Anthony J. Naldrett Magmatic Sulfide Deposits Geology, Geochemistry and Exploration

Anthony J. Naldrett

Magmatic Sulfide Deposits Geology, Geochemistry and Exploration

With 325 Figures

~Springer

PROFESSOR ANTHONY J. NALDRETT DEPARTMENT OF GEOLOGY UNIVERSITY OF TORONTO 22 RUSSELL ST. TORONTO, ON MSS 3B1, CANADA

E-mail: ajnaldrett@yahoo.com

Library of Congress Control Number: 2004108879

ISBN 978-3-642-06099-1 ISBN 978-3-662-08444-1 (eBook) DOI 10.1007/978-3-662-08444-1

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Author's Forward

As the time was approaching for me to graduate from the University of Cambridge with a B.A. degree in Geology, I started looking araund the world for interesting places where I could put the degree to good use. In 1957, Canada stood out as an ideal environment for a young Anglophone, three of my co-students had a cabin hooked on the Ernpress of Britain, which was scheduled to depart from Liverpool for Montreal in late July, and I took the fourth berth in the cabin. We arrived in Montreal on 28th July 1957, and after an entertaining weekend, I took leave of my friends to look for work in Toronto. I will always remernher the Monday moming when I started my job search amongst the grey office buildings near King and Bay streets. My firststop was at the old Bank ofNova Scotia building where Falconbridge bad their offices. Geof Mitchell, Falconbridge chief geologist, and Bill Taylor, his deputy, interviewed me and affered me a job in one of the company's mines at Sudbury. I was more interested in an exploration job, but they agreed to hold the position for me until the following evening. As I continued down my list of possible employers, I came to understand one of the maxims of the mining world, "employment depends on the price of metals". The then recent decline in the price of copper (to US$0.35/lb) meant that nobody was interested in affering an exploration job to an inexperienced young geologist from England. I was back that Monday evening accepting the job in the Sudbury mines, and two days later I was off on the train to Sudbury. It tums out that from that moment on my fate was welded to that of nickel in particular, and magmatic sulfides in general!

There are two principal types of magmatic sulfide deposit, those that are sulfide-rieb, generally containing in excess of 30% sulfide, which are exploited primarily for their Ni, Cu and/or Co, with the PGE comprising a by-product, and those that contain less than 5% sulfide, which are of interest primarily because of their PGE with Ni and Cu as the by-products. For the first 20 years of my career, I worked, both as company geologist and then researcher, primarily on deposits of the first type. It came to be

VI Author's Forward

appreciated that even though the PGE were only present in trace amounts, they could tell us much about the provenance of, and the processes that had operated in the formation of these deposits. This led me into studying PGE-rich deposits at a time when there was a growing commercial interest in them, driven by their increasing use in protecting the environment.

Looking back, I appreciate the tremendous benefit that an academic can gain from sabbatical leave. My first was granted in 1972, and I accepted Wilf Ewers invitation to work with the CSIRO in Perth, Western Australia as part of their research on the developing komatiite-related Ni sulfide camp in the Bastern Goldfields. This year gave me a grounding in this style of deposit and showed me that not all magmatic sulfides ores were the same as those at Sudbury! My second sabbatical in 1980 allowed me to accept Gero von Gruenewaldt's invitation to join the Bushveld Research Institute of the University of Pretoria, and coincided with my then developing interest in PGE deposits. This was the start of a 1 0-year lang close association with South Africa and the ores of the southern part ofthat continent, and without this start, Chap. 9 would never have been written.

