scheme s h o w n in the international c o l u m n is the result (largely accepted) o f Scythian stage divisions. This was largely Tozer's achievement. N o t so, however, his a t t e m p t to elimi-nate R h a e t i a n on the basis o f its very short (?unknown) duration. That has been preserved internationally for the time being. The Svalbard succession comprises largely shales and sandstones and the concretions in the shales are typically rich in a m m o n o i d s so that a m m o n o i d z o n a t i o n (as in Jurassic Europe) has b e c o m e the standard m e a n s o f correlation. This works well for

TRIASSIC HISTORY Harland etal. 1990

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208

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(13)

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210

210+5

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223

220+8

223

235

229+5

235

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241

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92

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Fig. 18.8. Triassic time scales.

Early and Middle Triassic time but the De Geerdalen Formation, largely of deltaic sandstones offers little help in precise correlation (Fig. 18.8). A new complication has arisen because the Global Stratigraphic Section and Point (GSSP) is a convention not yet agreed by the Triassic Subcommission of the Commission of Stratigraphy, of the IUGS. Normally the recommendation for the initial boundary of the later division would have precedence over opinions about the terminal point for the earlier division. The latest Permian stage (Changxingian) of the latest Permian epoch or sub-epoch Lopingian that are defined in southeast Asia may in part overlap the Griesbachian stage, so that, from a eastern Tethyan perspective, Otoceras boreale would be Permian. Until a decision has been made as to the position of the GSSP the matter is indeterminate and Triassic is used here in its traditional sense (Tozer 1988). Wignell & Twitchett (1996), as discussed below, identified anoxic facies in the Vardebukta Formation and related this to a biotic extinction event at or near the initial Triassic boundary. That is an opinion independent of the definition of the boundary.

18.4.2

Biostratigraphic correlation

Macrofossils. The entire sequence is now fairly well dated on the basis of bivalves and ammonoids (Tozer & Parker 1968; Mork, Knarud & Worsley 1992; Korchinskaya, 1969, 1970, 1971, 1972a, b, 1973; Ishibashi & Nakazawa 1989; Weitschat & Dagys 1989; M o r k et al. 1992; Campbell 1994). Tozer (1967) and Siberling & Tozer (1968) refined a zonal scheme for the Triassic stages of the North American Arctic. It is to this scheme that reference is made in Fig. 18.9 where it can be seen that a zonal scheme for Svalbard is slowly evolving and is now quite well established for the Smithian and Spathian (Olenekian) stages but as yet is rather sketchy for other stages. The scheme defined in the Canadian Arctic is therefore used for primary reference. (i) The Sassendalen Group is of Griesbachian to Early Ladinian age, with all six stages represented. (ii) The Vardebukta Formation at the base of the Sassendalen Group is of Griesbachian to Dienerian age. This is confirmed by the presence of fossils of the boreale zone in the main basin. The other three zones may well be present because sedimentation at the time seems to have been fairly

351

continuous. In parts of southern Spitsbergen on the Sorkapp-Hornsund High and in Bjornoya (?), the Griesbachian stage is absent (Dienerian strata lie with unconformity on Paleozoic and older rocks). (iii) The Sticky Keep Formation is of Dienerian to Spathian age. In the Kistefjellet Formation of the Sorkapp-Hornsund High, Dienerian to Spathian strata overlie Paleozoic and older rocks. Both the candidus and sverdrupi zones are indicated on Spitsbergen, the latter being confirmed in the west. The tardus and romunderi zones are confirmed in Spitsbergen and the Barentsoya/Edgeoya area. The tardus zone is absent in Bjornoya, where the romunderi zone is overlain unconformably by a nodule horizon which is only 20 cm thick but may be of Anisian and Early Ladinian ages. The subrobustus zone and the pilatus zone are represented by only one Spathian zone in Svalbard which is present in Spitsbergen, Barentsoya, Edgeoya and Nordaustlandet. The Spathian is probably lacking in Bjornoya. (iv) The Botneheia Formation of the Central Basin and the Svartkausane Formation of Nordaustlandet are of Anisian to Early Ladinian age, a period of time probably also represented by the Verdande Bed of Bjornoya which is a condensed sequence only 20cm thick. The caurus zone is confirmed elsewhere and the varium zone indicated. There is no evidence of the deleeni zone, but it is unlikely to be absent as no major breaks in sedimentation are noted. The chischa zone is confirmed in Spitsbergen and Barentsoya/Edgeoya. The Early Ladinian subasperum and poseidon zones are confirmed on Spitsbergen. (v) The Late Ladinian meginae and maclearni zones seem to be absent everywhere, suggesting a mid-Ladinian hiatus which marks the junction of the Kapp Toscana and Sassendalen Groups. The base of the Kapp Toscana Group is marked by the sutherlandi zone. (vi) The Kapp Toscana Group is of Late Ladinian to Liassic age. (vii) The bulk of the marine fauna of the lower part of the Kapp Toscana Group in Svalbard is of Early Carnian age. There are records of a Norian ammonite (Korchinskaya 1973). Younger ammonites are not found until the Brentskardhaugen Bed at the base of the Agardhbukta Formation. In view of the marginal marine to non-marine environments of much of the Kapp Toscana Group, pollen and spores have been extremely valuable for correlation, especially with their wide dispersal largely independent of sedimentary facies. (viii) The Tschermakfjellet Formation is of Late Ladinian to Late Carnian age. (ix) The De Geerdalen Formation extends from Late Ladinian (where no Tschermakfjellet Formation is present) to Norian time. (x) The Skuld Formation contains Late Ladinian sutherlandi zone fossils in its upper half and extends through to the Carnian stage. (xi) The Wilhelmoya Formation extends from the Norian through Rhaetian possibly into Liassic stages. The base had been dated as Rhaetian in age on palynology (Smith 1975; Smith et al. 1975; Bjaerke & Manum 1977), but macrofossils have now indicated a Norian age (Pchelina 1980; Korchinskaja 1980). (xi) The Brentskardhaugen Bed is Bathonian, containing mid-Toarcian, Early Aalenian and Bajocian bivalves and ammonoids in the derived phosphatic nodules (Wierzbowski, Kulicki & Pugaczewska 1981; B/ickstrom & Nagy 1985). It was probably finally laid down during the Bathonian transgression. It is now included, as the basal conglomerate of the Agardhfjellet Formation, in the Adventdalen Group. The Rhaetian Stage has presented a problem (e.g. Smith 1974, 1977, 1986). Continuous marine facies through the Triassic Jurassic boundary are few. The record suggests that the Triassic ammonoids were almost extinct before the advent of the new Jurassic stock, beginning notably with Psiloceras planorbis which clearly marks the initial Hettangian stage. The difficulty lies in distinguishing Norian from Rhaetien, if ammonoids are the index fossils. The original Rh/itische Gruppe in the eastern Alps of Europe was based not on fossils, but on a lithostratigraphic unit. Only in 1975 was the palynostratigraphy of this Austrian unit described by S. J. Morbey in 1975 (Smith 1977). This work established the stage in positive characters of a largely non-marine flora. Rhabdoceras suessi is the latest Norian zonal ammonite and Choristoceras marshi is exclusively Rhaetian, but is of very limited occurrence, as indeed is Sirenites from Hopen which is one of only four localities (others are Austria, British Columbia, Nevada and California) where Rhaetian ammonoids have been recorded; but no Norian ammonoids are known from Svalbard, nor are good Norian palynofloras known from Norian ammonitic facies. Figure 18.10 summarizes the Triassic stratigraphy of Svalbard.

352

C H A P T E R 18 ,-.4

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Fig. 19.6. Jurassic-Cretaceous international time scale (after Harland et al. 1990, with permission of Cambridge University Press).

and 'Berriasian' in Boreal areas. The Jurassic-Cretaceous Boundary Subcommission has been at work on the problem. The Subcommission, for the present, recommends the use of the 'Boreal Berriasian' Stage rather than 'Ryazanian', and the retention of the Volgian Stage until there is precise understanding of the Tithonian Stage in Boreal Regions. The base of the Berriasian is now taken at the appearance of the Riasanites riasanensis Zone and the base of the Volgian at the base of the Ilovaiskya klimovi Zone. The latter corresponds to the base of the Late Kimmeridgian. Otherwise the standard Tethyan nomenclature, that of Harland et al. (1990), is used.

19.4.2

Aalenian. The earliest Aalenian zonal index Leioceras opalinum occurs with Pseudolioceras macklintocki in the Brentskardhaugen Bed condensed sequence. Also Brasilia aft. bradfordense indicates possible presence of the murchisonae Zone (B~ickstr6m & Nagy 1985). These faunas show open seaways to Europe and widespread correlation with the standard Tethyan zonal scheme.

157.1- ~

~

>,

Toarcian. The earliest probable /n situ Jurassic ammonite is Porpoceras polare which occurs in a partly phosphatised horizon 4 m below the top of the Wilhelmoya Formation at Rurikfjellet (Bfickstr6m & Nagy 1985, p.12). However, the oldest fauna is probably present, reworked in the Brentskardhaugen Bed, where Dactylioceras toxophorum suggests the presence of the falciferum Toarcian Subzone. The bifrons to thouarsense zones contain Porpoceras and Pseudolioceras spp. Pseudogrammoceras fallaciosum, the subzonal indicator for the late thouarsense Zone, and Pseudolioceras indicate later Toarcian deposits (see Frebold 1929a; Kopik 1968; Wierzowski, Kulicki & Pugaczewska 1981; B~ickstr6m & Nagy 1985).

3.0

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Barremian

__~

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Cenornanian

the standard Tethyan scheme. Ammonite zonation elsewhere in the Arctic was summarized by Callomon (1994).

Firkanten Fm

Pg ~aleocene Danian Maastrichtian

Svalbard units

369

Ammonite zonation

Ammonites form the basis of the Jurassic and Cretaceous biostratigraphy of the Adventdalen Group, which is summarized below. There are no major faunal breaks in the marine facies between Late Bathonian and mid-Albian time. However, the Barremian and possibly also the Early Aptian stage are represented by non-marine facies, so there is a faunal gap here. The sequence of zones recognised in Svalbard is given in Figure 19.7. At a time of regression, particularly Bathonian and TithonianBerriasian, the Svalbard faunas were strongly Boreal and particularly the ammonites which cannot be directly compared with

Bathonian. Because Boreal ammonites were so distinct from those further south during most of Mid-Jurassic time, there are considerable problems in defining the Bathonian stage in Arctic regions. A generic sequence, derived from the Bajocian Cranocephalites, commences in the Bathonian Stage with Arctocephalites and continuous through Arcticoceras to Cadoceras, and characterises these areas. (e.g. Callomon 1959, 1976, 1985; Imlay 1976). Some Russian workers considered Arcticoceras to be Early Callovian (e.g. Saks 1976). Callomon's zonal sequence is used here and is summarized below. Bathonian Cadoceras calyx Cadoceras variabile Arcticoceras cranocephaloides Arcticoceras ishmae Arctocephalites greenlandicus Arctocephalites arcticus Bajocian Cranocephalites pompeckji Cranocephalites indistinctus Cranocephalites borealis. The oldest Bathonian ammonite recorded from Svalbard is the dubious ?Arctocephalites from Svenskeya. Arcticoceras is now known from Spitsbergen and Kong Karls Land. A. harlandi from Kong Karls Land is closely comparable with the Arcticoceras species found in the lowest part of the A. ishmae Zone of east Greenland (Rawson 1982). Slightly younger Bathonian forms which occur in Spitsbergen are the Kepplerites of the tychonis-svalbardensis group. These probably indicate the lower part of the A. cranocephalites Zone of east Greenland. This fauna occurs immediately above the Brentskardhaugen Bed (Agardhfjellet Formation) in central Spitsbergen, but is preceded by the Arcticoceras fauna in southern Serkapp Land and Kong Karls Land. Hence the base of the Adventdalen Group appears to be diachronous.

Callovian. The 'standard' ammonite subdivision of the Callovian stage is shown in Fig. 19.7. In the Retziusfjellet Member on Kongsoya, Pseudocadoceras chinitense, P. grewingki and Cadoceras multicostatum date it as Early-Mid-Callovian (Lofaldli & Nagy

370

CHAPTER 19

STAGE

PERIOD

Alblan

Aptlan

AMMONITE

BIVALVE

FORAMINIFERA

DINOFLAGELLATE

Euhoplltes Dlmorphoplltes & Inooeramus angllous lautus Gastroplltes beds beds Hoplltes H. Svalbardensls dentatus & Grycla beds Douvlllelceras Otohoplltes marnmlllaturn beds Leymerlella Leymerlella aoutloostata sz tardefuroata Leymerlella schrammenl sz I. spltsbergensls/ Tropaeum arotlcum beds lablaflformls beds

Pseudoceratlum polymorphurn beds

1

O uJ O

_>. s_ ~3

uJ

Hauterlvlan

Slmblrskltes dechenl Speetonlceras verslcolor

Valanglnlan

Dlohotomltes spp. Polyptychltes ramullcosta Temnoplychltes syzranlcus

Berrlaslan

To~rio & BoJarkla spp. beds Surltes spasskensls RJasan/tes rJasensls

14J

O

Tlthonlan

d) Klmmeridglan

Oxfordlan

Callovlan

O CO

< rv

Gardodlnlurn ordlnale beds

Barremlan

~) -"O "(3

Bathonlan

Inooeramus off. auoella/ I. sp. ex ~Ir. oolonlcus beds Buchla crasslcolls? Buchla sublaevls Buchla keyserllngl 'l Buchla Inflata Buchla volgensls Buchla okensls

Craspedltes nodlger Craspedltes okensls Vlrgatosphlnctes spp. Buchla russlensls Laugeltes groenlandlcus Dorsoplanltes maxlmus Buchla rugosa Dorsoplanltes panderl Buchla mosquensls Subplanltes/Peotlnatltes spp. ?Aulacost. autlsslodorensls Buchla tenulstrlata A. koch/ s.z. A. koch/ A. norwe~}Icurn s.z A. kltchlnl A. rnoclestum s.z. A. subkltchlnl s.z. Buchla concentrlca Amoeboceras bauhlnl Amoeboceras rosenkrantzl Amoeboceras regulare Praebuchla lata ................. Amoeboceras serratum Arnoeboceras glosense Cardloceras cordaturn Quenstecttooeras rnarlae Quenstecltoceras lamberfl Longaevlceras nlkltlnl Cadoceras apertum Retroceramus spp. Cadoceras calyx beds Kepplerltes lychonls Arctlooc. cranocephaloldes Arctlcoceras Ishmae

Increase In Haplophragmoldos sp. & Trochamrnlna sp.

Nelchlopsls kostromlopsls beds

Glomosplra sp. & Glomosplrella sp. beds

Gaudrylna aft. miller~

Ammodlscus zaspelovae Trochammlna rosaoea

Haplophragmoldes canulformls

Reourvoldes dlsputabllls

Trochammlna rostovzevl

Crussolla deflandrel -Wanaea flmbrlata Llesberglo soarburghensls -Waneo hysanota Melourogonyaulax planosepTa -Chlamydophorella ectotabulata Slrrnlodlnlum gross// Nannoceratopsls graollls

--3

BaJoclan

Aalenlan

>,

Toarclan

Pseudolloceras rnackllntockl Leloceras opallnum Pseudolloceras rosenkrantzl Pseudolloceras polare

Dodokovla bullula -Nannocoratopsls senex Mlkrocysta erugata

0 l.U Pliensbachlan

SRAI' Fig. 19.7. Summary of the biozonal schemes for Svalbard and the adjacent Barents Sea, largely after Smelror (1994) for Jurassic; ammonites after Owen (1988), Nagy (1970), Yershova (1983); bivalves after Surlyk & Zakharov (1982), Kelly (in Arhus, Kelly et al. 1990), including new data; foraminifera, Nagy et al. (1990); dinoflagellates, Smelror & Below (1991), compiled by S. R. A. Kelly.

1980). Callovian faunas have been found on Spitsbergen and Kongsoya which have all yielded Longaeviceras and Quenstedtoceras (?Eboraciceras) species of Late Callovian (probably athleta to lamberti zone) age.

Oxfordian. Standard Oxfordian ammonite zonation (Fig. 19.7) is based on a combination of Boreal (cardioceratid) and Tethyan ammonites. The cardioceratid zonation for the Mid- to Late Oxfordian is that of Sykes & Callomon (1979) based principally on faunas from northern Europe and Greenland. Yershova (1983) summarizes the sequence of ammonites from central and southern Spitsbergen and Kong Karls Land. But the names used should be treated with caution. Other significant articles are by Frebold

(1930a), Pchelina (1967), and in Kong Karls Land (BliJthgen 1936; Smith et al. 1976). The Early Oxfordian zones are represented by Quenstedtoceras mariae and Cardioceras cf. cordatum (Yershova 1983). The MidOxfordian is not so clearly recognisable in the 'Amoeboceras alternoides' assemblage, which may be Early-Mid-Oxfordian, is more widely recognised particularly from the A.regulare and A. rosenkrantzi zones

Kimmeridgian. The extension of the Volgian stage down to the base of the Subplanites zones of the Soviet Union (Pectinatites zones of Western Europe) means that the base of the Volgian stage corresponds with the base of the Tithonian stage and that the 'Late

JURASSIC AND CRETACEOUS HISTORY Kimmeridgian' of earlier British authors falls in the Tithonian stage. The Kimmeridgian Stage thus now consists of only the previous 'Early Kimmeridgian' zones (Fig. 19.7). In the most northerly regions the Kimmeridgian faunas are dominated by cardioceratids, and Russian and Polish authors (e.g. Pchelina 1967; Saks 1976; Birkenmajer, Pugaczewska & Wierzbowski 1982; Wierzbowski 1988) regard Amoeboceras (Amoebites) as characteristic of the earlier Kimmeridgian and Amoeboceras (Hoplocardioceras) as typifying the later Kimmeridgian stage. In Svalbard, Kimmeridgian faunas are widespread (e.g. Frebold 1930a; Pchelina 1967; Birkenmajer et al. 1982; Wierzbowski 1988). Earlier Kimmeridgian Amoeboceras (Amoebites), of the kitchini group are common, but definite later Kimmeridgian ammonites (Euprionoceras cf. sokolovi and Hoplocardioceras cf. decipiens) are recorded only from two localities on Spitsbergen. A Xenostephanus from Kongsoya may belong to the cymodoce or mutabilis zones but there is no evidence of the highest two zones of the Kimmeridgian Stage.

Tithonian (Volgian). As a stage name, Tithonian is preferred to Volgian because it is more globally widespread and based on Tethyan rather than Boreal faunas, so serves better as a standard for correlating northern and southern hemispheres (Harland et al. 1990). However, the zonal sequence applicable in Svalbard approximates to the type Volgian sequence of the Russian Platform with elements of the northern Siberian zones. Work to correlate these internationally remains to be done. Seven Volgian ammonite asssemblages/zones have been differentiated in Svalbard by Yershova & Pchelina (1982): Late Volgian

Craspidites nodiger Craspidites okensis Strata with Virgatosphinctes spp. and Buchiafischerina Mid-Volgian

Laugeites groenlandicus Dorsoplanites maximus Dorsoplanites panderi Early Volgian Strata containing Pectinatites spp. and Subplanites sp. The ammonites of the Svalbard Volgian show a progressive change from Early Volgian forms that are more Tethyan, through to the distinctly Boreal Late Volgian craspeditids. The sequence is most similar to that of the Russian Platform and N. Siberia. The Early Tithonian (Early Volgian) is represented by the appearance of Pectinatites and Subplanites. The Middle Volgian is characterised by Dorsoplanites, Laugeites, Pavlovia and Zaraiskites. The beginning of the Late Volgian is marked by the appearance of Virgatosphinctes and is followed by Craspedites.

Berriasian. The Berriasian Stage was defined at the base of the Cretaceous Period in the Tethyan province. It covers the Boreal Ryazanian Stage, which is more applicable in Svalbard as the ammonite fauna is similar to that of eastern Greenland, arctic Canada, England, N. Siberia and the polar Urals. The Ryazanian Stage is divided into two zones in its type area on the Russian Platform:

Surites spasskensis Riasanites rjasanensis. An earlier Chetaites sibiricus zone is present in northern Siberia and the northern Urals (Saks & Shulgina 1974). Because of the paucity of ammonite finds in Svalbard, the differentiation of the Berriasian Stage is not as clear as in Russia. No fully authenticated Early Berriasian ammonites have been found on Svalbard. Chetaites cf. sibiricus probably indicates the Chetaites sibiricus Zone (Yershova 1972a) and the rjasanensis zone may be indicated around Isfjorden by a possible Riasanites? cf. rjasanensis from the Agardhbukta area (Zhirmunskiy 1927) which although figured has not been subsequently confirmed. The Surites

371

spasskensis Zone is represented on Spitsbergen by Borealites, Surites, Praetollia and Tollia (Yershova 1972a).

Valanginian. The Boreal Valanginian fauna is similar to that of eastern Greenland, arctic Canada and Novaya Zemlya (Yershova 1980). It is characterized by Temnoptychites, Polyptychites, Europtychites, Astieriptychites and Neocraspidites. The stage boundaries are well defined, but correlation with the Tethyan zones is not yet possible. Two local zones can be recognized in Spitsbergen (Yershova 1980): Polyptychites ramulicosta and Temnoptychites syzranicus. The upper Polyptychites ramulicosta Zone fauna includes the following species: P. aft. ramulicosta Pavlow P. cf. rectangulatus Bogoslovsky Euryptychites aft. pavlovi Voronets Astieriptychites cf. astieriptychus Bodylevsky Neocraspedites gratissimus Yershova N. mirus Yershova N. aft. mirus Yershova. The lower Temnoptychites syzranicus Zone contains:

Temnoptychites (Russianovia) borealis Bodyl. T. bodylevskiyi Yershova. Hauterivian. The stratigraphy of the earliest Hauterivian of the Boreal realm is poorly known, but the late Early Hauterivian zone of Speetoniceras versicolor and the Late Hauterivian Simbirksites decheni zone are well represented in Arctic regions and can be recognized in Svalbard (Pchelina 1965; Yershova 1972b). Their correlatives in northwest Europe are also characterised by simbirskitids, but few are found in Tethys, so exact correlation of the Boreal Hauterivian/Barremian boundary is not yet possible. Barremian. No Barremian ammonites are known. Deposits in the interval are of non-marine facies.

Aptian. Late Aptian ammonites (Tropaeum arcticum) appear in the lower part of the Carolinefjellet Formation and continental deposition may have continued into Aptian time in Svalbard.

Albian. Nagy (1970) reviewed the occurrence of Albian ammonites in Svalbard and recognised six successive ammonite faunas which he correlated with the Albian Stage of northwest Europe. The earliest Albian ammonite recorded was Proleymeriella sp. indicating the early part of the tardefurcata Zone. Owen (1988) identified this as representing the schrammeni subzone. In the overlying faunas of Arcthoplites jachromensis (Nikitin) and A. birkenmajeri Nagy, Owen recognized the acuticostata Subzone from the presence of Leymeriella germanica Casey, Freboldiceras remotum Nagy and F. sigulare Imlay. After a faunal break the next ammonites including Otohoplites and some Grycia represent the later part of the mamrnillatum zone. The appearance of the MidAlbian is indicated by the Hoplites fauna with Grycia, which is placed in the earlier part of the dentatus Zone. The later dentatus and lautus zones contain Dimorphoplites, Euhoplites, and Gastroplites. No Late Albian fossils are known.

19.4.3

Belemnite ages

Doyle & Kelly (1988) have shown that the Mid-Jurassic to Early Cretaceous belemnites of Svalbard belong to the Arctic belemnite province of the Boreal realm, having affinities with those of other Arctic regions, although some taxa are common to the northwest European fauna as well. Stratigraphic ranges of the various species

372

CHAPTER 19 The evidence, particularly from bivalves, concerning the presence of the Bajocian, Bathonian and Callovian stages (B~ickstr6m & Nagy 1985) in the Brenstskardhaugen Bed is equivocal.

