Uranium Ore Deposits

ru FranzJ.Dahlkamp W"t-;-"

ia' / 1'' J...E

tJraniumOre Deposits With 161Figuresand55Tables

Springer-Verlag Berlin HeidelbergNew York London Paris Tokyo Hong Kong Barcelona Budapest

tQi)

Prof. Dr. Franz J. Dahlkamp

A+ n ^ ?

L0 OlbergstraBe D-5307Wachtbers Germany

ISBN 3-540-532&7Springer-Verlag Berlin HeidelbergNew York New York Berlin Heidelberg ISBN 0-387-532&LSpringer-Verlag

Libran of Conpress Cataloging in Publication Data Dahlkamp, Flenr J. Uranium ore deposits/ Franz J. Dahlkamp. lncludes bibliographical references and index. ISBN 3-54G5326f 1 (Berlin HeidelbergNew York: acid-freepaper). - ISBN 0-387-53261-l(Neu York Berlin Heidelberg:acid-freepaper) 1. Uranium ores. I. Title TN490.U7D28 1991 5fi.a'%2- dc20 91-%92CIP This work is subject to coplrig:ht. All rights are reserved.u,hether the whole or part of the material is concerned.speciicallv the rights of transiatjon,reprinting, reuseof illustratrons. recitation.broadcasring,reproductionon microfi.lmor in an1 olher war. and storagein data banks.Duplication of this publicationor pans thereof is permitted onlv under the provisions of the German Copvrig:htLau of September9, 1965.in its currenl version. and permission for use must aluals be obtarnedfrom Springer-Verlag.Violations are liable for prosecution under the German Copyright l-au. @ Springer-VerlagBerlin Heidelberg 1993 Pnnted in Germanl' The use of generaidescriptivenames.registerednames,trademarks.etc. in the publication doesnor implv. even in the absenceof a specificstatement,that suchnamesare exemptfrom the relevant protective laus and regulationsand therefore free for general use. Product Liability: The publishers cannot guarantee the accuracv of any information abour dosageand application connined in this book. In everv individual case the user must cbeck such information bl consultingthe relevant literature. Typesetting:Best-setTypesetter Ltd., Hong Kong Printing: Druiklrems Beltz, Hemsbach Binding: J. Schdffer.Grinstadt 32/3145-54 3 2 1 O - Prinred on acid-free paper

Preface An important prerequisiteto the long-term use of nuclear energy is information on uranium ore deposits from which uranium can be economically expioited. Hence the basic purpose of this book is to present an overview of uranium geology. data characteristic for uranium deposits, and a synthesisof these data in the form of a typological ciassification of uranium deposits supported by more detailed descriptionsof selecteduranium districts and deposits.An additional goal is to provide accessfor the interested reader to the voluminous literature on uranium geology. Therefore a register of bibliography as global as possible,extending beyond the immediate need for this book, is provided. The volume presented here was not originally designed as a product for its own sake. It evolved as a by-product during decadesof active uranium exploration and was compiled thanks to a request by the Springer Publishing Company. Routine research work on identifying characteristicfeatures and recognition criteria of uranium deposits, combined with associatedmodeling of types of deposits for reappiication in exploration, provided the data bank. The publisher originally asked for a book on uranium deposits structured as a combined text- and reference book. The efforts to condense all the text into a single publication were soon doomed. The material grew out of all feasible proportions for a book of acceptable size and price, a wealth of data on uranium geology and related geoscienceshaving become available during the past decade, too vast for one voiume. So the original idea had to be abandoned in favor of a two-volume publication. The contents of both volumes are arranged in such a way that each volume still represents,to an optimum degree, an entity. This first volume deals primarily with geological principles of uranium deposits amended by descriptions of seiected examples of deposits and districts. The companion volume contarns presentations of individual deposits organized by different countries. For the sake of the comprehensivenessof each volume, not all the information could be distributed without some repetition. Nevertheless, the interested reader is recommended to use both books for crossreference or as a guide for his own research and deposit modeling. Finally, it was the author's intention not only ro present data and his own views on uranium geology and metailogenesis. but also theories and models of other geoscientists(Chap. 5) , in order to stimuiate and encourage further research to achieve continuous progress in the understanding of uranium deposits and their metallogenesis.

FranzJ. Dahlkamp

P.S.: After finishingand proof printing of the manuscript.the opening of the former Eastern Block countnes dunng 1990 and 1991 providednew and more preciseinformation of uranium depositsin thesecountries.The availabledatahavebeenaddedasfar asfeasable

VI

Preface

in Chapter 4. Particularly one type of deposit characterizedby structure-bounduraniummineralizationassociated strata-controlled, with black shaleswas an important uranium source in severalEast Block countries.This type wasnot consideredeconomicby Western World standardsand wastherefore not designatedasa specialtype in the original manuscript.It now hasbeenincludedasType 16 StrataControlled,Structure-Bound.

Acknowledgements The author is indebted to the efforts of many geoscientistsand colleagues in the uraniumindustry,nationaland internationalinstitutions, and universitiesfor discussionsand reading and correcting variouspartsof the manuscriptand assisting in numerousother ways. Discussionswith them date back many yearsand have contributed tremendouslyto the understandingof uranium geology, and tbe decipheringof recognition criteria of uranium mineralizationson a local (individual deposit) and regional scale (uranium province). Their ideas, observations,and data have directly or indirectly become a part of this report. The author is most appreciativeto James A. Rasmussenand Elmer Stewartfor their endeavorto read and correctmost parts of the manuscript. He wishesto thank especiallythe followingindividualsfor reviewing and improving descriptionsof individual depositsor districts. (in brackets country, district, deposit reviewed): Adamek P. (Scandinavia),Adams S.S. (general),Arnaiz de GuezalaJ. (Spain), Barthel F. (general),Bernik J. (Yugoslavia),Brynard S.A. (South Africa, Namibia), ChenowethW. (ColoradoPlateau,USA), Coste A. (Limousin,France),CuneyM. (granites, France),DardelJ.R.M. (France),EwersG. (PineCreek Geosyncline.Australia),FritscheR. (mineralogy),FohseH. (general),FuchsH. (Brazii), Grauch R. (westernUSA). Gautier A. (brecciapipe deposits,USA), Haliadal' Ch.R. (easternUSA), HarshmanE.N. (WyomingBasins,USA). Hruby J. (CSFR),Kolb S. (Bavaria.W-Germany),Krol W. (Eastern Europe).MatosDiasJ.H. (Portugal).McCarnD. (general),Ott G. (general).RamdohrP. (mineralog-v, metallogenesis), RobertsonJ.A. (Blind River-ElliotLake, Canada).RuhrmannG. (Saskatchewan. Canada),RuzickaV. (CSFR).Saucier A.E. (GrantsRegion,N.M., USA), Smith R.B. (South Texas, USA), Tan H.B. (Canada), ThammJ. (ColoradoPlateau,USA), TauchidM. (general),VelsB. (general), Voss C. (general), Wallace A.R. (Schwartzwalder, USA), WutzlerB. (Australia). The numerous manuscriptswere repeatedly typed by Ms. Bartelmus,Bonn, Reichl,Leoben,Vollmer and Weyer,Essen.and Boody, Denver. Most drafts were preparedb,vMs. Gldssner.Drafting of cartoons of the types of depositswere performedby MRRD, Leoben, for which H. Kiirzl and J. Wolfbauer deservemy gratitude.

Contents Remarks, Definitions. Units Organizationof the Volume Citing of Authors .

1 ., ,)

Bibliography

2

Geological.Mineralogical,Mining and Related Terms. . . ConversionFactors Abbreviations

J J

I Introduction 1.1

Brief History of Uranium

r.2

Typesof Uranium Depositsand Occurrencesand Their EconomicImportance . . .

8

1.3

GeographicDistributionof Uranium Deposits

10

1.1

Resources. Reserves.Gradesand Productionof Uranium

t2

1.5

World Resources of Uranium

I+

l.o

UraniumProduction

15

2 Geochemistryand Minerochemistrvof Uranium . . . . . .

17

2.1

ChemicaiPropertiesof Uranium

17

2.2

GlobalGeochemical Abundanceof Uranium

I7

2.3

MinerochemicalDistnbutionand Abundanceof Uraniumin Minerals 2 . 3 . r MinerochemistryandCrystallographyof Uranium . . . . 2 . 3 . 2 MinerogenicDisrributionof Uranium ',

18 18 2l

1

GeochemicalDistributionandAbundanceof Uranium in Rocksand Waters 2.1.1 Uraniumin Magmatic/AnatecticEnvironments . . . .. . 2.1.2 Uraniumin Sedimentary Environments. . 2.1.3 Uraniumin MetamorphicEnvironments. . 2.1.1 Uraniumin Metasomatic Environments.. 2.,1.5 Uraniumin Waters 2.1.6 Uraniumin LivingOrganisms andTheir Decay Products 2.1.7 Uraniumin ExoterrestrialRocks

33 34

2.5

34

UraniumProvincesand Districts

23

28 30 JJ

vIII

2.6

Contents

CrustalEvolution and Related Uranium Distribution

36

SelectedReferencesand FurtherReadinefor Chapters2znd3

38

3 Principal Aspectsof the Genesisof Uranium Deposits

41

3.1.

The GlobalMetallogenicCvcleof Formationof Uranium Deposirs

The Time-RelatedOccurrenceof Uranium Deposits. . Time-Stratigraphic Reiationshipof Uranium Deposits Distribution of Uranium Resources Geochronological Relationshipof Geochronologic-Metallotectonic Uranium Deposits 3.2.4 Uranium DepositGenerationsandTheir Time-Stratigraphic Ranking. . . . 3.2 3.2.I 3.2.2 3.2.3

SelectedReferencesand FurtherReadinsfor Chapter3.2... ......

rAt 11

-ll

49 50

50 51 56

4 Typologyof Uranium Deposits.

JI

4.7 Type 1: Unconformify-Contact 4.7.7 Subtype1.1 Proterozoicunconformity-related 4.I.2 Subtype1.2 Phanerozoicunconformitv-related

57 66 68

4.2 Typel: Subconformiry-Epimetamorphic 4.2.1 Subtype2.1 Not albitizedsediments. 4.2.2 Subtype2.2 r'Jbitizedsediments

69 12

4.3 Type3Vein.. 4.3.1, Subtype3.1 Granite-related 4.3.2 Subtype3.2 Not granite-related. . .

74 77 82

4.4 Type4 Sandstone 4 .4.7 Subtype4.1 Tabular/peneconcordant . 4.4.2 Subtype4.2Rollfront.....

84 88 92

4.5

Type 5 CollapseBrecciaPipe .

94

4.6 4.6.7 4.6.2 4.6.3 4.6.4

Type 6 Surficial S u b t y p e 6 .D l u r i c r u s t e d s e d i m e .n. t. s. Subtype6.2Peat-bog.. . . . Subtype6.3 Karst-cavern.. Subtype6.4 Surfcialpedogenic andstructurefill . . . . .

ts

96

100 102 103 103

4.'l

TypeT Quartz-pebble (Lower Conglomerate Proterozoic) 4.7.7 Subtype7.1 U-dominatedwith REE 4.'7.2 Subtvpe'7.2 Au overU-dominant.. 4.8

Type 8 BrecciaComplex

704 lUO

107 108

Contents

IX

1 . 9 Type 9 Intrusive 1 . 9 . 1 Subtype 9.1 Alaskite (Cu-porphyry) +.4.Subtype .. ... 9.2 Quartzmonzonite 1 . 9 . 3 Subtype9.3 Carbonatite + .v . + Subtype9.-t Peralkaline syenite 4 . 9 . 5 S u b t y p e 9 .P5e g m a t i t e . . . .

110 112 t12 113 II4 114

4 . 1 0 Type 10 Phosphorite 4 . 1 0 . 1Subtype10.1 Phosphoria. . 4 . 1 0 . 2Subtype10.2 Landpebbte

1l)

II7 1i8

4 . 1 1 T y p e1 1 V o l c a n i c 4.11.1Subtype11.1 Structure-bound 4 . 1 1 . 2S u b t v o e 1 1 S . 2t r a t a - b o u n d . . . . . .

118 I20 121

,t 11 +.IL

r22 125 176

Type i2 Metasomatite Metasomatizedgranite 1.12.2Subtvoe 12.2 Metasomatizedmetasediments. . .

1 . r 2 .Subtype r 12.1

4.13 Type 13 Synmetamorphic ... 1.71 Type14 Lignite 4.74.I Subtype14.1 Joint-fracture-related .... 4.11.2 Subtype14.2 Stratiforn. . .

129 130

4.15 Type 15 BlackShale 4.15.1Subtype15.1 Bituminous-sapropelic blackshale 4.I5.2 Subtype15.2 HumiciKolmin alumshale

131 t32

4.16 Type 16 Strata-Controlled, Structure-Bound. . . . .

141 IJI

r32 IJJ

SelectedReferencesand Further Readine for

Chapter4

Examplesof EconomicallySignificantTypes Selected of UraniumDeposits 5.1

Uranium Examples of Unconformity-Contact-Type BasinRegion. Deposits(Type 1. Chap.4): Athabasca Canada

1a/

IJ+

r37

r-1 /

5.2

Examplesof Subunconformitv-Epimetamorphic-Type 168 Uranium Deposits(Tvpe2, Chap.4) UraniumDeposits 5.2.1 Subunconformity-Epimetamorphic Alligator River in Not-Aibitzed Metasediments: 168 UraniumField. Austraiia . . . UraniumDeposits 5.2.2 Subunconformity-Epimetamorphic in Albitized Metasediments: Uranium Citv Reeion. 101 ..:........... Canada Examplesof Vein-TypeUraniumDeposits(Type3. Chap.4) 5.3.1 IntragraniticVein UraniumDeposits:Limousinlla CrouzilleDistrict. France 5.3.2 PerigraniticMonometallicVein Uranium Deposits: PifbramDistrict. CSFR . 5.3

201 201

2r8

X

Contents

5.3.3 PerigraniticPolymetallicVein Uranium Deposits: District, CSf'R St. Joachimsthal/Jachymov Deposits in Contactmetamorphic Uranium 5.3.4 Perigranitic Rocks:IberianMeseta,Portugal-Spain. . . Not Granite-RelatedVein 5.3.5 Metasediment-Hosted, Mine, Front Uranium Deposits:Schwartzwalder Range.USA. Not Granite-RelatedVein Uranium 5.3.6 Sediment-Hosted, Deposits:Shinkolobrve.KatangaCopperProvince, Zaire . Examplesof Sandstone-Type Uranium Deposits (Type4.Chap.4) Depositsin 5.4.1 ExtrinsicCarbonAlumate-Uranium PhanerozoicSandstones: GrantsUranium Reeion.

