Understanding Mineral Deposits

856 Pages·2000·28.676 MB·English

by  Kula C. Misra (auth.)

UUNNDDEERRSSTTAANNDDIINNGG MMIINNEERRAALL DDEEPPOOSSIITTSS
U nderstanding
Mineral Deposits
by
Kula c. Misra
Department of Geological Sciences,
The University ofTennessee, Knoxville, U.S.A.
SPRINGER-SCIENCE+BUSINESS MEDIA, B.V.
A c.I.P. Catalogue record for this book is available from the Library of Congress.
ISBN 978-94-010-5752-3 ISBN 978-94-011-3925-0 (eBook)
DOI 10.1007/978-94-011-3925-0
Printed on acid-free paper
AII Rights Reserved
© 2000 K.C. Misra
Softcover reprint of the hardcover 1s t edition 2000
No part of the material protected by this copyright notice may be reproduced
or utilized in any form or by any means, electronic or mechanical,
incJuding photocopying, recording or by any information storage and
retrieval system, without written permission from the copyright owner.
To my wife, Geeta,
for her patience
during the years ofp reoccupation with the book
and the clutter it generated all around our home
TABLE OF CONTENTS
PREFACE xiii
CHAP1ER 1. INTRODUCTION 1
1.1. Mineral Deposit versus Orebody 1
1.2. Styles of Mineralization and Morphology of Mineral Deposits 2
1.3. Distribution of Mineral Deposits 3
1.3. Understanding Mineral Deposits 4
CHAP1ER 2. FORMATION OF MINERAL DEPOSITS 5
2.1. Ore-fonning Processes 5
2.2. Orthomagmatic Processes 6
2.3. Examples of Orthomagmatic Deposits 18
2.4. Sedimentary Processes 33
2.5. Metamorphic Processes 49
2.6. Examples of Metamorphic Deposits 54
2.7. Hydrothennal Processes 56
2.8. Examples of Hydrothennal Deposits 73
2.9. Summary 89
2.10. Recommended Reading 92
CHAP1ER 3. IN1ERPRETATION OF MINERAL DEPOSITS -I 93
3.1. Introduction 93
3.2. Geologic Setting 94
3.3. Ore Minerals 94
3.4. Ore-Gangue Textures 95
3.5. Stability Relations of Ore Minerals and Assemblages 107
3.6. Hydrothennal Alteration 116
3.7. Zoning 124
3.8. Fluid Inclusions 131
3.9. Trace Element Distribution 142
3.10. Recommended Reading 147
CHAP1ER 4. IN1ERPRETATION OF MINERAL DEPOSITS -II 148
4.1. Stable Isotopes 148
4.2. Suifurlsotopes 153
vii
viii CONTENTS
4.3. Carbon Isotopes 164
404. Oxygen and Hydrogen Isotopes 168
4.5. Lead Isotopes 177
4.6. Strontium Isotopes 186
4.7. Geothermometry and Geobarometry 193
4.8. Metamorphism of Ore Assemblages 219
4.9. Age of Mineralization 228
4.10. A Comprehensive Example: The Creede District, Colorado, USA 231
4.11. Summary 235
4.12. Recommended Reading 237
CHAPTER 5. CHROMITE DEPOSITS 238
5.1. Introduction 238
5.2. Types of Deposits 238
5.3. Distribution 239
SA. Stratiform Deposits 240
5.5. Podiform Deposits 244
5.6. Examples 248
5.7. Chromite Composition 256
5.8. Origin 261
5.9. Metallogenesis 267
5.10. Summary 270
5.11. Recommended Reading 272
CHAPTER 6. NICKEL (-COPPER) SULFIDE DEPOSITS 273
6.1. Introduction 273
6.2. Distribution 273
6.3. Types of Deposits 275
604. Examples 281
6.5. Ore Composition 292
6.6. Hydrothermal Alteration and Metamorphism 298
6.7. Origin of Kambalda-type Deposits 299
6.8. Metallogenesis 308
6.9. Summary 316
6.10. Recommended Reading 318
CHAPTER 7. PLATINUM-GROUP ELEMENT (pGE) DEPOSITS 319
7.1. Introduction 319
7.2. Types of Deposits 321
7.3. Examples 323
7 A. Ore Composition 335
7.5. Origin of Merenskky-type PGE Deposits 337
CONTENTS IX
7.6. Orgin of PGE-enriched Chromitites in Layered Intrusions 347
7.7. Metallogenesis 350
7.8. Summary 351
7.9. Recommended Reading 352
CHAPTER 8. PORPHYRY DEPOSITS 353
8.1. Introduction 353
8.2. Porphyry Copper Deposits 353
8.3. Porphyry Molybdenum Deposits 397
8.4. Porphyry Tin Deposits 409
8.5. Summary 412
8.6. Recommended Reading 413
CHAPTER9. SKARNDEPOSITS 414
9.1. Introduction 414
9.2. Skarns and Skarn Deposits 414
9.3. Types of Skarns and Skarn Deposits 417
9.4. Examples 428
9.5. Origin 437
9.6. Metallogenesis 441
9.7. Summary 448
9.8. Recommended Reading 449
CHAPTER 10. VOLCANIC-ASSOCIATED MASSIVE SULFIDE 450
(VMS) DEPOSITS
10.1. Introduction 450
10.2. Distinguishing Features 451
10.3. Distribution 452
10.4. Types of Deposits 455
10.5. Examples 464
10.6. Ore Composition 470
10.7. Hydrothermal Alteration 473
10.8. Metamorphism and Deformation 477
10.9. Origin 478
10.10. Metallogenesis 487
10.11. Summary 495
10.12. Recommended Reading 496
CHAPTER 11. SEDIMENT-HOSTED MASSIVE ZINC-LEAD 497
SULFIDE (SMS) DEPOSITS
11.1. Introduction 497
11.2. Distinguishing Features 498
x CONTENTS
11.3. Distribution 500
11.4. Types of Deposits 504
11.5. Examples 504
11.6. Ore Composition 521
11.7. Hydrothermal Alteration 523
11.8. Origin 524
11.9. Metallogenesis 530
11.10. Summary 538