~.~o

~o~o

Barremion Hauterivian Valanginian Berriasian

I I Ill I I

I I

Tithonian/Volgian

19.4.5

Microfossils

Foraminifera. Arenaceous foraminifera were used by Nagy et al. (1990) to establish 8 foraminiferal zones of Oxfordian to Berriasian age in the Janusfjellet Subgroup (Fig. 19.7). They are also of stratigraphic use in the Passet Member of Kongsoya which has now proved to be of Aalenian/Toarcian age on the basis of foraminiferal assemblages (Lofaldli & Nagy 1980). Calcareous foraminifera have only been recognised significantly at two horizons in the base of the Rurikfjellet Fm (the Wimanfjellet Member) of Berriasian age in Central Spitsbergen; and in the Tordenskj61dberget Member (Valanginian) of Kong Karls Land. From the submarine sections, formal Callovian to initial Cretaceous biostratigraphic zonations have been proposed (Smelror 1994).

Kimmeridgian Oxfordian Callovian Bathonian Bajocian Aalenian Toarcian

Fig. 19.8. Biostratigraphic distribution of belemnite genera in Svalbard. Solid bar indicates Svalbard occurrence; open bar indicates non-Svalbard occurrence (after Doyle & Kelly 1988). have been established in Kong Karls Land where they have proved particularly useful in the correlation, confirmation and refining of ages of the members of the Janusfjellet Subgroup. Only Lenobelus is Early Jurassic, it continues into the Mid-Jurassic where Paramegateuthis, Pachyteuthis, Cylindroteuthis also occur, the last two continuing into Late Jurassic where Lagonibelus appears. The initial Cretaceous Acroteuthis and Pachyteuthus continue through Berriasian into Valanginian and Hauterivian, which are marked by diversification and addition of Hibolithes and Cylindroteuthis (Arctoteuthis). With the exception of Hibolithes which is of Tethyan ancestry, the bulk of the genera are Boreal with strong specific links to other Arctic faunas. The principal belemnite descriptions were by Blfithgen (1936), Birkenmajer, Pugaczewska & Wierzbowski (1982), Doyle & Kelly (1988). The distribution of Svalbard belemnite genera is shown in Fig. 19.8. 19.4.4

Bivalves

The sequence of the marine bivalve Buchia is of biostratigraphic importance in Boreal Callovian-Hauterivian strata. In the absence of ammonites, and particularly in Svalbard, this allows correlation and dating at substage level. A zonal scheme was established by Zakharov (1981) for Siberia and the Russian Platform. Most of the zonal species are recorded from Svalbard and the Buchia zones recognized are shown in Fig. 19.7 and have been identified from published sources. Correlation can now be achieved between Svalbard and East Greenland (Surlyk & Zakharov 1982), Andoya, Lofoten Islands, Norway (Zakharov, Surlyk & Dalland 1981) and Europe (Kelly 1990). The earliest Buchia recognized in Svalbard is B. concentrica (J. de C. Sowerby) which ranges through Oxfordian-Kimmeridgian strata; B. russiensis characterizes the late Mid-Volgian. B. okensis and B. volgensis are particularly important for recognising the Berriasian Stage and recognising the Jurassic-Cretaceous boundary. The Buchia keyserlingi-sublaevis complex in the Valanginian and early Hauterivian concludes the history (see Fig. 19.7 for further zonal species).

Microflora support and in some places refine, dating based on ammonites. Marine microplankton from the Janusfjellet Formation have been studied and compared with those described elsewhere from northwest Europe and the Canadian Arctic by Smelror (1988) and in Kong Karls Land by Bjaerke (1977, 1978, 1980a, b). Stratigraphic ranges of dinoflagellates have been established, ranging from Hettangian-Toarcian (Smith et al. 1976; Bjaerke & Dypvik 1977) and ?Late Bathonian/Callovian to Hauterivian age (Fig. 19.7). Bjaerke recognized two assemblages within the Rurikfjellet Formation (1978) and three in the Agardhfjellet Formation (1980). Grosfjeld (1991) recognized that the uppermost Retziusfjellet Formation contained Barremian dinoflagellates. Smelror gave local stratigraphic ranges for dinoflagellate cysts and acritarchs in the Toarcian-Aalenian Passet Member and the Late Bathonian-Oxfordian Retziusfjellet Member and established the existence of a non-sequence at the top and base of the Retziusfjellet Member. Arhus (1991) described the dinoflagellate cyst stratigraphy of southeast Spitsbergen and the Barents Sea, although he fell short of establishing a formal zonal stratigraphy for the Early-Mid-Albian. He confirmed a late MidAlbian age for the Sch6nrockfjellet Member, the taxa are comparable to forms from northern Europe. From the Barents Sea Smelror (1991, 1994) proposed a formal Toarcian to Oxfordian dinoflagellate zonation (Fig. 19.7). Coccoliths. These have been useful locally, but a broader study covering the whole of Svalbard is needed. Verdenius (1978) argued a Valanginian age on the basis of coccoliths for the Tordenskjoldberget Member of Kong Karls Land, which was in agreement with the previous age attribution on molluscs.

Plants are useful in the Helvetiafjellet Formation where there are no marine fossils. Similarities have been noted in the Early Cretaceous floras of Spitsbergen, Franz Josef Land and the USSR by Vasilevskaya (1980, 1986), who dated the formation as Barremian-Early Aptian. 19.4.6

Jurassic-Cretaceous correlation in Svalbard

The correlation of the principal lithostratigraphic units on Svalbard and the adjacent Barents shelf is summarized in Fig. 19.9. 19.5

Jurassic-Cretaceous formations

The strafigraphic scheme is followed here, formation by formation, as concluded in section 19.3 which was based on mappable units and their classification and nomenclature. In this section their age and genesis are discussed. As a preliminary indication of age of the formations Fig. 19.7 plots against a time-scale the positive biostratigraphic evidence of age. The nature of each of the formations

JURASSIC AND CRETACEOUS HISTORY

MA

STAGES

SPITSBERGEN

56.5 6o.5

WILHELM4~(A

373

SVENSKGWA

KONGSOYA

HOPEN

BJORNOYA BASI N

Firkanten Formation

Thanetian

-60 65

Danian

- 70

Maastrichtlan

74 Campanian -80 83 86.5

Santonian

I

88.5 - 9o 9o.5

II

II 9i

Coniacian Turonian

II

Cenomanian 97 - 100

L

Albian -

M

110112

E

hfnrockfjellet Mb ZIIlerberget Mbr , [ - ~ Langstakken Mbr Innkjegla Mbr

L Dalkjegla Mbr Aptian

- 120

124.5

E

- 130 132 135

Barremian

_=,Festnlngen Mbr

WWWvVV

Hautedvlan

140.5 Valanginian - 140

150152.1 157.1

Tordenskjoldberget Mbr unnamed units

"lithonian Slottsm~ya Mbr

154.7 Klmmeddgian Oxfordian

-160161.3

?

Mbr (Mycklegardt]~ Bed)

Berdasian

145.6 -

El Managrem :~ Mbr

Glitref]ellet Mbr

O p p d a l s ~ t a Mbr

Dun6rt]ellet

Lardyfjellet Mbr

Callovian

Mbr

L

Retziusfjellet Mbr

Bathonian M

166.1

E

-170

3 Dmnbreen Bed 2 Marhegda Bed

Bajocian

1 Brentskardhaugen Bed

173.2

Passet

Aalenian

178

Mbr

-180 Toarclan 187 -190

~llensbachian 194.,=

i Smallega I Knorringfjellet Mbr Mbr

Tumlingodden Mbr

Sinemudan

- 200 203.,= 208 _210209.,=

Fig. 19.9. Summary of the Jurassic and Cretaceous stratigraphy of Svalbard and the adjacent Barents Sea (devised by S. R. A. Kelly).

Hettanglan

?

?

WVVWVVV

?

?

Mohnh~gda Mbr

Sjegren~ellet Mbr

Lyngofjellet Mbr

Kapp Koburg Mbr

Flats~en

?

Rhaetian

Bj~mbogen Mbr -220

[

Norian Tvillingvatnet Mbr

223

is discussed in sedimentary terms and the igneous component is separated to the last subsection.

19.5.1 Wilhelmoya Formation (Worsley 1973) The Withelmoya Formation spans the Triassic-Jurassic boundary. Its main description is in Section 18.3.3 of the previous chapter. Now that the Brentskardhaugen Bed is classified (here) at the base of the Agardhfjellet Formation the possible range of Jurassic strata in the Wilhelmoya Formation appears to be limited to the East Svalbard Platform. Unfortunately, the Jurassic strata listed by Klubov (1965a) on Wilhelmoya appear to be displaced. Therefore the principal information comes from the Mohnhogda and Sjogrenfjellet members on Kongs Karls Land, with Rhaetian, Hettangian and Sinemurian and possibly as late as Toarcian ages. Mention of Toarcian ages may appear to confuse the matter, because derived Toarcian fossils are abundant in the Brentskard-

haugen Bed which are, thus, interpreted as the result of erosion or winnowing of phosphatic concretions from the Wilhelmoya Formation. The Brentskardhaugen Bed is well established as Bathonian so that the Wilhelmoya Formation, before erosion, could have extended through the Liassic interval.

19.5.2 Janusfjellet Subgroup (Parker 1967) Re-establishing the Janusfjellet unit as a subgroup permits it not only to be constituted by the defining Agardhfjellet and Rurikfjellet Formations in Spitsbergen, but also to include the Kongsoya Formation in Kong Karls Land. These rocks, comprise a quite distinctive shaly package in which the Brentskardhaugen Bed seems to be accepted at the basal conglomerate of the Agardhfjellet Formation, rather than the top of the Wilhelmoya Formation. The top of the Subgroup is even more clearly defined where the resistant sandstone of the Festningen Member of the Helvetiafjellet

374

CHAPTER 19

F o r m a t i o n overlies the Rurikfjellet F o r m a t i o n . T h e following d e s c r i p t i o n a n d i n t e r p r e t a t i o n d e p e n d s largely o n D y p v i k e t al. (1991a, b).

Agardlffjellet Formation (Parker 1967) (40 to 290m). This unit, formed under shallow-marine shelf conditions, was dominated by clay. However, sand bodies were redeposited from earlier deltaic sediments. The shales were partly formed in anoxic conditions. The delta front was advancing in a NE-SW line from the northwest (Dypvik et al. 199 lb). The formation is rich in ammonites representing Callovian, Oxfordian, Kimmeridgian and Volgian stages. It is divided into four members. (1) Oppdalen Member (Dypvik et al. 1991a) comprises three beds: Brentskardhaugen Bed (Parker 1967), 0 . 2 - 4 m (1.3m at the eponymous locality). This 'Lias conglomerate' at the base has attracted much discussion, quite apart from the purely conventional matter as to with which formation it should classed. It is a widespread and easily recognizable horizon. It is a remani6 unit with pebbles which are phosphatic concretions containing i.a. Toarcian bivalves and ammonites and younger fossils ranging up to late Bathonian age. Its origin has been discussed many times. The pebbles are of phosphorite, quartzite and chert usually in a matrixsupported texture of well cemented sandy material and thus forms an easily mappable unit. The biota has been recorded by Wierzbowski, Kulicki & Pugaczewska (1981) and B/ickstrrm & Nagy (1985) who investigated the lithology and fauna. The clast fossils range from Toarcian to at least Aalenian while the matrix appears to be late Bathonian. Maher (1989) suggested a storm related origin. The Marhogda Bed (B~ckstrrm & Nagy 1985) (0.3 1.5m) follows with oolitic, glauconitic to chamositic sand/siltstone facies (Dypvik et al. 1991a). The Dronbreen Bed (Dypvik et al. 199 l a), 10-60 m is a sequence of loosely cemented sediments (sand, silt and clay). Lack of structure may indicate bioturbation. The main transport direction is suggested (Dypvik et al. 1991a) as towards S to SE. It is rich in ammonites, belemnites, bivalves, and foraminifers (Dypvik et al. 1991a). (2) Lardyfjellet Member (Dypvik et al. 1991a) 35 m. This member typifies the Agardhfjellet Formation of dark grey to black shales and paper shales, with common carbonate concretionary beds. The paper shales are rich in organic material, but are not fossiliferous; otherwise bioturbated sediments are a minor component. The grey shales are rich in fossils (bivalves, ammonites including Kepplerites, and belemnites). The concretions are dolomitic. (3) Oppdals~ta Member (Dypvik et al. 1991a) c. 225m appears as a siltysandy interval between the shaly members below and above. (4) Siottsmoya Member (Dypvik et al. 1991a) c. 100 m. This member resumes the typical facies of the Lardyfjellet Members with dominant grey shales and locally developed black and paper shales. In the upper part coarseningupward shale to sand sequences characterise horizons with Dorsoplanites. The upper levels contain the most abundant macro-faunas in the Rurikfjellet Formation. Concretions in the shales are typically red to yellow. Towards the top, light yellow concretionary (dolomite) beds dominate. Some of the thickness variation may be the result of Paleogene drcollement movement (Haremo et al. 1990). The post-Agardhfjellet pre-Rurikfjellet break.

N o t only does there a p p e a r to be a f a u n a l h i a t u s a n d a s e d i m e n t a r y d i s c o n f o r m i t y , b u t dolerite i n t r u s i o n s cut the lower f o r m a t i o n a n d are n o t k n o w n to p e n e t r a t e the Rurikfjellet F o r m a t i o n ( P a r k e r 1966, 1967). In western Torell L a n d the base o f the Rurikfjellet F o r m a t i o n is t a k e n at the base o f the P o l a k k f j e l l e t Bed ( B i r k e n m a j e r 1975). T h e age at this level is b e t w e e n Early K i m m e r i d g i a n a n d V o l g i a n ( B i r k e n m a j e r & P u g a c z e w s k a 1975). I n the east o f the C e n t r a l Basin the b r e a k at the base o f the M y k l e g a r d f j e l l e t Bed is b e t w e e n early Mid-Volgian and Valanginian (Birkenmajer, Pugaczewska & W i e r z b o w s k i 1982). It is t h e r e f o r e t e m p t i n g to d r a w a d i a c h r o n o u s b o u n d a r y for the base o f the Rurikfjellet F o r m a t i o n w h i c h y o u n g s eastwards.

Rurikfjellet Formation (Parker 1967) 40-290m. The Rurikfjellet Formation (Berriasian to Barremian) reveals an upwards-increasing sand content from the build-out of a delta system and partly reworked by storms. The delta front was advancing in a N-S line from the west (Dypvik et al. 1991b) Wimanfjellet Member (Dypvik et al. 1991a) is made of grey and partly silty shales, with some bioturbation. Lenticular concretions are reddish, sideritic

and up to a metre in diameter. Higher up their shape is spherical and they are composed of siderite and calcite. Bivalves, belemnites and occasional ammonites occur in lower concentrations than in the underlying formation. The Myklegardfjellet Bed (Birkenmajer 1980) 0.5-10 m forms the base of the Wimanfjellet Member in eastern central Spitsbergen. This clay unit is a distinct and widespread marker horizon often coloured reddish to yellow or greenish. It comprises two plastic-clay-rich horizons separated by grey shales. Glauconite occurs in variable concentrations. The clay carries some belemnites and foraminifers. The bed was deposited on a marine shelf and was subsequently altered by decomposition of its unstable glauconitebearing components. The event marks a change from predominantly shelf sedimentation controlled by global eustatic sea levels (Late Bathonian to Ryazanian) to a locally regulated deep sea to shallow shelf prodeltaic to deltaic mode (Ryazanian to Hauterivian) (Dypvik, Nagy & Krinsley 1992). This bed has been suggested as possibly containing distal ejecta from the (Mjolnir) impact in the Barents Sea (Gudlaugsson 1993; Dypvik et al. 1996). It has been dated at latest Tithonian to Early Berriasian from a shallow core 30 km outside the postulated crater rim (see Fig. 11.1 for location). Ullaberget Member (Rozycki 1959), comprises fine sands, silts and shales. In the south and at Festningen four coarsening-upward sequences were noted (Edwards 1976; Mork 1978) of 15 35 m totalling 85 m, generally hummocky cross stratification and bioturbation. Transport direction was towards the S and SE. Similar but less abundant fossils are found compared with underlying strata. The deposition of the Ullaberget sands is attributed to the progradation of the Festningen delta system. Uppermost Rurikfjellet Formation strata were investigated palynologically (Grosfjeld 1991). Dinoflagellate cysts indicated a Barremian age.

Kongsoya Formation (Smith et al. 1976) (see Kong Karls description in Chapter 5). The Kongsoya Formation is exposed in both main islands of Kong Karls Land: Svenskoya and in western and eastern Kongsoya. The successions differ in each outcrop area and reflect a time of minor tectonic instability. In Svenskoya to the west, the formation is represented by the Dunrrfjellet Member shale. In western Kongsoya, 30 km to the east three members were described, from the bottom: Passet (clay) Member. Retziusfjellet Member shale and Tordenskjoldberget Member limestone separated by disconformities. A further 25 km to the east in eastern Kongsoya the Nordaustpynten Shale Member is overlain by a poorly exposed unnamed unit. The Kongsoya Formation is included in the Janusfjellet Subgroup as an extension of it because of the dominant marine shale facies with belemnites. It differs from the two formations in Spitsbergen by its variability, its richly fossiliferous horizons especially limestones and most notably by its constituent lava flows which increase eastwards. It differs from the units below and above by its dominant marine argillaceous facies in contrast to their non-marine sandy facies. The Passet Member (Smith et al. 1976), 65 m is of clay, silt and little sand, with a conglomerate bed, clay ironstone nodules small belemnites and thin coal beds. Lofaldli & Nagy (1980) suggested that the middle and upper part of the member was deposited in a brackish environment; but the clay silt and belemnites suggest marine iagoonal conditions and indicate a Sinemurian to Toarcian age. Doyle & Kelly (1988) after a detailed study of the belemnites suggested a (?Toarcian), Aalenian, Bajocian age for the upper part. Dinoflagellates are consistent with Toarcian through Aalenian ages (Smelror 1988). Retziusfjellet Member (Smith et al. 1976), 75 m, is of black and grey shale with calcareous, ironstone or pyrite nodules, the calcareous concretions with ammonites, belemnites and bivalves, the whole suggesting formation in a marine inner shelf environment. Ammonites indicate ages from Late MidBathonian (ishmae zone) through Early and Mid-Callovian (e.g. Rawson 1982). Belemnites range through Kimmeridgian and (Volgian) Tithonian (Doyle & Kelly 1988). Dinoflagellate assemblages argue Late Bathonian to Early Callovian, then Callovian and in the upper part to middle Oxfordian ages (Smelror 1988). The discrepancy as to the Late Oxfordian through Volgian span may in part arise from the fact that these ages are represented in the Dun~rfjellet Member. Tordenskjoldberget Member (Smith et al. 1976), 30 m, comprises two equal divisions. The Lower division is a calcareous sandstone composed largely of prismatic fragments of the shell of the bivalve Inoceramus. It includes the 'Belemnite mounds' which are dated by Buchia as Early to Mid-Valanginian (Blfithgen 1936). Verdenius (1978) argued a Valanginian age from coccoliths and noted that a Valanginian to Barremian age had been suggested by Bjaerke. The belemnites and buchiids gave a clear Valanginian to Hauterivian age (Doyle & Kelly 1988).

JURASSIC AND CRETACEOUS HISTORY The Upper divisionof shales and siltstones has not provided evidence for age. Pchelina (pp. 60-64 in Krasil'shchikov 1996) abstracted Russian confidential reports on Mesozoic rocks. She noted i.a. that 'a peculiar metamorphic mineral assemblage with glaucophane, staurolite, kyanite and almandine, obtained from the Lower-Middle Jurassic deposits on Kongs Karls Land, and observed nowhere else in Svalbard, suggests that metamorphic rocks with glaucophane schists, probably associated with fault zones, may have been transported from the erosion area north and northeast of Kong Karls Land at that time'.

19.5.3 Helvetiafjellet and Kong Karls Land formations The Helvetiafjellet Formation is limited to Spitsbergen and the Kong Karls Land Formation to its own small cluster of islands nearly 200 km to the east. They have in common a non-marine sandstone and coaly shale facies following abruptly on the dominantly marine shales of the Janusfjellet Subgroup. They differ in that the Kong Karls Land Formation has conspicuous lava flows. But these cap the sequence above which nothing is preserved, whereas the Helvetiafjellet Formation is followed by the thick Carolinefjellet Formation. The two formations reflect a gently subsiding basin in Spitsbergen and a somewhat unstable shelf with lava flows in the east. In these respects, the Kong Karls Land Formation has similarities with the Franz Josef Land sequence, 400 km still further east.

Helvetiafjellet Formation (Parker 1967), 150m. Parker divided the formation into two members: the prominent massive sandstone Festningen Member below and the Giitrefjellet Member with more argillaceous interbeds above. The whole has been interpreted (Steel, Gjelberg & Haarr 1978) as an interdigitating deltaic facies with thick sets of cross-stratified, coarse distributary channel sandstones (which fine upwards), thin sets of ripple laminated siltstones, and interdistributary bay siltstones and clays, all generally with coarsening-upward sequences. A more detailed study of the Helvetiafjellet Formation by Gjelberg & Steel (1995) confirms a prior reduction of relative sea level with an angular unconformity slightly truncating Janusfjellet Formation strata. The formation itself reflects a fairly regular northwesterly transgression through Nordenski61d Land. The deltaic complex deposits thus retreated to the NW whence the sediments derived. The transgression probably reflects regular subsidence through Barremian time. There is no obvious correlation with the sequence stratigraphy and related sea-level curves as plotted in the Shell Geological D a t a Table, 1995, based on Haq et al. (1988). Indeed eustatic levels plotted insignificant change through this interval. In other words, as Gjelberg & Steel

Fig. 19.10. Summary of the lateral development of the Helvetiafjellet Formation (simplified by S. R. A. Kelly after Steel, Gjelberg & Haar 1984; Nemec et al. 1988a, b).

375

concluded, the formation shows 'the development of an overall retrogradational parasequence stacking pattern, interrupted by intervals of both aggrading and prograding parasequences'. In the south, where the thickness increases in this and the underlying unit, there is evidence of rotational collapse (in Festningen Member time) of Helvetiafjellet sandstones cutting into the Janusfjellet Formation with slide blocks, shaly and sandy turbidites (Nemec et al. 1988a, b). The slump structures measure up to 1.5 km horizontally and 50m deep into the underlying shales. They represent collapse of a delta front system (Fig. 19.10). Mork (1978) confirmed Challinor's conclusion that some rocks east of Hornsund, previously mapped as Triassic and Jurassic, are indeed Cretaceous. There was probably a confusion between the Kapp Toscana and Helvetiafjellet sandstones. This led to a revision of the thrust structures of Birkenmajer (1975).