?24 232

237

246

5.4

usA . 5.4.2 5.4.3

5.4.4

5.4.5

5.4.6 5.5

5.6

......... .

Vanadium-UraniumDepositsin Phanerozoic Sandstones: ColoradoPlateau.USA . ChanneliBasalUranium Depositsin Phanerozoic Sandstones: Monument Valley-WhiteCanyon Districts.USA . Roll-TypeDetrital Carbon-UraniumDepositsin Wyoming PhanerozoicContinentalBasinSandstones: Basins,USA. Roll-T1peExtrinsicSulfide-UraniumDepositsin PhanerozoicCoastPlain Sandstones: SouthTexas CoastalPlain,USA UraniumDepositsin ProterozoicSandstones: FrancevilleBasin. Gabon

250

250 ?70

284

290

305 319

Examplesof CollapseBrecciaPipe-TypeUranium Deposits(Type 5, Chap. 4): Arizona Strip Area, USA

3Z+

Examplesof Surficial-TypeUranium Deposits (Type6, Chap.4): SurficialUranium Depositsin DuricmstedSediments: YilgarnBlock,Australia.....

334

5.7

ExamplesofQuaru-PebbleConglomerate-Type UraniumDeposits(Tvpe7. Chap.a) 5.7.1 Uranium-RareEarth ElementsDepositsin QuartzPebbleConglomerate: Blind River-ElliotLake. Canada 5.7.2 Gold-UraniumDepositsin Quartz-Pebble Wit*'atersrandBasin.SouthAfrica . . Conglomerates:

353

Examplesof Intrusive-TypeUranium Deposits (Type9, Chap.5): AlaskiteUraniumDeposits; Rrissing,Damara OrogenicBelt, Namibia . . . .

366

5.8

Appendix (Table of U-Minerals)

343 343

373

Contents

XI

Bibliography.....

JIY

Locality Index

143

SubjectIndex

 

Remarks,Definitions,Units economic mineralizations ranging in size from small mineralogicalshowingsto almost economic occurrences. For this reason, the classification The emphasisof this volumeis on the charac- chapter was not restricted to types of economic terizationof uraniumdeposits. deposits but was amended to include types with Chapter 1 includes an introductory note in n o t t o m a r g i n a le c o n o m i cp o t e n t i a l . the form of a brief summarvof world uranium The views offered by the author in this and resourcesand their definitionswith respectto other chapters are his own interpretations. confidenceclassesand cost categories. This was though strongly influenced by discussions with consideredjustifiedinsofaras an understanding many coileagues.of data collected in the field of an ore depositcannotbe achievedfrom purelv and from pertinent literature study, and must geologicalparameters.Economicconsiderationsnot necessarily represent the final and correct haveto be included.Demandfor the commodity version. The reader is therefore strongly encourand, in the western worid. related price/cost aged to study the literature cited as references to factors dictate and define whether a localized form his own opinion, which may be contrary to metalconcentration is a depositthat canbe profit- the one presentedhere. ably exploited presentlyor in the future, or Chapter 5 contains abbreviated descriptions of whether it is a mineraloccurrenceof only scien- seiected major uranium districts or deposits contific value. sidered to be representative examples for types Uranium geochemistry hasbeendealtwith in a of uranium deposits of established or potential more general or subordinateway in Chapter2, future economic interest. This chapter was inintendedto provideonly the sufficientbasicinfor- cluded for various reasons. (1) to support and mation needed within the scopeof the work. complement the generalized descriptions in R.W. Boyle (1982) has publisheda compre- Chapter a, (2) to provide the reader with more hensive review on uranium (and thorium) geo- detailed data on important deposits and (3) to chemistry and the reader is referred to this present data and views of geoscientists workpublication for detailedinformationon the sub- ing on these deposits which are not necessarily ject. Concerning uranium metallogenesis,its congruent with those interpretations and hypoprinciples are at presentsufficientlywell under- theses presented in Chapter 4. stood only for some types of deposits,whereas Not all deposits are well researched. Some other types are understoodto a lesserextentand data are vague, if not biased or wrong. Othen in varving degrees.For this reasonand to avoid are presented ambiguously, being easily mistoo much speculationor geofantasy, the principal interpreted. Descriptions of the same deposit aspectsof the genesisof uranium depositshave or specific features thereof by different authors been addressedonly briefly in a separatechapter are not necessarilvunanimous. Interpretation of (Chaprer3) and summarizedin the presentation certain criteria may likewise be conflicting (see of tvpes of deposits(Chapter4). Nevertheless. also introduction to Chap. 3). The attempt was Chapter5 includesmore detailedviewsbasedon made to reconcile the conflicting data and deviatpublishedinformation of the depositsor distncts ing hypothesesas far as possible; but it has to be selected as representativeexamples for the admitted that this demanding task was not always important and economictypesof deposits. satisfactorily achieved. In any event, the vanous Chapter 4 forms the main part of the book views are presented and the reader is recomand describesthe principal recognitioncritena, mended to study the original literature and to dimensions,and metallogenetic aspectsof identi- come up with his own interpretation. For confied types of deposits. venience, a tabulation of uranium minerab is In order to comprehendeconomicdepositsand added in the Appendix. their parameters,it is equallyimportantto recogGraphic presentations and tables had to be nize and understand criteria typical for sub- limited to the extent considered necessary to

Organization of the Volume

Remarks. Definitions, Units

illustrate adequately the principles of geological setting and configurationof deposits.However, quantity and quality of illustrations are variable depending on the availabilit-v and reliabiiity of data in the sourcematerial.

lished since the final revision of the manuscript have been added in the bibliographv but, for technicalreasons,could be incorporatedinto the standingmanuscriptonly in exceptionalcases. The attempt was made to provide a bibliography as completeas possible,but some papers will still be missing.This deficiency does not reflect my disregard of the respective contriCiting of Authors bution, but should rather be excusedas an lmperfectionon my side.Proceedingsof workshops, All the main chaptersinclude a referencelist of symposia,etc. were in many instancesnot pubauthors whose data have been used directly or lished until several years later. Meanwhile, indirectly or who have contributed work to the some authors had publishedthe workshop data deposit or subject describedi-n that particular elsewhereor the data had been disseminated otherwiseand hencethe material may have had chapter.This schemewas selected inffuencedand may havefound accessto publicaa) to serveas referenceindex on literature per- tions of other workersprior to the printing of the taining to the respectivedeposit or subject. original presentation.Consequently,publication The list is restricted to respective principal yearsof referencedata do not necessarilyreflect uranium papers and to contributionsto the the first presentationof results. general geology with relevant or possible implicationson the uranium geology.Special pubiications not directly related to uranium geology,e.9., age datingsof rocks, are cited Geological, Mineralogrcal, Mining, and in the text (titles of the papers can be found listed according to the author's name in the Related Terms Bibiiography); b) to credit authors who have worked on the Connotation and spelling of geological and subject; mineral terms are in principle understood as and c) to reduce the immense repetition of authors' basedon thosegivenby: Thrush and the Staff of namesto a bearableminimum within the text. the Bureauof Mines(eds.),1968,in A Dictionary In this kind of synopticalreview, often using of Mining, Mineral, and RelatedTerms US Dept. numerouspaperson one singie depositor sub- of the Interior Washington,DC. ject, a completecitationof all authorswould in many instanceshave required a list of names Exceptionsor additionsto this are: after a coupleof sentencesor a short section. Alternatively, numbers referring to authors Uraninitelpitchblende: In this book "uraninite" and their papers could have been used. My is used for the macrocrystalline,more or less preferenceis, however, to see the name of euhedralvariety of UO2** which typicallv occurs an author and not a colorlessnumber which in rocks of higher P-T metamorphic grades requiresadditionalsearchin the bibliography (amphibolite grade and higher. conractmetafor the numbered individual. Although the morphic), igneous rocks such as granite and selectedsystemmay not satisf,vall authorswho pegmatite but also in vein and veinlike-type wish to seetheir namespreciselyrepeated,for deposits."Pitchblende"is usedfor UO2*r varithe sakeof easierreadingthey may forgiveme. eties of micro- or crypto-crystalline,colloform (collomorphous, botryoidal, spherulitic) habit which typically occur in low grade metamorphic and nonmetamorphicrocks such as greenschist Bibliography faciesmetasediments and sandstone, and in most vein and veinlike-type uranium deposits. It is This sectionis organizedin alphabeticalorder of understoodthat both varietiescrystallizein the authors providing complete coverageof papers samecrystallographic system,the cubic system, cited in the text and referencelists. Paperspub- but they have certain discriminating physico-

Abbreviations Table 1. Proposed terms for the alternativeidiomatic equivalentsof uranium oxides Habit

Terminology

Idiomorphic ( macrocrystalline) Collomorphous,botryoidal (micro-, cryptocrystalline) Sooty, earthy ( amorphous)

Uraninite Pitchblende Sootypitchblende

o( or

Euhedral(subhedral)uranrnire Colloform uraninite Soow uraninite

chemicalproperties(for detailsseeFritscheet al. although manv other metalsmay be presentbut in in press;Ramdohr1980,and Sect.2.3.1). t r a c e o r s u b e c o n o m i cq u a n t i t i e s . The term pitchblendehas been maintained Granitelgranitoid, pegmatitelpegmatoid, etc.: for traditionai reasons.It was the first name the terms are used synonymouslyand not in their used for black uranium oxide mineralsback strict genetic sense. Various authors appiy both in 1565(seeChap. 1.1)and is widelyused,par- words differently and it is not always clear under ticularly in Europe. Uraninite is a term com- which connotation. monly used for all kinds of uranium oxides in Regolith: refers to saprolite/paieosol. It is not American literature. Worldwide, both terms used in the senseoften applied in Canada, where are applied by a number of authors variablv also weathered rocks are called regolith. In this and in an overlappingway. The criteriaused by case. the term regolithic rock is here preferred. various geoscientiststo differentiate between Reserveslresources,grades:calculated in metric uraniniteand pitchblendeare sometimesconflict- tons (mt or tonnes) U3Os and percent (%) U3O8 ing and can lead to confusion. (respectively in ppm U for low grade mineralizaIn order to avoidfurther misunderstanding, it is tions) except for data published by NEA/IAEA that for the variousoxidephaseseither (presented in Chap. 1) which are in tonnes U met. suggested the classicalnames are applied or alternatively Costs, expendirures: in US $ unless otherwise the term uraninite is amendedby a descriptive stated. prefix to describehabit and/or physico-chemical Terminology, definitiow and classificatioru of properties of the uranium oxide in question resourcesand oroduction: seeSect. 1.4.-1.6. (seeTable 1). Secondaryuranium minerab: this term. commonly referring to coloredU minerals,wasabandoned in favor of "hexavalentU minerals"to Conversion Factors avoid coniusion. "Secondary minerals" are in several deposits.e.g., in surficialdeposits, = 1.1023 1mt sh.t. = 2200lbs of primary origin. Both terms, primary and = 1.18mtU3Og lmtU secondary.have been restrictedin this book to = 1 . 3 0 s h . t . U : O e =2 6 0 0 l b s U 3 O g lmtU their strict genetic sensedenotingprimary or lmtU3Os = 0.848mtU secondaryorigin of a given mineral. 1 m t U 3 O 3 = 1 . l s h . t . U : O s= 2 2 0 0 l b s U 3 O g Mineralization.alteration.etc.'.thesetenns are 1 sh.t.U3Os = 0.769mt U usedin both connotations. to denotethe process 1 sh.t.U3Os = 2000lbsU3Os implied and the productof the process. Slnb U3OB = $2.6/kgU Ore: synonymouswith minablemineraiization. = $0.3824llbUrOs S1/kgU Polvmeral lic minerali zationIp olymetallic miner alogy (corcespondingto complexmineralization/ mineralogy of some authors): mineralization containingat leasttwo differentmetalsincluding Abbreviations U in economicor potentiallyeconomicamounts. Monomemllic

min erali zatio n I mine r alo gy

(simple mineraiization/mineralogy): mineraliza- a . o . tion containine U only as recoverableelement, b . v .

amongothersor and others billion years: 1000m.y.

4

EAR lb. mt m.y. RAR

Remarks, Definitions, Units

estimatedadditionalresources pound (7000grains: 16 ounces : 451 grams) metric ton(s) million years reasonablyassuredresources

redox REE sh.t. U met WOCA

reduction-oxidation(boundary) rare earth elements short ton metallicuranium or natural uranium World OutsideCentrally Planned EconomiesAreas

1 Introduction

1.1 Brief Historyof Uranium compilationof the historical A comprehensive knowledgeabouturaniumincludingan extensive listing of uranium occurrences. known pnor to about 1900has been publishedby Kirchhermer (1963) in his book Dle Geschichtedes Urans (Historyof Uranium).

chemistTo(r)bern Olof Bergman(1735-1784), wascoinedin 1786by AbrahamGottlob Werner (I749-1817), i.e., prior to the discoveryof uranium. Another strikingly colored uranium mineral, "autunite", although known from variouslocationsin the early 18th century,was named in 1852 after a discoverylocalitv near Autun in the northeasternMassifCentral.where it was discoveredin 1800 by Joseph-Franqois de Champeauxde Saucy(I775-18.15.t. Eariiest coloredpicturesof uraniummineralsdatebackto 1797.showingyellow and green crystalsfrom Cornwall.

