Subsurface sediment mobilization

Subsurface Sediment Mobilization

Geological Society Special Publications Society Book Editors R. J. PANKHURST (CHIEF EDITOR) P. DOYLE F. J. GREGORY J. S. GRIFFITHS A. J. HARTLEY R. E. HOLDSWORTH

A. C. MORTON N. S. ROBINS M. S.STOKER J. P. TURNER Special Publication reviewing procedures The Society makes every effort to ensure that the scientific and production quality of its books matches that of its journals. Since 1997, all book proposals have been refereed by specialist reviewers as well as by the Society's Books Editorial Committee. If the referees identify weaknesses in the proposal, these must be addressed before the proposal is accepted. Once the book is accepted, the Society has a team of Book Editors (listed above) who ensure that the volume editors follow strict guidelines on refereeing and quality control. We insist that individual papers can only be accepted after satisfactory review by two independent referees. The questions on the review forms are similar to those for Journal of the Geological Society. The referees' forms and comments must be available to the Society's Book Editors on request. Although many of the books result from meetings, the editors are expected to commission papers that were not presented at the meeting to ensure that the book provides a balanced coverage of the subject. Being accepted for presentation at the meeting does not guarantee inclusion in the book. Geological Society Special Publications are included in the ISI Index of Scientific Book Contents, but they do not have an impact factor, the latter being applicable only to journals. More information about submitting a proposal and producing a Special Publication can be found on the Society's web site: www.geolsoc.org.uk.

It is recommended that reference to all or part of this book should be made in one of the following ways: VAN RENSBERGEN, P., HILLIS, R.R., MALTMAN, A.J. & MORLEY, C.K. (eds) 2003. Subsurface Sediment Mobilization. Geological Society, London, Special Publications, 216. HURST, A., CARTWRIGHT, J. & DURANTI, D. 2003. Fluidization structures produced by upward injection of sand through a sealing lithology. In: VAN RENSBERGEN, P., HILLIS, R.R., MALTMAN, A.J. & MORLEY, C.K. (eds) Subsurface Sediment Mobilization. Geological Society, London, Special Publications, 216,123-137.

GEOLOGICAL SOCIETY SPECIAL PUBLICATION NO. 216

Subsurface Sediment Mobilization

EDITED BY P.VANRENSBERGEN Ghent University, Belgium

R.R. HILLIS University of Adelaide, Australia

A.J. MALTMAN University of Wales, UK and

C.K. MORLEY University of Brunei Darussalam, Brunei Darussalam

2003

Published by The Geological Society London

THE GEOLOGICAL SOCIETY

The Geological Society of London (GSL) was founded in 1807. It is the oldest national geological society in the world and the largest in Europe. It was incorporated under Royal Charter in 1825 and is Registered Charity 210161. The Society is the UK national learned and professional society for geology with a worldwide Fellowship (FGS) of 9000. The Society has the power to confer Chartered status on suitably qualified Fellows, and about 2000 of the Fellowship carry the title (CGeol). Chartered Geologists may also obtain the equivalent European title, European Geologist (EurGeol). One fifth of the Society's fellowship resides outside the UK. To find out more about the Society, log on to www.geolsoc.org.uk. The Geological Society Publishing House (Bath, UK) produces the Society's international journals and books, and acts as European distributor for selected publications of the American Association of Petroleum Geologists (AAPG), the American Geological Institute (AGI), the Indonesian Petroleum Association (IPA), the Geological Society of America (GSA), the Society for Sedimentary Geology (SEPM) and the Geologists' Association (GA). Joint marketing agreements ensure that GSL Fellows may purchase these societies' publications at a discount. The Society's online bookshop (accessible from www.geolsoc.org.uk) offers secure book purchasing with your credit or debit card. To find out about joining the Society and benefiting from substantial discounts on publications of GSL and other societies worldwide, consult www.geolsoc.org.uk, or contact the Fellowship Department at: The Geological Society, Burlington House, Piccadilly, London W1J OBG: Tel.+44 (0)20 7434 9944; Fax+44 (0)20 7439 8975; E-mail: enquiries @ geolsoc.org.uk. For information about the Society's meetings, consult Events on www.geolsoc.org.uk. To find out more about the Society's Corporate Affiliates Scheme, write to [email protected]. Published by The Geological Society from: The Geological Society Publishing House Unit 7, Brassmill Enterprise Centre Brassmill Lane BathBA13JN,UK (Orders'. Tel.+44 (0)1225 445046 Fax+ 44 (0)1225 442836) Online bookshop: http://bookshop.geolsoc.org.uk 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. © The Geological Society of London 2003. 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 0305-8719/007$ 15.00. British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library. ISBN 1-86239-1416 Typeset by Sends Filmsetting Limited, Manchester, UK Printed by Cromwell Press, Trowbridge, UK.