Kong Karls Land Formation (Smith et al. 1976), 50m. The sandstones appear only to be preserved in the hill tops because of the overlying or interbedded protective lava flows 5-20m thick. The sandstones are not so resistant as those on Spitsbergen. Three members constitute the formation, one for each of the three outcrops. In each case they appear to rest unconformably on, and occasionally truncate, the underlying strata. In Svenskoya the formation, is represented by the Kiikenthalfjellet Member, (Smith et al. 1976), 65 m. At the base is a well consolidated, discontinuous brown sandstone, presumably a channel fill. The main body is of alternating sandstone, harder and softer and with intervening clay and carbonaceous material. Nearer the top are two beds of coal - one nearly 1 m thick. The sequence matches that of the Helvetiafjellet progression from Festningen through Glitrefjellet members. Two lavas occur at or near the top in contact or with thin sandstones between, and one connects with a sill. In western Kongsoya in the type section at Tordenskjoldberget in the Hhrfagrehangen Member, 14m. Similarly there are two lava flows at the top of the succession and sandstones with plant and tree trunk fossils and with thin coals. (Gothan 1907 described the flora). The sandstones are more conglomeratic. In eastern Kongsoya is the Johnsenberget Member, 50 m, with 20 m lava above 30 m sandstone and conglomerates. The island still further to the east, Abeloya, comprises blocks of basalt and dolorite not rising to more than 5 m above sea level. Because in Kongsoya the general dip is to east, it is likely that this island exposes the igneous rocks higher in the Kong Karls Land Formation as a quite distinct unit. The Helvetiafjellet and Kongs Karls Land formations show a progression eastwards, and possibly southeastwards, towards greater volcanic components. This is reflected not o n l y in the

376

CHAPTER 19

presence of lava flows in the Kongs Karls Land Formation, but in the volcanic content of the sediments. A plant-bearing tuffaceous horizon in the Kong Karls Land Formation may correlate with a tuff conglomerate east of Van Mijenfjorden where rounded andesitic pebbles up to 5cm diameter were recorded (Hagerman 1925). Similar horizons have been recorded elsewhere (Pchelina 1983). The composition of the sandstones has been investigated by Edwards (1978, 1979), Elverhoi & Bjorlykke (1978), Elverhoi & Gronlie (1981). In Spitsbergen the arenites have up to 95% to 25% mostly with a volcanic component. In Kong Karls Land quartz ranges from 50% down to 5%, the balance being volcanic fragments with feldspar and mica. Cement is quartz, calcite, illite or chlorite. The age of either formation, (Helvetiafjellet or Kong Karls Land) is not easily determined from contained fossils. In Spitsbergen, underlying strata are Late Hauterivian to Barremian and overlying strata are Late Aptian. There appears to be a stratigraphic break following the Janusfjellet sedimentation so the Helvetiafjellet Formation is most likely Barremian to Early Aptian. The Kong Karls Land Formation from internal palaeobotanical evidence is Valanginian or younger. Palynomorphs (Smith et al. 1976) include (presumably derived) Early Jurassic and (probably contemporaneous) Early Cretaceous forms. The lack of angiosperm pollen suggests an age not later than Albian or Cenomanian. Underlying strata constrain the age as Mid-Valanginian or younger. Thus a Barremian age is consistent with the evidence, but this is perhaps a convenient/conventional age. It could be Aptian or both. This conclusion was reinforced by Grosfjeld (1991) who reinvestigated constraints on the initial boundary of the Helvetiafjellet Formation. Dinoflagellate cyst species show that the youngest beds of the Rurikfjellet Formation are Barremian. From this it was concluded that no hiatus between the Rurikfjellet and Helvetiafjellet formations could be demonstrated as was previously thought.

19.5.4

Carolinefjellet Formation (Parker 1967)

The formation was thicker and more complete in the southeast partly because of the greater contemporary subsidence there, but mainly because Late Cretaceous tilting up to the NW led to successively deeper erosion to the N W so that 850m on the east coast are reduced to 200 m at Isfjorden, with a maximum of 1000 m (Fig. 19.11). The age ranges from Late Aptian through Albian. The base is almost transitional with the Helvetiafjellet Formation below, but is marked by the appearance of compact fine sandstones with well developed ripple and plane bedding laminations, and the disappearance of coaly shales; shales and mudstones may overlie the channel sandstones of the earlier formation. The top is always marked by the unconformably overlying basal conglomerate of the Paleocene Firkanten Formation. The overall environmental pattern is one of marine shelf sedimentation with facies ranging from tidal coastal to open shallow marine. Steel et al. (1978) recognized upward-coarsening sequences in the three sandier levels which suggest lower delta front facies developing delta lobe progradation. Both high and low energy environments are evident. Storm waves inducing bottom currents are indicated by cross-bedding. On the other hand, kerogen composition suggests shallow marine low-energy conditions with repeated phases of deltaic progradation and lobe abandonment marked by carbonate horizons (Bjoroy & Vigran 1979). Sediment source is from the north and northeast. Dropstones in fine-grained sediments have been taken to indicate ice rafting which is not inconsistent with a palaeolatitude of 65~ (Vincenz & Jelenska 1985; Frakes & Francis 1988). Dalkjegla Member (Parker 1967), 100m, is the equivalent of the Lower Lamina Sandstone of Hagerman (1925) and is best seen at Langstakken, 131 m. It is a fine, grey-green, often glauconitic,

Fig. 19.11. Fence diagram showing lateral variations in the Carolinefjellet Formation (after Nagy 1970).

JURASSIC AND CRETACEOUS HISTORY laminated to thinly bedded sandstones, with small-scale crosslaminations and alternating with dark grey-black shale and siltstone. Near the top is a conglomerate bed and locally there are carbonate concretions. The sparse fauna include ammonites, bivalves, scaphopods, ophiuroids and trace fossils. Innkjegla Member (Parker 1967), 430 m, is the Cretaceous Shale of Hagerman (1925). The type section is at Langstakken. Nagy (1970) distinguished a lower part of shale with lenses of clay ironstone and calcareous concretions and an upper fossiliferous shale-siltstone unit with beds of grey-green laminated sandstones and of clay ironstone. Chert and quartzite pebbles and boulders up to 50 kg weight are interpreted as glacial dropstones (Pickton 1981). Langstakken Member (Parker 1967), 178 m, is the 'Upper Lamina sandstone' of Hagerman (1925) and formed of grey-green, finegrained, platy cliff-forming sandstones with finer thin horizons. Bivalves, scaphopods and ammonites are scarse and poorly preserved. Zillerberget Member (Nagy 1970), 210m, is Parker's (1967) unnamed shale unit, comprising grey shale and siltstone with minor beds of grey-green fine-grained platy sandstone, and common clay-ironstone lenses. Bivalves and worm tubes (Ditrupa) are common; ammonites, gastropods and echinoderms less so. The formation is limited to southeast Spitsbergen. Sch6nrockfjellet Member (Nagy 1970), 83 m, is the upper sandstone member limited to south east Spitsbergen and of grey-green finegrained, well-bedded cliff-forming sandstone. Rare bivalve and crinoid fragments are found.

/12 ~

-81 ~

377 /15 ~

/18 ~

121~

124[

/ 5

--80 ~

~

~

'~'

oe

m,

0

...

,

Z9 o

~

Age of the Carofinefjeilet Formation. Marine faunas include ammonites, bivalves, gastropods, scaphopod, echinoids, crinoids, and range from Aptian to mid-Albian. The rich spore pollen assemblage at the base of the Dalkjegla Member at Festningen indicates an Early Aptian age and bivalves from the same member are also probably Aptian. Innkjegla Member faunas are Aptian to Albian. Five successive Albian ammonite assemblages were recognised by Nagy (1970). In the Dalkjegla Member are 'Crioceras' and Late Aptian to Early Albian spores. The Langstakken Member with Early Albian, Zillerberget-Early to mid-Albian ammonites and the Sch6nrockfjellet Member undated by ammonites but contained late Middle Albian dinoflagellates (.&rhus 1991).

IP

4' 7 7 ~

..

19.5.5

Jurassic-Cretaceous basic igneous rocks

Doleritic intrusions are abundant, especially in eastern Spitsbergen, the islands of Hinlopenstretet, Barentsoya, Edgeoya and Kongs Karls Land (Fig. 19.12). Lavas are known from Kong Karls Land. Sills may extend for 30km and range from 5 to 150m in thickness averaging 30-40m. They are often seen to be joined by thin dykes, 10-15 m thick. Only a weak differentiation is visible in the thickest sills. The petrography was described by Backlund (1907a, b) and again by TyrreU & Sandford (1933) who distinguished four main classes.

(A) Normal medium- to fine-grained facies constitute the main bulk of occurrences with a plexus of ophitic texture with plagioclase laths in a background of pyroxene and skeletal crystals of iron ore. The rocks are typically non-porphyritic and contain patches of imperfectly crystallised mesostasial matter. The large feldspars are bytownite and the smaller ophitic laths are An55 acid laboradorite. The pyroxenes approximate to enstatite-augite or pigeonite. Irregular areas of red non-pleochroic serpentine indicate former olivine. The skeletal ores are of titaniferous magnetite. The mesostasial matter is a fine complex of plagioclase laths, quartz, chlorite and pyroxene altered to brown hornblende and biotite with needles of apatite in an ill-defined base of alkali feldspar.

~-

U 0,,

km,

,

27 o

"

30 =

100

76 o /18 ~

121 ~

Fig. 19.12. Map showing the distribution of Jurassic-Cretaceous igneous rocks (sills and dykes) (based on Tyrrell & Sandford 1933, with permission of the Royal Society of Edinburgh).

(B) Coarse gabbroic and pegmatitic varieties exhibit fresh olivine and micro-pegmatite which may culminate in a pegmatite of quartz, hornblende and biotite with a nearly colourless (uniaxial) pyroxene. These late-formed groundmass pyroxenes are enriched in iron (towards hypersthene) and magnesium (towards enstatite). There is evidence of transformation from olivine to pyroxene and the olivine co-exists with quartz. Reddish biotite and deep greenish hornblende occur at the margins of the micropegmatite.

378 (C) sills and and

CHAPTER 19 Marginal varieties. Towards contacts with country rock of and dykes ophitic texture is lost in favour of an intergranular finely intersertial texture. Feldspar phenocrysts may develop olivine disappear.

(D) 'White trap' modification sills penetrating Triassic and Jurassic rocks prefer carbonaceous strata. The result is of fine magnesian minerals and even of feldspars by carbonates of calcium, magnesium and iron. This facies may account for Nordenski61d's 'hyperite'. Tyrrell & Sandford (1933) made a critical compilation of available chemical analyses and concluded with averages of selected work (Table 19.1). The differences between the two groups are probably not significant and the chemistry confirms the impression from field work that the same magma was responsible. Birkenmajer & Morawski (1960) described dolerite intrusions of Wedel Jarlsberg Land. Teben'kov, Burov & Vanshteyn (1980) reported that the rocks range in composition from porphyritic olivine dolerite (up to 13% olivine) to coarse-grained leucocratic gabbro~lolerite. The most widespread compositions are finegrained tholeiitic ophitic quartz dolerites with plagioclase 40-50%, pyroxene 35-40%, olivine 2-4%, quartz 1-8%, ore minerals 4-10% (mainly ilmenite and titano-magnetite). Intrusive contacts have fine-grained porphyritic facies with glassy patches. Wegand & Testa (1982) reported on the petrology and geochemistry of the Hinlopenstretet dolerites. The age of the intrusions was long debated. Tyrrell & Sandford (1933) concluded a range within Late Jurassic and Early Cretaceous. Parker (1966) observed pre-Cretaceous evidence of intrusions. Many are seen to cut Triassic strata, occasionally Jurassic and exceptionally Cretaceous Janusfjellet Sub-group strata. The youngest rocks to be cut are probably Berriasian. The intrusions could all be of that age or younger or spread through a much longer time span. The Kong Karls Land lavas are probably related and their ages can be determined approximately from fossils in the interbedded strata. Throughout Kong Karls Land, in Svenskoya and in western and eastern Kongsoya, lavas occur within the Kong Karls Land Formation of probable Barremian age. Earlier lavas are found in the east of the Kongsoya Formation down to the Nordaustpynten shale. Thus volcanism spread through Kimmeridgian to Barremian time. Moreover, it could have begun earlier in the east, where the lowest beds are at sea level, or later because the uppermost units in the Kong Karls Land Formation cap the hills (Smith et al. 1976). Isotopic determinations were first attempted (Gayer et al. 1966; Frisov & Livshits 1967) but with too little precision to have stratigraphic significance. The principal study by Burov et al. (1977) yielded 45 determinations from Isjforden, Storfjorden, Barentsoya, Edgeoya, Wilhelmoya and Nordaustlandet. Inspection of the list suggests that quartz-dolerites are typical of ages spread around

Table 19.1. Averages of chemical analyses ma&" by Tyrrell & Sandford (1993) in percentages

SiO2 AI203 Fe203 GeO MgO CaO Na20 K20 H20 TiO2 P202 MnO

4 Intrusive dolerites

4 Lavas

49.2 14.4 3.4 10.1 5.4 9.4 2.0 1.0 1.6 2.9 0.2 0.4

48.8 13.9 4.6 9.9 6.0 9.7 2.7 0.7 1.4 1.5 0.4 0.2

140Ma (?Tithonian to Hauterivian or Barremian) and younger olivine-dolerites range around l l 0 M a (?Aptian-Albian). Burov et al. concluded two maxima at 1444-5 and 105• 5Ma. More significant perhaps is their plot showing the older intrusions to be in Spitsbergen and the younger in eastern Svalbard. Analytical data were not given. Kovaleva & Burov (1976) published further details. Manecki (1987) reported prehnite in dolerite dykes in Wedel Jarlsberg Land. Birkenmajer (1979a) examined the thermal metamorphism of palynomorphs affected by the intrusions. Hughes, Harland & Smith (1976) had considered this as one factor in a wider problem to account for the poor showing of palynomorphs in some areas (see Fig. 20.6). Palaeomagnetic studies were reported by Spall (1968), Krumsiek, Nagel & Nairn (1968), Halvorsen (1973, 1974), Jelenska et al. (1978b), Aiinehsazian & Vincenz (1979), Vincenz et al. (1981), Vincenz & Jelenska (1985). In connexion with the palaeomagnetic work, further isotopic ages of 110 + 5 and 66.8 + 43 Ma were reported notably from dykes in the Vimsodden area of southwest Wedel Jarlsberg Land.

19.6

Jurassic and Cretaceous biotas

Marine and non-marine facies alternated so precluding a complete succession for either environment; but at the same time giving an impression of both land and sea. In a word this impression is commonly labelled 'Boreal', partly because the diversity of faunas appears to have diminished pole-wards so yielding faunas with many individuals and few species. However, this basic concept was challenged by Crame (1992), but does appear to work for the Jurassic and Cretaceous molluscs (Crame 1993). A further constraint on marine life and on its taphonony is the anoxic facies of the Janusfjellet Subgroup, in which environments limited life to a few adapted forms while at the same time protecting them from active predators. Preservational controls hinder indentifications. Faunas from mudstones are frequently crushed and easily weathered. Wellpreserved faunas are restricted to concretionary horizons which do not occur at all stratigraphic levels.

19.6.1

Marine biotas

The most evident biota, typical of all marine strata are molluscs: ammonites, belemnites and bivalves which not only contributed significantly to most collections of macrofossils, but provide reliable material for precise correlation. The ammonite succession is outlined in Section 19.4.2.

Ammonites, in so far as appropriate facies are available, occurred throughout, but often only as flattened impressions. Particularly good three dimentional preservation occurs in the Middle Jurassic calcareous concretions of Kongs Karls Land. They yield a typically Boreal succession with European affinities containing Toarcian through Albian species, with only the Bajocian stage unrepresented. Key ammonite papers are: Pompeckj (1899); Nathorst (1901); Stolley (1912); Spath (1921); Frebold (1929a, b,c); Bodylevsky (1929); Sokolov & Bodylevsky (1931); J. Weir (in Tyrrell 1933); Blfithgen (1936); Frebold & Stoll (1937); Rozycki (1959); Klubov (1965a); Pchelina (1965a, b,c, 1967); Kopik (1968); Yershova (1969, 1972a,b, 1980, 1983); Nagy (1970); Rawson (1982); B/ickstr6m & Nagy (1985); Kopik & Wierzbowski (1988); Weirzbowski (1988); Wierzbowski & Arhus (1990); Wierzbowski & Smelror (1993); Birkenrnajer & Wierzbowski (1991).

Belemnites are readily preserved and collected because of their durable calcite rostra, but require complete specimens to enable distinction of particular species from amongst the eleven genera or

JURASSIC AND CRETACEOUS HISTORY sub-genera known (Doyle & Kelly 1988). In contrasting preservation in the Brentskardhaugen Bed, it is usually only the phragmocones that occur. Species are listed in Section 19.4.3. Important earlier records include Lindstr6m (1865), Lundgren (1883), Sokolov & Bodylevsky (1931), Bltithgen (1936), Stoltey (1938). More recent records include Pchelina (1967), Birkenmajer & Pugaczewska (1975), Birkenmajer et al. (1982), Brckstr6m & Nagy (1985) and Doyle (1987). Ditchfield used Kong Karls Land belemnites for isotopic palaeotemperature studies (see Section 19.6.3 below).

Bivalves. The principal references are: Lindstr6m (1865); Lundgren (1883); Sokolov (1908); Sokolov & Bodylevsky (1931); Weir, (1933); Bliithgen (1936); Frebold & Stoll (1937); Soot-Ryen (1939); Birkenmajer & Pugaczewska (1975); Wierzbowski, Kulicki & Pugaczewska (1981); Birkenmajer & Pugaczewska (1982); Yershova (1983); Bfickstr6m & Nagy (1985). Brentskardhaugen Bed phosphatized sandstones contain the most diverse bivalve faunas of the Jurassic-Cretaceous sequences on Svalbard. The Toarcian-Aalenian and possibly up to Bathonian time interval is represented by byssate pteriids, pectinids, reclining oysters, shallow infaunal heterodonts, trigoniids and deep burrowing myoids which indicate well oxygenated and high energy conditions consistent with influence under storm-related conditions (Maher 1989). The Janusfjellet Subgroup mudstones have a less diverse fauna, usually of thin-shelled pteriids, including pectinids with sparse heterodonts and deep-burrowing lucinoids and myoids. Deposit feeding nuculoids are characteristic. Locally, fauna may be abundant, but forming low to medium diversity disarticulated valve assemblages. One distinctive assemblage from the Bathonian of Kong Karls Land is dominated by the inoceramid Retroceramus.cf, buluniensis (Koshchelkina). In Oxfordian-Hauterivian strata Buchia is particularly common. The Helvetiafjellet non-marine facies contain undescribed unionid bivalves. The return of marine condition in the Carolinefjellet Formation gave rise to relatively diverse benthic assemblages which have not been monographed.

Gastropods form a small element of the benthos.

Scaphopods as bottom dwellers are often preserved (some early records confused them with the worm Ditrupa).

Worms. Tubes of Ditrupa are common, Carolinefjellet Fm.

especially in the

Brachiopods are rare, even compared with more temperate biotas. Perhaps in the cooler waters they were still less able to compete with bivalves. Lingula cf. ovalis J. Sowerby and Discinisca sp. are cosmopolitan forms and were described with Ptilorhynchia sp. and Terebratulina sp. by Sandy (in Arhus et aL 1990), together with Cheirothyris sp. a more distinctive boreal form known from the Russian Platform.

Echinoderms are scarce: Crinoids, asteroids and ophiuroids were reported from the Carolinefjellet Formation (Nagy 1963).

Cirripedes. The plates are generally rare, but Zeugmatolepis? borealis Collins (in Arhus et al. 1990) was described from the Bjornoya Basin. Borings of Rogerella occur commonly in belemnite rosta (Doyle & Kelly 1988).

379

Corals are rare and only known from the occurrence of Thecocyathus from the 'Neocomian' of Kongsoya (Lindstr6m 1900). Stromatolites/oncoliths are recorded from the Willhelmoya Formation of southwest Spitsbergen (Krajewski 1992b). Foraminifers have been described (Lofaldli 1978, Lofaldli & Nagy 1980, Nagy & Lofaldli 1981; Nagy, Lofaldli & Brckstr6m 1988, Nagy et al. 1990). Agglutinated bottom-dwelling forams have a greater preservation potential than the more soluble planktonic forms and so most has been written about them. The faunas are well known from central Spitsbergen and in Kong Karls Land where the less consolidated sediments permit better preparation of material. (Fig. 19.7) Indeed, it is the agglutinated (quartz sand) forms which dominate. Lofaldli & Nagy (1980) reported low diversities. Four assemblages were named: two in the lower and two in the upper members of the Kongsoya Formation, but only the upper (Retziusfjellet Member) assemblages had ammonite control. One sample, only in the upper assemblage of the Retzuisfjellet Member, included three times as many species of non-agglutinated forams indicating their existence in the biota but poor chance of preservation. It may be significant that an investigation on the mainland of Spitsbergen showed that a richer agglutinating assemblage and the only calcareous assemblage were reported from the Rurikfjellet Formation (Nagy & Lofaldli 1981). This tends to confirm that the underlying Agardhfjellet Formation, with its sediments rich in organic carbon, inhibited the preservation of thin calcareous skeletons. Foraminiferal assemblages have proved useful mainly as environmental indicators in the Janusfjeltet Subgroup in Spitsbergen and Kong Karls Land (Bjaerke, Edwards & Thusu 1976; Lofaldli & Thusu 1977; Lofaldi & Nagy 1980, 1983; Nagy, Lofaldli & Brickstr6m 1988). Arenaceous foraminifera are predominant, generally indicating a neritic environment. Species diversity decreases with higher TOC levels, associated with increasingly anaerobic conditions. Calcareous species appear in significant numbers only occasionally, where there is increased availability of carbonate. This is associated with a more open marine environment, e.g. in the Tordenskjoldberget Member of Kong Karls Land (Lofaldli 1978). Foraminiferal mats form a distinct organo/sedimentary facies in the Wilhelmoya Formation in Van Keulenfjorden (Krajewski 1992a). Stromatolites. In the low sedimentation rate conditions of formation of the Brentskardhaugen Bed, Krajewski (1992a, b) records stromatolites in two forms. Firstly, they occur in association with foraminiferal mats as broad crusts. Secondly, they occur as oncolites in association with the phosphatised pebbles of the bed. These confirm formation under photic conditions, i.e. very shallow water. Vertebrates. There is no comprehensive review of Svalbard vertebrates, although Heintz (1964) summarized the occurrence of Jurassic reptiles. Saurians occur frequently as fragments in the Brentskardhaugen Bed (e.g. Wierzbowski, Kulichi & Pugaczewska 1981; Brckstr6m & Nagy 1985). Complete vertebrate remains are rare compared to the Triassic deposits. Woodward (1900) described a complete fish, Leptolepis nathorsti, from the Dun6rfjellet Member on Svenskoya and Ginsburg & Janvier (1976) record it as fragments in the Brentskardhaugen Bed of Lardyfjellet. Plesiosaurs have been most commonly reported: Tricleidus from the Lardyfjellet Member on Lardyfjellet (Callovian/Oxfordian) (Ginsburg & Janvier 1976) and at Sassendalen (?Oxfordian); and unidentified forms from the Oxfordian of Janusfjellet (Wiman 1913) and the Slottsmoya Member south of Deltaneset (Persson 1962). Calcareous nanofossils would be even less likely to survive but a Valanginian association of coccoliths was reported (Verdenius 1978) from the Tordenski61dberget Member.

380

CHAPTER 19

Dinoflagellates are a significant marine element and have some chronostratigraphic value (Fig. 19.7) (Bjaerke 1977; Bjaerke 1980a, b; Smelror & ,~rhus 1989; Smelror 1988; Arhus 1991; Arhus et al. 1990; Grosfjeld 1991). About 200 species have been identified from Kong Karls Land where the less consolidated strata afford superior preparation of samples.

Trace fossils. Although trace-fossils are widespread, especially in marine Jurassic and Cretaceous strata of Svalbard, there has been no systematic review or established ichno-facies scheme. However, ichnotaxa are frequently cited. Transgressive high energy sandstones, e.g. the Wilhelmoya Formation contain Arenicolites, Chondrites, Diplocraterion, Monocraterion, Rhizocorallium, Teichichnus and Thalassinoides, indicating high and moderate energy bottom conditions (B~ickstrrm & Nagy 1985; Worsley & Mork 1978; Krajewski 1992b). With deepening water in the Janusfjellet Subgroup, Chondrites and Muensteria become more characteristic in the silts to grey mudstones (Birkenmajer 1980). Locally bioturbation may be intense, homogenising the sediment, but in the black shale facies e.g. of the Lardyfjellet Member bioturbation is absent. Lithic hardgrounds are generally absent, but locally skeletal remains such as belemnites are hosts to Rogerella (attributed to boring barnacles) and ?Talpina (boring bryozoan) (see Doyle & Kelly 1988, e.g. pl. 8 fig. 10) in the Tordenskjoldberget Member of Kongsoya. The Helvetiafjellet Formation contains rootlet structures and some vertical traces possibly attributable to Skolithos (Edwards 1976a). Vertebrate trackways of dinosaurs occur in the Festningen Member (de Lapparent 1962; Edwards, Edwards & Colbert 1978). Doubtless a great variety of traces exists in the Carolinefjellet Formation from which Frebold (1931, p. 1.4, fig. 2) illustrated a sinuous trace on a rippled surface.