By the late 1980's, another factor was about to influence the direction of my science. A freer flow of information was sweeping behind the iron curtain and soon this curtain, in the shape of the Berlin wall, came tumbling down. As a result of an association with Vilen Zharikov, I had already developed a productive relationship with scientists of the Institute of Experimental Mineralogy of the Russian Academy of Sciences. The events of the late 80's gradually allowed increasing collaboration on scientific topics that previously had been closed to foreigners. In 1990 I received an invitation from Anatoly Vasily Filatov, General Director ofthe Noril'sk Kombinat, to visit the mines at Noril'sk. My first visit took place in January 1991, and was followed by four subsequent visits. These have resulted in my coming to know and make friends with many Noril'sk geologists to whom I owe a huge debt of gratitude for showing me their outstanding work and increasing my understanding of the geology of magmatic sulfides so much. In particular, I would like to acknowledge Valeri Andrew Fedorenko of TsNIGRI and formerly of the Noril'sk Expedition. His intelligence and encyclopedic knowledge of Noril'sk geology has remained of incalculable value to me and many other western scientists during our research on the Noril'sk area. Chap. 4oftbis book is based on research stimulated by my visits to Noril'sk.

Author's Forward VII

As research on the Noril'sk deposits moved into top gear, another "distraction" appeared on the horizon! A small company, Diamond Fields Resources Inc., had encountered a deposit of nickel sulfide in the course of their search for diamond indicator minerals in central Labrador. They asked me to augment their knowledge on the subject of nickel by acting as their consultant. I agreed, and this led to a research programme that was collaboratively funded by Canada's Natural Seiences and Engineering Research Council and initially Diamond Fields and then their successor company, the Voisey's Bay Nickel Company. The world-wide interest that was stimulated by the Voisey' s Bay discovery meant that many distinguished researchers were eager to collaborate in the programme, and l've done my best to summarise the results in Chap. 6.

Despite the opportunities that have presented themselves to wander far from home, and the distractions that these wanderings have brought, home has always been Sudbury. It's where I started in 1957, and where I have always returned intellectually. The evolution in geological understanding about Sudbury over the last 40-50 years has been extraordinarily exciting, and it has been a privilege to watch it and make some small contributions myself. The evolution came about because of the lateral thinking of one man, Robert Dietz, who developed the impact hypothesis. This was what was needed to bring many workers, with backgrounds that would never have drawn them to take an interest in a layered intrusion and its nickel deposits, to come to Sudbury and apply their special knowledge. Sudbury is an object lesson as to the importance of a multi-faceted approach in research, and, again, I have tried to capture salient features of this lesson in Chap. 8.

I cannot conclude without paying especial thanks to certain individuals who have helped me so much during my scientific career. Professor Edward Hawley, Professor and Chair at Queen's University, was the reigning authority on Sudbury mineral deposits when I had decided to artend graduate school, and he taught me how to ask the right questions without which research is pointless. Gunnar Kullernd passed through Queen's on a lecture tour in 1963, and invited me to work with him as a Post-Doctoral Fellow at the Geophysical Laboratory from 1964 to 1967. Working with Gunnar and others at "The Lab" exposed me to the use of experimental data in the solution of geological problems. It also allowed me to mix and make friends with the very vital group of young experimental and theoretical petrologists who were working in

VIII Author's Forward

Washington DC in the mid 60's. These were undoubtedly the halcyon days of the US Geological Survey's interest in theoretical, as opposed to empirical, approaches to the solution of geological problems. Professor Les Nuffield invited me to retum to Canada from Washington and take up a position at the University of Toronto in 1967. I can never thank him enough for giving me the time and resources to develop my research interests during my early years, years when it is so easy for a young professor to be "ground down" by the daily preparation of courses and departmental administration. Above all, I thank my students, Post-doctoral Fellows and Research Associates, to whom this book is dedicated, and whose ideas and hard work have contributed so much to the University of Toronto's research output on magmatic sulfides.

