Table Of ContentAnthony 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: [email protected]
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 10 -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
Their's was the greater part
NickAmdt Eric Hoffman
Mohammed Asif Craig Jowett
Steve Bames Dorota Kiersnowski
Sarah-Jane Bames Ross Large
Tucker Barrie Chusi Li
Alistair Borthwick Peter Lightfoot
Gerhard Brugmann Heather MacDonald
Greg Cameron Paul Mainwaring
Ian Campbell Dave Moore
Gang Chai Ted Muir
Tom Clark Walter Peredery
Paul Coad Reza Pessaren
Debbie Conrod DonRae
Chris Doyle "Raja" Rajamani
Murray Duke B.V. Rao
DentonEbel Eva Schand!
Valeri Fedorenko Randy Scott
Cesar Ferreira Filho Brian Scribbins
Derek Fisher Tim Searcy
David Good Hiromi Shima
Megally Graterol Jagomohan Singh
Tony Green John Thompson
Larry Greenman Oleg Valeyev
Roger Hewins
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