Temperatures of the ambient sea water have been the subject of comparative research in both Antarctic and Arctic biotas (see below 19.6.3)

19.6.2

Terrestrial biotas

Inevitably, the evidence for land-dwelling organisms depends largely on preservation of swamp accumulations.

Vegetation was earliest recorded in macroflora by Heer (1876); Nathorst (1897b, 1913); Gothan (1910, 1911) and Walton (1927). From these most subsequent accounts have been derived. Early records of 'Rhaeto-lias' flora should be treated as Triassic (see Chapter 18). Jurassic floras were claimed to show some uniformity of global environments (Seward 1931) and the best records are from MidJurassic strata especially in England and the Antarctic Peninsula). Only a small proportion of taxa has been recorded from Svalbard. Of these Seward tabulated (p. 343) the following with ranges thus: T, Triassic, J, Jurassic, K, Cretaceous. Equisetales Equisetites columnaris (etc.) Filicales Cladophlebis denticulata (etc.) Gleichonites Ginkgoales Ginkgoites Baiera Czekanowskia Phoenicopsis Coniferales Araucarites Pinites Podozamites

J TJK TJK TJK JK TJ J JK TJK TJK

The Early Cretaceous flora of Spitsbergen as described by Heer (1876), Nathorst (1897), Floris (1936), Vasilevskaya 1980, 1986 was based mostly on impression fossils mainly of Ginkgo, Elatides, Podozamites, Pinites (Pityocladus) and Pseudotorellia, with fragmentary remains of pteridophytes and very rare cycadophytes. Bose & Manum (1990), commenting on the above, showed that a revised taxonomy results from new laboratory methods to reveal the inner structure of seemingly unpromising material. A pilot study of 'Scidopytis'-like fossils demonstrated greater differences from modern analogues than was earlier suspected and a new family (Arctoityaceae) was established, which occasionally formed a dominant element in forests around 55 ~ to 65~ in Early Cretaceous time. This family can be traced back to middle Jurassic material. Jurassic and Early Cretaceous palaeolatitudes probably lay between 60 ~ and 70 ~ south of the present latitude. The problem is therefore not so much why the floras are poorer than in temperate latitudes, but how such luxuriant growth could survive the dark winters even if the global temperatures were more equable and warmer. This problem was, however, addressed by Spicer & Parrish (1966) for Aptian-Albian Alaskan floras. Deciduousness, not necessarily angiospermous, is one adaptation. Angiosperm origins may well be traced back through earliest Cretaceous and Jurassic time if we knew what to look for (Hughes 1994) but the obvious explosion in the evolution of flowering plants only becomes evident everywhere in Late Cretaceous fossils, as for example in West Greenland. But the lack of Late Cretaceous outcrops in Svalbard precludes the possibility of completing that story from our rocks. Thus, the change to the succeeding Paleogene flora is the more dramatic. Vertebrates. Dependent on the vegetation, vertebrates must have been a significant element amongst terrestrial animals. Remarkably the most notable is Iguanodon whose footprints in the (probably Barremian) Festningen sandstone at Festningsodden (Heintz 1963; de Lapparent 1962 have perplexed palaeobiologists as to how such a large animal could survive on vegetation at 60-70~ latitude with dark winters, whether by a store of body fat or migration. A dinosaur that wandered too far north accidentally is unlikely, because of the discovery of Allosaurus footprints in 1976, mentioned from south of Kvalv~gen on the southeast coast of Spitsbergen (Edwards, Edwards & Colbert 1978; Aga et al. 1986; Hjelle 1993, p. 41). It is arguable that footprints could do no more than distinguish bipedal herbivorous ornithopods (including Iguanodon 'Cretaceous') and bipedal carnivorous theropods (including Allosaurus 'Jurassic/Cretaceous'). However, different genera would not reduce the problem. Larger carnivores depend on other large-bodied animals and in turn on luxuriant vegetation. Little has been done to investigate in the supradeltaic and swamp deposits what other animals may have been around. Only molluscs are recorded including bivalves and the gastropod 'Lioplax" (Lundgren 1883; Sokolov & Bodylevsky 1931).

19.6.3

Jurassic and Cretaceous climates

The Cretaceous Period in particular is generally thought to have enjoyed warm climates. Many recent climatic simulation attempts have chosen Cretaceous data partly for this reason and also for the relatively wide accessibility of Cretaceous strata. Herman & Spicer (1996) in a study based on leaf physiognomy argued that the Arctic Ocean remained systematically above 0~ even in winter and so suggested that poleward heat transport must have obtained throughout the year. On the other hand ice transported stones, carried off beaches by thin sea ice has been reported from both Cretaceous and Paleogene sediments (Pickton 1981; Steel 1977). Blocks up to 50kg of chert and quartzite were recorded in the Innkjegla Member (Late Aptian-Albian). Small rounded clasts also occur in the Janusfjellet Subgroup close to the Jurassic-Cretaceous boundary.

JURASSIC AND CRETACEOUS HISTORY P. Ditchfield (pers. comm.) investigated stable oxygen and carbon isotopes (180 and 13C) from the carbonates in Jurassic and Cretaceous fossil shells in order to establish the ambient ocean palaeotemperatures in Svalbard. Three studies have been reported with average temperatures as below: From belemnites of Kongs Karls Land, Kongsoya Formation (Ditchfield 1997): Aalenian-Bajocian 12.7~ Mid-Bathonian-Kimmeridgian 9.4~ Early-Mid-Valanginian 7.7~ From belemnites in the Agardhfjellet Formation (Janusfjellet Subgroup) of western and central Spitsbergen (Ditchfield pers. comm.): ?Callovian (Lardifjellet Mbr) 16.6~ ?Oxfordian-Kimmeridgian (Oppdals~ta Mbr) 14.9~ ?Kimmeridgian-Tithonian (Slottsmoya Mbr) 7.6~ From bivalves from the Carolinefjellet Formation of Spitsbergen (Ditchield & Staley 1996): Early Albian (6.5-10. I~ 8.3~ They concluded a time of little or no glaciation. The general impression is one of cooling from warm Mid- and Late Jurassic to cooler Cretaceous temperatures. This, however, may not have been a global change, but quite possibly the narrowing or closing of a marine connection to the south.

STAGES TRANSGRESSION/ REGRESSION

MA h.,L

I

n

19.7.1

-e0

S5

i;

Oanian

19.7.2

Mid-Late Jurassic events (Bathonian-Tithonian)

This interval corresponds broadly to the record in the Agardhfjellet Formation in Spitsbergen and the Passet and Retziusfjellet members of the Kongsoya Formation. Throughout the outcrop areas, transgression leading to normal marine conditions prevailed in which deeper water, with deposition of muds, occasionally anoxic, occurred. Dypvik (1978) discussed

. . . .

9

. . . . .

..

. . . . .

...

. . . .

..-

:.~~'~:'~':~~'i,~'~"~ N ' R ; ~

'

I MaastrichUen

74

i major uplift

Caml~nian -80

83

ss,s

Santonlen

-9o

es.5 9o,5

Coniacian Turonisn

:

97

"

Cenomanian

100

L

Albian

-- 110112

I

T6 ..~ M, ~

,

E i

]

~ ~.,'~.,'~.,? e ,

p~= ~ ^

shelf

",,'~"

ab

T 5 ~ Aptian

L

rn,-..:

~ r ) a l marine deltaic-'~"--~

~'Pnlsroin=~ ] matin=

124.5

14o.s

- 140

:-.? .'! :..:. . ....

Barremian

-1~32

Hauterivian

r4

Valanginian

~"

135

Biostratigraphic correlation is not sufficiently precise during the transition from Triassic faunas to suggest exactly where the boundary should be. However, the interval referred to here is that represented by the upper part of the (Rhaetian-Liassic) Wilhelmoya Formation. Indeed, whereas the earlier dating is obscure, the later dating is clear because the final consolidation of the Brentskardhaugen Bed was Bathonian. This interval is, thus, almost exactly Liassic, i.e. Hettangian through Toarcian. But there was a marked Toarcian marine flooding event. From the beginning of this interval the Billefjorden lineament was active in demarcating a positive area to the west, with little subsidence over a shallow marine shelf, whereas to the east subsidence was significant, although sedimentation kept pace in a deltaic environment so that thick mainly non-marine sands formed. Thus, during 30 million years an average of 30 m of strata were preserved in the west rising to 300 m in the east i.e. net relative sea level changes of 0.001 mm and 0.01 mm a -1 in rounded terms. The differential is significant, the magnitude is insignificant, it could be epeirogenic or eustatic. The sources of sediment were in the east. Evidence of the westward extension of the marine area is lost in the Paleogene orogeny. Evidence of any northward extent of Liassic deposits was removed by Late Cretaceous uplift and erosion (Fig. 19.13). From a study of coals, Michelsen & Khorasani (1991) showed that burial curves display a significant difference between Triassic and Jurassic-Cretaceous subsidence. The Jurassic-Cretaceous subsidence pattern is typical of extensional sedimentary basins, with stretching and cooling, whereas Triassic-Early Jurassic rapid subsidence terminated in a long period of no subsidence, except in the Eastern Platform.

...

:~.i.i:i.-....:.i:-.-.%1:-..!.-.:.i:..-...:.i:.-:.-:(:

- 7o

Jurassic and Cretaceous events in Svalbard Latest Triassic-Early Jurassic events (Rhaetian-Toarcian)

EVENTS I FACIES

I . . . . . . .

S0.5

- 12o

19.7

381

/

145.61

j outer shelf

~

Berdasian

R4 #

"rithonian

T3

- 150152.1

,

154.7Kimmeridgian

RT2 ~ ,

~'".':'"~shelf 9..~.,...,- ,,,,,.,-

157.1 Oxfordian 1 -16o 161.3

Callovian

deltaic

outer s h e l f

1~.1 ........_......__~ ~ . . ~ ! i : t 2

-170

Bajocian

173.5

_~

_.~

starved shelf

178

Aalenian

.~....~~ ~ ~ , ~

Toarcian

..~.. !:::.:':. ::.:;:..~.;.-..~, ; :":::',::'".'~

le7 -190 Pliensbachia~

~ '~ "" marine

marginal

194.5

-200

Sinemurian

208

Hettangien ,

Rhaetian

i!!i:~i:.::!i:ili!!ii!!i:i'-'.i.i-).:.i:ii~

,

Fig. 19.13. Summary of events in the Jurassic and Cretaceous history of Svalbard (devised by S. R. A. Kelly). the carbonate component. The areas of subsidence reversed somewhat so that the thickest deposits formed west of the Billefjorden lineament. But a relatively stable environment continued with say 300m sediment preserved during the following 25 million years with a marginally greater rate of subsidence if 100 m of sea water be added say 1 mm in 60 years. (i.e. 1.6cm 1000 a-l). Coarsening-upward sedimentary cycles in the Callovian-Volgian were shown by Dypvik (1992a) to have average periodicities of 850,000 years comparable to Alpine Triassic Lofer facies carbonates. He estimated accumulation rates of 0.4-0.9 cm 1000 a -1 based on sections at Lardyfjellet and Oppdals~ta.

382

CHAPTER 19

The Billefjorden lineament continued as a significant control, not only defining the eastern margin of the Central Basin, but as an axis with thinner sedimentation. Similarly, but on less evidence, the Lomfjorden Fault Zone appears as a positive feature. Isopachs show that the Central Basin was also bounded on the west and probably by the persistent Kongsfjorden-Hansbreen Fault Zone or an incipient Palaeo-Hornsund Fault further west bounding north Greenland. Towards the end of this interval, igneous activity is evident. Dolerites intruded the Agardhbukta strata at the eponymous locality in Storfjorden (Gripp 1929) and in Torrell Land (Rozycki 1959), and are unconformably covered by Rurikfjellet strata. This is the youngest direct age in Spitsbergen for the ubiquitous intrusions, though pyroclastic sediments occur higher up (Parker 1966). This was accompanied by slight tectonic disturbance as there is evidence along the Billefjorden Fault Zone that the Agardhfjellet Formation was downfaulted to west and so preserved, but removed to the east. The Rurikfjellet Formation truncates this faulted unconformity (Parker 1966; Harland et al. 1974). The fault flanks an anticline which is also truncated so that further to the east the Agardhfjellet Formation again appears beneath the Rurikfjellet Formation. Along the axis of the fold the Rurikfjellet Formation rests directly on the Kapp Toscana Group strata. Figure 19.14, from Parker (1967), shows evidence for intraJanusfjellet Subgroup movements as further activity along the Billefjorden and Lomfjorden fault zones. This evidence was seemingly ignored in favour of Paleogene tectonic thickening on the same fault zones (Andresen et al. 1992; McCann & Dallmann 1996). Paleogene tectonic thickening of Mesozoic strata on these fault zones was perhaps first noted by Parker (1966). The Mjolnir (seismic) structure in the southern Barents Sea (approximately 29 ~ to 30~ 73~ ' to 74~ was interpreted as an impact crater (Gudlaugsson 1993). A drill core obtained by I K U 30km outside Mjolnir's rim showed anomalously high iridium, chromium and nickel concentrations which, together with shocked quartz grains, confirmed an impact event (Dypvik et al. 1996). The age of the strata rich in these components was estimated at late Volgian (Tithonian) to early Berriasian. The coeval Janusfjellet Subgroup was also tested for enrichment in Cr and Ni (which could also have a basaltic origin) and Ir. In each case these concentrations were systematically lower providing a standard background. The Myklegardfjellet Bed in Spitsbergen was said to be deposited at the same time.

recognised coarsening-up cycles with periodicities of 285 000 years comparable to Milankovitch orbital periodicities. Higher in the formation sedimentation rates increased further reflecting proximity of a coastline with high clastic input. Further igneous activity is evident in dolerite intrusions with a wide range of isotopic ages but with one peak at 144+ 5Ma, i.e. Earliest Neocomian (Burov et al. 1977).

19.7.4

The interval is represented by the Helvetiafjellet coarse prograding delta complex sandstones in Spitsbergen and the Kong Karls Land Formation with similar sandstones and basaltic lavas. Terrestrial facies spanned the whole Central Basin. Volcanic activity in the east extended westwards as seen in tufts and sediments with a high volcanic component. There is a distinct disconformity, even an angular unconformity, in Kong Karls Land at the base indicating the onset of more disturbed conditions. It is a short but a distinct episode with about 80 m preserved in the north and centre, thickening in south Spitsbergen to 150m during an interval of about 7.5 million years, i.e. 0.01-0.02 mm a -I . Contemporary instability of a delta front is seen in the slumping at the base of the Helvetiafjellet Formation of southeast Spitsbergen.

19.7.5

Aptian-Albian events

Up to 1000m (The Carolinefjellet Formation) is what is left from this interval of not more than 27 million years, roughly 0.04 mm a -1 . Aptian-Albian intrusive activity may have peaked in the east at 1 0 5 + 5 M a (Burov et al. 1977), and continued till at least 100 + 4Ma. This was a precursor to the Late Cretaceous regional uplift. A distinct basin developed bounded on the southwest by the Sorkapp-Hornsund High but without noticeable imprint of the Billefjorden Lineament. Sediment was derived from the north area which was rising.

19.7.6 19.7.3

Barremian events

Late Cretaceous (Gulf) events: (Cenomanian-Maastrichtian)

Neocomian events (Berriasian-Hauterivian) The record of Late Cretaceous events is not preserved in any formations in Svalbard, but rather in the erosion of pre-existing strata. Strictly this lacuna commenced in the Late Albian, sediments of which have not been recognized in Svalbard. Michelsen & Khorasoni (1991) believed that up to 1000m of Late Cretaceous strata were eroded, based on continued Aptian-Albian sedimentation rates.

This interval is represented by the extensive Rurikfjellet Formation in Spitsbergen. By and large the situation in the previous interval continued. Similar thickness of somewhat sandier facies are preserved in Spitsbergen, say up to 300 m in about 13 million years. Dypvik (1992a) gave an accumulation rate of 2.1 cm 1000 a -1 for the Valanginian in the lower part of the Rurikfjellet Formation. He

2~ $3

J

o ,~ ~$"base of Helvetiafjellet Formation -o~'~ ~ (FestningenMember) =~ o Ruriktjellet Formation ~

~_.

Agardhfje~

, ....

-kapp Toscana Formation

~.h;;k_

"~ -~=~

Breikampen Lardyfjellet Runkfjellet Formahon ..... ri ~Rurikfjellet

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I

300! 200" 1001

o[0

~

~

A

g

a

r

""-Kapp "T~ na F~ m'ati~

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d

10km

Formation I hfjellet Formatio~

eastern'" ~'i .-[.~7..'~. ]7. S: fault belt Kapp Toscana Formation

HighestDorsuplaniteshorizon Highest Amoeboceras rosenia horizon BrentskardhaogenBed (LiasCongl..... 5

::r ~ =m

re) . . . . . . . . .

Fig. 19.14. Lateral variation of the Agardhfjellet and Rurikfjellet formations across Spitsbergen (after Parker 1967, fig. 5, reproduced by permission of Cambridge University Press). The 'western fault belt' is the southern extension of the Billefjorden Fault Zone and the eastern is that of the Lomfjorden Fault Zone.

JURASSIC AND CRETACEOUS HISTORY

383

The most obvious event is the continued tilting upwards to the north or northwest so that the youngest Carolinefjellet strata are preserved only in the south and older members are truncated successively northwards by the sub-Paleocene unconformity. Just south of Isfjorden only the lowermost two members remain. Progressing northwards the Paleocene at Kongsfjorden eventually cuts down through the lowest Triassic formation into Permian strata. The average tilt is about 1 in 100 or 0~ '. The differential uplift at the latitude of Kongsfjorden compared with the uppermost Carolinefjellet Formation strata in the south is about 2.5 kin. This did not all happen in Late Cretaceous time as is evident from the earlier supply of sediments from the north. But supposing the tilting were limited to the 32 million years of Late Cretaceous time, it would represent a maximum average uplift rate of 0.05 mm a -] whereas if the uplift was spread over, say, the last 50 million years of Cretaceous time the rate would be 0.025 mm a -1 or approximately the rate of subsidence in the south. A consistent picture of relatively stable platform emerges subsiding differentially to the south and southeast through Jurassic-Cretaceous time at an increasing rate for 110 million years and culminating in the net uplift only at a similar rate in the last 30 million years. The Eastern Platform may well have continued to take on sediment, probably at a reduced rate, but the whole record has disappeared from Barremian time onwards. The argument that these epeirogenic changes, both subsidence and uplift, were the result of thermal expansion of the mantle was put forward for the whole Carboniferous through Cretaceous sequence of Svalbard (Harland 1969). A similar calculation for a hot spot in the centre of the British Isles gave quantitative results very similar to those adduced for Spitsbergen (Cope 1994). For Spitsbergen, however, the hot-spot, or more likely hot zone, was further to the north. Indeed it was the locus of the future fission

Figures 19.15a and b show mid-Jurassic and mid-Cretaceous palinspastic reconstructions respectively. The Jurassic frame reflects the beginning of Atlantic spreading by rifting, with Arctic events analogous to the initial Triassic rifting in the Appalachians from which latitude the Atlantic fission slowly extended northwards. These are the first indications of the break-up of Laurasia. The contemporary positions of the Russian far eastern block, east of the Verkoyansk orogenic zone and of the Alaskan terrane have been plotted according to the conclusions of a CASP Regional Arctic Programme study. The Cretaceous frame indicates that the Canada Basin had already been opened. The volcanism in Kong Karls Land and Franz Josef Land correspond to the initial mantle heating that was about to initiate sea-floor spreading in the Eurasian Basin along the Nansen-Gakkel Ridge. McWhae (1986) projected a tectonic history of northern Alaska, Canadian Arctic and Spitsbergen from Early Cretaceous time. D. G. Smith (1987) attempted a similar tectonic sequence of smallscale diagrammatic reconstructions (Pennsylvanian through Miocene). These have little impact on the interpretations in this work.

(a)

Co)

M I g-J U RAS S.~, Omolon ~

, ~

Oloy ZoneJ ~/" V

~

along the Nansen-Gakkel spreading ridge and no doubt related to the Cretaceous magmatism. Worsley (in Aga et al. 1986) suggested that the differential uplifting to the north may have caused E-W faulting that had some control in the configuration of the present fjords. A case needs to be made. The diastrophic rate is very slight.

19.8 19.8.1

The tectonic frame

MID-CRETACEOUS

.P:ikol:msk ~ " ' V ~,-- . V - ~ - -

Svalbard in a Jurassic-Cretaceous regional context

Inyali-DebaBackArc Basin

217 m Skilvika Formation, 115.5 m Rochesterpynten Formation, 50-100 m at the base. The Rochesterpynten Formation is a complex unit investigated in 1975 when the whole section was measured by Harland & Pickton (Thiedig et al. 1979; Harland, Hambrey & Waddams 1993, p. 100). It consists very largely of Vendian-type diamictite clasts similar to those in the Kapp Lyell Group of the main outcrop and had been previously mapped as Precambrian basement. It was interpreted as a tectonosedimentary melange produced at an active fault scarp with very large slipped blocks of tilloid. The original large block of Precambrian tillite (the first Svalbard record) as described by Garwood & Gregory (1898) as the Fox Point tillite was not located. It was concluded that the blocks with large boulders derived from part of the (Vendian) Lyellstranda Formation no longer exposed, that it was probably of Paleocene age and had suffered some consolidation and tectonism before deposition of the overlying Skilvika Formation. Dallmann (1989) described the localities in some detail and postulated two faults separating the complex from older and younger rocks each with downthrow towards the Calypsostranda Group. It might thus be a Paleogene rejuvenation of part of an older fault system and/or initiated in the early stages of the West Spitsbergen Orogeny. Dallmann et al. (1993) mapped it as a splay of the Recherchebreen Fault. Skilvika and Renardodden formations have not been distinguished by age. Thiedig et al. (1979), on available evidence, argued a doubtful Paleocene age, but later work on dinocysts (Head, Manum & Throndsen 1986) suggested a Late Eocene to Oligocene age. Such a younger age was accepted by Steel et al. (1985) who plotted these strata as in a similar tectonic environment to Forlandsundet, but somewhat later, i.e. probably Oligocene. The succession is a dominantly coal-bearing clastic sequence of sandstones, siltstones and shales with a rich flora listed by Thiedig et al. (1979) who also reported the discovery of the trace fossils Ophiomorpha and bivalves Fellina and Conchocele couradii indicating occasional marine incursion into a delta (flat) sequence. Manum & Throndsen (1986, p. 116) noted that the coal reflectance data indicate a much higher rank than the coals of Forlandsundet. Two, possibly extreme, hypotheses to account for this are either an overburden of 6-8 km or a much higher thermal gradient resulting from neighbouring magmatic activity.

20.5.5

Offshore Paleogene sedimentation

Steel et al. (1985) summarized the seismic and DSDP evidence for a significant sediment wedge up to 7 km thick west of the Hornsund Fault and east of the Knipovitch Ridge and probably later than most of the deposits hitherto considered. This is partly because these strata appear to rest on new oceanic floor which would not have been available until the initial (Oligocene) spreading to form the Greenland-Norwegian Basin. This is complex story, mainly of Neogene events and will therefore be followed in Chapter 21.