Tony Naldrett University Professor Emeritus, University ofToronto, April2004

Dedication

To my Students, Post-doctoral Fellowsand Research Associates in the Department of Geology,

University of Toronto

NickAmdt Mohammed Asif Steve Bames Sarah-Jane Bames Tucker Barrie Alistair Borthwick Gerhard Brugmann Greg Cameron Ian Campbell Gang Chai Tom Clark Paul Coad Debbie Conrod Chris Doyle Murray Duke DentonEbel Valeri Fedorenko Cesar Ferreira Filho Derek Fisher David Good Megally Graterol Tony Green Larry Greenman Roger Hewins

Their's was the greater part

Eric Hoffman Craig Jowett Dorota Kiersnowski Ross Large Chusi Li Peter Lightfoot Heather MacDonald Paul Mainwaring Dave Moore Ted Muir Walter Peredery Reza Pessaren DonRae "Raja" Rajamani B.V. Rao Eva Schand! Randy Scott Brian Scribbins Tim Searcy Hiromi Shima Jagomohan Singh John Thompson Oleg Valeyev

Acknowledgments

This book would never have been written without the enormous amount of help provided by Valeri Fedorenko. Valeri was the translator of the Russian version, published in 2003. He not only drafted all of the figures, but gave encouragement and helpful advice at all stages while I was writing it and it was being prepared for publication.

I am grateful for the copyright holders of the originals of many of the figures reproduced in this book for permission to use them. In particular, I would like to acknowledge:

The Canadian Institute of Mining, Metallurgy and Petroleum for their permission to reprint Figures 3.11 and 3.14, previously published in the Transactions of the Canadian Institute of Mining and Metallurgy, vol. 76; Figures 10.6 and 10.7, previously published in the Bulletin ofthe Canadian Institute of Mining and Metallurgy, vol. 77; Figure 6.7, previously published in Exploration and Mining Geology, vol. 5; and Figures 9.3, 9.4, 9.8, 9.9, 9.14, 9.20, 9.26, 9.27, 9.35, 9.36, 9.38, 9.40, 9.41, 9.42, 9.43, 9.44, 9.45, 9.46 and 10.19, previously published in "The geology, geochemistry, mineralogy and mineral beneficiation of platinum-group elements" Special Publication No. 54.

The Oxford University Press for their permission to reprint Figures 2.1 0, 2.11, 3.3, 5.13, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6 and 9.48 previously published in the Journal of Petrology; and Figures 2.2, 2.16, 9.5, 9.7, 9.13 and 9.49 previously published in MAGMATIC SULFIDE DEPOSITS by Anthony J. Naldrett, Copyright - 1989 by Oxford University Press Inc. and used by permission of the Oxford University Press Inc.

The American Journal of Science for their permission to reprint Figures 6.32, 6.33, and 6.34 from the paper by A. Kerr appearing in the American Journal of Science, vol. 303.

Contents

1 Introduction ............................................................................................ l 1.1 Classification of Magmatic Sulfide Deposits .................................. 1 1.2 Size and Composition ofDeposits ................................................. 13 1.3 General Considerations for the Genesis of the Deposits ............... 17

2 Theoretical considerations .................................................................. 21 2.1 The solubility of su1fur in silicate melts ........................................ 21

2.1.1 Effect ofTemperature ............................................................. 24 2.1.2 Effect of Pressure .................................................................... 25 2.1.3 Influence of fe1sification of mafic/ultramafic magma ............ 27 2.1.4 Variation of Solubility of Sulfide During Fractional Crystallization of a Layered Intrusion .............................................. 27

2.2 Partitioning of Chalcophile Metals between Sulfides and Silicate Melts ..................................................................................................... 30

2.2.1 Partitioning of nickel between sulfide and silicate liquids ..... 31 2.2.2 Partitioning ofNi between Olivine and sulfide liquid ............ 35 2.2.3 Partitioning ofPGE between Sulfide and Silicate Melts ........ 36 2.2.4 Effect ofratio ofmagma to sulfide ......................................... 40

2.3 Relevant Phase Equilibria .............................................................. 42 2.3.1 The System Fe-S-O and its application to natural ore magmas ............................................................................................. 43 2.3.2 Relevant Sulfide Systems ....................................................... 50

2.4 Fractional crystallization of sulfide liquids ................................... 57 2.4.1 Partition coefficient ofNi and Cu between mss and coexisting sulfide liquid ..................................................................................... 59 2.4.2 Partition of noble metals ......................................................... 59 2.4.3 Modeling of fractional crystallization of sulfide melts ........... 62