Distributors USA AAPG Bookstore PO Box 979 Tulsa OK 74101-0979 USA Orders: Tel. + 1 918 584-2555 Fax+1918 560-2652 E-mail [email protected] India Affiliated East-West Press PVT Ltd G-l/16 Ansari Road, Daryaganj, New Delhi 110 002 India Orders: Tel.+91 11 327-9113 Fax+ 91 11326-0538 E-mail [email protected] Japan Kanda Book Trading Company Cityhouse Tama 204 Tsurumaki 1-3-10 Tama-shi, Tokyo 206-0034 Japan Orders: Tel. + 81 (0)423 57-7650 Fax+ 81 (0)423 57-7651 E-mail [email protected]

Contents

VAN RENSBERGEN, P., HILLIS, R.R., MALTMAN, AJ. & MORLEY, C.K. Subsurface sediment mobilization: introduction MALTMAN, AJ. & BOLTON, A. How sediments become mobilized Shallow subsurface sediment mobilization OWEN, G. Load structures: gravity-driven sediment mobilization in the shallow subsurface HARRISON, P. & MALTMAN, A. J. Numerical modelling of reverse-density structures in soft non-Newtonian sediments PARIZE, O. & FRIES, G. The Vocontian clastic dykes and skills: a geometric model BANKWITZ, P., BANKWITZ, E., BRAUER, K., KAMPF, H. & STORR, M. Deformation structures in Plioand Pleistocene sediments (NW Bohemia, Central Europe) LEDESERT, B., BURET, C., CHANIER, E, FERRIERE, J. & RECOURT, P. Tubular structures of northern Wairarapa (New Zealand) as possible examples of ancient fluid expulsion in an accretionary prism: evidence from field and petrographical observations DRAGANITS, E., GRASEMANN, B. & SCHMID, H.P. Fluidization pipes and spring pits in a Gondwanan barrier-island environment: Groundwater phenomenon, palaeo-seismicity or a combination of both? HURST, A., CARTWRIGHT, J. & DURANTI, D. Fluidization structures produced by upward injection of sand through a sealing lithology L0SETH, H., WENSAAS, L., ARNTSEN, B. & HOVLAND, M. Gas and fluid injection triggering shallow mud mobilization in the Hordaland Group, North Sea PRALLE, N., KULZER, M. & GUDEHUS, G. Experimental evidence on the role of gas in sediment liquefaction and mud volcanism GAY, A., LOPEZ, M., COCHONAT, P., SULTAN, N., CAUQUIL, E. & BRIGAUD, F. Sinuous pockmark belt as indicator of a shallow buried turbiditic channel on the lower slope of the Congo basin, West African margin NOUZE, H. & BALTZER, A. Shallow bottom-simulating reflectors on the Angola margin, in relation with gas and gas hydrate in the sediments VAN RENSBERGEN, P., POORT, J., KIPFER, R., DE BATIST, M., VANNESTE, M., KLERKX, J., GRANIN, N., KHLYSTOV, O. & KRINITSKY, P. Near-surf ace sediment mobilization and methane venting in relation to hydrate destabilization in Southern Lake Baikal, Siberia Polygonal faults and sediment mobilization CARTWRIGHT, J., JAMES, D. & BOLTON, A. The genesis of polygonal fault systems: a review NICOL, A., WALSH, J.J., WATTERSON, J., NELL, P.A.R. & BRETAN, P. The geometry, growth and linkage of faults within a polygonal fault system from South Australia STUEVOLD, L.M., FAERSETH, R.B., ARNSEN, L., CARTWRIGHT, J. & MOLLER, N. Polygonal faults in the Ormen Lange Field, M0re Basin, offshore Mid Norway BERNDT, C., BUNZ, S. & MIENERT, J. Polygonal fault systems on the mid-Norwegian margin: a long-term source forluidfflow HIBSCH, C., CARTWRIGHT, J. HANSEN, D.M., GAVIGLIO, P., ANDRE, G., GUSHING, M., BRACQ, P., JUIGNET, P., BENOIT, P. & ALLOUC, J. Normal faulting in chalk: tectonic stresses vs. compactionrelated polygonal faulting MERTENS, J., VANDENBERGHE, N., WOUTERS, L. & SINTUBIN, M. The origin and development of joints in the Boom Clay Formation (Rupelian) in Belgium WATTRUS, N.J., RAUSCH, D.E. & CARTWRIGHT, J. Soft-sediment deformation in Lake Superior: evidence for an immature Polygonal Fault System?