398

CHAPTER 20

20.5.6

Thermal degradation of organic matter

(a) Preservation of palynomorphs. The relative preservation and abundance of palynomorphs in Svalbard varies considerably with location and age. Hughes, Harland & Smith (1976) outlined samples investigated as good, fair and poor and plotted these on a map (Fig. 20.6). From this pre-Eocene samples within the West Spitsbergen Orogen are poor, but post-Eocene samples from the graben were good. Results from ?Early Eocene and Paleocene through Carboniferous samples within the Paleogene Central Basin and Bjornoya were fair. Good results obtained from almost all Mesozoic to Carboniferous samples north and east of the Central Basin. A poor result from a Devonian sample in northeast Andr6e Land correlates with its position in a Svalbardian folded zone with some cleavage. The distribution tells a clear story, but the degradation processes may be complex. Buchan et al. (1966) had suggested (for the Central Basin data) one or more factors: depth of burial, proximity to igneous activity and dynamic metamorphism to which Hughes et aL added mantle heat flow related to distance from active spreading at plate margins. These are essentially thermal processes related to a tectonic environment. Manum et al. (1977) followed with criticism, especially of depth of burial, and argued from evidence of varied degradation within similar situations (e.g. comparing with vitrinite reflectance measurements) that there must be a diagenetic effect following on the vagaries of the sedimentary environment. Both factors clearly contributed in various circumstances and for example both Hughes et al. and Manum et al. agreed with 1/~

I~~

2d~

215~

3~~

~80~ I

79ON.--" RLS

O

~,ND

78~ ~

OYA

0 I

=

km

=

=

100 I

77ON~

~76ON

sequence

IVl

Mid-Tertiary ?Oiigocene ?Miocene

p

Lower Tertiary ?Eocene Paleocene

K

WestSpi~bergen Orogen

Cover

~75ON Palynomorph preservation

T

BJORNOYA

O

good

["'] poor /

Early Jurassic to Late Triassic Mid- & Early Triassic

(b) Vitrinite reflectance measurements. A more direct approach to depth of burial was by vitrinite reflectance studies - mainly of coal fragments. Coal occurs in Svalbard sediments of various ages as do palynomorphs. The American classification of coal rank (ASTM) follows with the boundaries between the ranks in approximate reflectance values (R0) from a table by Throndsen (1982): Peat/0.26/lignite/0.38/subbituminous: A, B & C/0.5/high volatile/1.1/medium volatile/1.5/low volatile/1.9/anthracite: semi/2.6/normal/5.0/meta-anthracite. The German divisions between Braunkohle, Steinkohl and Anthrazit being respectively at about R0 0.63 and 2.2. From a study of coals in the Todalen Member of the Firkanten Formation in the eastern part of the Central Basin around Longyearbyen Throndsen (1982) found a NE gradient with R0 values from about 0.8 at Grumantbyen, between 0.7 and 0.6 in the mines south of Adventdalen to about 0.4 near the Billefjorden Fault Zone. This led to a calculation of overburden of 2.5 reducing to 1.5 km over a distance of about 30 km with a sharp drop around Longyearbyen. Hence differential subsidence to the southwest of the Billefjorden Fault Zone and loss by erosion of up to 1.5 km of overlying strata. Michelsen & Khorasani (1991) reported a more extensive investigation throughout Svalbard and including also Carbonifereous, Triassic and Cretaceous coals which are also relevant to the interpretation of Paleogene tectonics as well as throwing light on their environments of formation. Serpukhovian coals at Trygyhamna and Bellsund within the West Spitsbergen Orogen yielded semi-anthracite coals of R0 = 2.02 compared with the Tournaisian high volatile coals near to Pyramiden (Birger Johnsonfjellet Member R0 = 0.89-0.91). Cretaceous coals from Adventdalen (N of Longyearbyen) are highvolatile bituminous A rank R0 ----1.01 rapidly and systematically decreasing to the north and east. The Tertiary coals were the main subject of study. Paleocene coals of (Ny-,&lesund differ from the Central Basin with no indications of marine influence, and are of high volatile bituminous rank C (R0 = 0.55) mainly of vitrinite. Late Eocene coals of the Forlandsundet graben have R0 = 3-4 due both to deep burial plus high heat flows. Whereas magmatic heat (e.g. Cretaceous sills) would not be uncommon, its effect appears not to have caused a significant regional thermal degradation. During Paleocene-Eocene subsidence, Carboniferous strata were rapidly heated to their maximum temperatures of around 190~ in western Spitsbergen and around 150~ in Central Spitsbergen, then slowly cooled during the uplift and erosion. This may have led to Tertiary or earlier gas generation from Carboniferous coals, but Paleogene coals had not approached thermal phase of cracking. Nyland et al. (1992), from a study of well samples, concluded that reflectance methods gave the most consistent results for calculating overburden in the southeastern Barents Sea. They found the greatest loss of >2000m to apply to a zone 100km wide including Bjornoya and extending northwards (presumably into the West Spitsbergen Orogen). This loss is consistent with the overburden estimate of Michelsen & Khorasani from R0 = 1.34 in the Tunheim Member coal in Bjornoya.

Permian to "middle" Carboniferous

Q ~ ) fair

MM

J

sequence

Eady Cretaceous Earliest Cretaceous to Mid-Jurassic

the implication 'that Tertiary sediments of significant thickness did not extend east of the present Spitsbergen Trough' (Manure et al., p. 129).

I

Old Red sequence

C

Early Carboniferous and Latest Devonian

D

Mid-Devonian to Earliest Devonian

Fig. 20.6. Map showing the geographic/stratigraphic distribution, preservation state and sedimentary facies of palynomorph assemblages (reproduced with permission of Cambridge University Press from Hughes, Harland & Smith 1976).

(c) Fission-track measurements. Nyland et al. from fission track data tentatively suggested two episodes for this uplift and erosion. The first (at 40-50 Ma) would correspond to the West Spitsbergen Orogeny and the second to a post-Miocene isostatic responsible to removal of ice. Blythe & Kleinspehn (1994) from apatite and zircon fissiontrack studies, concluded with evidence for Eocene cooling of Spitsbergen and the Barents Shelf.

PALEOGENE HISTORY

20.5.7

Sedimentation and erosion in a strike-slip regime

From what has gone before and from what follows it should be clear that Paleogene sedimentation and tectonics is dominated by strike-slip (transcurrence) with transpression and transtension between Svalbard and Greenland. The basins are responses to transtension and the orogenic structures to transpression. Otherwise the continuing strike-slip component is taken up by transcurrence, which may not leave a sedimentary or structural mark at least where the fault zone moves with pure strike-slip. Suffice to remark that a fairly comprehensive study from this point of view was contained in the paper by Steel et al. (1985).

20.6

Paleogene structures

Palaeogene structural events in Svalbard are most evident from west Spitsbergen, where basement and cover sequences are involved in broadly eastward-directed compressional deformation (the West Spitsbergen Orogen), including the Tertiary fold-and-thrust belt (Fig. 20.7). The West Spitsbergen Orogen (Harland & Horsfield 1974) was defined as a 300 km long belt, made of the western parts of Oscar II Land (plus Prins Karls Forland), Nordenski61d Land, the western tip of Nathorst Land, Wedel Jarlsberg Land and Sorkapp Land. It is bounded by the sea along the west coast, Kongsfjorden to the northwest, the northern platform to the northeast, and by the Central Basin in the east and southeast. Within the segment north of Isfjorden four zones have been distinguished (Harland & Horsfield). From the west, these are: (1) the western basement complex of Prins Karls Forland; (2) the Paleogene graben system of Forlandsundet; (3) the basement zone of western Oscar II Land; and (4) the fold-and-thrust belt of eastern Oscar II Land. Zones 1 and 3 are formed mainly of pre-Devonian strata, Zone 2 of Paleogene strata and Zone 4 of Carboniferous through Early Cretaceous rocks. Zones 1 and 3 show effects of some pre-Carboniferous and of Paleogene deformation whereas in zones 2 and 4 tectonism was demonstrably Paleogene. (5) A fifth zone may be added to the above to accommodate the folded Permian and Triassic strata of Sorkappoya and Tokrossoya. This only appears in the extreme south. It appears to trend offshore west of zone (1) and/or (3) but the continuation further north in relation to that of the Prins Karls Forland zone (1) is problematic. Zones 3 and 4 are continuous southwards, hence dividing the full length of the orogen into two main belts; a western basement zone (Western Basement High of Dallmann et al. 1993) and an eastern fold-and-thrust belt. The latter is divided from the Central Basin by a thrust front, which in effect marks the eastern edge of the orogen, although adjacent parts of the Central Tertiary Basin are also slightly deformed. Concommitant deformation has also been recognized on the Billefjorden and Lomfjorden fault zones to the east, and syn- or post-orogenic extension created the Forlandsundet Basin, which separates Prins Karls Forland from Spitsbergen. Bergh, Braathen & Andresen (1997) described the western basement interaction, the central thin-skinned tectonics and the eastern thrust structures, with a 20 km shorten in Oscar II Land.

399

The time sequence and regional tectonic context of these structures will be attempted in Section 20.7 below.

20.6.1

Western basement zone, including Prins Karls Forland

Apart from the Paleogene graben system (e.g. Forlandsundet) there is no direct stratigraphic evidence as to the age of the structures within this zone.

Prins Karls Forland, an elongate island 85 km in length but never more than 12 km in width, consists of rocks (the Forland Complex) of groups probably of Vendian through Silurian age. The conspicuous fold and thrust structures verge to the west or southwest (Atkinson 1960; Manby 1986). Their deformation was certainly post-Vendian and probably post-Silurian. There was probably a postVendian pre-Silurian tectono-thermal event which metamorphosed the Scotia and earlier groups as identified in the Sutorfjella conglomerate clasts in the Barents Formation of the Grampian Group. By correlation with Oscar II Land the Barents Formation might be coeval with the Bullbreen Group and the earlier schistosity might be equivalent to the Eidembreen Event of early to mid-Ordovician age. No earlier tectonism is evident in the island, nor has there been any clear demonstration of Silurian or Devonian tectonism of significant intensity on the mainland. The western province, to which the basement of Oscar II Land belongs, was probably beyond the range of the Caledonian Orogeny at that place and time. The simplest hypothesis is that the conspicuous fold and thrust structures correspond to the established Paleogene structures of the West Spitsbergen Orogen in Oscar II Land as was concluded in section 9.8 above. The failure of Manby to distinguish his D1 and D2 except in detailed structural fabrics, makes it likely that his two folding events which he said were coaxial, but without stated criteria to distinguish them, might well be phases in one orogeny. If this argument stands then the hypothesis of Lowell (1972) for a dextral transpressive (flower) structure rooted in the Forlandsundet Graben may yet be justified (Fig. 9.10). As concluded in Chapter 9 the 'basement' is largely of Precambrian rocks which were probably metamorphosed in Ordovician time and the lower groups in the south arched in Paleogene time when the late Vendian, and the supposed Early Paleozoic strata were overfolded and thrust over the lower groups.

Forlandsundet. The intense dextral strike-slip Kaffiayra m61ange on the east side of the sound suggests a potential root zone within the orogen.

Oscar II Land. On Broggerhalvoya the northernmost part of the orogen is exposed, both basement and cover rocks are involved in large-scale stacked nappes. Because these structures are confirmed stratigraphically as post-Paleocene, Broggerhalvoya is described with the rest of the fold-and-thraast belt in Section 20.6.2. Mention is again made here of the observations noted in Chapter 9 where the analysis of verging structures in Bullbreen

Fig. 20.7. Schematic cross-section of the northern segment of the West Spitsbergeb Orogen, with a conjectured root zone in the Forlandsundent Graben. The sequence of events, with subsequent normal faulting, cannot be shown in one sketch (after Nottvedt, Livbjerg & Midboe 1988).

400

CHAPTER 20

Group strata north and south of St Jonsfjorden by Ratliff et al. (1988), that they took to be mid-Paleozoic, could equally well be argued to be mid-Paleogene. This includes evidence of a NW-SE zone with dextral strike-slip. Between Engelskbukta and St Jonsfjorden is a complex eastern margin to the graben. The flattish terrain of Sarsoyra and Kaffioyra exposes disordered hillocks of older rocks interpreted by Ohta et al. (1995) as a dextral shear zone with slices of rocks to the Vestg6tabreen Complex south of St Jonsfjorden. These are bounded to the east by the Sarsoyra Formation, a strip of Ordovician-Silurian strata also matched to the south near Motalafjella, and also previously considered to be Carboniferous. Just north of St Jonsfjorden and southwards as far as Eidembreen there are low angle thrusts (with klippen) of Vendian, Ordovician and possibly Silurian strata resting on Vendian rocks. They dip westwards and apparently verge eastwards. The thrusting is later than the mid-Ordovician tectonism. That in the coastal cliffs of the same mountains (in Skipperbreen) are wedges of Carboniferous strata involved in the tectonism supports an observation (W.B.H.) of a sliver of coral-bearing rock (probably of Carboniferous but conceivably of Early Paleozoic age) in the main thrust surface. Just north of Eidembukta is a wedge of fossiliferous Carboniferous rocks faulted in with the Vendian strata. South of Eidembukta at Farmhamna, vertical fossiliferous Carboniferous strata are subparallel to Vendian strata on which they appear to have rested unconformably. Still further south at Daudmannsoyra is a well exposed infaulted sliver of fusuline bearing limestone. These occurrences are adjacent to, and analogous with, the main Paleogene graben immediately to the west. The map interpreting the Vendian outcrops of Oscar II Land (Fig. 9.2, from Harland, Hambrey & Waddams 1993, p. 56) shows a projected thrust fault trending approximately NW and probably verging NNE as with Broggerhalvoya to the north.

Nordenski61d Land. South of Isfjorden the older (Vendian) outcrop occupies the strandflat (Nordenski61dkysten) east of which is a mountain range formed of steeply dipping Carboniferous strata, resting unconformably on the Late Proterozoic rocks and marking the western boundary of the fold-and-thrust belt. The structures in the older rocks have been tentatively shown (Figs 10.2 & 10.3) in schematic outcrop with a somewhat similar fault trending NW-SE with a postulated thrust vergence to the NE. On the south side of the fault are two elongate outcrops of Early Carboniferous rocks appearing as small graben or half-graben (Harland et al. 1993, p. 87).

Wedel Jarlsberg Land. To the northeast of Kapp Lyell is the Calypsostranda outcrop, a graben or half-graben trending NW-SE. This may be in line with the Forlandsundet graben (zone 2 above), a suggestion reinforced by submarine evidence of a further basin structure between the Paleogene outcrops. Dallmann (1989) showed the fault trace extending south into the Recherchebreen fault system. Further south the NNE-SSW-trending Orvindalen Fault shows an apparent dextral displacement of 5-10km and similar trending faults are necessary beneath the larger Torellbreen glaciers, but their nature has yet to be elucidated. Apart from the faults, the broad plunging syncline in the north and the extremely complex fold system in Vendian and older rocks of western Wedel Jarlsberg Land could well be Paleogene but cannot be constrained decisively. East of Hansbreen (in the Central Province) the main deformation of Vendian, Cambrian and Ordovician basement in east-vergent thrusts must be excluded from Paleogene consideration. They are demonstrably pre-Triassic and probably Silurian in age. Far more intense tectonism is demonstrably Proterozoic as seen in the protobasement with the Nordbukta, Isbjornhamna and Magnethogda groups. Mid-Cretaceous dykes ( l l 0 + 5 M a ) and a possibly younger intrusion (66.8 + 4.3 Ma) as determined by Vincenz et al. (1981) in

connexion with palaeomagnetic investigations in the Vimsodden area of Wedel Jarlsberg Land, have suffered minor strike-slip faulting during the Paleogene orogeny (Birkenmajer 1986, 1993c). His 1993 paper discussed other deformation events in the Western Basement Zone. He argued for strong Caledonian or preCaledonian folding. According to the interpretation in this work, o n l y Paleogene or pre-Caledonian (sensu stricto) folding is postulated, namely Ordovician and ?Mesoproterozoic for the preElveflya Formation rocks. This could be a test case for this aspect of the conflicting hypothesis. According to the interpretation in this work, the VimsoddenKosibapasset Fault (VKF) of Czerny et al. (1992) is a faulted unconformity and would thus be a major NE-vergent thrust in the Paleogene orogeny.

Sarkapp Land. Most of the east of Sorkapp Land is occupied by the fold-and-thrust belt (see below). The central core of Precambrian and Early Paleozoic strata was largely unaffected by Paleogene movements because the extensive westerly dipping thrusts are truncated by flat-lying Triassic strata. The basement zone here appears to have been relatively rigid. However, southwest of Oyrlandet and in Sorkappoya is a fold belt, possibly merging southwards with the main fold-and-thrust belt, but striking NW-SE and projecting offshore. The Norsk Polarinstitutt map C13G (Winsnes et al. 1992) shows cross-sections with gently westward dipping thrusts through the zone west of the fold-andthrust belt and thrusting Triassic over Jurassic strata. This is zone (5) mentioned above (p. 399).

20.6.2

Fold and thrust belt

The belt extends for approximately 300km in a NNW-SSE direction from NW Oscar II Land to Sorkapp Land, but is never more than 30km wide and in some cases less than 10km wide. It is bounded by the basement zone to the west, and by the northern platform and Central Tertiary Basin to the east. Although Tertiary deformation has affected both those two elements, most of the deformation and shortening associated with the West Spitsbergen Orogeny is observed in the Carboniferous through Paleocene strata of the fold-and-thrust belt. The first detailed study over almost the whole belt was by the late A. Challinor between 1960 and 1969 as part of the Cambridge Svalbard Exploration Programme. His crosssections, based on mapping by the group and hitherto unpublished, have been simplified and are presented in Fig. 20.8a, b. Challinor's sections, although not balanced, provide a good insight into the overall structure of the orogen and the variation in structural styles from north to south. The work was done at a time before current terminology was applied to fold-and-thrust belts, but even so, some of these elements can be identified from his sections and most notably the ramp-flat geometry characteristic of a variable competence layered sequence.

Oscar II Land. The fold-and-thrust belt in Oscar II Land is extensively exposed, with a maximum width across strike of 30 km and length of 80 km (Harland & Horsfield 1974). The region can be sub-divided into three zones on the basis of the Tertiary structures present (Maher 1988). In the west is the basement-involved fold and thrust zone; in the centre a thin-skinned fold belt with minor thrusts; and in the east a thin-skinned thrust belt. The eastern zone marks the thrust front to the belt, although not the easternmost limit of Tertiary deformation. The most studied parts of Oscar II Land are Broggerhalvoya, St Jonsfjorden and LappdalenMediumfjellet, in the western, western/central and eastern zones respectively. On Broggerhalvoya the orogen is unusual in that it trends WNW-ESE (as opposed to NNW-SSE everywhere else). It involves both basement and cover rocks (Orvin 1934; Challinor

PALEOGENE HISTORY 1967) with little tectonic contrast between them. Three nappe complexes are exposed there, characterized by duplex structures in lower nappes, and fold pairs and imbrication in the upper nappe. They overthrust the Paleocene coalfield to the extent that drift mining extended about 1 km beneath the thrust front (Hanoa 1993). At least 18 km of shortening has been accommodated within the stack, with 12km in the uppermost nappe (Manby 1988). In the NW of the peninsula the rocks are mainly post-Devonian; in the SE pre-Devonian (mainly Vendian and Sturtian) rocks predominate. Movement directions in the NW are more northerly than elsewhere, and in the SE are northeasterly; the two zones are separated by a major N-S sinistral transfer zone. The variation in vergence direction can been attributed to either (i) the structures being at a restraining edge of dextral transpressive motion in contrast to the remainder of the belt that would be parallel to the strike-slip component or (ii) to movement over an oblique/lateral ramp, possibly formed by a basement buttress, within a dominantly WSW-ENE orthogonal convergence model (Maher 1988). These models are discussed more fully in Section 20.7. In the Vegardfjella-Wittenburgfjella area of southeastern St Jonsfjorden the western zone of basement-involved thrusting and the central zone of NE-verging folds are exposed (Maher & Welbon 1992; Welbon & Maher 1992). The basement-cover rocks involved are mainly of Permian and Triassic age deposited in the St Jonsfjorden Trough (Gjelberg & Steel 1981). The thrust system consists of three major detachments, at least one of which may represent an earlier basin fault that has been reactivated (Maher & Welbon 1992). The two lower thrusts are rooted within and carry basement rocks, and cut up to a roof thrust with at least 3.2 km of displacement. Ramp-flat geometries prevail with flats commonly in the Gipshuken Formation evaporites. The zone of folding to the east is 8 km wide and also affects Permian and Triassic strata. The structural geometries indicate that deformation is controlled by underlying thrusts, with slip transferred along a basal detachment in the Gipshuken Fm gypsum. Total shortening in the area was estimated to be approximately 13 km (Welbon & Maher 1992). The most studied parts of the eastern thrust zone and thrust front are in the Lappdalen-Mediumfjellet area (see synthesis of Bergh & Andresen, 1990). Four thrusts are present in each of the two localities; each associated with large- and small-scale thrusts and folds. Deformation is generally characterised by structural variability within different stratigraphic levels, i.e. stacked ramp-fiat geometries with fault-propagation (tip-line folds) and fault-bend folds, out of sequence thrusting, and decollementhorizons within the Permian Gipshuken Formation gypsum and Triassic Botneheia Formation shales. Displacements on the main thrusts vary from 200 m to over 1 kin, with a total shortening of at least 4 kin. The upper-most thrust at Lappdalen cuts down-sequence in the Gipshuken evaporites, and at Mediumfjellet the top thrust is out-of-sequence. Bergh & Andresen (1990) proposed that the thrust front formed as an eastward-vergent in-sequence (piggy-back) thrust belt, that was then cut by out-of-sequence thrusts that gave rise to an apparently hinterland-dipping duplex. Along the southern edge of Oscar II Land lies the NE-SW oriented Isfjorden Fault zone (Harland & Horsfield 1974; Ymerbukta Fault of Ohta et al. B9G, 1991), which separates intensely deformed Mesozoic rocks to the NW from sub-horizontal Cretaceous to Tertiary rocks in the SE. The fault has been interpreted as an oblique ramp with a vertical displacement of approximately 400m (Bergh et al. 1988; Bergh & Andresen 1990), and is one of many such features within Oscar II Land (Dallmann et al. 1993). The marked contrast between the fold belts north and south of Isfjorden cannot be explained simply by a fault. It is probably the result of thrusting to the north against the relict Nordfjorden Block. This is replaced south of Isfjorden by the Paleogene basin which provided no such barrier. Therefore, south of Isfjorden some of the east-vergent movement took the form of bedding thrusts within incompetent strata beneath the Paleogene Van Mijenfjorden Group. They did however surface in thrust structures along the Billefjorden and Lomfjorden Fault zones. One difference between north and south is that the d6collement zone to the north was

401

effective in the Gipshuken Formation evaporites, whereas to the south Mesozoic shales provided the medium. Nevertheless total stratal shortening north of Isfjorden was probably greater.

Nordenskiiild Land. Western Nordenski61d Land comprises three zones: the western basement high, the central fold belt, and to the east the Central Tertiary Basin (Orvin 1940). The fold belt, approximately 40 km long and 9 km wide, affects a 3.7-5 km thick sequence of Carboniferous to Tertiary strata that lies unconformably upon Late Proterozoic metamorphic basement (Hjelle et al. 1986). Its eastern edge is largely hidden beneath Gronfjorden and Fridtjovbreen. It is the highest exposed level of the fold-and-thrust belt in west Spitsbergen (Dallmann et al. 1993). The Permian Kapp Starostin Formation forms a marker horizon across the fold belt and is most conspicuously affected by the deformation; the presence of Paleocene rocks within some of the folds proves the event to be of Tertiary age. In general, the strata are deformed into open, upright anticline-syncline pairs or monoclines, with amplitudes and wavelengths on the scale of hundreds of metres (Maher, Ringset & Dallmann 1989). Folds are oriented NNW-SSE and commonly plunge to the north or in some cases to both north and south; axial planes are usually upright or have a slight westerly inclination. The average transport direction is 060 ~. Figure 10.8 compiles and simplifies the map and sections by Braathen, Bergh & Maher (1995) interpreting the structure of the whole fold belt in Nordenski61d Land. Whether or not the detailed projections upwards and downwards are justified is not the point. The contribution is a 3D presentation of this remarkable and accessible structure. A distinctive feature of this study is a longitudinal (N-S) section in addition to several transverse (E-W) sections. This shows a northward component of vergence to complement the ubiquitous eastward component. It is thus consistent with dextral transpression; but whether partitioned in time is not clear. Figure 15 of Braathen et al. (1995) is repeated here as Fig. 20.10. Braathen & Bergh (1995) discussed some further structural implications.