2.5 Extemal sources of sulfur ............................................................... 63

3 Komatiite-Related Deposits ................................................................ 67 3.1 Archean Komatiite-Related Deposits ............................................ 67

3.2.1 General information about Archean komatiites and associated mineralization ................................................................................... 67

XII Contents

3 .1.2 Deposits of the Wiluna-N orseman greenstone belt (Eastem Goldfields, Western Australia) ......................................................... 71

3.2 Early Proterozoic Komatiite-Related Deposits ............................. 97 3.2.1 Deposits ofthe Cape Smith belt, Quebec, Canada ............... 101 3.2.2 Deposits ofthe Thompson Nickel Belt, Manitoba, Canada .118

4 Ore deposits associated with flood basalt volcanism ...................... 137 4.1 Ni-Cu-PGE deposits ofthe Noril'sk region, Siberia .................... 139

4.1.1 Geological Setting ................................................................ 141 4.1.2 Permo-Triassic Volcanism ................................................... 144 4.1.3 Ore-Bearing and Related Intrusions ..................................... 163 4.1.4 Ore Deposits ......................................................................... 195 4.1.5 Summary ofthe model for the Noril'sk Ore Camp .............. 238

4.2 Mineralization ofthe Lake Superior Region (North America) .... 239 4.2.2 Duluth Complex ................................................................... 246 4.2.3 Crystal Lake Gabbro ............................................................. 257 4.2.4 Conclusions arising from Keweenawan Mineralization ....... 258

4.3 Deposits Associated with the Karoo Flood Basalt of Southem Africa .................................................................................................. 259

4.3.1 General information .............................................................. 259 4.3.2 Geology of the Insizwa Complex ......................................... 261 4.3.3 The Insizwa intrusion at Waterfall Gorge ............................ 264 4.3.4 Petrography ........................................................................... 269 4.3.5 Mineralogy and Mineral Chemistry ..................................... 270 4.3.6 Evidence relating to Contamination and Ore Genesis at Waterfall Gorge .............................................................................. 273 4.3.7 Conclusions for the Insizwa Complex .................................. 276

4.4 Flood Basalt Provinces as Environments for Mineralization ...... 277

5 Deposits of the Pechenga area, Russia ........................................•.... 279 5.1 Regional geology ......................................................................... 279 5.2 Geology ofthe Pechenga Structure ............................................. 280 5.3 Geochemistry ofFerropicritic Rocks ........................................... 287 5.4 Comagmatic Relationship between the Ferropicritic V oleanie rocks and the Ore-bearing Gabbro-wehrlite Intrusions ...................... 288 5.5 Gabbro-wehrlite intrusions .......................................................... 290 5.6 Magmatic Sulfide Deposits ......................................................... 296

5 .6.1 General information .............................................................. 296 5.6.2 Sulfur isotopic Composition ofOres and Country rocks ...... 297 5.6.3 Ni, Cu and PGE variations and Re-Os isotopic systematics ofthe Ores and Ore-bearing Intrusions ......................................... 301

5.7 A Genetic Model for the Pechenga Ores ..................................... 304

Contents XIII

6 Voisey's Bay and other deposits, Labrador, Canada .....•.....•......... 307 6.1 History of discovery and exploration .......................................... 307 6.2 General geology ........................................................................... 307 6.3 Geology ofthe Voisey's Bay intrusion ....................................... 310 6.4 Petrography of Rock Types ......................................................... 320 6.5 Olivine and Plagiodase Compositions ........................................ 323

6.5.1 Stratigraphie Variation in Olivine and Plagiodase Composition ................................................................................... 323 6.5.2 Ni and Fo content ofOlivine in Different Rock Sequences .325

6.6 Geochemistry ofVoisey's Bay Rocks ......................................... 327 6.6.1 Major Elements ..................................................................... 327 6.6.2 Trace Elements ..................................................................... 329 6.6.3 Isotope Geochemistry ........................................................... 335