Discovery and first publications: Uranium was discoveredin 1789by Martin Heinnch Klaproth (1743-1817), pharmacist and professor for chemistry in Berlin. Klaproth detected the element when analyzingpitchblendefrom the Early uraniummining:During the first decadesof George Wagsfort mine at Johanngeorgenstadt.the 19thcentury,uraniumore was recoveredas Erzgebirge (Saxonian Ore Moun- by-productin Saxony,Bohemia,and Cornwall. S2ichsisches tains). Uranit was the first name proposed. In about 1850, mining for uranium as a main that was changedin 1790to uranium,the name productstartedin Joachimsthal now in the CSFR. derived from the planet Uranus discoveredin First recoveryof uranium ore in North America 1781by FriedrichWilhelmHerschel(1738-1822). was reportedin 1871from the Central City area, A.lthoughKlaproth discovereduraniumhe did Colorado. In Cornwall, the South Terras mine not manage to produce the new element in its openedfor uranium production in 1873.During metailicstate.Heatingof the "gelbenUrankalks" the past century, additional discontinuousor (yeilow uranium lime) with reducingsubstances occasionalminingof uraniumore hastaken place resultedonly in blackoxide.Other uraniumcom- in Autunois/lvlassif Central.in Oberpfalz(Upper poundsproducedalreadyin 1789inciudenitrate, Palatinate)/Bavaria. and at Biilingen/Sweden. suifate,phosphate,acetateand potassium-and In Saxony,approximately110t of uranium sodium-diuranate.Klaproth established the were recoveredduring 1825-1898.mainly from important propertiesof uranium for commer- the Erzgebirge. Total sales price was about ciai application,e.g., the coioring effect on a 525000Marks or the equivalentof "t.70 Marks/ glassmelt. kg U met. In Bohemiaberween1850and 1898, Uranium mineralshad beennoticedby miners Joachimsthalproduced in excessof 620t U of tor a long time prior to their chemicalidentifica- mainly high grade ore (Joachimsthalyielded a tion. and had given rise to a variety of specu- total of about100001Ubeforeit finallyclosedin lations on their composition.Pitchblendeof 1968). the SaxonianOre Mountains(Erzgebirge)was Cornwall.England,producedat least300tU mentionedin 1565as "Bechblende",a dialect in the 19th century,most of it comins trom the version of the German "Pechblende".Other SouthTerrasmine nearSt. Stephen(ca.275t). accountsof pitchblendedate back to the years In Colorado,USA, minesof the CentralCity 1727 (Joachimsthal, Erzgebirge) and 1763 district yielded approximately 50t high grade (Wittichen,Schwarzwald/Black Forest)where it uraniumore until 1895.The Wood mine wasthe was referred to as "schwarzebleyschwereErzt- most productive one. Mining of carnotite ore Arth" (black. lead-heavyore type). Green and startedin 1898in the ParadoxValley, Montrose yellow micasand ochers,the relation of which to Counry (now Uravan Mineral Belt), yielding uraniumwasfirst suspected in I778, couldlater be annua.lly about10tU metal. establishedas uranium minerals by Klaproth. Striking discoveriesof uranium deposits in The name "torbernite". namedafter the Swedish this centurvprior to World War II were in 1913

1 Introduction o I

'i \ i F

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ai

t

;

o

I ?1

o o

I It lf o -

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if'E#

la

FI o

llr

=o

, @:lxo

-u

x^o-@S ooi9:O v q * ; !

F^-.^

s

8st=

Ec o - - ue !

- .E 9.e . -^ C

.=

-.

O

:

T E

o

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-

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LO )

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n

b

:;od Y ^; oN

ell o

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=

)

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;

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EfSF ;cg6

i90000 mt U (10000mtU Russia:>120000mt U (70 000mt U (175 000mt U (160000mtU Uranium occursalso in copperdeposits,and is CsrR:>5oooomtU beingrecoveredas a by-productof copperleachEast Germany:ca. 90000mtU ing in India,whichhassignificant resources of this Hungan': >20000mrU type, totalling 23000 tonnesU, and the USA, Terminologrof Resourcesof Individual Deposits (asusedin Chap. 5)

UraniumProduction

15

2000tonnesU in Belgian Congo, now Zaire. Eleven percent was of approximately with resources of this produced in the CSFR and the remaining 8% copperores. Also Chilereportsresources 5000t U. in the USA, Portugal, and other countries. type, totallingapproximately Four production centers yielded the bulk of the ore. Port Radium on Great Bear Lake, NWT, Canada, Shinkolobwein Katanga, Congo. St. Erzgebiree, CSFR, and Joachimsthal/Jachymov, 1.6 Uranium Production the Colorado Plateau. Colorado-Utah. USA. Additional producers include the uraniumNoteworthy uranium production started at the mica mines of Portugai, which provided 35g beginnin-eof the 20th century,up to World War II r a d i u m b e t w e e n1 9 1 1a n d 1 9 3 9 .a n d t h e u r a n i u m chiefly in responseto the demand for radium. The vanadium depositsof Tvuva-Muvun in Ferghana. fiqures for radium production thus reflect the Uzbekistan. which delivered 2.1g radium from rragnitude of uranium exploitation during this approximately 1000mt uranium ore. After World : e r i o d . b a s e d o n a r e c o v e r yr a t i o o f l g R a p e r W a r I i a n d p r i o r t o 1 9 9 2 ,a l m o s t 1 0 0 0 0 0 0 m t U were produced in WOCA countries, and an 3mtU. For 1937. mining statisticsquote a world pro- estimated 350000 to 400000mtU in the former duction of 10gRa. equivalent to slightlv more Eastern Block countries. with the largest conthan 120mt U. Canada provided approximately triburions from the CIS. CSfn. and East 66% of the amount. Some 15% came from the Germanv.

 

2 Geochemistryand Minerochemistryof Uranium

In 1982 Boyie gave a comprehensivereview of rhe geochemistryof uranium. Garrels and Christ ( 1 9 6 5 ) , L a n g m u i r ( 1 9 7 8 )a n d R o m b e r g e r ( 1 9 8 4 ) among others provide data and diagrams of uranium solution - mineral equilibria. The other authors referenced (see end of chapter) discuss uranium behavior during processesactive in the various geoloeical environments. The reader is referred to this literature for detailed information ,nd additionai literature. More detailed informaiion on uranium activity related to ore-forming events in individual deposits or districts is provided in Chapter 5.

2.1 Chemical Properties of Uranium

p o r t a n t . T r i v a l e n t ( U 3 * ) a n d p e n t a v a l e n t( U 5 - ) u r a n i u m c o n s t i t u t e i n t e r i m s t a q e s .b e i n g p r a c tically stable only under laboratory conditions. H e x a v a l e n tu r a n i u m ( U 6 - ) h a s a n i o n i c r a d i u s o f 0 . 8 0 A . w h e r e a st h a t o f t e t r a v a l e n tu r a n i u m ( U o * ) i s e i t h e r 0 . 9 7 A o r 1 . 0 1 A . d e p e n d i n go n the coordination number 6 or 8 respectively. Uranium is a distinctlv tithophile element with a high affinity to oxygen. In nature. uranium occurs neither as native metal nor as sulfide. arsenide or telluride. In most subsurface environments uranium occursas U"*. while the hexavalentstate (U6-; is stable merelv under oxidizing conditions prevailing at and near the surface.

Abundanceof 2.2 GlobalGeochemical Uranium

Physico-chemical data of uranium are atomic number 92, atomic weight 238, density 18.9g/cm3, melting point 1405"C,oxidation stages6, 5, 4, and The average crustal abundance of uranium is 3 (Table 2.1). 2.7 ppm (Taylor 1961) but different lithologies In Mendeleev's Periodic Table, uranium is have a wide range of U tenor, as rvill be discussed placed in group VI below chromium, molybdenum, and tungsten. Uranium belongs to the actinides characterized by close chemical relationships and peculiar contraction behavior of ionic radius simriar to the lanthanides. Of the four oxidation states,stages-l (Ua*) and 6 (Uu-) are geochemicallyand mineralogicailyrmTablel.l. Phvsico-chemi.u,-Ou,u of uranium .\tomlc ;rumber

Atomic weiqht

Valencies (oxidarion staees)

U

(u'*) u'r*

(u'*) u"*

Natural lsoropes

Percent fraction

Haif-life time

tJ?34 U 235 u 23,q

0.0058% r.6 x 105 t) i29'o 7.3x iOd ()qrr"i, .{.5x 1oe

lonrt radii

Coordination numDer

1 . 1 3A 1.12A 1 . 1A 6 0 . 9 7A 1.014

+

0.80A

6

6 b

8

0

j0

20

-<J l0 "0 Crdea ot oounoonce

c0

70

3c

Fig.2.l. Relativeabundanceofuranium in the continental crust comparedto other selectedelements.(After Dodd In: Robertson et al. 1978)

18

2 Geochemisn-v and Minerochemisrry of Uranium

later- Although uranium is widely distributedin crustal rocks and minor accumulationsare common. uranium is not an abundant element, as illustrated in Fig. 2.1, that displaysthe relative abundanceof selectedelementsin the continental crust. Uranium is slightly more common than metalssuch as As, Mo, W, and Sn, but is much less abundant than Pb, Zn, Cu, or Ni, and it is about one-fourth as abundant as thorium. Table 2.2 shows a supplementarvcomparison of the order of enrichment factors of some metalsrequired for formation of economicgrade concentrations.

c) uranium phaseshydrolyzein the presenceof solutions; d) uranium forms complexes or ion paws with a great variety of anions in aqueous environments; e) uranium has to be reducedor complexedto precipitateasmineralsfrom aqueoussolutions. but alsohasa tendencyto be adsorbedon cla1,, organic. and other particles or on certain hydroxides(Fe, Zr, Ti etc. hydroxides); f) uraniumforms a greatvariety of mineralsof its own, the bulk of them basedon hexavalent uranium,and onlv a few on tetravalenturanium (dominantlyuraninite,pitchblende).

Table 2.2, Comparison of cnrstal abundance, order of payabiliry grades, and respective enrichment facton of

ielectedmerals Metal

Crustal abundance(ppm)

Payabilitl grade(%)

Enrichment factor

2.3.1 Minerochemistry and Crystallography of Uranium

In natural mineralsuraniumis presentonly in its hexavalent and tetravalent state of oxidation. 10 Tetravalenturanium is by far the most important 2m l't50 80 r25 ion although only stableunder reducing condit70 143 ions. With increasingoxidation potential U4* 16 3r25 transforms into the hexavalentstate. 1q U 2.7 uranium has in natural minerals Tetravalent Sn 2.0 1000 Au 0.004 1250 predominantlythe coordinationnumber8, i.e., it Pt 0.002 2s00 forms a centralcationsurroundedin equidistance by eight anions, normally oxygen ions. In this case,the ionic radiusof Ua* is 1.01A. In addition, Uo* occurswith the coordinationnumber 6, then havingan ionic radiusof 0.97A. 2.3 Minerochemical Distribution and In magmatic and metamorphicenvironments Abundance of Uranium in Minerals including hypogene hydrothermal conditions the tetravalent uranium prevails. Principal ore minerals formed are uraninite and pitchblende Boyie (1982),Dybek (1962),Langmuir (1978), also referred to as nasturan and uranpecherz Romberger(1984),Smith (1984),amongothers, (Ramdohr 1980t Sobolewa and Pudov Kina have discussedin much detaii the geochemical 1957).Both mineralscrystallizein the isometric processesinvolved in uranium mineral formasvstemand are of the formulaUO2*". Pure Uation. In essence,their findingsmay be briefly 02 phasesdo not existin naturedue to selfoxidasummarized as follows. tion by radioactivedecay.Uraninite commonly In nature. uranium interactsand associates containsTh. REE. Pb and but not necessarily with a number of eiementsand compoundsin other elements,and hasgenerallya higher lattice complexwavsdue to the followingpropertiesand constant(ao > ca. 5.46A), and lower oxidation tendencies: state than pitchblende(a6 5.36 to ca. 5.465A)a) variableoxidation states,mainly lJa* and U6* Pitchblende may containCa, Si, Ti, Pb. andother as mentionedearlier; impuritiesbut rarelyTh and REE (Figs.2.2,2.3) b) variablecell units; all cell units are of large The compositionof both phases,however,relies size,hencepermit substitutionfor elementsof strongly on the formational environment and similar ionic radii predominantlyin rock con- conditions(for detailsseeauthorslistedin Figs. stitutingaccessorv minerals; 2.2 and2.3\. AI Fe Cr Ni Cu Pb

81,300 50.000

35 50 35 i I 5 0.2 0.2 0.0005 0.0005

4-J

MinerochemicalDistribution and Abundanceof Uranium in llinerals

l9

d e g r e eo f o xr d o t i o n )a z.g

mefornofphi c )a z.s

----J-z

z

metosedimenis )\

r'mefqsomotic

Pegmotitic

r,/

hydcoihermot tr.

vein\

\

t. \

i^

:Protunc0nr. \

oo9

rolnlori

\_!or t

metomorphic

\^

Pegmotitic

Fig. 2.2. Correiation diagram of oxidation degree-latticeconstant for uranium oxrde phases and their tentative attribution to genetic fields. (total of 120 samples).(Fritsche et al. in press,basedon data from Brooker and Nuffield 1953(dos and extrapolatedsolid line), Xu et al. 1981,Cathelineau et al. 1981,Fritsche et al. 1988)

In addition, the uranous ion substitutesfor a The uranyi complex displays a linear dumbbell variety of cationsof similarsizeand chargein the shaped structure, 3.4A long and 1.-lA rvide, in iattice of accessoryminerais in igneousrocks. which the hexavalent uranium is flanked by two SuitabieelementsincludeTh. Ce.Zr.Ti. Nb. Ta. oxygen ions. The uranyl complex is fairly stable Mo. W. Ca. and REE. The desreeof substitution and pret'erentiaily forms minerais with layered is a function of the sizeand chargeof the replaced stmctures of the basic formulas ion. Therefore the uranium tenor in the various -'xH2O o r B ( U O ; ; 1R O + ) : - . x H u O , host minerais varies in a large range from less A ( U O T X R O a ) than 1% U in rock consrituringaccessory min- w h e r e R i s P 5 ' , V 5 = o r A s 5 * , A i s K o r N a , a n d erals,up to about l0%U in manycomplex(Ta, B i s B a . C a , C u , F e r * . M g , P b . \b. Ti) oxides. to more than 20% in thorium Additionally, the uranyl ion tbrms hydrous oxide and thorium silicate(urano-thorianireand minerals with MoO1, SO.1,CO3, SiO3. SeO3,and urano-thoriterespectively). TeO3 as anions and a variety of cations. Hexavalent uranium occurs as mineral conThe cations are not strongly bonded and can be stituent in two configurations,as an individual substituted easily. The H2O component indicates ion having the coordination number 6 and an the necessity of a hydrous environment for minionic radiusof 0.80A, and as a complexion, the eral formation and mineral instability when the uranyl complex. The latter is the more frequent water becomes expeiled, for example at eleand forms many mineral speciesin oxidizing vated temperatures. In contrast to the uranous environments. ion (U4*), a diadochicincorporation of the uranyl The uranvl complex (UOr)t* develops in complex into other crystal structures is impossible aqueoussolution accordingto the formula for two reasons: Ua* + 2H2o = (Uu* O.)t* + 4H+ * 2e

20

2 Geochemistrv and Minerochemistryof Uranium

TiO2 r uroninile o uroninile? r pitchbtende o titcttblende? r U-Si-Ti-O-phose

tii' 3o ^ '" "ri: r" " o ^ ,l' i :, l' )',';;: trl'i-il

SiO2

:s:* /-E*=*:i'

CaO

r uroninite o uroninitc? r piichblende o gitcfiblende?

a a

o

tl aa a I

I. a

Th02

a) the dumbbell-shaped morphology is incompatible *'ith the structure of other minerals constituting complex ions; b) the uranvl complex, as stated above.is instable at elevated temperatures as found in igneous a n d m e t a m o r p h i ce n v i r o n m e n t s .