Wedel Jarlsberg Land and Nathorst Land. The fold belt in Wedel Jarlsberg Land and Nathorst Land is east of the terrane boundary from Recherchefjorden to Hansbreen and east of the 'Hornsund High' with dominant eastward-verging Caledonian folds and thrusts that comprise the western basement high. A series of overlapping thrust zones occurs through Midterhuken at the western tip of Nathorst Land (Fig. 10.9) and central Wedel Jarlsberg Land (Dallmann 1988a; Dallmann et al. 1993). The kinematics of some of these have been described and discussed, principally the Bravaisknatten thrust zone on Midterhuken (Maher, Craddock & Maher 1986; Maher 1988; Ringset 1988; Maher & Welbon 1992), the Berzeliustinden thrust zone (Dallmann 1988a, b), the Supanberget area thrusts (Dallmann & Maher 1989), and the northern Hornsund area (Kvalfangabreen-Adriabukta; Dallmann 1992b). There is a common pattern at all localities of eastward thrusting, rooted in basement, repeating and/or overturning platform strata with large associated folds, in places recumbent, and shortening of up to 2 km. The main phase of thrusting was followed by folding and by later extensional faulting. As in the St Jonsfjorden area of Oscar II Land variations in the thickness of Carboniferous strata and internal unconformities suggest an original basin-graben structure (Maher & Welbon 1992), which may have also controlled the Paleogene geometry. The fold belt is exposed especially well both north and south of Hornsund. East of Hansbreen (E of the main Precambrian terrane) strata dip westward but young eastward and with steep east-verging thrusts. There is a remarkable sequence: Vendian through Cambrian, Early Ordovician, Devonian, Carboniferous, Permian, Triassic, Jurassic, Cretaceous and Paleogene. There are of course minor breaks and there appear to be unconformities at least at the initial Devonian and Paleogene boundaries.

402

CHAPTER 20

(.)

South of Hornsund flat-lying Triassic strata rest unconformably on, and truncate the, older strata so that there is good evidence that the main deformation was probably Silurian (Caledonian). However, the style is similar through the basal Devonian unconformity and as far as the open folding of the Cretaceous terrane. At least this eastern part was subject to Paleogene deformation and it would seem that Caledonian structures were also reinforced in Paleogene time. In general, the more southerly exposures represent higher structural levels than in the north, with Mesozoic and Paleocene strata involved as well as the Late Paleozoic successions. One notable difference of the structures in Wedel Jarlsberg Land and Nathorst Land is that detachment surfaces do not occur within evaporite horizons of the Gipshuken Formation, as such lithologies did not develop in the area. Instead, flat thrusts appear to be controlled by shale horizons in Carboniferous and Early Permian strata, and as these horizons are discontinuous they may also control the locations of the frequent ramps present, such as those that occur in the Supanberget area (Dallmann & Maher 1989).

PRINS

KARLS

~,///

/

///////

79~

3

6~

Sorkapp Land divides into five zones from west to east: /

"\

'i2-E

/

(i)

,SFJO O N'

...., .

(ii)

/

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~ENSKIOLD

/

(iii)

16'

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L

L

s

U

N

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HORNSUND '~

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_--------- 27

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Deformation in the fold belt is most intense around Hornsund, and decreases southwards to the point where it is manifest only as a single monocline. Part of the fold-belt is formed by a broad syncline in Devonian and Carboniferous strata, named the Samarinbreen Syncline (Dallmann 1992b). The eastern limb of the syncline becomes more tightly folded towards the edge of the fold belt, and involves Carboniferous to Cretaceous rocks. Large-displacement thrusts are present in the area. Folds have inclined to recumbent axial surfaces with eastward vergence where this is shown. Dallmann (1992b) described the structural evolution of the area in terms of wedge insertion and backthrusting followed by foreland-directed thrusting and associated folding. The positions of the faults are probably controlled by pre-existing structures relating to Caledonian and Adriabukta (Carboniferous) events. The western fold belt of Tokrossoya and Sorkappoya is certainly Paleogene and could well have compensated in the south for the decreasing southerly contraction of the main fold belt.

:/

20.6.3

~" ~

./" l

a fragment of a western fold belt deforming Permian and Triassic strata as seen in Tokrossoya and Sorkapppoya and trending NNW-SSE offshore; a triangular area of flat-lying Carboniferous and Triassic strata west of the Hansbreen Fault Zone; the main Caledonian fold and thrust belt forming the higher mountains and indeed a reactivated Caledonian basement; the main eastern fold and thrust belt with Paleogene deformation of the Devonian through Jurassic strata; a wide outcrop of gently folded Cretaceous strata appearing through ice fields and just touching the Paleogene of the Central Basin in the easternmost outcrops.

25km

I

/

/:18~ Fig. 20.8. (a) Map showing the location of selected unpublished structural profiles of the West Spitsbergen Orogen. (b) Unpublished cross-sections of the West Spitsbergen Orogen from large scale sections surveyed by A. Challinor 1960-1969.43 sections from Broggerhalvoya to Sorkapp Land selected, simplified and reduced by C. Townsend and L. M. Anderson.

West Spitsbergen Paleogene graben

The West Spitsbergen Paleogene graben system includes the Forlandsundet Graben, the submarine line to the south, and the Calypsostranda ?half graben. The first and third of these have reasonably dated Paleogene strata already discussed. The Forlandsundet Graben contains evidence of deformation of both Paleozoic and Paleogene strata (both early Paleocene and the mainly extensional faults forming half- or full-graben structures of Gabrielsen et al. 1992) as well as probable late or post depositional deformation in an overall transpressive regime. Tectonic models for basin formation generally involve several phases of extension and compression, all with a strike-slip component (e.g. Harland 1979; Lepvrier & Geyssand 1985; Steel et al. 1985; Lepvrier 1990a, b; Gabrielsen et al. 1992). Movement occurred along basin boundary faults rather than within the basin itself. Several strike-slip models

PALEOGENE HISTORY

403

(b) KEY TO UNPUBLISHED STRUCTURAL PROFILES OF THE WEST SPITSBERGEN OROGEN

Van Mijenfjorden Gp

Adventdalen Gp

Kapp Toscana and Sassendalen gps

Tempelfjorden and Gipsdalen gps

Billefjorden Gp Devonian

CZ A

Aspelintoppen Fm

Cz F

Firkanten Fm

Kc KH

Carolinefjellet Fm Helvetiafjellet Fm

Kj Jj

Rurikfjellet Fm Agardhfjellet Fm

TKT TSK Tv

Kapp Toscana Gp Sticky Keep Fm Vardebukta Fm

PKS

Kapp Starostin Fm

PG

Gipshuken Fm Nordenski61dbreen Fm

CpN CBT

.........................

Formation boundary Top of Kapp Starostin Formation

"~'~--Thrust

Extensional fault

Br~ggertinden Fm

Co

Orustdalen Fm

CA

Adriabukta Fm Marietoppen Fm

DMA

Group boundary

++++++++++++++++++i

ere-Devonian basement + + + + + + + + + + + + + + + + + + ++++++++++++++++++

No vertical exaggeration Horizontal = Vertical

404

Fig. 20.8(b). (continued).

CHAPTER 20

PALEOGENE HISTORY

Fig. 20.8(b). (continued).

405

406

Fig. 20.8(b). (continued).

CHAPTER 20

PALEOGENE HISTORY

Fig. 20.8(b). (continued).

407

408

Fig. 20.8(b). (continued).

CHAPTER 20

PALEOGENE HISTORY have been presented for the formation of the basin, including a suggestion that it may have formed by pull-apart within a relay zone between two NW-SE-trending dextral strike-slip faults situated offshore (Lepvrier 1988, 1990). It is concluded here that the whole development was in a dextral strike-slip zone. There was a pre-orogenic transtensional basin which was compressed in the orogenic climax in which the dextral transpression (shearing of the Kaffioyra Zone) continued into further transtension with further deposition. Then there was further minor transpression before the strike-slip motion may have been largely transferred to the west of the orogen.

20.6.4

Structures of the Eastern Platform and Central Basin

Billefjorden Fault Zone was first recognized as a significant strikeslip tectonic lineament extending through Spitsbergen by Harland (1969), although sections of it had previously been described (e.g. McWhae 1953). Its major strike-slip history was primarily Silurian and Devonian followed by intermittent extensional dip-slip movement, with Carboniferous through Jurassic sedimentary control. The fault zone then located Paleogene reactivation with thrust structures in the cover strata (Permian through Jurassic) and followed later by further normal dip-slip faulting (Parker 1966; Harland et al. 1974; Ringset & Andresen 1988). Generally not observed as a single fault, the zone usually consists either of a series of parallel faults, or of N-S-trending folds that are regarded as having formed above a hidden fault. For example, north of Isfjorden, several large extensional faults occur within a zone up to 3 km wide, cutting Devonian and Carboniferous strata (Harland et al. 1974; McCann & Dallman 1995). The faults appear to have had an original eastward extensional throw but have been reactivated with reverse movement. Most of the fault zone traverses pre-Paleogene terrane, nevertheless a Paleogene age for the renewed activity is conjectured because no other age would match the evidence. On the south side of Isfjorden in eastern Nordenski61d Land, the continuation of the fault zone is marked by a series of folds inferred to lie above faults. This was illustrated by Parker (1966, 1967) who distinguished clearly between contemporaneous Mesozoic movement and presumed Paleogene folding and thickening (see Figs 4.4 & 19.4). The strata either side have been affected by small-scale imbricate and duplex structures and by decollement zones (Haremo et al. 1990; Haremo & Andresen 1992; Haremo, Andresen & Dypvik 1993). The folds consist of two east-facing anticlines within Late Jurassic and younger sequences; to the north the folds are replaced by a thrust with minimum shortening across it of 1.5km. Underlying rocks of the Lower Janusfjellet Subgroup contain imbricate and duplex structures, but no evidence of the folds. This has been interpreted by Haremo and co-workers as evidence of a decollement zone situated at the top of the Janusfjellet Subgroup. A second d~collement has been interpreted to lie beneath the Jurassic sequences, as underlying Triassic rocks of the Sassendalen Group also contain imbricate and duplex structures. The zone in that area therefore preserves structures related to both thin- and thick-skinned deformation, controlled by the inferred presence of steeply dipping Paleozoic faults that were reactivated. Lomfjorden Fault Zone. Along most of its length, the Lomfjorden Fault Zone has a down-to-the-east displacement, but the dip of the fault varies from east to west. As with the Billefjorden Fault Zone, it may have Paleozoic origins, but without major strike-slip and with some Paleogene reactivation. The youngest strata affected are of Early Cretaceous age, and no Tertiary strata are exposed close to the fault. But as there is no evidence for Late Cretaceous deformation, a Paleogene age must be the most likely and so related to the West Spitsbergen Orogeny. The southern end in the Agardhdalen area has been studied (Andresen, Haremo & Berg 1988; Andresen et al. 1992; Haremo & Andresen 1992). The

409

Mesozoic sequence exposed there is deformed into an east-facing (verging) asymmetric anticline/monocline, with a total uplift of the west side with respect to the east of 500 m. The fold was considered to relate to a westdipping reverse fault at depth. The fold rotates small-scale reverse faults (within imbricate and duplex systems) situated in the Triassic Sassendalen Group, and similar structures occur to the south within the Janusfjellet Subgroup. Andresen et al. (1992) considered these zones to indicate the presence of decollement horizons at the same stratigraphic levels as at the Billefjorden Fault Zone, namely near the base of the Janusfjellet Subgroup and near the top of the Sassendalen Group (Botneheia Formation). The Central Basin immediately east of the fold-and-thrust belt is slightly deformed by the West Spitsbergen Orogeny. Along the western basin margin the strata dip between 5~ and 25 ~ east, and in places (e.g. Sorkapp-Hornsund area) broad low-amplitude folds occur within the basin (Dallmann 1992b). Thrust faults are rarely seen at surface but have been inferred at depth, particularly beneath surface anticlines, in seismic sections (e.g. at Grimfjellet in Torell Land; Orheim et al. 1988). The presence of the decollement horizons at equivalent levels adjacent to the Billefjorden and Lomfjorden fault zone and the minor folds and thrust splays within the basin, has suggested to some workers (e.g. Andresen, Haremo & Bergh 1988) that the decollements may extend beneath the entire basin. Nordfjorden Block plunges south beneath the Paleogene strata of the Central Basin. Whereas it appears that stresses f r o m the West Spitsbergen Orogeny in the west were transmitted to the east in bedding-thrust zones beneath the Paleogene cover, to the north similar structures can be observed at the surface where the Gipshuken evaporites preserve the evidence of the orientation of the ENE vergence (Harland, Mann & Townsend, 1988). At this latitude the thrust zones, with evident deformation at the Billefjorden Fault Zone (which bounds the Nordfjorden Block to the east), do not dip into the Billefjorden Trough where the lower gypsiferous strata escaped deformation in this way.

20.6.5

Paleogene structures in north and northwestern Spitsbergen

Structures in this area were considered in Chapter 8 where two structural elements were concluded to be the consequence of the West Spitsbergen Orogeny with its northeast vergence. (i) The sinistral offsets of the Raudfjorden and Breibogen faults of up to 2 km at about 3 latitudes. (ii) The deformation of post-Devonian lamprophyre dykes, isotopically dated at about 309 Ma in Pennsylvanian time, with Devonian cleaved strata necking the dyke with some cleavage (Manby & Lyberis 1992). This is a little further north than Kongsfjorden where Paleogene northeast-verging thrusts were active. As with the Billefjorden Fault zone to the south, Paleogene reactivation in a thrust regime is typical. However, it has been claimed that many more structures, herein attributed to Early and Late Devonian deformation episodes, may be Tertiary (Manby 1988) or post-Caledonian (Thiedig & Manby 1992; Manby & Lyberis 1992; Manby et al. 1994). In Chapter 3 it was argued that West Spitsbergen Orogeny tectonism was mainly Eocene and not Late Cretaceous or early Paleocene as suggested by Lyberis & Manby (1993). The structures in Devonian strata east of the Breibogen Fault have been claimed to be Svalbardian, i.e. Late Devonian (e.g. in Chapters 8 and 16). They are demonstrably so in the south where they are truncated by unconformable Tournaisian or even latest Famennian strata, and exhibit westward-verging folds and thrusts. Similar verging structures are found in the north without the age constraint of the cover. There is no reason to suppose otherwise, since the deformation dies out westwards and the Paleogene deformation would be most intense in the west and eastward verging. Critical support for a Paleogene age might be taken from Manby & Lyberis (1995), who note that vertical N-S pressure solution cleavages imply a greater overburden than the available

410

CHAPTER 20

Devonian strata should have provided and that cover strata of presumeably later Paleozoic and Mesozoic strata provided the necessary overburden. There are two uncertainties in this argument. (i) There was probably more Devonian sediment at that time than presently preserved and the overburden could have been doubled by tight folding. (ii) There may have been no Mesozoic or even Permian strata there by Eocene time because the evidence from the sub-Paleocene unconformity is that the north of Spitsbergen was uplifted gently in late Cretaceous time so that late Albian strata are preserved in south Spitsbergen and with a tilt of less than 1~ All Mesozoic strata were removed at the northern margin of the Ny-Alesund coalfield. If the northward uplift was tilted only half a degree another 50 km to the north, another 2 or 3 km of Btinsow Land Supergroup rocks would have been eroded. Mesozoic sedimentary facies maps confirm such a source of sediment in the north by Barremian time. The situation west of the Breibogen Fault was different with Early rather than Late Devonian deformation. In the southwest, where Manby (1988) and Thiedig & Manby (1992) suspected postDevonian (Paleogene) deformation on Blomstrandhalvoya, the age of the deformation cannot be constrained and that it could be Svalbardian (here considered more likely Haakonian, i.e. early Devonian). The thrusting verges westwards, which would favour Devonian over Paleogene deformation. On the other hand, although the structure and sedimentation of Blomstrandhalvaya fits the Haakonian N-S strike-slip fault model, it is likely that the north to northeast thrusting a few kilometres to the south in Broggerhalvoya had some effect and the extensive calcite veining might thus be Paleogene.

20.6.6

Offshore northwest Spitsbergen

The Yermak Plateau, Sjubrebanken, Danskoya Basin and Norskebanken have been introduced in section 8.6 above. These features, and the Yermak Plateau in particular, probably developed as a submarine volcanic province (mainly Late Eocene-Early Oligocene) after Anomaly 18 when Spitsbergen, Greenland and the Lomonsov Ridge were separating (at what has been referred to as a triple junction) and completed by anomaly 13 (Jackson et al. 1984). That is the area where (i) the dextral strike-slip zone (De Geer Line) separating Svalbard and Greenland meets (ii) the Nansen-Gakkel spreading ridge of the Eurasian Basin and (iii) the sinistral strikeslip zone postulated between Greenland and Ellesmere Island (once referred to as the Wegener Line). This is not well documented. It may have been a rather wider zone expressing the sinistral transpression in the Eurekan Fold Belt of Ellesmere Island.

20.7

This was an essential option in the original transpressive concept; whereas Maher & Craddock (1988) presented the same 'decoupling' mechanism as an alternative to transpression. In their context, partioning and decoupling are the same (Fig. 20.9). The Paleogene story is thus one of dextral strike-slip along the De Geer lineament with intermittent and sporadic transpression and transtension. The development begins with a tendency to transtension so allowing subsidence for the development of the earlier Van Mijenfjorden Group in the Central Basin. The West Spitsbergen Orogeny resulted from a transpressive collision between Svalbard and eastern North Greenland. Faleide et al. (1991) described this as a well-constrained dextral displacement along the De Geer Line of 550 km, with partitioning into 'a tangential low stress strike-slip component and a normal high stress compressive component forming the fold and thrust belt'. Subsequently at about Anomaly 13, the same dextral strike-slip progression resulted in simple transcurrence or transtension, with the active opening of the Greenland and Norwegian basins as Svalbard moved south with respect to Greenland. West of Svalbard and southwest of Bjornoya compressive structures collapsed into margin-parallel grabens. The relating structures, especially in the fold and thrust belt, are conspicuously compressive with ENE vergence in Spitsbergen. This direction was more precisely confirmed by the long axes of anhydrite bodies in the Gipshuken Formation (Harland, Mann & Townsend 1988). Mention has been made of occasional evidences in the orogen of a dextral transpressive component. However, in general, it must be assumed that the dextral strike-slip progression was nearly continuous, as indicated by the oceanic magnetic anomalies. Of particular interest is the Broggerhalvoya virgation in which the fold belt swings round from a NNW-SSE to a NW-SE and WNW-ESE trend, with corresponding swing in the vergence of overthrusting almost towards the north. Lyberis & Manby (1993) calculated a 40 km shortening based on deformation of Carboniferous and Permian strata and possibly more if the pre-Carboniferous rocks are considered, as they are intimately involved in the thrust structure. This direction cannot thus be a minor deflection in

cy

Structural sequence

The stratigraphic timing of tectonic events is poorly constrained as is evident from the variety of opinion indicated on Fig. 20.11. These paragraphs attempt only to distinguish the structural sequence in terms of relative movements between the Greenland and BarentsBaltic plates. There is little doubt that the overall Paleogene story concerns the mobile zone between these plates. Late Cretaceous uplift and some magmatism heralded the thermal separation of the two plates by initial spreading of the Eurasia Basin along the Nansen-Gakkel Ridge at the northern end of a transform fault system, the southern continuation of which compensated the motion by (further) opening of the North Atlantic, Greenland and eventually the Norwegian basins. No sequence of relative lithospheric plate movements throughout a significant sector of the globe is possible without some segments of mobile belts being oblique rather than perpendicular or parallel to relative plate transport. Thus zones of transpression and transtension are inevitable although they may be reflected structurally in a variety of ways including partitioning into component orthogonal components (Fig. 20.9; Harland 1971).

\.

,,)

%.... S

SINISTRAL

DEXTRAL

Fig. 20.9. Schematic model illustrating possible structural configurations within an area of strike-slip deformation, tc, transcurrence (pure strike-slip); cp, compression; xt, extension; tt, transtension; tp, transpression.

PALEOGENE HISTORY FESTNINGEN

the NNW-SSE trend of the orogen; and it is unlikely for such a major deflection from the trend of the main fold belt to be the result of orthogonal ENE transport meeting an obstacle at the end of the belt. It is entirely compatible with the NE-vergent transpressive hypothesis for the orogeny where there is no need for partitioning into compressive and transcurrent components. Elsewhere that appears to be necessary. A. McCann (pers. comm.) has described an eastward vergent N-S thrust fault separating the Red Bay Group strata from the Precambrian horst through the length of the BiskayerfonnaHoltedahlfonna terrane has been referred to (in Chapter 8) as a Devonian structure and is mapped as connecting to the north with a N W - S E fault beside Hornemanntoppen. There are no younger age constraints on this fault and it would also be consistent with the Paleogene stress regime. The fold belt north of Isfjorden appears much wider than to the south. The curvature of the Broggerhalvoya virgation was caused by the obstruction in the north of the main strike-slip component (hence thrusting) and in the east by the Nordfjorden Block (with thin-skinned thrusting). South of Isfjorden the transpression was partitioned into strike-slip faulting and ENE thrusting even beyond the Central Basin. A thorough structural study of a relatively simple segment of the orogen by Braathen, Bergh & Maher (1995) has already been referred to with evidence of a northerly as well as a westerly vergence in the thrust structures. Their interpretation of a structural sequence is illustrated in Fig. 20.10 with initial north-south shortening followed by eastwest shortening in turn followed by inversion, uplift and easterly verging rotation and then by collapse from a late extension. The above model fits a general conclusion that the initial transpression was an oblique dextral compression verging N N E and against the somewhat westward protruding terrane of northwest Spitsbergen. This movement would have accentuated the curvature of the structural area and blocked further northward thrusting. Thereafter the transpression would have been partitioned into ENE verging compressive and N N W strike-slip (transcurrent) faulting (Fig. 20.11).

BELLSUND

North-South shortening

STAGE 1 Initial shortening

..\ Initial East-West shortening

STAGE 2a

Pk

Initial inversion

STAGE 2b

Major inversion, uplift and rotation

STAGE 2c

~

KT

Late extension

STAGE 3

Major inversion

Uplift and erosion

~

~-Pk,

Late extension

HH Pk

Carboniferous extensional faults

=""

411

Paleogenefault movements

Fig. 20.10. Interpretation of the structural development of Paleogene structures in Nordenski61d Land (with permission after Braathen, Bergh & Maher 1995). See also Fig. 10.8.

K2

Paleocene Dan I Tha

Orvin 1940

Ypr

All Pg dp

Hadand 1961

up (dn)

Atkinson 1963

Tilt up to the N

}

Eocene Lut I Brt

//

cp

FSG Collapse of W coast horst

dp /dp

tp

Birkenmajer 1972

dp

Lowell 1972

dp

/tt

L

cp

Xtdptt tt

N~ttvedt 1988 Lyberis & Manby 1993

cp

up cp &dn extensional grabens

t

~

i

tp & Spitsbergen trough

tt

up

extension FSG

ext FSG etc tt (D6) / /tp

xt tt

I

North of Ist}orden only

tp (D5)

Craddock 1985

tp

tp WSO

--dp

Kellogg 1975

Steel et al. 1985

tp, up at,d dn t

tt CB1 & CB2 cp

and FSG

Zx/C0

-~

Major & Nagy 1972

Ng,

xt

I

Fig. 20.11. Historical review of Paleogene tectonic models for Svalbard, symbols as follows: cp, compression; dn, denudation; dp, deposition; xt, extension; tc, transcurrence (strike-slip); tp, transpression; tt, transtension; up, uplift; FSG, Forlandsundent Graben; WSO, West Spitsbergen Orogen.

Oligocene Rup I Cht

Prb

All cp folds precede faults

dp

Harland 1969, 1971

Hanisch 1984

I

I

tp

/tt

tp

xt xt

tt (FSG)

dp !