1 9 21 35 51 73

95

109 123 139 159

173 191

207 223 245 263 283

291 309 323

vi

CONTENTS

Deep subsurface sediment mobilization MORLEY, C.K. Mobile shale related deformation in large deltas developed on passive and active margins HILLIS, R.R. Pore pressure/stress coupling and its implications for rock failure TINGAY, M.R.R, HILLIS, R.R., MORLEY, C.K., SWARBRICK, R.E. & OKPERE, B.C. Pore pressure/stress coupling in Brunei Darussalam - implications for shale injection MORLEY, C.K. Outcrop examples of mudstone intrusions from the Jerudong anticline, Brunei Darussalam, and inferences for hydrocarbon reservoirs VAN RENSBERGEN, P. & MORLEY, C.K. Re-evaluation of mobile shale occurrences on seismic sections of the Champion and Baram deltas, offshore Brunei McCLAY, K, DOOLEY, T. & ZAMORA, G. Analogue models of delta systems above ductile substrates TOTTERDELL, J.M. & KRASSAY, A. A. The role of shale deformation and growth faulting in the Late Cretaceous evolution of the Bight Basin, offshore southern Australia TALUKDER, A.R., COMAS, M.C. & SOTO, J.L Pliocene to Recent mud diapirism and related mud volcanoes in the Alboran Sea (Western Mediterranean) YASSIR, N. The role of shear stress in mobilizing deep-seated mud volcanoes: geological and geomechanical evidence from Trinidad and Taiwan DEVILLE, E., BATTANI, A., GRIBOULARD, R., GUERLAIS, S., HEREIN, J.P., HOUZAY, J.P., MULLER, C. & PRINZHOFER, A. The origin and processes of mud volcanism: new insights from Trinidad DEYHLE, A., KOPF, AJ. & ALOISI, G. Boron and boron isotopes as tracers for diagenetic reactions and depth of mobilization, using muds and authigenic carbonates from eastern Mediterranean mud volcanoes PARNELL, J. & KELLY, J. Remobilization of sand from consolidated sandstones: evidence from mixed bitumen-sand intrusions Index

335 359 369 381 395 411 429 443 461 475

491 505 515

Subsurface sediment mobilization: introduction PIETER VAN RENSBERGEN1, RICHARD R. HILLIS2, ALEX J. MALTMAN3 & CHRISTOPHER K. MORLEY4 1

Renard Centre of Marine Geology, Universiteit Gent, Krijgslaan 281-S8, Gent, Belgium. (e-mail: pieter_yanrensbergen @yahoo. com) 2 National Centre of Petroleum Geology and Geophysics, University of Adelaide, Adelaide, SA 5005, Australia 3 Institute of Geography and Earth Sciences, Aberswyth University of Wales, Aberystwyth, SY23 2AK, UK. 4 Department of Petroleum Geosciences, University of Brunei Darussalam, Bandar Seri Begawan 2023, Brunei