UOo-

Fig.2.3. aTiO2-SiO2-CaO trianglefor uraniumoxide phasesshowing the content variationsof these compounds.Segment,l correspondsto uraninite and pitcbblendein sensustricto which typically occur in igneous,metamorphic and sedimentaryenvironments. Segment2 correspondsto Uoxide phaseswith relative high Si-content.segmentJ to Si-richU-oxide phasesand coffinite, and segment4 to Ti-rich U-oxide phasesand brannerite.Mineral phases of segments2 to 4 are often associatedwith redistributed and metasomatic mineraiizations.(Fritscheet al. in press.including data from Aikiis and Sarikkoia 19871Cathelineauet al. 1982;Feather1981;Feather and Giatthaar 1987;Fritsche et al. 1988;Hilenius et al. 1986;Li Tiangang and Huang Zhizhang 1986; Monon and Sassano1972; Pageland Ruh.lmann1985: von Pechmannand Hiirtel 1988;Ruhlmann 1985).b CaO-ThO2-UO2 triangle for U-oxide phasesof seggnent1 (a) showingthe content of thesecompoundsin pitchblendes(field 1) and uraninites(field 2). Uraninite has commonly lower Ca contents (?i-"?e=yi= ::.i^E'=t--i: =Z_fl =:: a 7-'-7' c:t=-cr

Et r,

u=i i; 7==i - - ir :1: iv vt;c iEiE? +;i !

a=?, t =

:

:: i E: E=1E'=7EEEr EE?EE,IZii=?.=, ?=EE '2='i 'Z '= .z.Z

.--t :

=-= l= =-..

i=;-ii.raE5e=

c-"-= ! ze

ceai.+El

2== a == =F :: :

:ts

dL

:-: e7 L r-,

O.

i

=

i?

a

q

.:

2.=

s

i

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=a

=

=

i

a

=

=

=

.=-:

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ze

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;

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ct=

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'a. =.'=

?

-

t===.

+!

z

p-

?=

?

-i!3-3=

i:-=- ?

,N > 'a

The Time-RelatedOccurrenceof Uranium Deposits

a1

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-_4t .!

E I

-2

:

a 2

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:

7V

tr -=

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(,

ii:=

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ti 'xr- v" i;t .r !o ' e =i>9==a

;g o E .9--:.

=;'- X:3i; =; :E::E

o

a a

E!!E;i ::;EE

-: -^ 'Li j - - =a ,

2E;=E;= ;9 . : : - ': - 2 = 4.=

L

U.

-IO

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=/,1.=

E t , i= ?= ,r=

=Z=

r'L


: ;

L= L

i\'

U

ET :>: :.:'' = ttt

._; 9>

'v, Y =7.

.€EE * q =

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vt)

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t)

: F.se; :=

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:=

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c:€

6*ru ZNN

DLi. c&=

2i.ot

T-vpeI : Unconformit;--Contact

!

-ar:5 -r.=>-:

>

+ - 1- -=. - : 5 4

= -/

? i= .- I i= Z= 2 i!

== =1 =: :;

iv

.=:. 2n

=

:=

^ = E,i . - 1

_

t

.=)o -:

2:

I;

--.

=

-

= J

-a ] ( ier= i ai I ai i .,-,a -,;

-

-

i 1.2 -$E := it zi

2t

=

' .- -=: \

-i:

I

=:

j-= ii! t:;ij;i



?

?

=. /

t

=. h

!

4 \

.= !.:5o -:---

r >

3i: 31:

==7E

-?= J \

>

n

-= J

C-

rO

i iz

=,2 .2 =a

-= ., "=. -=2 ,f =

+> :n

6i

=

'r l=

2

I

. =

i =

z ;

;) t=

=: ?: ==

=?o

-^J^

= a

ii

=a ==

c =t

=:

9=i

' =- =a ?j: '=: ; i

z

n=2 ;'i= 1% U3O8).Ni is commonlythe mostnotabiyenrichedassociated metal.

Two typesof alterationare distinguished:

Age Constrains Correspondto thoseof class1.1.1. Dimensions/Resources Individualdepositsare a few 10m to ca. 1500m long. a few meters to ca. 100m wide and a few meters to 25m thick. containinga few 100 to >i25000mtU3Os at grades ranging from ca. 1 to I41LU3Os. Districts may contain up to 200000mtU3Os and more. Examplesof Middle Proterozoic Unconformirycontact,Class1.1.2 Clay-BoundDepositsl Occurrences

H ost Rocl<sI Structures

- pre-mineralization: albitization, Fe-chlontization, sideritization; - syn-to post-mineralization: silicification,argillitization (smectite, illite, minor kaolinite), carbonatization,pyritization,hematitzation. Ore and AssociatedMinerab Coffinite, minor pitchblende and tetragonal c-U3O7,and alterationproductsthereof (uranyl vanadates). Gangue or similar minerals: Illite, smectite. dolomite,calcite,siderite. Metaliic minerals; Pyrite, minor marcasite. galena,sphalerite.hematitereplacingpyrite. Mode of Mineralization U minerals occur as disseminationsand fine veinletsforming smallore bodies.The ore bodies straddlealong the post-Hercynianunconformin' most commonlywhere the unconformityis transectedby faults. Mineralizationoccurs either in the basement(Bertholdne)or cover sandstone (Bennac)or in both (Le Roube). Age Constraints

Mineralization in the type examplesformed in with intrusion Jurassictime, contemporaneously Canada:Cluff Lake "D", Collins Bay, Dawn of basicdikesand approximately time-equivalent Lake, Maurice Bay, Midwest, McClean, P2- to globaltectonicsmarkedby the incipientstaee NorthlAthabasca Basin,Saskatchewan of tbe openingof the North Atlantic ocean.

Type2:Subconformity-Epimetamorphic 69

lResources Dimensions

4.2 Type2: Subunconformity(Fig.a.2) Individualdepositsmay be up ro 1000mlong, a Epimetamorphic iew metersto 50m wideand may extendup to ca. 30m aboveand ca. 30m belowthe unconformity. Definition Resources are a few tensto ca.2000mtU3Os at gradesof 0.1 to 0.15%U:Oe. raverage) Subunconformitv-epimetamorphic deposits

are strata-structure-boundin metasediments below an unconformity on which clastic sedimentsresr. Remarks Type example deposits occur below an early Differencesberween subtype 1.1 depositsin Middle Proterozoic unconformity that is overlajn Saskatchewanand those of subtype I.2 in by early Middle Proterozoic clasticsedimentsand .{vevron, France include (a) well-developed volcanics. :lbitizationin Avevronartributedto diagenesis of Deposits consist of peneconcordantlenses or :over sediments. Albitizationis practicallyabsent tabular mineralizationsemplacedjn fracturesand in class1.1.2depositsin Saskatchewan. (b) Clav breccias within distinct stratigraphic units. Host minerals associated with mineralization are strata are predominantly pelitic (subt,r-pe2.2 dominentlyillite and smectitein Aveyron, and or carbonatic (2.1) sediments with intercalated illite and Al-, Mg-chloritein Saskatchewan. (c) carbonaceoushorizons of Iate Lower Proterozoic Metal associarionis more simplein Aveyron than age metamorphosed to amphibolite grade facies in Saskatchewan. (d) Cover sedimentshave con- and superimposed by retrograde (greenschist) trastingredox environmentsin Aveyron, whereas metamorphism. Granitic-migmatitic complexes thosein Saskatchewan are uniformlyoxidized.(e) occur discordantly in the metasediments. paleoGraphite horizonsare of only minor importance weathering of the crystalline rocks was oniy mild in Aveyron. (Pagel1989). (in contrast to areas of "unconformitv-contact"

TyPc

- EPTMETA}'ORPHIC 2. SUBUNCONFORUITY (stsoto-stsucturc bound in lotc Lorcr Protsozoic mctorcdimcnta)

Subtypc

2.1

not olbitizcd mctss.dimontl

Typc cxomplcr(cloar)

2.2

olbitzcd mctosGdimqntt

o) Jobiluko, b) Rongcr I, c) Foy, Koongoro Rum Junglc Vcrno

d) Gunnor

EARLY MIDDLE PROTEROZOIC

ls

LATELOWER PROTEROZOIC inqrcosc of No-mctqcomoticm ? incrcoacd dcrrclopmcnt of pcAmoUtce ond onotaritcc ?

Fig. 4.2

El

cbstic covr

A

mctsscdimcnts

f,|

No-mctocomotitc-obititc,

E E

$dimcntr

onotcctita lotc orogcnic intruaivc

le ts A

U mincrolizstion

ond volconics

migmotitc

M N

a a

G

vRRn

dolcrits pcAmotitc foulL brcccio boneitionol fociss contoct

70

4 Typology of Uranium Deposits

deposits). Principal uranium phases are pitchsarily developed adjacent to and at intersectionsof major faults (particularly evident blende and uraninite. Intense and extensivehost in Beaverlodgedistrict) rock alteration surroundsmineralization. Two settings of mineralization are recognized - Host structuresare faults, fractures. breccias, stockworksarranged more or less peneconon the base of Na-metasomatismof the host and other features: cordantto attitude of strata metasediments Aheration Subtype 2.1: not dbitized metasediments Type Example: a) Jabiiuka, Koongara, b) Ranger, Alligator Rivers district. Australia Subtype 2.2: dbitized metasediments Type Example: c) Fay-Verna, d) Gunnar. Beaverlodge district, Canada References: Beck 1986; Dahlkamp and Adams 1981; Ferguson and Goleby (eds.) 1980; lAEAiFerguson (ed.) 1984;Needham et al. 1988;Tremblay 1978 a), b), c), and d) refer to type examplesshowninFig. 4.?.

- Mild paleoweathering-relatedalteration of basement (in Beaverlodgedistrict of more physicalthan chemicalnature) - Pervasivediageneticalterationincluding Mg-. Li- and B-metasomatism of severalgenerations imposed on both basement and overlying sedimentsand reflected by tourmalinization (dravite), carbonatization(calcite, dolomite). argillitization.sericitizationetc. - Intense mineral-relatedwall rock alteration including argillitization, chloritization, desilicification, silicification, sulfidization and hematitization - Widespreadpre-ore albitization of basement rocks hostingsubtype2.2 deposits

Subtype 2.1 does not display albitization but of both Mineralization extensiveMg-, Li-, and B-metasomatism host metasediments and overlying sediments. Principal uranium minerals are pitchblende, Subtype 2.2 exhibits albitization of host rocks partly of high intensity up to albitite formation uraninite and alteration products thereof (coffinite, etc.). For associatedminerals and and also shows a stronger structural control and contains relative abundant gangueminerals as metals,seeTable 4.2 comparedto subtype2.1. Gangue minerals are associatedwith subtype 2.2but rare or absentin subtype2.1 Most deposits,particularlyall large ones are Principal RecognitionCriteria monometallic except for some containing locally Au; some smaller deposits are poivmetallic(Rum Jungle:Cu, Pb, Zn) Host Environment Several generationsof mineralization exist, - Orogenicbelts mainly derived by redistribution of primary - Merasediments (schist, gneiss) with intermineralization(locallyinto cover sandstone) bedded graphitic horizons of pelitic and Ore distribution consistsof U disseminations psammiticeugeosvnclinal or lacustrineongin or massiveveinletswithin host structures - Regional metamorphosed to amphibolite Mineralizedstructuresare arranged + penegrade locally up to granulitegradefacies concordantto attitude of host strata - Retrograde greenschistfacies metamorphic Type example (a) Jabiluka and Koongara overprint . display the most pronounced strata-bound - Presenceof granitic-migmatiticcomplexesand structurecorrelation,whereasgoing from type pegmatitedikes in basement examples(b) to (c) and (d) the strala-structure - Cover by continental clastic sedimentswith relationshipbecomeslessevident intercalatedand transgressive basicvolcanics Mineralizationis fairly continuous - Post-sedimentary diabase/dolerite dikes Depth persistenceis variable but can extend - Brittle deformation of host strata by intense to great depth (>1600m in Beaverlodge faultins and brecciationoften but not necesdistrict)

T ype 2: Subconformity-Epimetamorphic 71 Table 4.2. Associatedmineralsand metals Gangueminerals

Others(replacement, authiqenic.etc.)

Vein fillings

Basement

Overlyingsandstone Locally Mg-chlorite, tourmaline (in Kombolgiesandstone and basement)

c)

Calcite,dolomite,quartz, chlorite(?)