This work

Up toN

tctp

dp

I

ltpup (tc) tt L

(cp)

tc

dn

tc

412

CHAPTER 20

The ENE compression had its deep axis in the strike-slip shear zone (the root zone of the nappes) which changes eastwards from steeply W-dipping thrusts to thin-skinned (often bedding) thrust structures. These low angle thrusts and related folds slide over the Nordfjorden Block to the north mainly in Permian strata. To the centre

TIMESCALE Miocene 0 tO

Aquitanian (Aqt)

Ma 23.3-

GREENLAND GREENLANE SVALBARD

mOMALuLABRADOR 6

0

29.3-

38.6

Bartonian (Brt) 42.1

13 _15 16

17 19

36 Ma

~ !

i

A t?

~rj t--

22 23 24

60.5

26

65.0

27 28 29

o

Danian (Dan)

56 Ma

tp through WSO and E North Greenland and to S

59 Ma

tp off Hornsund tt Sorkapp to NW of Bj~rn~ya and tp S of Bj~rn~ya

30

Maastrichtian (Maa)

31

69 Ma

On Hornsund Fault Zone tc off N. Svalbard tt S. of Hornsund and tp W. of and to SE of Bj~rn~ya

80 Ma

Dextral tc on Troll Land Fault Zone tp to SE of Svalbard

32

0

CB6

I

CB5 CB4 CB3 CB2 CB1

PENEPLANATION

33

Campanian (Cmp)

Ir

o

0

!

74.0

0

._1 II LL .J

tc within WSO and E North Greenland tt SW of Bj~rnoya

WSO

25

Thanetian (Tha)

I

IL 49 Ma

56.5

E North Greenland, with spreading SW of Spitsbergen

UPLIFT

]

? "1

O

Ypresian (Ypr)

o o

tt through WSO and .,Q

Lutetian (Lut) 50.0

tO

._

~

18

o

o 0 ILl

i

12

35.4

Priabonian (Prb)

10

FSG

Rupelian (Rup)

to

SVALBARD

MOLLER & SPIELHAGEN 1990

o_~ ~O N ~ r

7

Chattian (Cht)

o 0 o~

0

and south, the Central Basin escaped much folding at the surface except along ancient fault zones. The bedding thrusts probably favoured Mesozoic shales beneath the overlying Cretaceous and Paleogene sandstones. Evidence for this is in the thrust structures that surface over the buried Billefjorden and Lomfjorden fault zones, and also elsewhere.

Tilt up to N

83.0" Santonian (San) Coniacian (Con) Turonian (Tur)

86.6 _ 88.51 - 90.4

Cenomanian (Cen) 97.0 o Q o in

o

34

Carolineflellet Fm

Albian (AIb)

LLI

ilro7. Fig. 20.12. Paleogene time-scale, with major magnetic anomalies. Regional tectonic events are indicated with reference to Svalbard (after Harland et al. 1990; Miiller & Spielhagen 1990). Key: WSO, West Spitsbergen Orogeny; FSG, Forlandsundet Graben; tp, transpression; tt, transtension; tc, transcurrence; CB1-6, Central Basin Paleogene formations.

PALEOGENE HISTORY

413

In Chapter 9 it was suggested that the seemingly west-verging fold and thrust structures in the Prins Karls Forland Horst were not Caledonian, but part of the same Paleogene West Spitsbergen Orogeny. If so then the 'flower structures' of Lowell (1972) may be a useful model. A schematic diagram of the structures in mid western Spitsbergen is drawn in Fig. 20.7 combining features from Nottvedt et al. (1988) and from Lowell (1972).

20.8

Regional tectonic sequence

The above structural conclusions were arrived at before, and then independently of, the ocean-spreading data that became available in the Arctic. Thereafter, the various palinspastic models could be related to oceanic magnetic anomalies and so in turn to the time scale. This was especially valuable in Svalbard tectonics because of the weakness of Tertiary stratigraphic correlations. The first, and remarkable impact in this way, was perhaps the reconstructions by Pitman & Talwani (1972) who, by extrapolating plate motions from North Atlantic data well to the south of our area of interest, showed a sequence of motions between Greenland and Svalbard (with the Barents-Baltic plate) in which successive positions between Greenland and Scandinavia with Svalbard were depicted (their fig. 7). From this, in their fig. 8, Spitsbergen progressed dextrally past eastern North Greenland and then plots a collision between them at about 47 Ma. Their anomalies were dated (in that exercise) consistently 3 or 4 million years younger than in the scale adopted here in Fig. 20.12. Consequently on that reckoning the maximum plate overlap would be nearer 51 Ma which is Late Ypresian here. In any case an Eocene orogen is consistent with their data. Many further plate tectonic studies have been made, not least by Srivastava & Roest (1989) whose data were adopted by Mtiller & Spielhagen (1990) in their study of late Cretaceous and Paleogene evolution of the Central Basin, as copied here in Fig. 20.13. A summary of the Paleogene palaeogeography of Svalbard is shown schematically in Figs 20.15 and 20.16 (a-c) to illustrate the largerscale kinematics during this time. These events are plotted against a time and anomaly scale in Fig. 20.12 in which the range of opinion as to the ages of the Paleogene strata CB1-CB6 is narrowed to be consistent with available evidence. Kinematic models for the Cenozoic evolution of the Greenland Sea area generally show a stepwise opening, with a northeasterly propagating rift axis (Eldholm et al. 1988). The plate configuration between anomalies 23 and 13 (54-36 Ma) gave rise to transpression between northeast Greenland and western Svalbard as rifting progressed, the resulting effect being the West Spitsbergen Orogeny, with maximum shortening and distributed transpression, from late Paleocene to early Eocene (Fig. 20.14). As separation of Greenland and Svalbard progressed, so the effects of transpression rapidly waned, such that by anomaly 21 (49.5 Ma) transpression was largely confined along the Senja Fracture Zone (Fig. 20.14a). The early Oligocene plate reorganisation in the North Atlantic at anomaly 13 (36 Ma), during which relative plate motion changed to northwest, gave rise to a predominantly tensional regime in the northern Greenland Sea area and along the western Svalbard and Barents Shelf margin, with extensional faults being active along the Hornsund Fault Zone (Fig. 20.14b). Other kinematic models along similar lines have been produced by Srivastava (1985), Jackson & Gunnarsson (1990), Lepvrier (1992), Kleinspehn & Teyssier (1993) and Teyssier, Tikoff & Manby (1995). The Eurekan Orogeny recorded extensively in Ellesmere Island, was the sinistral counterpart coeval with the dextral Spitsbergian Orogeny. However. the compressive component was more pronounced and instead of a simple sinistral shear zone along the postulated Wegener Fault of the Nares Strait, compressive fold structures are distributed rather generally so that the displacement was pervasive. This structure has been debated for many years, for example by De Paor et al. (1989).

b

Fig. 20.13. Sequence of maps showing the motion of Svalbard relative to Greenland (fixed) for latest Cretaceous to Oligocene time. Diagonal shading indicates overlap; bold dots indicate gaps (with kind permission of Elsevier Science, Amsterdam after Mtiller & Spielhagen 1990).

20.9 20.9.1

Paleogene tectono-sedimentary history Pre-Firkanten Formation events

There is a gap in the onshore record between the Albian Sch6nrockfjellet Member of the uppermost (Carolinefjellet) formation and the early Paleocene Firkanten Formation of the Paleogene Van Mijenfjorden Group. The gap is not less than 32 million years. In structure the hiatus is seen as an unconformity with overstep, but no overlap. As detailed in Section 19.7.6, the whole Nordenski61d Land Supergroup of Mesozoic strata is overstepped northward, with an average angular unconformity of 0034p, i.e. eroding about 2500m of strata in 250km from south Spitsbergen to Kongsfjorden. The tilting was attributed to thermal expansion of the mantle prior to the opening of the Eurasian Arctic Ocean Basin along the Nansen-Gakkel Ridge (Harland 1969a).

414

CHAPTER 20

\

. - -

@

"I ,

\

,% \ ~

I

SVALBARD

Q!

/

I 1

0~'ot~

r5o E

/, s S

BJORNOYA

~,s" s

SR

sS

II

S/

s S s s SS

TFP

70~

o

. ,~

~ .......

2~,12b~(

~-

.-

I

n

c.._

\

•o•s•~

(9

~A%~ ~

...,. "" ~ (~)

ooooooOOo~176176176

"f, oo~"

s

fAY

.__,

15~

0

L_.

]

200 km I

This fission probably began in earliest Paleocene time but the earliest ocean striping age is 5 3 M a (from Harland et al. 1990 timescale) between anomalies 25 and 24, and was the northern and final phase in the spreading of the Atlantic Ocean, through the Norwegian and Greenland basins. The effect of this was to institute or develop a dextral transform fault zone between Svalbard and northeastern Greenland. Thus the movement of Svalbard away from the previously adjacent Lomonosov Ridge to the north was accompanied by dextral strikeslip against Greenland and with a corresponding spreading in the Norwegian-Greenland Sea basins at the southern end of the fault zone. The contrary idea of a late Cretaceous-Early Paleocene orogeny with North Greenland pressing against Svalbard at this stage (e.g. Hanisch 1984; Lyberis & Manby 1992; Manby & Lyberis 1997) may be rejected on three grounds: (i)

a Late Cretaceous orogeny is inconsistent with the evidence of coeval slow tilting referred to above; (ii) the orogenic structures contain deformed Firkanten and younger formations; (iii) the plate tectonic evidence of Late Cretaceous compression in North Greenland was not necessarily opposite Spitsbergen at that time (Fig. 20.13a & b).

J

Fig. 20.14. Diagrammatic model for the Cenozoic sea-floor spreading, dextral strike-slip and transpression between Svalbard and Greenland for (a) Anomaly 23 (54 Ma) and (b) Anomaly 13 (36 Ma). Numbers in circles refer to fault zones: (1) Trolle Land Fault Zone; (2) Hornsund Fault Zone; (3) Senja Fault Zone; (4) Bj6rn6ya-S6rkapp Fault Zone; (5) Florlandsundet Graben; (6) Breibogen Fault Zone; (7) Billefjorden Fault Zone; (8) Lomfjorden Fault Zone. Letters refer to submarine features: HB, Hammerfest Basin; LH, Loppa High; SH, Stappen High; SR, Senja Ridge; TB, Troms6 Basin; TFP, Troms-Finnmark Platform. Numbers refer to anomalies, with shading indicating areas of transpression (adapted with permission from Eldholm, Faleide & Myhre 1987).

The model of spreading referred to here has been accepted by most other geoscientists. It was first suspected by Harland (1961) and Heezen (1961) and was formulated by Harland (1965, 1967) and has been amply confirmed by ocean spreading data not then available. Nevertheless the Kronprins Christian Land (dextral transpressive) Orogeny in eastern North Greenland has been argued as Late Cretaceous (H~kensson & Pedersen 1982; Pedersen 1997). The dextral transpressive deformation in that region began earlier. Greenland had begun to separate from Labrador at about Anomaly 33 (i.e. approximately at 80 Ma). That spreading of the Labrador Sea until about Anomaly 13 (c. 35Ma) spanned Santonian through Priabonian (Late Eocene) stages. Thus, from about 80 or even 90 M a to about 60 Ma Svalbard moved north together with Greenland, with little or no differential movement between them, and this corresponds approximately to the stratigraphic hiatus with gentle tilting of Svalbard prior to the fission. Lateral tectonic stress probably had little effect other than inducing some jointing. At first sight it might seem that the Paleogene dextral strike-slip zones were determined by the Silurian-Devonian sinistral strikeslip fault zones, seen onshore. But, the evidence supports the view that most of the onshore fault zones, although reactivated by compression or extension, did not take up the dextral motion which instead sliced through to the west of Spitsbergen. It seems probable

PALEOGENE HISTORY (Smith pers. comm., in press) that Bjernoya was attached to eastern North Greenland in Late Proterozoic through Paleozoic and Mesozoic time and did not move northwards with the other Svalbard terranes by sinistral strike-slip. But when the Paleogene dextral faulting developed, Bjornoya became separated from Greenland and moved south with Svalbard.

20.9.2

Mid-Paleocene events ( 6 3 - 5 7 Ma)

This interval refers to an indefinite time span to include Late Danian and Early Thanetian or Selandian for example 63 to 57 Ma (Fig. 20.15). Land to the north and east of the Central Basin was drained to a deltaic front advancing into a sea whose extent to the west has been obscured by later tectonism. The Central Basin following a Mesozoic platform sequence extended to the north so as to include the Ny-Alesund coalfield. These conditions prevailed with the deposition of CB1 and CB2 of this Central Basin (Firkanten and Basilika Formations) and the coeval Ny-Alesund Subgroup; possibly also the I~yrlandet strata. Signs of tectonic disturbance are observed in the Ny-Alesund Subgroup where the Tvillingvatnet Member (of the Kongsfjorden Formation) rests unconformably on truncated beds of the Kolhaugen Member.

BFZ

415

It is probable that Svalbard (with Eurasia) began to part from Greenland along a dextral strike-slip zone, at first with pure transcurrence, possibly with some transtension, so deepening the Central Basin and possibly initiating the Forlandsundet Graben to the west. A strike-slip zone could already have been operating just west of the Central Basin, without noticeable effect on sedimentation provided there was no significant transpression or transtension. The deepening of the Central Basin following CB1, with the basal conglomerates of the Firkanten Formation, exceeded sediment supply with the retreat of delta fronts and the largely argillaceous CB2 (Basilika) sedimentation.

20.9.3

Latest Paleocene-Eocene ( 5 8 - 3 8 Ma)

The strata from CB3 through CB6 record the filling of the basin and the new source of sedimentation in the west (Fig. 20.16a, b & c), corresponding to the initial uplift of the West Spitsbergen Orogen, thus yielding advancing delta deposits into the Central Basin. The earliest evidence of such disturbances could be latest Paleocene. The evidence for the main tectogenesis of the West Spitsbergen Orogeny is seen in the soft sediment slumping and deformation in CB3 to CB6. It has been argued that the main deformation was at least postFirkanten Formation from the classic work of Hoel & Orvin (1937) and Orvin (1934, 1940). Harland (1961) depicted a greatly extended orogenic belt within which the Forlandsundet Graben formed, probably at a late stage. In 1965 to 1969 the orogeny was argued to be the effect of oblique collision with Greenland as a result of dextral strike-slip. This transpression model for Paleogene history (a)

BFZ o

;.iP

":..:.

o

- ~

I

-l-xJ

_

m

m

_

_

_

% _--

---

H

_ .~.--..=_-

~

~

-

~ ~

? -z

Mid-Paleo

~

Land/ sourcea r e a

~

Deltafront/ shoreface

~

Proximalalluvium

~

Prodelta/ offshore

Deltaplain/ tidalfiats

Fig. 20.15. Palaeogeographic map of Spitsbergen in Mid-Paleocene time.

Deposition of upper Firkanten and Basilika formations. H, Hornsund Fault Zone; BF, Western Boundary Fault; BFZ, Billefjorden Fault Zone; LFZ, Lomfjorden Fault Zone (adapted with kind permission of Elsevier Science, Amsterdam from MiJller & Spielhagen 1990).

Latest Paleocene

\

"~

Fig. 20.16. Paleogene palaeogeographic maps of Spitsbergen. (a) Deposition of the Hollendardalen Member (Sarkofhgen Formation); (b) deposition of the middle Gilsonryggen Formation; (c) deposition of the upper Battfjellet and Aspelintoppen formations. For key refer to Fig. 20.16 (adapted with kind permission of Elsevier Science, Amsterdam from Miiller & Spielhagen 1990).

416

CHAPTER 20

(b) BFZ

:."i i '.1

Late Early Eocene

(c) BFZ

Early Mid-Eocene Fig. 20.16. (continued).

was developed i.a. by Lowell (1972) a n d in m o r e detail by Steel et al. (1985). The current view in this w o r k is that the initial g r a b e n was f o r m e d in the preceding interval. In plate tectonic terms this transcurrent-transpressive phase corresponds to the c o n c u r r e n c e of seafloor spreading in both the L a b r a d o r Sea and the Eurasia Basin a n d G r e e n l a n d - N o r w e g i a n seas. D u r i n g this phase the zone is a transform fault zone connecting the Eurasia Basin with the G r e e n l a n d - N o r w e g i a n Seas. M a g n e t i c a n o m a l y patterns are consistent with a very tight (transpressive) passage in Eocene time. The transpressive hypothesis is based on the fact that compressive structures were f o r m e d (often with E N E vergence) t h r o u g h o u t m u c h o f the length of the orogen, coinciding with a time o f d e m o n s t r a b l e dextral strike-slip. T h a t the main structures a p p e a r to be compressive is typical o f transpressive situations w h e r e partitioning of strain compensates c o m p r e s s i o n by transcurrence, i.e. strike-slip faulting. This is consistent with the c o n t e m p o r a r y d e v e l o p m e n t of parallel graben structures. H o w e v e r , the n o r t h Oscar II L a n d virgation, verging N to N E , fits a distinctive transpressive origin a n d is consistent with the hypothesis of dextral motion. Instances o f dextral strike-slip within the orogen have been referred to in C h a p t e r s 9 a n d 10. The processes that led to the visible Paleogene structures m a y be s u m m a r i z e d as follows. (a) Ocean stripes confirm the simplest hypothesis that Spitsbergen moved uniformly from its initial position, north of North Greenland, to its present position along dextral strike-slip fault zones. Thus two adjacent plates (Laurentia and Eurasia) were sliding against each o t h e r with northeastern Greenland and Spitsbergen almost in contact. (b) Following a transtensional phase (in which the Central Basin deepened and the Forlandsundet Graben developed), at or about 58 Ma the plates moved together and their adjoining margins transpressed. Transpression continued until about 37 Ma with a climax at about 45 Ma. (c) The visible result of this transpression was first overfolding and thrusting in Spitsbergen towards the NE or NNE in Breggerhalvoya. The structures in Breggerhalvoya conform to a dextral transpressive deformation (only) because the way to the north (of Kongsfjorden) was blocked. Subsequently the main dextral strike-slip displacement must have been in fault zones to the west because the strike-slip movements continued throughout. Therefore, in most of the orogen the strain would have been partitioned between the ENE thrust structures onshore and the strike-slip zone(s) offshore. It is no argument against transpression to say that the strike-slip zones do not exist because they very likely could not be seen beneath sediments offshore. There are, however, several pieces of strike-slip structure even on land (in Chapters 9 and 10) and especially the Kaffieyra shear zone of Ohta et al. (1995). However, they are not necessary to this argument. The actual structures have been outlined in the foregoing section. They dip westwards towards a possible root zone and extend eastwards often with thin-skinned deformation and as part of an extensive decollement. (d) The root zone could lie in the Forlandsundet Graben if, as is suggested here, the WSW verging folds and thrusts in northern Prins Karls Forland are on the other side of the root zone. (e) Mineralization. It has already been noted that metallic sulphide occurences are almost entirely limited to the western province and this has been correlated with a probable origin within a north Greenland-Ellesmere Island-type basement. It may also be generalized that the minerals occur mainly in carbonates and associated with fault breccias. It so happens that this whole terrane lies within the West Spitsbergen Orogen so that the genesis may well be Proterozoic, Paleozoic or Paleogene and it could have resulted in more than one event. The simplest hypothesis, and the author's preference, is to follow Hjelle (1962), that all occurrences may be from Proterozoic basement rejuvenated in Paleogene time because there may not have been another extensive orogenic suture since Proterozoic time. An alternative route from depth could be via the Silurian-Devonian sinistral fault zones to the east, within or to the west of the observed basement. The Eidembreen Ordovician event while bringing up blueschist facies from depth does not appear to be mineralised in this way. This might support the earlier suggestion that the Vestg6tabreen Complex is metamorphosed subducted Vendian strata and that the source of metals is pre-Vendian. Further speculation is not profitable without some geochemical survey of the problem.

PALEOGENE HISTORY

20.9.4

?Late Eocene-Oligocene events (c. 35-23 Ma)

With the stabilization of the Labrador Sea, Greenland again became fixed to Laurentia and the continued seafloor spreading in the Eurasia Basin and on the Greenland-Norwegian Sea was accompanied by transtension in the linking transform fault, so joining these ocean basins by a connecting strip of expanding ocean. In particular, the Yermak Plateau submarine eruptions may belong to the earlier part of this interval. This development with transtension may have allowed the later stages of sedimentation in the graben. But the principal beneficiary of sedimentation was the offshore shelf and the newly formed ocean floor west of Svalbard, so receiving debris from the erosion of the uplifting orogen. This story, with the complex pattern of submarine faulting, basins and highs, continuing to the present day, is followed in the next chapter (21).

20.9.5

Plate-tectonic sequence

The foregoing history of events in Svalbard fits neatly into the plate-tectonic sequence that is now well established through ocean stripe studies. Before this precision was available the first model of dextral strike-slip translated Spitsbergen from a position north of North Greenland to its currently mobile situation. This sequence was first related to Spitsbergen sedimentation and tectonics in 1964 (Harland 1965) and amplified somewhat in 1966, 1967 and 1969 showing the West Spitsbergen Orogen to be the result of a glancing collision with eastern North Greenland at about Eocene time. The earliest ocean stripe projection to this area was from data far south in the North Atlantic Ocean by Pitman & Talwani (1972) and it almost exceeded what was required with a significant overlap of Greenland and Spitsbergen at that time. This was good confirmation, if confirmation were needed, of the age of the West Spitsbergen Orogeny. M a n y further refinements in the sequence of plate motions followed, e.g. Talwani & Eldholm (1977), Srivastava & Tapscott (1986), Srivastava & Roest (1989). Mfiller & Spielhagen (1990) made a convenient synthesis of the 1989 reconstruction with the Spitsbergen tectonostratigraphic story which is followed and illustrated in Fig. 20.13 (from their figs 3 and 6). 'For the time between chrons 33 and 25 the resulting differential motion is by right-lateral strike-slip. The plate boundary was most probably located in northeast Greenland at the Troll Land fault system as a continuation of the Senja fracture zone [then] the plate boundary jumped eastward to the Hornsund Fault Zone. A drastic counter clockwise change in spreading direction in the Labrador Sea between chrons 25 (59 Ma) and 24 (56 Ma) caused transpression between Greenland and Svalbard, resulting in about 50-70 km shortening and a 30 km strike-slip motion. Strike-slip dominated transpression characterised the period from chron 24 to 21 giving rise to 160km of dextral strike-slip and 15-20 km of shortening. The relative motion between Greenland and Svalbard was dominated by strike-slip until chron 13 (36Ma) subsequently followed by transtension, after seafloor spreading in the Labrador Sea had ceased.' (from Mfiller & Spielhagen 1990, caption to their fig. 6, p. 162).