Subsurface sediment mobilization (SSM) - which includes soft sediment deformations, sand injections, shale diapirs and mud volcanoes - is more widespread than previously thought. The ever-increasing resolution of subsurface data yielded many new observations of SSM, not only from regions obviously prone to sediment remobilization, such as an active tectonic setting or in a region with exceptionally large sediment supply, but also from tectonically quiescent areas. Until now, all the different aspects of SSM have largely been treated as separate phenomena. There is very little cross-referencing between, for example, studies of mud volcanoes and those of sand injections, although both are caused by sediment fluidization. Divisions according to sediment type, mobilization depth or triggering mechanism make little sense when trying to understand the processes of SSM. There is a gradation in mobilization processes that cause considerable overlap between categories in any classification. Hence, it is necessary to integrate our understanding of all types of SSM, regardless of scale, depth, location, grain size or triggering mechanism. In addition, polygonal faults are important in this context, as this nontectonic structural style is closely associated with sedimentary injections and may also reflect large scale mobilization. The main goal of this volume is to help develop a more integrated understanding of subsurface sediment mobilization. It contains specific case studies and a number of overview papers about the mechanisms of sediment mobilization in the subsurface (Maltman & Bolton), about polygonal faulting (Cartwright) and about shale diapirs (Morley). Other recent review papers were published about sand injections by Jolly & Lonergan (2002) but additional pertinent remarks are presented here by Hurst et al and about mud volcanism and mud diapirism by Kopf (2002) and Dimitrov (2002). Older but important reviews are found in Maltman (1994) and Jones & Preston (1987).

The contributions in this volume are divided into three sections: shallow subsurface sediment mobilization, polygonal faulting and deep-seated sediment mobilization. We have arbitrarily put the limit between the shallow and deep subsurface at 500-1000 m, which is about the maximum depth of sand injections (Jolly & Lonergan 2002) and the depth of onset of sand lithification, the lower depth limit of shallow fluid generating processes and the common transition depth to regional abnormal pore fluid pressure. Although there are significant differences between shallow processes, deep processes and polygonal faults, the boundaries between these processes are not clear and there is considerable overlap. This review paper aims to link the contributions together into this common framework.

Shallow subsurface sediment mobilization Unconsolidated sediment in the shallow subsurface is most prone to subsurface remobilization: the porosity is high, cohesion and intergranular bonds are low and fluid production rate by compaction is high. Liquefaction, plastic flow and fluidization can occur. The most important fluid source in the shallow subsurface is pore water being lost through consolidation. At greater depths, but still within what we have classified here as the shallow zone, bacterial gas generation and gas hydrate accumulation/decomposition can be important, depending on the concentration of organic matter, bacterial processes, inflow of hydrocarbon gases, temperature and pressure. This section is further divided here into three subsections: mobilization related to pore water - mostly confined to very shallow depths; mobilization related to in situ gas generation and gas hydrates; and mobilization related to injection of gas or overpressured fluids from a deeper source.

From: VAN RENSBERGEN, P., HILLIS, R.R., MALTMAN, AJ. & MORLEY, C.K. (eds) 2003. Subsurface Sediment Mobilization. Geological Society, London, Special Publications, 216, 1-8. 0305-8719/037$ 15 © The Geological Society of London.

2

P. VAN RENSBERGEN ETAL.

Shallow mobilization related to expelled pore water Maltman & Bolton provide a review of the mechanisms by which sediments can be mobilized, how solid sediment can change to a fluid and back to solid again. The two most important requirements are pore-fluid overpressure, to cause fluidal state by liquefaction or fluidization and the occurrence of an hydraulic gradient to induce flow. Sediment mobilization structures can be divided into load structures, characterized by folding of an interface and fluidization structures, characterized by injection of fluidized sediment into the host rock. Load structures range from simple load casts to pseudo-nodules, ball-and-pillow structures and water-escape cusps (Owen); their size varies from millimetres to several metres. They most commonly affect the interface separating sand from clay; hence the deformation has implications for the lateral and vertical permeability and connectivity of sandstones. The morphology of load casts and flame structures are mostly explained in terms of viscosity contrast and fluidal behaviour. For example, Harrison & Maltman use numerical modelling to simulate flow driven by buoyancy forces resulting from reversedensity stratification to study the different roles of initiating conditions, inertia and rheological behaviour on the morphologies and timing of formation of natural features such as load casts and flame structures. Owen, on the other hand, suggests that the varying morphologies of load casts and flame structures may be caused by different growth rates rather than differences in viscosity. The varying degrees of deformation in this case could be controlled by the magnitude and duration of the driving force. Fluidization structures result from rapid migration of fluids through unconsolidated sediment. A large variety of loading mechanisms can trigger fluid flow in the shallow subsurface, ranging from earthquakes to footsteps (Maltman & Bolton). Sediment volcanoes and sand injectites are typical results of fluidization. Rapid fluid expulsion through sands often occurs along isolated pipe-like conduits. Differences in mineralization, cementation and grain packing may preserve such fluidization pipes in the rock record and bear witness to past fluid flow events. Draganits etaL interpreted concentric cylindrical pipes (1.5m high, 0.8 m in diameter) in Lower Devonian barrier island arenites of the North Indian Gondwana coast in the Himalayas as fluidization pipes. Based on the depositional setting and the stratigraphic framework Draganits et al. inferred that increased hydraulic head in the beach sands pore fluids following a rapid sea level rise may have caused the numerous spring pits and fluidization pipes. Ledesert et al. studied tubular concretions (0.6 m in diameter) in Mio-Pliocene sediments at the