Chlorite Sericite/illite Kaolinite Silica Quartz Carbonate Hematite Hematite Epidote

d)

Quartz (?) Calcite(?) Chlonte (?)

b)

Metals

Cu, Pb, Zn Co, Ni, Pb C u . P t ,A u , A g A s , S e ,S

Albite Calcite

ua to d referto typeexamples in Fig..1.2

Age Constrains -

No age constraint except limitation to orogenies younger than late Lower Proterozoic

-

All major deposits known are associatedwith upper Lower Proterozoic sediments metamorphosed during the Hudsonian or time equivalent orogenies (ca. 1900 to 1700m.y. ago)

Metallogenetic Aspects

had opened within the uraniferous strata. In contrast,in areasof closedsystems,i.e., those that lack the above listed criteria, uranium remainedin situ and formed stratiformsynmetamorphic mineralizations(Type 13). The position of more structurally dominated mineralization [type examples(c) and (d) at Beaverlodge]or more lithologicallycontrolledmineralization[(a) and (b) in the Alligator Rivers district] may be relatedto zonesinfluencedby Na-metasomatism, In migmatization and/or palingenesis/anatexis. regions where subunconformity-epimetamorphic depositswerecoveredby earlyMiddle Proterozoic continental sediments,the cover protected the depositsagainst weatheringand erosion. More or lessintensediageneticallyinducedmagnesium and boron metasomatismoccurredin both crystalline basementand overlyingsandstoneas displayed in the Alligator Rivers distnct. These processes very probably created diagenetic modificationsin the depositsincluding redistribution. partly into the overlyingsandstoneas at of the uranium Beaverlodge,and recrystallization and intense host rock alteration. Still younger processesled to further modifications,as reflectedby severaigenerationsand isotopeagesof uranium and associatedminerais.

Subunconformitv-epimetamorphic uranium deposits have a complex, polyphase evolution. Deposits in the Alligator Rivers and Beaverlodge districts most likely have their roots in late Lower Proterozoic time when peiitic-psammitic sediments interbedded with carbonaceous horizons collected anomalous amounts of uranium and other metals. It is possiblethat pre-metamorphic relocation of uranium led to the formation of sandstone-type deposits such as those in the Franceville Basin, Gabon. During Lower to Middle Proterozoic times these sediments were regionally metamorphosed to amphibolite and locally to granulite facies. In regions of open systems, i.e., in tectonically active terrane characterized by anatexis, migrnatism, metasomatism, acidic and mafic intrusions. and brittle defor- Remarks mation, uranium was locally mobilized by late metamorphic and/or metasomatic hydrothermal a) Monometallic subunconformitlr-epimetamorphic U deposits particularly those of Lower to processesand reconcentrated in structures which

72

4 Typology of Uranium Deposits

Middle Proterozoicage,often havemediumto Alteration large resources(up to >200000mtU-rOs)at wallrock alteration and extensive metalow to medium grade (0.2-0.4%U3Os) but Strong (Mg. B, Li) of several generations, somatism may also contain sectionsof very high grade both basement and sandstone latter affected The (several % U3O8). In contrast,polymetallic tourmalinization (dravite), and includes cover depositsexceptthosewith gold (e.g.,Jabiluka) (Mg andior Fe-rich), carbonatichloritization have small resources. (calcite. dolomite), sericitization. argiliitb) Although all large depositsof this category zation desilicification, and silicification and ization, known are associatedwith Lower to Middle Alteration related to mineralihematitization. Proterozoic rocks. similar depositsmay also very intense and may extend is zation commonly occur in comparablegeologicalenvironments (m variable distance to i0'sm) into wall rocks. to with youngerorogenic-metamorphic associated events. Ore and Associated Minerals

4.2.1 Subtyp2.l: metasdiments

Not albitized

Australia TypeExample:PineCreekGeosyncline, Monometallic (except for local Au concentration): a) Jabiluka, Koongara,Austraiia; b) Ranger One, Australia Polymetallic:Rum Jungle (a) and b) refer to Fig. 4.2) References: Ewen et al. 1984; Ferguson and Goleby (eds.) 1980; IAEAlFerguson (ed.) 1984;Needham et al. 1988

H ost Ro cl<sI Structures

Principal uranium minerals are pitchblende, rarelv uraninite and alteration products thereof (coffinite, brannerite, sooty pitchblende). Associated minerals/metalssee under main headins.

Type2. Mode of Mineralization or massiveveinsfilling U occursasdisseminations fractures.brecciasand stockworks, + peneconcordantto attitudeof the strata.Mineralizationis more or lesscontinuousand may extendto more than 500m below the unconformity. Most ore is monometallicexceptfor some small deposits (Rum Jungle) and locally payable gold values (Jabiluka, Koongara). Several generations of uranium mainly derived by redistribution and recrystall2ation (rejuvenated U/Pb ages) of primary mineralization partly by diagenetic processes.Mineralizationis controlledby both structure and lithology as reflectedby emplacementin cataclasticzones * peneconcordantto folded metamorphosedstrata and often adjacent to graphitic horizons. Other recognition criteria inciude intense, partly pervasivechloritization, sericitization.argillitization,andhematitizationof wallrocks;wide-spread halosinto coversediments of tourmalinization,carbonatization, silicification, etc.; (former) presenceof continentalcover sedimentsand volcanics;minor paleosoldeveiopment prior to sedimentation and numerouspegmatite and diabase(dolerite)dikes.

Metasediments(schist,gneiss)with intercalated graphitic layers and carbonatic horizons derived from pelites and psammitesof eugeosynclinal or lacustrine origin, regionally metamorphosedto amphibolite-granulitef acies. Migmatitic/anatectic complexes occur near deposits. Pegmatite and diabase/doleritedikes intrude host sequences.Continental sandstone with intercalatedand discordantbasicvolcanics. if not eroded. overlie mineralizedareas. Host rocks are deformedby intensivefaulting and brecciation. Structurescontainingmineralization consist of fractures, brecciasand stockworks arranged+ peneconcordant to attitude of strata.Type examples(a) Jabilukaand Koongara display the most distinct strata-boundstmcture correlation whereasthat of examples(b), Age Constraints Ranger One and Rum Jungle is more structure All examplesknown are associatedwith upper prominent. [,ower Proterozoic sediments metamorphosed duringan orogenyat about1700to 1900m.v. ago.

Type3: Subconformitv-Epimeramorphic 73 DimensionslResources Individual deposits may be up to >1000m long, several tens to more than 400m wide a n d i n e x c e s so f 5 0 0 m d e e p . c o n t a i n i n gu p t o 200000 mt U3Os at (averase) gradesrangingfrom 0 . 1 t o 0 . 4 % U j O 8 o c c a s i o n a l l yt o > 1 % U r O s . Districts may contain up to -100000mtU3O5. Remarks F o r m o r e d e t a i l ss e e C h a p t e r 5 . 2 . 1

E.ramp les of Subunconformi n'-Ep imenmo rp hic, Subvpe2.1 Nor Albitized fulerasedimenu lOccurrences Deposits

consist of fractures. breccias, and stockworks arranged + peneconcordant to the attitude of strata. Structural control is more prominent as in s u b t y p e2 . 1 . Alteration Extensive and locallv intense Na-metasomatism and strong wall rock alteration of severai generations modified the basement.Na-metasomatism is a pre-ore phenomena and locally achieved albitite formation. Host rock alteration of preto svn-mineralization age includes pervasive hematitization. chloritization. epidotization, carbonatization.and silicification.

Australia:Alligator Rivers district.Rum Jungle Ore and Associated Minerab district, ? South Aliigator River district/Pine Principle uranium minerals are pitchblende, Creek Geosyncline,Northern Territory, ? Kinrarely uraninite and alteration products thereof tyre, West Australia (coffinite. brannerite, sooty pitchblende). Associated mineralsimetals (see under main heading, Tvpe 2).

4.2.2 SubtyP 2.22Albitized metasediments

Mode of Mineralizarion

U occurs as disseminations or massive veins filling fractures, breccias and stockworks, + peneconcordant to attitude of the strata. Mineralization is more or less continuous and may extend to a considerable depth (>1600m). Most ore (ed.) References: 1986:Tremblay1978: is monometallic except for some small deposits Beck 1986;Evans Ward 198.1 (e.g., Nicholson). Severalgenerationsof uranium mainly derived by redistribution (iocally into catacover sandstone) and recrystallization (reclastic Host RockslStructures juvenated U/Pb ages) of primary mineralization. Metasediments (schist, gneiss) with intercalated Mineralization is controlled by both structure graphitic layers derived from pelites and psam- and lithology as reflected by emplacement in strucmites of eugeosynclinal or lacustrine origin, tures + peneconcordant to folded metamorphosed regionallv metamorphosed to amphibolite- strata and often adjacent to graphitic honzons. 3ranulite facies and partlv Na-metasomatizedto Other recognition criteria include intense, partly eibititerocks. pervasive chioritization, sericitization, argillitiMigmatiticranatecticcompiexesand/or granitic zation, hematitization. carbonatization, siiicifiintrusions occur near deposits. Pegmatite and cation. etc. of the host rocks; (former) presence diabaseidolente dikes cut the host rocks. Con- of continentai cover sediments and volcanics; tinental sandstone with intercalated and dis- little or no paleosoi (regolith) development prior cordant basic volcanics. if not eroded. overlie to sedimentation and numerous pegmatite and mineralized areas and may carry (redistributed) diabase(dolerite) dikes. mineraiization. Host rocks are deformed by intensive faulting Age Corctrains and brecciation. often but not necessarily developed adjacent to and at the intersection of All major deposits known are associated with major faults. Structures containing mineralization upper Lower Proterozoic sediments metamor-

Type Example: Beaverlodge, Uranium City region,Canada monometallic:c) Fay - Verna; d) Gunnar polvmetallic:c) Nicholson (c) and d) refer to Fig. 4.2)

4 Typologyof Uranium Deposirs

phosed during the Hudsonian Orogeny(ca. 1700 to 1900m.y-).

Subtype 3.1: granite-related (Fig. 4.3a)

D irnensio nsIResour ces

Class3.1.1: intragranitic (Limousin t1'pe) Type Examples:3.1.1. 1 veinsin granite: Fanal'. France 3.1.1.2disseminations in episyenite pipes:Pierresplant6es.France

Individual depositsmay be metersto 100m long, several meters to more than 100m wide and in excess of 1600m deep, containing up to >15000mtU3O, at (average)gradesranging from 0.1 to 0-4ohU:Os. Districtsmay containup to 25000mtUrOa. Remarl<s For more detailssee Chapter5.2.2. Examplesof Subunconformity-Ep imetamorphi c, Subrype2.2 Albitized MetasedimensDepositsl Occurrences Canada: Bolger, Dubyna, Hab, Lake Cinchi Beaverlodge,Saskatchewan

4.3 Type 3: Vein (Figs.4.3a,b)

Class3. 1.2: perigSanitic Type Examples:3.1.2.1 veinsin (meta)-sediments: monometallic (Bohemiantype) Pifbram. CSFR 3.1.2.2veinsin metasediments: polymetallic (Erzgebirgetype) St. Joachimsthal/ Jachymov.CSFR 3.1.2.3in contact-metamorptucs : (Iberian type) Alto Aientejo. ponugal Subtype 3.2: not granite-related (Fig. 4.3b) Class3.2.1: in metamorphicrocks Type Example: Schwartzwalder,USA Class3.2.2: in sediments(polymetallic) Type Example: Shinkolobwe,Zaire References:IAEA/Fuchs (ed.) 1986;Basham and Matos Dias 1986; Derriks and Vaes 1956; Fnedrich er al. l9g7; Kolektiv CSSR tS84; Poty et al. t9g6; Ricb et al. lgTl: Ruzicka 1971;Wallact 1986

Definition Vein deposits consist of uranium mineralization in lensesor sheetsor disseminations filling joints, fissures,brecciasand stockworksin deformedand fracnrred rocks. Size and complexity of vein sets are variable. Distribution and intensityof mineralization are irregular. Principal uranium phases are pitchblende.uraninite and coffinite.Gangue mineralsare alwayspresent.Uranium may form monometallic mineralizations or polymetallic mineralizations.Associated metals include Co, Ni, Bi, Ag. Cu, Pb, Zn, Mo and/orFe in form of sulfides, arsenidesor sulfarsenides.Wall rock alteration is commonly restricted to a narrow margin(200m) long, mm to lm (more than 100m) wide and m to several 10m (>a50m) deep. Reserves are up to ca. 25000mtU3Os at (average)grades raneing from 0.1 to >1% U3Os. Districts may contain up to several 10000mt

U:os. Remarks

Shinkolobwe and other vein deposits of class 3.2.2 display a vein to stockrvork qvpeore distribution discordanr to strata. resembling in many aspects. notablv in its ore and eangue mineral association and strucrural controi eranite-related vein deposits of class 3.1.2.2. Major differences Ore and Associated Minerals include absence of granitic intrusions, a relative ?rincipal uranium minerais are uraninite (at continuity of mineraiization. and in the case of Sirinkolobwe) or pitchblende and alteration pro- the Katanga copper belt. anomalously uraniferous ducts thereof. Associated minerals may include sediments which mav have provided the source Co-Ni sulfides and selenides.sulfidesof Fe, Cu. for uranium and the associated elements. For more details see Chaoter 5.3.6. Mo, Pb, Zn, a.o. and trace amounts of precious metals, phosphates (monazite) etc. Gangue minerals are carbonates (magnesite, dolomite), quartz, chlorite etc. Examples of Vein, Class 3.2.2 Not Granite.\t ode of M ineralizstion

ReIated (P o ly merallic ) D epo s itsI O ccurrencesin Sedimens

Uranium and gangue minerals occur in veins, USA: ? Pitch MinerMarshall Pass. Colorado stockworks, along bedding planes, as breccia Zair e: Kalongwe. SwambolShaba

U

4 Typologyof Uranium Deposits Class4.1.2: vanadium-uranium(a, b) Type Example: a) Uravan Mineral Belt, USA, (Salt Wash type) b) Mounana, Gabon (Franceville rype)

4.4 Type 4: Sandstone (Fig. 4.a) Definition Sandstoneuranium deposits occur in reduced continentalfluvial and less commonly in mixed fluvial-marine(arkosic)sandstonesthat contain, are interbeddedwith and bounded by less permeable horizons. Primary uranium phases are generallyof tetravalentstateuranium and consist dominantlyof pitchblendeand coffinite. Associated organic material in Phanerozoic (post-Devonian)deposits(type 4a) is of terrestrial plant origin as distinct to marine, algae (?) derived material in Proterozoic deposits (type 4b). Based on configuration, spatial relation to the depositionaland structuraienvironmentand/ or elemental associations,sandstoneuranium depositsmay be divided into three overall subtypes and further into classesthat can be gradational into eachother:

Subt"vpe4.1: tabular/peneconcordant( (a) Phanerozoic. (b) Proterozoic)

Class4.1.3: basalchannel(a) (Chinle type) Type Example: Monument Valley, USA Subtype4.2: rollfront (or roll-type) (Phanerozoic) Class4.2.1: continentalbasinassoc.witb detrital carbon (Wvoming rype) Type Example: Wyoming Basins,USA Class4.2.2: mixed fluvial marine assoc.with extrinsic sulfide (South Texas type) Type Example: South TexasCoastalPlains, USA Subtype4.3: tectonic-lithologic Type Example: a) Grants Uranium Region, USA b) Mikouloungou, Gabon [Descriptionof subtlpe 4.3 is includedin sections4. 1.1 and a.1.2(b)l References: (a) Adams and Saucier 1981; Adams and Smith 1981; Boyle 1986; Chenoweth and Malan 1973; Crew 1981; Crawley 1983; Grutt 192: Galloway 1985; Granger and Finch 1988; Grutt 1972; Harshman and Adams 1981; Rackley 1976; Thamm et al. 1981; IAEA/ Finch (ed.) 1985; Turner-Petersonet al. (eds) 1986 (b) Diouly-Osso and Chauvet 1979;Gauthier-l-afaye 1986

Class4.1..1:ertrinsic carbon (a) (Westwater Canyon rype) Type Example: Grants Uranium Region, USA

4. Sondstone

Type

{o/Phonerozoic: ossocioted with orgonic moteriol of terrestriol ptont origin) { b , / P r o t e r o z o i c :o s s o c i o t e o w i t h o r g o n i c m o i e r i o l d e r i v e d f r o m o l g o e )

S u b t y p e 4 . 1i o b u l o r Closs 1.1.1

4.2 rollfront

4 . 3 t e c t o n i c - l i t h o l o g i(co ,b )

r,.'1.3

humote-uronium (o) chonnel./bosol {o) L t.t

1.2.2 introcrotonic/ coost-oloin,/mixed continenlol bosin lo) fluviol-morine io)

v o n o d i u m - u r o n i u m ( c .b )

Fl

Fig. 4.4

U minerolrzotion

l.l

s o n os l o n e

lv

t:

s i l i s lo n e

I wwY l.Ig

volconic flows {bosolt)

l -l

mudstone

l{ .+l |5

bosemenl {gronitic)

w-q

v o l c o n i c l os t i c s

A ,*0,

Type 4: Sandstone

Tabular deposits also referred to as peneconcordant deposits consist of uranium matrix impregnations that form irregularly shaped frequently elongated lenticular masses within selectivelv r:duced sediments. The mineraiized zones are, 'rn a large scale, oriented parallel to the depositional trend but, on a small scale, they crosscut sedimentary features of the host fluvial sandstone. Further subdivision into classes is based on uranium fixing agentssuch as amorphous organic material of extrinsic origin (e.g., humate), or detrital plant debris of intrinsic origin, or metallic ::sociations (vanadium) that occur in fluvial ;)stems. Deposits in sandstonechannels incised into unconformably underiying sediments or crystalline rocks are referred to as basai channel deposits. The primary mineralization may be redistri''stack" deposits in buted into secondary uranium the host sandstone. Rollfront deposits consist of arcuate zones of uranium matrix impregnations that crosscut sandstone bedding extending from overlying to underlying less-permeable horizons. The zones are convex down the hydrologic gradient. They display diffuse boundaries with reduced sandstone on the down-gradient side and sharp contacts with oxidized sandstone on the up-gradient side. The normally oxidized up-gradient sandstone can also be in a reduced state if it has been ;e-reduced through the influx or re-introduction of reductants as found in some deposits of class .1.2.2.The mineralized zones are eiongate and sinuous approximately parallel to the strike, and perpendicular to the direction of deposition and groundwater flew. Further subdivision of rollfront deposits is based on emplacement either in inracratonic basins fiiled with continental fluviai sediments end containing detrital carbon as a potential reductant.or in mixed ffuviai-marinesedimentsof coastal plains containing pynte and marcasite as potentiai reductant that originated from influx of H2S into the host sands. Tectonic-lithologic deposis are discordant to strata. They occur along permeabie fault zones with iinguiform impregnation ,of the adjacent clastic sediments where uranium may form rather thick ore bodies which are also referred to as stack deposits when denved from redistribution of uranium.

Principal

Recogaition

85

Criteria

Host Environment -

Immature permeable sandstone.feldspathicor arkosic, more rarely quartzose and cherty sandstone, pebble conglomeratesor marginal marile or eolean siltstone and sandstone - Dominantlv medium to coarse grain size. rarelv fine or verv coarse (pebble)-grained - Mostly cross-stratified and with lenticular bedding - Coetficient of permeabiiity 75 to 350llm2lday (Austin and D'Andrea 7978) - Abundance of U precipitants/reductants, panicularly carbonaceousmaterial (fragments of woody material + coaiified. humic components, amorphous humate). hydrocarbons (petroleum. "dead oil") and/or sulfides(H2S, pyrite) - Tuffaceous material may be present as volcanic debris within host sands. interbedded tuff-rich layers or overlying bentonitic mudstone derived from tuffs - Often interbedded with impermeable horizons (mudstone) Minerulization -

Multiple mineralized horizons may exist Roilfront deposits are crescent-shapedin crosssection, transgressive to stratification of host sands, in pianview they resemble an irregularly laid pipe; roll fronts can occur in multiple superjacent horizons - Boundaries of mineralized bodies are in some deposits sharp and continuous whereas in other deposits they are highly irregular and diffuse - Tectonic-lithoioeic ore bodies of stack type are muiti-shaped. sometimes Chnstmas-tree like, depending on smlctural distribution and impregnation of permeabie horizons adjacent to host structure - Configuration. size and composition of subtypes seeminglv are a function of (a) rype and permissivity of aquifer/host sandstone, (b) stratigraphic interbedding of permeable with impermeable beds. (c) kind, mode, and distribution of reductants and/or complexing agents, (d) derivation. hydro-chemistrv and flow rate of eroundwater svstem

86

4 Typologyof UraniumDeposits

ated to keep uranium in solution for transport, and limited to the point that reduction can take - Principal distribution in sedimentsof middle placein order to precipitateuranium in ore grade Paleozoicto Tertiary age, i.e., after develop- quality and quantity. Complexingagentssuch as ment of lush terrestrial vegetation carbonateions are highly capable of enhancing - Minor in Precambriansandstones,particularly the solubilityand mobility of the uranyl ion in the in those containing carbonaceous material form of carbonateor other complexesin groundsupposedlyof algae origin (e.g., Franceville water that is neutral or alkaline and that may Basin, Gabon) be oxidizingor reducing(Hostetler and Garrels 7962\. For precipitation,the hexavalenturanium in solutionmust be reducedto tbe tetravalentstate MetallogeneticAspects to form pitchblende or coffinite, the principal uranium minerals in most reduced sandstone Generallyit is acceptedthat sandstoneuranium low-tem- deposits. Under certain conditions uranium deposits are of diagenetic-epigenetic perature origin. Groundwater chemistry and mineralsmay also crystallizein an oxidizing enmigration are instrumentalin uranium leaching vironmentwhen complexingagentsare present, from source rocks and its transportationto a for example vanadium compounds, to fix the chemicalinterfacecommonly provided by reduc- uranyl-ionin form of uranyl vanadateswhich are ing or complexing agents where uranium is fairly stable in oxidized rocks. To reduce the deposited.Essentialparameterscontrollingthese hexavalent uranium a reductant is required. processesand localization of uranium mineral- Many substanceshave been invoked as uranyl ization are depositionalenvironment,host rock reductantsincluding + coalified vegetal, woody' lithology, permeabiiiry. adsorptiveireducing fragments(coalificationnot higher than subbiorganicmatter (humate), agents, adequatesolutions, a uranium source, tuminous),structureless petroleum,"dead" oil, "sour" natural gas.hydroand apparentlyan arid to semi-aridclimate. Fluvial, first cycle feldspathic or arkosic sand- gen sulfide,and pyrite or other sulfides.Bacterial stonesof limited thickness(1% U3Os. Districts may contain up to 300000mtU3Os.

Tvpe exampie is V-U mineralization in the Salt Wash Member of the Late Jurassic Morrison Formation as present in the Uravan Mineral Belt, Utah-Colorado. USA. Host rock is a fluvial fine- to medium- and coarse-grained feldspathic to quartzose sandstone. This unit ranses from 50 to 120m thick, is red. brown or gray in color. and contains 5 to 15% tuffaceous material and abundant organic debris in the form of logs and frasments of vegetal trash. These materials accumulated particularlv at sites where paleochannels change direction, in mud bars or changes in stream load carrving ability. Sandstone lavers are interbedded with reddish and _gravsiltstones and bentonitic mudstones. The Salt Wash Member is pan of a coaiescing alluvial fan formed by a svstem of aegrading braided streams. The Uravan Mineral Belt occupies a transversal zone rvhere grain size of the sandstoneis transitional from medium to fine. Sourcearea for Salt Wash sedimentswas the sranitic Mogollon Highland. Positive areas forned by sait diapirs and associated anticlines within the basement controlled river orientation and facies pinchouts during Salt Wash time.

Remarks

Alrcrailon

The Grants Uranium Region is 175km long and up to 80 km wide and includesfive mining districts

Reduction alteration is recognized chielty by color changes and is most obvious in mudstones

DimensionsI Resources( Grants U ranium Region)

90

4 Typologyof Uranium Deposits

turning from purplish or reddish to gray-greenat contacts with mineraiized sandstoneswhich are stainedtight yellow-brown. Common authigenic transformations include pyritization, calcitization, and argillitization. Detrital ilmenite and magnetiteare corroded.

sandstonehad resourcesof a few hundred to severalthousandtonnesuranium. For more detailsseeChapter5.4.2. Examplesof Sandstone,Class4.1.2(a),Tabular, Vanadium-Uranium Deposiu/ Occurrences

Argentina: Rodolfo (C)/Cosqindistrict Australia: Bigrlyi (P)AJgaliaBasin *Principalore mineralsin reducedzonesare pitch- USA: La Sal-La Sal Creek (M). Lukachukaiblende, coffinite, and vanadium minerals. Carrno (M), Henry Mountains (M)/Colorado Oxidized zones are dominated by uranyl Plateau vanadates.commonlycarnotiteand tvuyamunite. Associatedminerals are pyrite and marcasite. Class4.1.2:(b) Vanadium-uranium(Franceville Mo, Cu and Se mineralsoccur in trace amounts. type) (Proterozoic) Vanadium-uraniumratio is 5: 1 to 10:1 in the Uravan Mineral Belt and in other Salt Wash Type Examples:FrancevilleBasin. Gabon districts1 :1 to 15:1. 4.1.2.1tabular:Oklo. Gabon 4.l.2.2tectoniclithologic: Mounana and Mikouloungou,Gabon Mode of Mineralization Ore and AssociatedMinerals

Class 4.1.2 minerelization is characterizedby vanadium-uraniumassociatedwith plant debris. Mineralization occurs as disseminationsfilling pore spaces, coating sand grains and replacing interstitialclay, organic substances, and cementing material. U-V minerals have accumulatedin commonly small pods which locally are highly mineralizedtree tmnks. The pods may display shapes ranging from tabular, concordant to bedding to roll-typ€. Deposits consist of clusters of pod-like bodies aligned parallel to the paleochannel,where thev may occur in severalsuperjacent sand horizons. Distribution of depositsis rather erratic. DimensionsIResources( Uravan Mineral Beh) Individual deposits(ore trends in brackets)may be up to 200m (up to a few km) long, 7 uranvl bi-carbonateand alkaline and saline playas. leads to accumulation of U in final residues:evaporationof tri-carbonate comDlexesare dominant and

-.-__

100

4 Typologyof UraniumDeposits

soil moisture associatedwith capillary rise of groundwatermay be the mechanismfor U enrichments in pedogeniccalcretesor ferricretes in hot climatesand perhapsof the structurally controlled mineralizationsin moderateclimates such as the autunite depositsof Daybreak, USA; - interaction of two or more groundwaters,for example mixing of separate uraniferous and vanadiferous groundwaters resulting in deposition of carnotite (Mann and Deutscher 1978). For extensivediscussions of the abovesummarized mineralizationprocesses,the reader is referred. among others, to Arakel (1988), Boyle (1982, 1984), Briot (1978), Carlisle et al. (1978), Hambleton-Jones(1976), Mann and Deutscher (1978),Samama(1984). For more details on the menllogenesis of subrype6.1 depositsseeChapter5.6. Additional detailson the formationof subtype 6.2,6.3, and6.4 mineralizations aregivenbelow. Subtype 6.2, peat - bog, metallogeneticaspecsi Noteworthy mineralization has formed in glaciated terrane of cold to cool temperateclimatesof the northern hemisphere,and in recenttimes as indicated by strong radioactive disequilibrium. Prerequisite for optimal U accumulation are organic-rich channels or basins through which a relatively constant filtering of uraniferous surface or groundwaters orcurs. The waters collect the uranium by weathering and leaching from uraniferous granites, volcanics,or other lithologies.For example,in the FlodelleCreek area, probable source rocks are provided by the CretaceousPhillipsLake Granodioritecontaining 4 to 80ppmU (av. 16ppmU), part of whichmust be presentin leachableform asreflectedby sheargradingas controllednear-surfacemineralizations muchas500ppm U. Uranium-transporting waters appearto be neutralto slightlyacidandmay carry several hundred ppmu. Otton and Zielinski (1985)report for the Flodelle Creek headwaters a pH-rangefrom 5.85to 7.55,and contentsof 17 to 318ppmU associatedwith high covariationof Ca2*,Na*, Mg+, and HCO3- ions. A mechanismthat is essentialfor the fixation of uranium is not so much reduction but ion exchangeand adsorptionon organicmaterial as reflectedby the high correlationcoefficientof up to 0.8 for U to organicmatter.