417

Within this overall kinematic sequence, which he did not question, Lepvrier (e.g. 1992) from local structural studies proposed two phases in the dextral transpressive tectonism on dynamic grounds. In phase 1 the maximum horizontal stress al was oriented 10-20~ i.e. at about 45 ~ to the transform trend and so by 'coupled' transpression generated the NW-trending folds and thrusts verging NNE. Phase 2 followed, with a: oriented 70-80 ~ i.e. E N E producing the N N W fold and thrust belt in which case the transpression was 'decoupled' so that the conspicuous compressive component was allied to an inconspicuous (yet in places evident) strike-slip component. It may be recalled that the concept of decoupling or partitioning components was explicit in the original formulation of transpression (Harland 1971) and has been affirmed many times (e.g. Faleide e t al. 1988; Haremo & Andresen 1988; Maher & Craddock 1988). Lepvrier (1992) further suggested a net dextral strike-slip of 550 km in the first 20-25 million years of Svalbard's translation past North Greenland. This contrast in part accounts for the different structural styles north and south of Isfjorden and even for the Isfjorden Fault separating them. As pointed out by Wennberg, Hansen & Andresen (1992) the changing stress and strain orientations need not require changing directions of plate motion when curvatures in the plate boundaries might account for changes between transpression and transtension as was illustrated by Harland (1971). Pedersen (1988) referred to three structural events in the late Mesozoic platform break-up between Greenland and Svalbard (i.e. in the Wandel Sea strike-slip Mobile Belt): (1) the extensional, Ingeborg Event with Jurassic listric normal faults; (2) the transtensional, Kilen Event; (3) the main compressional-transpressional tectonism of the Kron Prins Christian Land. Strike-slip Orogeny (striking NW-SE), accompanied by structural inversion of the basins with three structural phases: (i) transpressional shear with anastomosing joints; (ii) en ~chelon dome folding with thrusts which are cut by (iii) dextral strike-slip faults. This event is dated 'Late Cretaceousearliest Tertiary time'. A late Paleocene-Eocene age correlating with the West Spitsbergen and Eurekan orogenies was favoured by Soper et al. (1982), whereas a Late Cretaceous age as favoured by Hgtkensson & Pedersen (1982). H~kensson (1988) admitted the uncertainty of the evidence supporting these two views while favouring the second. Correlation with the West Spitsbergen Orogeny would be convenient, but not necessary (for which a Cretaceous age has been advanced and rejected). Three 'pronounced lineaments' regarded as fundamental faults were mentioned in the northeast corner of Greenland by Pedersen et al. (1992): Harderfjord Fault Zone (E-W, HFFZ), East Greenland Fault zone (N-S, EGFZ) of ancient origin and the post Ellesmerian Trolle Land Fault system (NW-SE, TLFS) of the Kron Prins Christian Land Orogen. A further arcuate thrust fault (Kap Cannon Thrust zone) with e. NW-SE compression would be consistent with the dextral TLFS. In conclusion, whereas Paleozoic sinistral fault zones and the Cenozoic dextral fault zones migrate and do not necessarily coincide, the net effect is a reversal of the motion of the main body of Svalbard. The sinistral collision zone became the Lomonosov Orogen. It became a ridge when northern Svalbard was separated from it dextrally by the N a n s e n - G a k k e l fission and spreading, a likely consequence of the heat accumulating in the thickened continental crust.

Chapter 21 Neogene-Quaternary history W. B R I A N H A R L A N D

with contributions by C L A R E

F. S T E P H E N S

Glacial history of Svalbard: Neogene-Holocene, 429

21.1 21.2 21.2.1 21.2.2 21.2.3 21.2.4 21.3 21.4 21.4.1 21.4.2 21.5 21.5.1

Neogene-Quaternary time-scale, 418 Plate motions (C.F.S.), 418

21.7 21.7.1

Anomaly 25 to 13 time, 418 Anomaly 13 time, 421 Post-Anomaly 13 time, 421 Present-day spreading, heatflow and seismicity, 421

21.7.2 21.7.3 21.7.4 21.7.5

Deep structure of Svalbard, 421 Neogene-Holocene volcanism and thermal springs (C.F.S.), 423

21.8

Eruptive centres, 423 Fluid springs and seepages, 424

21.6

Neogene-Holocene uplift and erosion, 427

21.8.1 Glaciofluvial-fluvial sediments, 432 21.8.2 Alluvial fans, talus cones and rock glaciers, 432 21.8.3 Raised-beach morphology, 432 21.8.4 Permafrost and patterned ground, 432 21.8.5 Freeze-thaw processes, 433 Post-glacial sea-level changes, 434 21.9

Neogene-Pleistocene marine sedimentation (W.B.H. & C.F.S.), 426

Moffen, 427

21.6.1 Neogene shaping of Svalbard, 428 21.6.2 Quaternary development of land-forms, 429

This is the final historical chapter in this work outlining principal post-Paleogene events. Section 21.1 summarizes the time scale for these events. The evidence for this is mostly in the interpretation of geomorphic features of uplift and denudation with little preservation of onshore sediments until after the main glaciation had ceased its erosive activity. The consequential depositional record is thus mainly submarine until Holocene time, when it could relate to onshore history. Figure 21.1 shows the distribution of Neogene and Quaternary volcanics, hydrothermal zones and areas of recent seismic activity. Many geoscientists are preoccupied with the closing stages of this story and another volume this size might be needed to do justice to Quaternary studies in Svalbard. This chapter brings geologic history to the present, whereas Chapter 22 is concerned with observable processes whose time scale is that of the scientists themselves and thus moves from geological to geoscientific time. To the adage that we interpret the past from the present it is equally true that we interpret the present from the past. Indeed, this is the essence of the historical enterprise that has motivated this work

21.1

Neogene-Quaternary

time scale

This geo-historical chapter spans a time interval through to the present, with the consequence that human perspective coupled with a record of events increasingly available has led to successively shorter time divisions to accommodate the data. There has been a corresponding muddle over conventional divisions. Here (for consistency in this work) the classification is adopted from Harland et al. (1990) where its history and rationale was discussed (Fig. 21.2). Indeed, some detail there is hardly applicable in Svalbard; but the objective of international correlation, especially of submarine deposits remains. Currently the successive magnetic anomaly values are in use. Each numbered anomaly ideally is in two parts. The older being a reversed magnetic polarity and the younger being of normal, present day, polarity. However, many anomaly numbers span several reversed and normal episodes and the normal events may be referred to as chrons. These are not detailed here but may be found with some discussion in Harland et al. (1990) and more specifically in Myre et al. (1995, p. 32). The main problem for the later part of the Pleistocene Epoch is that glaciation has removed most of the record on land until the latest retreats. Many of the Holocene events can be correlated stratigraphically, as by volcanic pumice in raised beach deposits, and the later sequence of biotas reflects climatic fluctuations rather than evolutionary progress.

21.2

Glacial episodes, 429 Moraines, 431 Submarine glacier-fed sedimentation, 431 Submarine glacial plowmarks, 431 Uplift and subsidence in relation to glaciation, 431 Pleistocene and Holocene surficial geology and geomorphic features, 431

Plate motions

The Neogene-Pleistocene plate motions that directly affected the tectonic, geological and geomorphic development of Svalbard are considered with their broader context in terms of the overall evolution of the area, both spatially and temporally. Therefore, this section encompasses the plate motions from the time of opening of the Norwegian Sea to the present, and spreading throughout the Norwegian-Greenland Sea and the Eurasia Basin (Fig. 21.3).

21.2.1

Anomaly 25 to 13 time

The Norwegian-Greenland Sea opened between anomalies 25 and 24 (Talwani & Eldholm 1977) (that is c. 53Ma according to Harland et al. 1990); Greenland moved northwest relative to Eurasia. Active sea-floor spreading was also initiated in the Eurasia Basin at this time and has since been confined between the Lomonsov Ridge and the Barents Sea shelf (Eldholm et al. 1984; Srivastava & Tapscott 1986; Kristofferson 1990). The subsequent motion between Greenland and Svalbard was dextral strike-slip along the NNW-SSE-trending Hornsund Fault Zone. Plate tectonic reconstructions prior to Anomaly 13 show an overlap between Greenland and Svalbard which results from strike-slip motion until Anomaly 13 (Srivastava & Tapscott). During anomalies 24 to 21 time simultaneous spreading occurred all round Greenland (Srivastava & Tapscott) including spreading in the Labrador Sea linked to the Mid Atlantic Ridge at an active triple junction at the southern end of the Labrador Sea (Nunns 1982). The change in direction of motion between Greenland and North America at Anomaly 24 time, associated with the opening of the Norwegian Greenland Sea, resulted in the Labrador Sea spreading obliquely to the ridge axis (Roots & Srivastava 1984). A quiet magnetic zone in the centre of the Labrador Sea is interpreted by Roots and Srivastava as the result of spreading between margins that were highly oblique to the spreading direction. Spreading in the Labrador Sea slowed significantly after Anomaly 21 (Nunns 1982; Srivastava & Tapscott 1986) and had ceased by Anomaly 13. The initial direction of spreading between Greenland and Eurasia was NW-SE, parallel to the transform faults bounding the Norway Basin (Nunns 1982). As a consequence of spreading slowing considerably in the Labrador Sea, the spreading direction in the NE Atlantic began to change towards an east-west spreading orientation. The new spreading was not parallel to the transform faults within the Norway basin and resulted in compression across

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The characteristic thermal structure of Svalbard glaciers is polythermal (also referred to as sub-polar), where some areas of the ice are at the pressure melting point and other areas are colder (Schytt 1964; Baranowski 1977; Jania 1988). Schytt (1969) described the thermal regime of the ice caps on Nordaustlandet, based on the distribution of shallow temperatures, as an annulus of cold ice surrounding an interior at the pressure melting point. This superficially inverted distribution of internal ice temperatures is accounted for by the significance of the release of latent heat through meltwater refreezing and the formation of superimposed ice on many Svalbard ice masses. Surface meltwater percolates into and refreezes in the snow and firn on the upper part of the ice masses, providing an important source of heat. By contrast, meltwater produced at lower elevations at the ice surface simply runs off over an ice surface which is only permeable via large crevasses and moulins. There is thus no source of latent heat in the glacier ablation area, where ice is also thinner than over much of the accumulation zone. The characteristic thermal structure of cold ice in the ablation zone, often overlying temperate ice, and ice at the pressure melting point in the upper, accumulation zone has been observed at many Svalbard ice masses. Ice temperatures of this general form have been measured using instrumented boreholes and have been inferred from multi-frequency radar data (e.g. Odeg~rd et al. 1992; Jania et al. 1996) and from numerical modelling simulations (Nixon et al. 1985). However, some Svalbard ice masses, especially those which have undergone significant thinning as a result of surge activity, are known to be below the pressure melting temperature throughout (e.g. Dowdeswell et al. 1995). Such thin, cold ice masses often have a very low accumulation area ratio and are in a consistently negative mass balance regime (Section 22.6.1). The hydrological structure of Svalbard ice masses is linked to their thermal regime, and particularly to temperatures close to the

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bed. In turn, the structure of the basal hydrological system will have implications for glacier flow rates and for the triggering of surge behaviour (Section 22.3.2). Glaciers that are cold throughout, for example the 3km 2 Scott Turnerbreen (R. Hodgkins pers. comm.; Dowdeswell et al. 1995), have a single-component drainage structure. Supraglacial meltwater provides the source, and water routing to the margin is via supraglacial and ice-marginal channels. There is no basal drainage system identifiable from hydrogeochem-

ical analyses of the bulk meltwaters (Hodgkins et al. 1995). Ice velocity is very low and the bulk of the glacier is essentially stagnant. By contrast, glaciers where at least part of the bed is at the pressure melting point, for example the 44 km 2 Finsterwalderbreen (Nixon et al. 1985; R. Odegfird pers. comm.), are more active; Finsterwalderbreen flows at up to 25 m a -1 . In addition, measured velocities on Finsterwalderbreen double during the melt season (Nuttall et al. 1997), and preliminary analyses of time-dependent

MODERN GLACIERS AND CLIMATE CHANGE measurements of the glacier hydrogeochemical signal indicate that a basal drainage system does develop in summer (Wadham et al. 1997).

The dynamic regimes of Svalbard ice masses are diverse, with individual glaciers and ice-cap drainage basins being characterised by 'normal' flow, periodic surge-type behaviour or continuous fast flow (Dowdeswell 1986). Glaciers in the former category tend to flow at a few tens of metres per year and have typically parabolic icesurface profiles (Fig. 22.5a). Fast-flowing glaciers and ice-cap outlets tend to flow continuously at hundreds of metres per year and to have surface profiles which are of low gradient relative to 'normal' flow. The outlet glaciers of southern Vestfonna in Nordaustlandet provide a clear example of fast flowing outlet glaciers separated by ridges of slower moving ice (Fig. 22.6).

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22.3.2 Ice dynamics, surging and fast glacier flow

a)

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An intermediate ice-dynamic category is provided by ice masses of surge-type, which exhibit cyclical instabilities in the form of short phases of rapid motion (a few months to a few years), punctuating significantly longer periods of quiescence and stagnation (20-200 years) (e.g. Meier & Post, 1969; Raymond 1987). During the active phase, mass is transferred rapidly down-glacier in association with heavy surface crevassing and an advancing surge front (Fig. 22.7). In the quiescent phase, there is net accumulation of mass in an upper 'reservoir area', which thickens and steepens to a critical point, at which fast flow is triggered by a reorganisation of the hydrological system at the ice-bed interface, and associated changes to the geotechnical properties of any soft basal sediments (Clarke et al. 1984; Kamb 1987). The mechanism which triggers glacier surges is, therefore, independent of any direct climatic control. Prior to the active phase, glacier surface profile is steep and, conversely, the surface profile is very flat during early quiescence (Fig. 22.5). Svalbard is one of several regions worldwide where a relatively large number of glaciers and ice caps are known to surge (Fig. 22.1). Others regions include Alaska, the Yukon, Iceland and the Parmirs. Almost 100 Svalbard ice masses have been observed to surge (e.g. Liestol 1969, 1993; Schytt 1969; Dowdeswell et al. 1991; Hagen et al. 1993; Lefauconnier & Hagen 1991). One of the largest surge events observed anywhere was that of Bfftsvellbreen on Nordaustlandet, whose advance around 1936 covered some 600 km 2 of previously unglacierized area (Schytt 1969). A number of recent surges of Svalbard glaciers appear to have an active phase of particularly long duration relative to surges in other regions from which observations are available (Dowdeswell et al. 1991). The quiescent phase of the surge cycle is also relatively long (50-500 years) for the few Svalbard ice masses for which evidence is available. The surge front (Fig. 22.7b) has been observed to propagate down-glacier for between three and ten years on Svalbard ice masses, as compared with less than one to two years elsewhere. Surge velocities in Svalbard are also relatively slow compared with other areas. The transfer of mass from an upper reservoir area to a lower receiving area is, therefore, accomplished over a considerably longer period in Svalbard. The rapidity with which surges terminate also differs between Svalbard and Alaskan glaciers. The surge of

442

CHAPTER 22 iiiiiiiiiiiiiiiiiiiiiiiiii~i~ i .......

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Fig. 22.7. Photographs of a surge of Bakaninbreen, Spitsbergen. (a) The heavily crevassed surface of the surge-type glacier during its active phase. (b) The active surge front advancing into stagnant ice. (Reproduced with permission from Dowdeswell et al. 1991.) Usherbreen in Spitsbergen terminated slowly, with a decrease in velocity towards quiescent phase values occurring over several years (Hagen 1987). By contrast, very abrupt surge termination, over only a few days and linked to major changes in basal hydrology, was observed at Variegated and West Fork glaciers in Alaska (Kamb 1987; W. D. Harrison pers. comm.). Such systematic differences in surge duration between Svalbard glaciers and those elsewhere should be a reflection of: (i) the differing rates of operation of basal processes; (ii) the operation of different kinds of basal processes; or (iii) a combination of the above.

22.4 22.4.1

Ice-ocean interactions Tidewater glaciers

Tidewater glaciers (Fig. 22.8), which are ice masses with marine margins grounded below sea level, make up over 1000 km or almost 20% of the coastline of the Svalbard archipelago (Table 22.1; Dowdeswell 1989). Most tidewater glaciers have ice cliffs of only a few hundred to a few thousand metres in length. However, the tidewater margins of Austfonna in Nordaustlandet form an ice cliff of about 130 km in length broken only once by a small rock outcrop (Fig. 22.3b). These terminal ice cliffs provide a significant site of glacier mass loss by iceberg production in addition to any losses by ablation and meltwater runoff. Most tidewater glacier margins exhibit transverse crevassing, indicating that these areas are in longitudinal tension (Hodgkins & Dowdeswell 1994). The crevasses are important in the

iceberg calving process and provide a constraint on the dimensions of the resulting bergs. Hughes (1992) developed a theory of iceberg calving from tidewater glaciers in which calving rate is controlled by bending creep behind the terminal ice cliff, and depends on ice cliff height, forward bending angle, crevasse spacing and water depth. The rate of iceberg calving from tidewater glaciers is also related empirically to water depth (Brown et al. 1982), presumably because buoyancy increases with depth. There is evidence to support this relationship from the small numbers of Svalbard tidewater glaciers for which observations of terminus velocity and water depth immediately offshore are available (Pelto & Warren 1991). The near-terminus velocity and calving rate of Kongsbreen, a tidewater glacier in northwest Spitsbergen, have been measured from high-resolution satellite imagery (Lefauconnier et al. 1994). This tidewater glacier is flowing at up to almost 8 0 0 m a -~ and calving about 0.25 km 3 of icebergs into the adjacent fjord system. Plumes of turbid meltwater upwell from point sources at the base of many tidewater ice cliffs, and are assumed to be derived from a basal hydrological system (e.g. Elverhoi et al. 1980; Pfirman & Solheim 1989; Dowdeswell & Drewry 1989). It is, however, very difficult to measure the discharge of meltwater at these sites. Sedimentation from these meltwater plumes is the dominant influence on marine deposition in fjord locations proximal to tidewater ice cliffs (Elverhoi et al. 1980, 1983).

22.4.2

Icebergs

The icebergs calved from the margins of Svalbard tidewater glaciers and ice caps are varied in form (Fig. 22.9). The dimensions and

MODERN GLACIERS AND CLIMATE CHANGE

Fig. 22.8. The terminus of a Spitsbergen tidewater glacier top; Nordenski61dbreen. Tensional crevasses parallel to the margin are shown, and the glacier is flowing from right to left. Beyond the terminus, to the left of the glacier front, the sea-surface is covered by a layer of shore-fast sea ice. (Source: Dowdeswell 1989.) dynamics of the parent ice mass are likely to affect both the shapes of calved icebergs and their rate of production (Dowdeswell 1989). Tidewater glaciers of a few kilometres in terminus width are found in each of the major fjord systems in Spitsbergen- Hornsund, Van Keulenfjorden, Van Mijenfjorden, Isfjorden, KongsfjordenKrossfjorden, Woodfjorden-Liefdefjorden, and Wijdefjorden. Based on observations in Kongsfjorden (Dowdeswell & Forsberg 1992), each of these fjord systems is likely to be characterised by the production of relatively large numbers of small bergs (width < 10 m) and fewer large icebergs of irregular shape. This statement is supported by: (i) the similarity in ice dynamics between the tidewater glaciers entering these fjord systems and (ii) aerial reconnaissance and photographs of these fjords (see Dowdeswell 1989). Certain ice masses in eastern Svalbard may also produce significant numbers of relatively large (>100 m length) tabular icebergs. This is particularly the case for the long lengths of terminal ice cliffs present around eastern Nordaustlandet and Kvitoya (Dowdeswell 1989). It has also been observed that Negribreen, a tidewater glacier at the north end of Storfjorden, east Spitsbergen, which last surged in 1935-36 (Vinje 1989), has produced a number of tabular icebergs in excess of 100m length since that time (Dowdeswell 1989). Vinje (1989) has also proposed that interannual variability in the occurrence of icebergs in the Barents Sea may be linked with surge activity in eastern Svalbard. The icebergs produced at the ice-ocean interface are important for glacial geological reasons, in addition to their role in glacier mass balance. Where debris is included within them, they form a process of sediment transfer from the terrestrial to the marine environment (Dowdeswell & Dowdeswell 1989). As the icebergs melt, this ice-rafted debris is released and is deposited on the sea floor, often forming characteristic sedimentary structures and facies (Gilbert 1990). If iceberg keels contact the sea floor, scouring and associated sediment reworking also takes place.

443

Fig. 22.9. Photographs of the contrasting morphology of icebergs derived from Svalbard glaciers. (a) A tabular iceberg of about 600 m in length within newly formed sea ice, east of Nordaustlandet (courtesy of D. J. Drewry). (b) Iceberg of irregular shape in a Spitsbergen fjord. The maximum freeboard is about 5 m.

22.5 22.5.1

Late Holocene glacial events and chronology Moraine systems

Fluctuations in the position of glacier termini can reflect changes in climate, through the effects of shifts in temperature and precipitation on glacier mass balance. However, the links between climate and glacier fluctuations are not simple and glacier dynamic factors must also be considered. Ice masses in most areas of the High Arctic have been retreating for much of the twentieth century, whether their margins end on land or in marine waters (Dowdeswell 1995). On Svalbard, aerial photographs acquired at intervals since the 1930s show that many glaciers are in retreat from clearly defined terminal moraine systems, with the exception of those that have surged. Chronological control for the last few hundred years is usually provided by radiocarbon and lichenometric dating methods. Andrb (1986) and Werner (1993) have used calibrated lichen growth curves to show that glaciers retreated from prominent moraine systems in north and northwestern Spitsbergen from about the turn of the century. In a number of areas of Svalbard, the moraine systems marking the end of the 'Little Ice Age' cool period represent the most extensive ice advance during the Holocene (Werner 1993). The analysis of early reports and maps, together with the availability of systematic aerial photography since 1936, shows two typical types of glacier terminus behaviour (see Lefauconnier & Hagen 1991). The first is terminus advance, presumably rapid, associated with the active phase of the surge cycle. The second is a

444

CHAPTER 22

more general retreat from moraine systems probably dating from a Little Ice Age maximum, linked to changing environmental conditions and, in some cases, to stagnation during the quiescent phase of the surge cycle. Prominent moraine ridges, sometimes protruding beyond the line of the coast where tidewater glaciers are present, mark the recent extent of these ice masses. Within Svalbard fjord systems, aerial photographs, expedition charts and lateral moraine sequences indicate that significant tidewater glacier retreat has taken place in the last 100 years or so. For example, the lateral moraines of Lillieh66kbreen, a tidewater glacier in northwest Spitsbergen, were dated using lichenometric methods (Werner 1990), implying retreat from the turn of the century from a maximum Holocene position related to the Little Ice Age climatic cooling. Glacier retreat since the end of the nineteenth century has been between approximately 2 and 3 km for Lillieh66kbreen, and echo sounder profiles of the fjord floor show that the lateral moraines can be traced as submarine terminal moraines across the sea bed (Sexton et al. 1992). Liestol (1976) has made similar observations of submarine moraines in Van Keulenfjorden at the margins of Nathorstbreen.

22.6

Glaciers and climate change

22.6.1

Climate records and glacier mass balance

Meteorological records acquired from western Svalbard since 1911 show an abrupt rise in mean annual air temperature of almost 5~ after about 1920, fluctuating about this higher level since that time (Hanssen-Bauer et al. 1990; Fig. 22.10). This climate change is linked to the termination of the cold Little Ice Age over the North East Atlantic sector in general (Kelly et al. 1982; Grove 1988), with Svalbard representing an end member of particular climatic sensitivity due to its position at the northern extremity of relatively warm ocean currents and depression tracks. The relationship between inputs of mass to glaciers, as snow or refrozen meltwater, and mass loss, in the form of meltwater runoff and iceberg production (for tidewater glaciers), is known as glacier mass balance. If, over a balance year, inputs exceed losses, then an ice mass has a positive balance, and vice versa. However, long time series of glacier mass balance observations are scarce and losses by iceberg calving are very difficult to quantify, restricting mass balance data largely to ice masses ending on land (Dowdeswell et al. 1997). Measurements at a number of Svalbard glaciers from 1950 onwards (Fig. 22.11) demonstrate that mass balances have been

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consistently negative (Hagen & Liestol 1990). Reconstructions, based on statistical correlations between climate and glacier mass balance for the period since climate records began, extend this conclusion back to the second decade of this century (Lefauconnier & Hagen 1990). This implies cumulative net losses of mass of the order of tens of metres water equivalent over this period. This is why the bulk of Svalbard glaciers, which were close to their maximum extent for the last 10 000 years at the start of the twentieth century (Hagen & Liestol 1990; Werner 1993), have undergone sustained retreat and thinning since that time (Section 22.5).

22.6.2

Modelling glacier response to future climate change

Modelling the mass balance of Svalbard glaciers using an energy balance approach provides a method of assessing their sensitivity to possible future climatic perturbations (see Oerlemans 1992). The model (Oerlemans 1993), which calculates the components of ice surface energy balance, takes meteorological data, the area distribution with altitude of the ice mass, and parameters defining the global radiation as input values. The mass balance of a glacier surface is expressed as: M = Jyear [ ( 1 - f ) m i n ( 0 ; - B / L ) +

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Fig. 22.10. Temperature records from Svalbard for the period since 1912, including both mean annual and mean July values. The data are synthesised from two stations in western Spitsbergen (Isfjord Radio and Svalbard Lufthavn). (Source: Hansen-Bauer et al. 1990).

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