6.7 Mineralization within the Voisey's Bay Intrusion ....................... 338 6.7.1 Types ofMineralization ........................................................ 338 6. 7.2 The Ni and Cu content of Sulfide Mineralization from Different Mineralized Environments .............................................. 341 6.7.3 Noble metal content ofSulfides from Different Mineralised Environments .................................................................................. 350 6. 7.4 Sulfur Isotopes ...................................................................... 356

6.8 Geological Model ........................................................................ 357 6.9 Condusions as to the genesis ofthe Voisey's Bay Deposit ........ 360 6.10 Other deposits associated with the Nain Plutonic Suite ............ 361

6.10.1 Troctolite/gabbro related .................................................... 361 6.1 0.2 Mineralization associated with Anorthosites ...................... 3 70 6.10.3 Mineralization associated with Ferrodiorites ...................... 371 6.1 0.4 Lessons to be learned from the Minera1ization associated with the Nain Plutonic Suite ........................................................... 372

7 The Jinchuan deposit, China ............................................................ 373 7.1 Geology ofthe deposit ................................................................. 374 7.2 Petrography .................................................................................. 375 7.3 Geochemistry Of The Intrusive Rocks ........................................ 3 79

7.3.1 Majorelements ..................................................................... 379 7.3.2 Trace elements ...................................................................... 384

7.4 Olivine Compositions .................................................................. 384 7.5 Petrogenesis ................................................................................. 387

7.5.1 MgO/(MgO+FeO) ratio ofthe parental magma ................... 387 7.5.2 Composition ofthe parental magma ..................................... 387 7.5.3 Constraints on Magma Emplacement and Differentiation ... 389

7.6 Sulfide Mineralization ................................................................. 391 7.6.1 Geology ofthe Ore Bodies ................................................... 391

XIV Contents

7.6.2 Geochemistry of Sulfide Ores .............................................. 393 7. 7 MetaBogenesis ............................................................................. 402 7.8 Genetic model for the Jinchuan deposit... ................................... .403

8 Deposits of the Sudbury Camp, Ontario, Canada .......................... 405 8.1 Some History ............................................................................... 405 8.2 Geology ....................................................................................... 406

8.2.1 Regional Setting ................................................................... 406 8.2.2 Geology of the Sudbury Structure ........................................ 408 8.2.3 Evidence for Explosive Nature of the Sudbury Structure ... .413

8.3 Units ofthe Sudbury Igneous Complex ...................................... .416 8.3.1 MainMass ............................................................................ 417 8.3.2 Sublayer and its Inclusions ................................................... 420 8.3.3 Offsets ................................................................................... 424

8.4 Geochemistry ofthe Sudbury Igneous Complex ........................ .424 8.4.1 Major Elements .................................................................... 424 8.4.2 Trace Elements ..................................................................... 429 8.4.3 Isotopes ................................................................................. 436

8.5 Sulfide Ore Deposits .................................................................... 439 8.6 Metal contents of different Ore Deposit Types .......................... .449 8.7 Ore mineralogy ............................................................................ 451 8.8 Relationship of Ore Deposits to the Rocks of the Complex ....... .457 8.9 Discussion ofthe Origin ofthe SIC and its Mineralization ........ .458

8.9.1 Impact Events ....................................................................... 458 8.9.2 Development ofthe SIC and its Associated Mineralization.461

8.10 Conclusions ............................................................................... 477

9 Platin um group element (PGE) deposits .......................................... 481 9.1 PGE in Mantle-derived Rocksand Mafic/Ultramafic Lavas ....... 481 9.2 Mechanisms for the Concentration of PGE ................................. 489 9.3 Classification ofPGE deposits on their Morphology and composition ........................................................................................ 492 9.4 Deposits in layered intrusions ...................................................... 495