Hikurangi subduction margin, on the northern Wairarapa coast of New Zealand's North Island. The concretions are attributed to the flow of carbonaterich water through silty sediment. The extent of cementation suggests that possibly two episodes of fluid expulsion occurred. The first episode occurred relatively early, when the sediment was unconsolidated during the fluid flow. The second episode occurred after consolidation of the sediment, possibly during a compressional event. Another type of fluidized sand injection is shown in spectacular outcrops in the Vocontian Basin (SE France). Complex networks of clastic sills (up to 10 m thick and several km long) and dykes, injected into a thick marly deep-water succession, are found in the channel banks, fed laterally from sandy channels. From the outcrop it appears that sand was injected into the channel banks contemporaneously with sand deposition in the channel. Dykes branching off lateral sills were injected downwards into the deep-water mud. These injections are probably not related to upward fluid migration along a hydraulic gradient but rather to fractures formed by sudden loading by turbidites (Parize etaL).

Sediment mobilization related to gas and gas hydrate The role of gas bubbles in sediment with regard to subsurface sediment liquefaction and sediment extrusion was studied by laboratory experiments on soil samples by Pralle et al. They found that small amounts of enclosed gas bubbles render the soil compressible and consequently enhances local shearing, pore pressure build-up and structural damage. It was observed that liquidized, overpressured sediments form mud chambers, whose excess pressure is released through cracks and other discontinuities. Subsequently the liquidized sediment migrates upward, driven by its own overpressure and by the buoyancy of the enclosed gas bubbles, until extruded at the surface. This model has strong similarities to the description of the mud volcano feeder system in Barbados by Deville etaL In shallow subsurface sediment in marine or deep lacustrine basins, the occurrence of gas accumulations and migrations, together with gas hydrate formation and decomposition, causes a complex hydrodynamic setting with localized fluid and sediment extrusion features. Gay etaL document pockmark distribution that, in the absence of gas hydrate, follows closely the flanks of the meandering turbidite channel on the lower slope of the Congo fan, offshore West Africa. They also found that active gas venting occurred in a zone where the excess pore pressure exceeded the vertical confining pressure of the overlying sediment wedge and that this active zone migrates seaward in step with progra-

SUBSURFACE SEDIMENT MOBILIZATION: INTRODUCTION

dationof the sediment wedge. Sediment properties and thus fluid migration patterns change drastically when gas hydrates are present. Hydrates block the sediment pores and decrease the permeability and hydrate formation requires large amounts of water and locally causes overcompaction. Hydrate dissociation releases large volumes of gas (mostly methane) and can locally generate overpressure. A detailed geophysical study by Nouze & Baltzer of anomalous reflections also at the lower slope of the Congo fan identified three zones of abnormal pressure lying sub parallel to the sea floor. Overpressure related to hydrate accumulation and dissociation as follows: free gas accumulation at the base of the hydrate occurrence zone, free gas accumulation by hydrate dissociation at the top of the hydrate occurrence zone and a shallow layer of overpressured, undercompacted sediment, also interpreted as the result of hydrate dissociation. From geophysical studies in Lake Baikal, Siberia, Van Rensbergen etal. describe localized hydrate dissociation by injection of hydrothermal fluids at the base of the hydrate layer, triggering gas injection and short-lived mud volcanism.

Sediment mobilization related to gas and fluid injection. The ability of fluids to mobilize shallow sediment is demonstrated by L0seth et al. for vertical fluid migration and injection into the Tertiary Hordaland Group in the northern North Sea. Gas, oil and formation water from the Jurassic reservoirs in the deep Viking Graben gave rise to injection along vertical chimneys into the shallow (