11.11. Recommended Reading 538
CHAPTER 12. SEDIMENT-HOSTED STRATIFORM COPPER (SSC) 539
DEPOSITS
12.1. Introduction 539
12.2. Distinguishing Features 540
12.3. Distribution 541
12.4. Types of Deposits 544
12.5. Examples 545
12.6. Ore Composition 559
12.7. Origin 561
12.8. Metallogenesis 567
12.9. Summary 571
12.10. Recommended Reading 572
CHAPTER 13. MISSISSIPPI VALLEY-TYPE (MVT) ZINC-LEAD 573
DEPOSITS
13.1. Introduction 573
13.2. Distinguishing Features 573
13.3. Distribution 575
13.4. Examples 578
13.5. Ore Composition 588
13.6. Alteration 590
13.7. Brecciation 591
13.8. Origin 593
13.9. Metallogenesis 602
13.10. Summary 607
13.11. Comparison of VMS, SMS, SSC, and MVT Deposits 608
13.12. Recommended Reading 612
CHAPTER 14. URANIUM DEPOSITS 613
14.1. Introduction 613
14.2. Types of Deposits and Distribution 613
14.3. Examples 627
CONTENTS
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14.4. Mineralogy and Textures 635
14.5. Origin 636
14.6. Metallogenesis 647
14.7. Summary 658
14.8. Recommended Reading 659
CHAPTER 15. PRECAMBRIAN IRON-FORMATIONS 660
15.1. Introduction 660
15.2. Iron-formation 660
15.3. Distribution 661
15.4. Iron-formation Facies 662
15.5. Types of Iron-formations 667
15.6. Examples 669
15.7. Ore Composition 675
15.8. Metamorphism 678
15.9. Secondary Enrichment 680
15.10. Origin 680
15.11. Time-bound Distribution ofIron-formations 694
15.12. Summary 696
15.13. Recommended Reading 697
CHAPTER 16. GOLD DEPOSITS 698
16.1. Introduction 698
16.2. Distribution 699
16.3. Types of Gold Deposits 699
16.4. Examples 725
16.5. Origin of Hydrothermal Gold Deposits 731
16.6. Metallogenesis 749
16.7. Summary 756
16.8. Recommended Reading 759
REFERENCES 761
INDEX 839
PREFACE
Mineral deposits have supplied useful or valuable material for human consumption
long before they became objects of scientific curiosity or commercial exploitation. In
fact, the earliest human interest in rocks was probably because of the easily accessible,
useful (e.g., red pigment in the form of earthy hematite) or valuable (e.g., native gold
and gemstones) materials they contained at places. In modem times, the study of
mineral deposits has evolved into an applied science employing detailed field
observations, sophisticated laboratory techniques for additional information, and
computer modeling to build complex hypotheses. Understanding concepts that would
someday help geologists to find new mineral deposits or exploit the known ones more
efficiently have always been, and will continue to be, at the core of any course on
mineral deposits, but it is a fascinating subject in its own right, even for students who
do not intend to be professional economic geologists. I believe that a course on
mineral deposits should be designed as a "capstone course" that illustrates a
comprehensive application of concepts from many other disciplines in geology
(mineralogy, stratigraphy and sedimentation, structure and tectonics, petrology,
geochemistry, paleontology, geomorphology, etc.).
This book is intended as a text for such an introductory course in economic
geology, primarily for senior undergraduate and graduate students in colleges and
universities. It should also serve as a useful information resource for professional
economic geologists. The overall objective of the book is to provide the reader with a
critical understanding of selected classes mineral deposits: how are they distributed in
space and geologic time, what are their distinguishing and general characteristics, and
what can be inferred about their genesis from the available data. The expectation is
that the information and discussions in this text will provide students with an insight
into the formulation of appropriate exploration strategies for various classes of mineral
deposits and kindle their interest in further research on aspects of mineral deposits that
are poorly understood or that remain unresolved.
As an applied discipline, the study of economic geology requires a background in
other disciplines of geology (particularly mineralogy, petrology, structural geology,
and stratigraphy and sedimentation) as well as in allied sciences, such as physics and
chemistry. It is assumed that the student has had one or more courses in these subjects
and is in a position to appreciate the applications of various principles taught in those
courses to issues related to mineral deposits. There is an emphasis on geochemistry
throughout the book; this is necessary because the formation of almost all mineral
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