Subrype6.3, karst-cavern,metallogeneticaspectsi The most likely sourceof uranium is tuffaceous sediments formerly overlying the Madison Limestone. Uranium is thought to have been leachedfrom the pyroclasticsduring the present erosioncycleby groundwaterswhich transported it downwardsto be redepositedin the karst openings as uranyl vanadates. Subrype6.4, surficial pedogenicand structurefill, metallogenicaspects:The most appealing hypothesison mineral formation at Daybreak,USA is supergene leachingof uraniumfrom a uraniferous quartz-monzonite during a period of deep weatheringsince Tertiary times and subsequent redepositionof the uraniumasopen spacefillings along a fluctuatingwater table. The actual cause for precipitation of the relative high grade uranium remainsopen for speculation.A similar type of near-surfacestructure-controlled deposit, with uranium derived from uraniferousrhyolitic volcanicsand supposedlyprecipitatedby H2S or hydrocarbons,occursat Mina Cotaje, Bolivia (ca. 100mtUsOs,0.1%U3O8).

Remarks Surficial uranium deposits are commonly relatively small and of low grade except those depositsusedastype examples.From the latter only Yeelirrie, Australia, is of large and potentially economicsize.Mining of the small depositsmentioned was possibleunder exceptionalfavorable conditions (nearby mill, amenability to heap leaching,etc.).

4.6.1 Subtype6.1: Duricrustedsediments (1984); References: Butt et al. (1984);Hambieton-Jones Mann andDeutscher(1978)

Class6.1.1: Fluvial valley-fill (also referred to as calcrete, groundwater-calcrete or valley-calcrete type) Type Example: Yeelirrie, Australia Reference: Cameron1984

Yilgarn

Block,

T;"pe 6: Surficial

H ost Ro cks IA lte ratio n I Structures Mineralization is hosted by nonpedogenicearthy or porcellaneous, porous calcrete or highly ,:arbonatizedfluvial and alluvial sedimentscom,osed of dolomite, calcite, clays, feldspar and locally gypsum and celestite.The calcretegrades laterally and downward into ciav-quartzand argillaceous grit sediments from rvhich it has been derived by groundwater-related aiteration. Calcretizedsedimentsoccupy the axial portion of shallow valleys up to a few km wide and up to 200km long. Basement topography under valleys ;raslocally strong relief with abrupt drops of up to jome tens of meters. For example, at Yeelirrie a basement high chokes the channel section. Calcrete forms near-surface. semi-continuous highiy elongated, tabular lenseswhich may be 20 to 150km [ong,0.5 to 4km wide and 2 to 15m thick. Longitudinal topographic gradient of channelsis rather gentle, between0.05 and 0.1%. Channel-filling alluvium and calcrete commonly oroaden into wide flood plains and deltas in their iower course prior to terminating in playas. In other regions (e.g., Namibia) insteadof, or in addition to calcrete, channel sediments may have been transformed into silcrete or gypcrete providing the host for mineraiization.

l0l

from a few deposits. Sepiolite occurs often and a t t a p u l g i t ei s o c c a s i o n a l l vp r e s e n r .B a r b i e r e t a l . (1980) estimate that in the Mudueh occurrence. Somalia. berween 5 and 20",'" of mineralized samplescontain attapuleite and sepiolite. This is also the case in the Hammadas. Ain Ben Tili area, Mauritania. from where Braun (1914) reports a clay minerai associationschange within the sedimentarv profrle from bortom to top as follows: the basalcongiomerateconrainsmontmorillonite and iilite. the mid section. montmorillonite and attapulgite: and in the top calcareouscap. montmorillonite decreasesand sepiolite appears. Smectite is present in several deposits. Briot (1978) found in Yilgarn Block deposits an interlayered illite,'smectite clay and suggests that smectite denved bv alteration of illite. Smectite and illite are aiso present in the Tumas River occurrence. Namibia. Kaolinite and illite exist often in surficial uranium occurrences. but their relationships to mineralization is unclear in some cases whereas in others they are the only clay minerals present. At a shon distance away from deposits other clav mineral assemblages may occur. Briot (1978) noticed chlorites with traces of illite and talc along the margins of the Yeelirrie deposit. Dimensions lResources

Ore and Associated MineraklMode of Mineralization Principal ore mineral is carnotite and rarely other uranvl-minerais. Carnotite occurs as stringers, seams and disseminations in earthy calcrete, as fracture coating and vug lining in porcellaneous calcrete, and as grain coating in clay-quartz sediments immediately beiow the calcrete. Mineral distribution. although highlv irregular in detail, displaysa general continuity in form of flat-lying .;rallow elongated lenses up to a few meters :hick. Most of the mineralization is emplaced immediatelv beneath the present water table and is best developed in the transition zone below the calcrete. Pagel (1984) notes that in valley-flll and lacustrine/playadepositsin various countries.the uranium minerais are commonly associatedwith a variety of other minerals. Celestite is known from :t number of deposits but is largely erratically distributed and confined to specific parts of a deposit. Its presence is reflected by Sr contents of as much as 6"/". Fluorite and baryte are reported

Nonpedogenic vallev calcrete U deposits may extent several km long, a few tens of meters to ca. 2km wide and 19/').andtracesofPt, Os. Ir, etc. Host Environment - Subrype7.i is monometallicexcept for occa- Oligomictic quartz-pebble congiomerate comsionallyrecoveredREE minerais,subtype7.2 polymetallic.gold being the main product posed of well-rounded and weil-sortedpebbles (mean diameter 5 to 7 cm) of predominantly - UiTh ratio of conglomeratematrix: 1 to 15 quartz and lesser chert (10 to 20%) in highly - Stratiform- matri-x-bounddisseminationof U and associatedminerals pyritiferous siliceous matrix containing minor f'eldspar,sericite, chlonte, and heavy minerals; - Ore localization and concentrationcorrelate with well-sorted and densely packed quartzeither submetamorphic or metamorphosed to pebbles reflecting control by hydrodynamic lower greenschist facies

106

4 Typologyof Uranium Deposits

processes,abundance of pyrite and its predecessors,presence of internal parrings of pyrite-rich arenite and occasionally argillite lenticular in shape and srructured by trough or tabular crossbed sets, proximity to unconformitiesor disconformities. - Geometry of uraniferous conglomerate ore bodies is highly variable, dependingon the topographyof pre-conglomerateunconformit1,, commonlyby far longer than wide and rather thin Age Constraints

Remarks Lower Proterozoicconglomeratedepositsare of very low to low grades(0.01to 0.L5%U3Os)but containlargeresources.Depositsmined primarily for gold yieldinguraniumasby-productappearto have a longer renn economicperspectivecomparedwith strictly uranium producers.

Examplesof Type 7 Quartz-PebbleCongtomerate (Undifferentiated) Deposits/Occrurences

Brazil: Serro do Corrego/Jacobina, Bahia, - Restricted to earll' Lower Proterozoic time QuadrilateroFerrifero prior to oryatmoversion,(ca. 2200m.1'.ago) Canada: Agnew Lake/Ontario, Sakami Lakel Quebec India: westernKarnataka USA: Phantom Lake/Jv{edicineBow - Sierra MetallogeneticAspects Madre, Wyoming, Black Hills/SouthDakota A modified placer metalloeenesisis commonly Russia:? Noril'sk/northernSiberia forwarded for U mineralization in Lower Proterozoic quartz-pebble conglomerate deposits. The origin of uranium is generally accepted as synsedimentarydetrital, uraninite, 4.7.1 SubtypeT.l: U-dominant with REE and other heavymineralsdepositedas placersin fluvial or deltaic environments.The source of Type Example: Elliot Lake - Quirke Lake disuranium is thought to be Archean granite. The trict, Canada other heavy minerals are considered to have References: Robertson 1989; Ruzicka 1988 derived from either granite or greenstones. Liberationof ore mineralsoccurredessentiallyby Host RockslStructures physicalweatheringand erosion.Prerequisitefor such a proposition is an anaerobicatmosphere Pvritic oligomictic quartz-pebbleconglomerate permitting fluvial transport of uraninite and (termed "reef') of fluvial origin, deposited in other minerals which are instable and easily braided-streamchannels,with lateral migration weathered in an oxidizing environment. An coalescingconglomeratesinto thin crossbedded anaerobicatmosphereprevailedon earth during sheets,interbeddedwith quartzitebanks, chiefl1' the Archeen and eariy Lower Proterozoicuntil in paleovalleys scouredinto Archean greenstones oxyatmoversionin the middle Lower Proterozoic mainly but also into granite. Three different @a. 2240m.y. ago). Since then, the oxygenated channelsystems(termed"trend") are recognized atmosphereprohibits longer transport of uran- in the Elliot Lake-Quirke Lake district. inite,andhenceexcludes formationof thistypeof No structuralcontroi, exceptfor concentration conglomeratedeposit. in channeisand their abutmentagainstbasement in the highs,and post-oredisplacements. llhe diverseheav-vmineralsassociations various districts primarily reflect petrologically different sources. Aheration Post-depositionalredistribution and mineral crystallizationmainly by diageneticprocessesIed No ore-relatedalteration,but deep essentiallv to the formation of a suite of authigenicore and physicalweatheringand erosion of the Archean associated mineralssuchas brannerite.rutile and paleosurface. Granitesare weatheredto a quartzanataseby reactionof U with ilmenite, pyrite by microclinerock displayinga relic granitetexture sulfidizationof magnetite,the sulfidesupposedly containing sericite derived from plagioclase derivedfrom volcanism. destruction,and somechlorite.Ferromagnesian

Type 7: Quanz-pebbleConglomerate(Lower Proterozoic)

minerals and ferric iron have been removed whereas ferrous iron minerais (pyrite) and tetravalent uranium (uraninite) are still present, reflectingweathering under anaerobicconditions. The weathering is geochemicallyexpressedby Ca ieachingindicated by high KiCa ratios (>a0) due to almost complete decav of plagioclase.

107

4.7.2 SubtypeT.2:Au over U dominant SouthAfrica Type Example:Witwatersrand, Anhaeusserand Maske (edsl 1986:Pretorius References: 1976:Hallbauer 1986

H ost Ro cks IA lrcr atio n I Structures

Pyritic, oligomictic quartz-pebble conglomerate of fluvial ongin interbedded with quartzite, Uraninite. U-Ti oxyde phases (brannerite), cof- arkose. shale and volcanics.Carbonaceousmatef i n i t e . t h u c h o l i t e . u r a n o t h o r i t e .u r a n o t h o r i a n i t e . rial occurs in several horizons. Deposition of r n o n a z i t e x. e n o t i m e , l o c a l l v g u m m i t e . conglomerates in several separate stratigraphic P y r i t e ( 5 t o 2 0 w t . % ) . a l l a n i t e . i l m e n i t e , cycleswithin six large fluvial fans on the north and i h r o m i t e , c a s s i t e r i t e ,m a g n e t i t e , r u t i l e , z i r c o n . west side of the Witwatersrand Basin. sarnet, spinel. tourmaline. titanite, apatite, DVroxene. Ore and Associated MineraklMetak Ore and Associated MineraLs

Uraninite (2 to 6% Th). uranothonte. brannerite, thucholite, native gold and platinoid (Os. Ir, Ru, Uranium is the primary commodity produced Pt) minerals. with occasionalrecoveryof Th and someREE, Pyrite. arsenopyrite, pyrrhotite, cobaltite, particularlyY. gersdorffite, galena, chromite, zircon in relative Several generations of ore and associated abundance and about 60 more minerals in extreminerals occur as disseminateddetrital and mely small quantities.

,VIode of M ineralization

redistnbuted matrix componentsin at least seven congiomeratichorizons that range from Mode of Mineralization 0.5 to >3.5 m thick. Three of the thickerreefs (1.5 to 3.6m) have uraniumgradesof 0.05 to Gold is the main product (.:

-

l.--

. -++**+--t-++ -+?+++--+-r++

0.5

Minerqlizotio

m

E l - l - l I

stroto-bonsgressivecc-bn, bn, cp, U

r:] l-l

stoto-fonsgressave vein cc-bn, U upgroded sbotobound

y

ffi

ferruginous discordont body

F:]

discordont polymict breccios

E

gronitic ond polymict breccios

l--l

K-feldspor-rich biotite gronite

E

unconformity

n

foult

sboto-bound hem-bn-cp-py-U stoto-bound sid-chl-py

t::l l:':::l

oxidotion

bn=bornite. cc=cholcocitei cp=cholcopyrite.py=pyrite, chl=chlorite,hem=hemotite,sid-siderite r) ideolizedofter OlympicDom, Austolio/Roberts 1988 L AT YRRD Fig. 4.8

the lower section of the mineralizedsequence (Olympic Dam Formation), and silicification and sericitization in the upper section. -',{ineralization -

Association of Fe. Cu. U. REE, Au, Ag, with trace amounts of other metais. abundant hematite. and a varietv of gangue minerals dominantlv quartz and fluorite - Principal U minerals are pitchblende. subordinate coffinire. locallv minor brannerite:Cu occurs mainll" as sulfides,in basal part of the deposit associatedrvith abundant pyrite - Sulfide and associated minerals form two modes of mineraiization: older strata-bound assemblagesof dominantly Fe- and Cu-sulfides and vounger strata-transgressivemineralization of predominantly Cu-sulfides - Strata-bound mineral assemblageis bornite (chalcocite)-chalcopyrite-pvrite associatedwith subordinate to trace amounrsof mineralsof U, Au, Ag, REE. Co, Ni, and abundanthematite. Principal gangue minerals are quartz. serrcite. fluorite, and minor sidente and barvte. Verti-

cal zonation is reflected by sulfur-rich, copperpoor assemblage (pyrite-chalcopyrite) at the base gradine upwards to a relative Cu-rich, S-poor assemblage(bornite-chalcopyrite).Ore and eangue minerals impregnate the hematiterich matrix of polvmict brecciasbut also occur in rock fragments.They constitute5 to 20 vol. % of the matrlx in the form of disseminations, replacements.void-fiIl, and occasionallyas thin stratiform lavers. The concentration of suifides displaysa consistentrelationshipto the amount of matrix Strata-transgressivemineral assemblage is chalcocite-bornite associatedwith subordinate U, minor amounts of other sulfides.arsenides/ arsenatesof Cu, Ni, Co. native Au, Ag, and Cu, and abundant hematite. Principal gangue minerals are fluorite, quartz. and subordinate sericite. chlonte. Ore and gangue minerals form veinlets. veins. irreguiar lensesrestricted to structurallv prepared linear zones paralleling the long axis of the graben Strata-bound mineralization characteristically displavssimultaneousrhythmic precipitationof hematite and sulfides

110

4 Typology of Uranium Deposits

- Strata-bound miner:lization commonly is mineralization,but below strata-transgressive spatialoverlappingexists

named "Breccia Complex" type. Although of hugesize,accessable U amountsare restrictedto the quantitiesrecoverableas coproductto Cu-Au mining.