9.4.1 Bushveld Complex ............................................................... 496 9 .4.2 Stillwater Complex ............................................................... 523 9.4.3 Great Dyke of Zimbabwe ..................................................... 532 9.4.4 Munni Munni Complex, Western Australia ......................... 538 9.4.5 Layered intrusions ofNorthem Finland ............................... 540 9.4.6 Intrusions of Sudbury area in Central Ontario, Canada ........ 554 9 .4. 7 Intrusions in East Greenland ................................................. 561 9.4.8 The Sonju Lake Intrusion, Duluth Complex ......................... 564 9.4.9 Genetic Models for Deposits in Layered Intrusions ............. 566

Contents XV

9.5 Non-stratabound Deposits ........................................................... 580 9.5.1 Lac des lies PGE-bearing Complex ...................................... 580 9.5.2 The Longwoods Igneous Complex, New Zealand ................ 591

9.6 Deposits of the Urals Platinum Belt ............................................ 592 9.6.1 Nizhny Tagil type Mineralization ......................................... 593 9.6.2 Volkovsky and Baron type Deposits .................................... 600

9.7 Summary ...................................................................................... 610

10 Summary and use of genetic concepts in exploration ................... 613 10.1 Concepts used in Exploration for Ni-Cu Ores ........................... 613

I O.I.I Genetic Concepts and their use .......................................... 613 I 0.1.2 Empirical Concepts and their use ....................................... 6I7 IO.I.3 Teetonic Setting ofthe Deposits ......................................... 6I8 I 0.1.4 Methods for Determining whether a given Igneous Body has developed Immiscible Sulfide .................................................. 627 I O.I.5 Use of Cu/Zr Ratios in volcanic rocks and layered intrusions ........................................................................................ 648 IO.l.6 Use ofthe Noril'sk model in selecting other regions for Exploration ..................................................................................... 650

I 0.2 Exploration for PGE in Layered Intrusions: Concepts and Methods .............................................................................................. 655

I0.2.1 Use ofCu/Pd and Cu/Pt ratios in bulk rock compositions ( example of the Bushveld Complex) .............................................. 658 I0.2.2 Use ofvariation ofPGE contents in bulk rock compositions and calculated PGE tenors in sulfides (example ofthe Fox River Sill) ................................................................................................. 658

Appendix ................................................................................................. 669

References ............................................................................................... 677

Index ........................................................................................................ 725

List of abbreviations

An - Anorthite Ap- Apatite Aug-Augite bn-Bomite bnss - Bomite solid solution Br - Bronzite cc - Chalcocite ccss - Chalcocite solid solution Chr - Chromite cp - Chalcopyrite Cpx- Clinopyroxenite cub - Cubanite cv - Covellite D- Nemst partition coefficient dg - Digenite Di - Diopside En - Enstatite Fa- Fayalite FeOT- Total Fe calculated as

Feü Fo- Forsterite f02 -Oxygen fugacity fS2 -Sulfur fugacity god- Godlevskite hz - Heazlewoodite Ilm - Ilmenite iss - Intermediate solid solution K0 - Exchange partition

coefficient L - Liquid in phase diagrams Liq -Liquid in text M/S - Metallsulfur ratio, e.g.

Ni/S, Pt/S mh - Mooihoekite mill - Millerite mod%- Modalpercent MORB- Mid Ocean Ridge

Basalt

mss - Monosulfide solid solution OIB - Oceanic Island Basalt 01- Olivine Opx - Orthopyroxene PI - Plagiodase pn - Pentlandite pn(h)- High-temperature

pentlanditein phase diagrams

pn(l)- Low-temperature pentlandite in phase diagrams

po - Pyrrhotite po(h)- Pyrrhotite (hexagonal) po(m)- Pyrrhotite (monoclinic) poss - Pyrrhotite solid solution ppb = mg/t ppm= g/t put- Puteronite py- Pyrite Q -Quartz R = R Factor- Mass ratio of

silicate magma to sulfide liquid (involved in equilibration)

SCSS- Sulfur content at sulfide saturation

Sil.m -Silicate magma sp - Sphalerite Sul- Sulfide Sul.l - Sulfide liquid Sul.m -Sulfide melt tal- Talnakhite TiMt- Titaniferous magnetite tr - Troilite Vap -Vapour viol- Violarite vs- Vaesite