Age Constraints Not established(host rocks at Olympic Dam are Middle Proterozoic,not oider than ca. 1600m.y. and sericitealterationis about i320m.y. old). Metallogenetic Aspects

4.9 Type 9: Intrusive (Fig.a.9) Definition

primary, Intrusivedepositsconsistof disseminated Roberts (1988) suggestsfor the Olympic Dam non-refractory uranium minerals, dominantlv deposit that it originated from a large evolving uraninite.uranothorianiteand/or uranothoritein hydrothermal system in an extensional con- rocks of intrusivemagmaticor anatecticorigin. tinental environment.During an early, more or Deposits are of low to very low grade (20lesssynsedinentaryepisode,hydrothermalfluids 500ppmU) but may contain substantialrecontaining ferrous iron are thought to have sources.Further subdivisionis basedon host rock entered sulfate-rich sedimentary environments petrology: forming by rhythmic precipitation of sulfidesand hematite strata-boundmineralizationin coarse clasticsediments.Continuousmodfficationof the Subtype9.1: alaskite mineralizationoccurred. In a final stage,extenType Example: Rcissing,Namibin sive high level intrusive activity of probably alkalinenature interactedwith and superimposed Subgpe 9.2: quartz-monzonite Cu- Type Example: Bingbam, USA widespreadstructurecontrolledtransgressive on older strata-bound the U-Au-minera[zation Subtype9.3: carbonatite mineralization. Type Example: Phalaborwa,S. Africa

Dimensions/Resources

Subtl'pe 9.4: perdkdine syenite Type Example: Kvanefjeld. Greenland

Olympic Dam is large in size, extendingover an Subtype9.5: pegmatite area of up to 7km long, 4km wide and 300m thick. Within this area. structurally controlled Type Example: Madawaska,Canada mineralizationoccursin linear zones,ereaterthan References:Alexander 1986;Brynard'and Andreoli 1988; 6km long, up to 0.7km u'ide, and more than Berning 1986; Camisani-Calzolari et al. 1985; Maurice (ed) 1982;Ssrensener al. 19'71 300m thick. Total resourcesof the deposit amount to ca. 32mio.mtCu, I.2mio.mt U3O6and 1200mtAu. Averagegrades are I.6"h Cu, 0.06%U3Osand Subrype9./ is in medium-to very coarse-grained 0.6glmtAu. This amount includeshighergrade alaskitebodies ranging in size from large stocks sectionswith probable reservesof 450mio.mt and domesto tabuiardikesand smalllensesdiscontaining ca. 11mio. mt Cu, 360000mtU_1Os cordantly to concordantly within isoclinally and 270mtAu, at grades averaging2.5"/oCu, folded highll' metamorphosedand migmatized No uraniumrelatedalterationis 0.08%U:Os, 0.6glmtAu and 6glmtAg (Roberts metasediments. present. 1e88). Subrype9.2 consistsof very low gradeuranium disseminationsin highly differentiated granitic to (cupriferous)quartz-monzonitic(copper porRemarks phyries)complexes. prospect Dam Olympic and the nearbyAcropolis Subrype9.3 is associatedwith differentiated are the only known depositsof the tentatively (cupriferous)carbonatitecomplexes.

Type 9: Intrusive

9.

TyP. SubtYPe

INTRUSIVE

9.1

oloskite

9.3

corbonotite

9.2

gronite/ monzonite

9.4

perolkoline syenite

9.5

pegmotite

rr

E

+l

'.pl tl I

+

lttl

tJ minerolizotion

r.-l

anatectic intrusive

tt +' - t- l

magmatic intrusive

g

pegmatite

w

metasediment

l_

100 to 200m

Fig.{.9

lil

.'A

Subnpe 9.-l is in peralkaline syenitic domes or stocks. Uranium phases are commoniy of more refractory nature. Strbtype9.5 is in dikes of granitic. rarely syenitic unzoned pegmatite of silcious and mafic tendency (aegirine-augite).

'RRD

|

Age Constrain* No ageconstraintsexceptfor restrictionto mobile belts. Minerali:ation

- Principal U milerals: t thoriferousuraninite, uranothorianite,uranothoriteand/or uraniferPrincipal Recognition Criteria ous refractory minerals (typical for subtype 9.-l). iocally in weatheredzoneshexavalentU Host Environment minerals - Si'n- to post-orogenic intrusions within intra- - U-minerals finely dispersed ubiquitously throushouthostrock in subwpes9.i to 9.4: in cratonic mobiie belts. pockets and clustersirregularly distributedin - Commonly sharp contacts and narrow consubnpe 9.5 pegmatite tactmetamorphic aureoles around intrusions - Subtypes 9.1 and 9.1 are late leucocratic - ThrU ratio generally

"\

Fig. 5,4. Eagle Point, NW-SE cross-sectionacross the Eagle South ore zone u,ith distribution and grades of U mineralization and extensionof associatedalteration zones. The section demonsrratesthe persistenceof pttchblende veins into grear,depthof at least 400m belou' the surface.(After Eldorado ResourcesLtd. 1987)

minor brannerite, and some amorphous uranrum- are described from several deposits. e.g., Ke1' carbon material (carburan) and in weathered Lake (Voultsidis et al. 7982). Von Pechmann zones hexavalent U minerals. Most of the (1985) argues against this determination, and uranium and associatedminerals are present in contends that the mineral phase is uraninite, at several senerations.Euhedral crvstals of aU.O, Key Lake at least. The misleading X-rav peaks

Uranium Deposits Examplesof Unconformity-Contact-Type a

1,15

N ' s e c ti o n

:J ' ihlckness )n ma' :.:ce __.n-.n ' t>,uu -:

l-ic

:1-lc0

f

'soltne of unconio'-rti, elevolron lrn m,

f

=oult wilh dip dr:e:lron

(in sradeIhickness. doned\combinedwith Fig. 5,5. East Athabascadistrict.Cigar Lake. isolinemap of U accumulations a isolinesof unconformltvelevationancib lnrerpreredstrucluresystemsat the uncontormitvdisplavingthe correlation betweenthe three parameters.{.\fter Fouqueset al. 1986)(repnnted with permissionof The CanadianInstituteof llining and Metallurgy)

o s.l m 100

s

N

-

\ unconformrty co. r30 m b€tow surfdce

0 +

3

S'

N' o.s.l. m

b

50-

3 e l i k r o nA t h o b o s c o G r o u p l-:---:-:t i ". . .l :Fresh secrments

I

:-----1 Grey olte.ed sedrmentg

N

, m i n e r o t i z o t i o' 3no o p p m u

t--=-1 r"l -)l

N

, m r n e r o l i z o t i o,n1 z s o h l J

lone Ji renemotrlizotlon

A o h e b i o nW o l i o s t o n G r o u o l M o r n t y g r o p h i t e - o i o t i t e - c o r d t e r r tgan e i s s c u t c y o e g m o t o r d

through the easternpan of the depositshowingdistribution Fig. 5.6. East Athabascadistrict. Cigar L-rke, cross-sections of low and high-grade U mineralization. and halos in the AthabascaGroup of grav alteration (associatedwith Fesulfidization) and rehematitization. Note the relatively sharp boundariesof the high-grade U mineralization. (After Fouques et al. l9E6) (repnnted wirh permissiontrom The CanadianInstitute of llining and lvletallurgy)

146

5 Selected Examples of Economically Significant Types of Uranium Deposits U contents Pod

N-l

% u3or mt U30s

o.7g 65

N-3 0.69 85

N-2

SW 210 900

N-l

1t1

1180

2.56 31 3 0

>E 073 830

Condy Loke 0.35 17

I

3

+

Condy Loke Pod N-Pod I

z2

McCleon Loke

9.6 y'N-eoat

N - P o d2

tz t,

Condy'Loke ti::\

.f,9

[email protected]

6.2

o.77@

SE -Po d

€

U

Robbrl-Eors SW-Pod M r n e r o lr 2 ( r 1 l o n

+ ry M cC t e o n Loke

Arsenrdes P y r rt e Brovoite Siderite Hemotite

'-t-

60

42 A

Condy'Loke Pod

N-Pod 1

N-Pod2

'Condy'Loke

y'N-eoaszzt ,frft

a6 \=/

fAza

\;4V

w\-

SE-Pod

R o b b i t - E o r s SW-Pod Minerotizolion

I

Fe-chlo. te Mc-chio. l€ Koolrnl€ l l l ri e

c

Gnu

a

ffi

C i r c l e o r e o = l o t o l 7 o o f m r n e r o l i z o i i o nl o ) C i r c l e o r e o = t o l o l 7. ol cicy conleni {b) broDnrlrc ololrttc g n e i s s ( m e t o - p e l i t e ) AnomolousU {'200oom U/4.3m)

@

U Ore pod

-:l

U M i n e r o l i z o i i o no b o v e u n c o n f o r m i t y

mm

U M i n e r o l i z o i r o nb e l o w u n c o n f o r m i t y

Fig. 5.7. East Athabascadistrict, McClean. Correlation of U mineralizationwith graphitic gneissand rhe unconformitv is displayedin the plans (graphitic units interpreted from EM and drill hole daa)l Arcks iirow the per.entugesof ,0 and other metallic minerals and b clay minerals in the-various.orepods (numbers at circles give total percentage of roct fraction). (After Wallis et al. 1985, 1986) (reprinted with permissionfrom Th-e Canadian institute of Je,spective Mining and Metallurgy)

Examplesof Unconformitv-Contact-TypeUranium Deposits

Fig. 5.8. Eastern Athabasca Basin region, range of contents of selectedelementsin unconformity-contact deposits in the Wollaston Belt. (Heavy line gives contents for both classesof deposits, dashed line only for fracnrre-bound type mineraiizationclass1.l. l, dots representbulk and sqrarespit grab samplesfrom the Gaertner ore body, Key Lake, only sampleswith >0.1% U3Os). (After G. Ruhrmann wrinen pers. commun. basedon data from Eldorado ResourcesLtd. 1986;Fouques et ai. 1986: Ruzicka 1986. 19881Wray et ai. 1SAS)

Table 5.4, Key Lalie, Gaertner ore body, parageneticassemblagesof mineralization. (After Ruhrmann and von Pechmann1989) Assemblage U

Ni. Fe, Cu. Co. U

U and Gangue

Age m.y.

ca- 14O0

ca. 900

a. i00

Minerals

Uraninitcl

Ra-mmelsbergtel Niccolite I Gersdorffire Bravoite I Covellite Hauchocornite Breilhauptite lrrite Borrutc I ChalcopyriteI Coffinire I

Calcite Siderite Sericite Dolomite Rutile Apatrte

Uraninite II Uraninite III UranirureIV Uraoinite V

N i . F e .C u .P b ,Z n . U

Anatase RammelsbergteII Kerogen Marcasite Bomite II Gesdorffite BravoiteII

Maucherite Milterite I Bismuthinite

Galena I Vaeyle Miuerire II Niccolite II

Sohalenre Millerire lll Coffinire II Galena II Digenire Chalcopyrite II

148

5 SelectedExamplesof EconomicallySignificantTwes of Uranium Deposits

Table 5.5. Cars*'ell Structuredistrict, summaryof mineral parageneses,geologicalsettingand age of mineralization in basement and overlving sediments.(After Ruhlmann l9&i and l-aind 1986. reprinted with permission from The Canadian lnstiture of Mining & Metallurgy and the Geologrcal Associationof Canada) Subeconomic/pre-ore

Stage

Redisribution/l-ate ore

Matn ore II

Assemblage

Monaziteul:rmnr te

Pitchblende Uraninite-selenideuraninite sulfide

Uraninite sulfide

Pitchblende- Pitchblendehematite c:rbonatc

Coffinitesulfidc

Uraniferous phase

Monazile (th) Uraninite

Pitchblende Brannerite Uraninite Uraninite

Uraninite

Pitchblende

Coffinite

Nonuraniferous phase

Molvbdenite Prrite Galena

P.vrite Altaite - paraguanaiuatite Chalmpwite Guanajuatite - ciausrbalrte Galena Calavente - trogralire Freboldite - gersoorffi te Nickeline- skutterudle Galena- chalcolrrrtc Molvbdenum sulides Gold - bismuth

Gangue

Garnet

Albite Chlorite

Chlorite (Mg/Al)

Quanz

Host rock

Garnet - rich peg:rratoid

Feldsparrock

Basement& saadstone

Basement

Sandstone Basement

Basement

Sandstone Basemenr

Textural characreristics

Disseminated

Fractures

Coatings around the "zone d boules"

Fractures

Fractures

Fractures

Fractures

Characteristic element assoc,

u-lll

U-Mo-Bi-Se-S (Te-Ni-Co)

U-Mo-PbZn-Cu-S

U-Fe

U-Co-Ptr Cu

U.Si

I T

Molybdenumsulphide Galena- pynte Chalcopvnte Sphalerite Tennantite

Hematire Magnetite Limonite Goethite Gold

Pitchblende Chaicopvnte Galena Pvnte

Pl nte Galena

Caicite

Age. m.1'-'

19

1330?

1150- 1050

820-890

380

AJI ages

All ages

Types of occulTences

Sophie

Numac

Claude- D-N Dominique- Peter

OP - ClaudeDomin - Peter

Donna D-N

All n'pes

All types

" Reference see Geochronologv.

Table 5.6. Eastern AthabascaBasil region, published analvsesof selectedelementsof U mineralizerion in fracturebound deposits (class1.1.1). The ore typically containshiCh U gradesand low valuesof the otber metals except for Pb which is largell'radiogenic. (valuesare in ppm exceptwhere noted). (After a Eldorado ResourcesLtd. 1987.composite sample from 02 zone Eagle North; b Ruzicka 1986,nine drill core samples;c Ruzicka 1986.five grab samples from variouspans of the deposit) Eagle Point

Ag As Au B Ba Be Bi Co Cr Cu Fe

5 60 006

Rabbit Lake

b n.a. 7000 1



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