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Reviews in Economic Volume 12

APPLICATION OF RADIOGENIC ISOTOPES TO DEPOSIT RESEARCH AND EXPLORATION

CONTENTS

Pb Isotopes, Ore Deposits, and R.M. Tosdal, J.L. Wooden, and R.M. Bouse Metallogenic Terranes Re-Os Isotope of Magmatic D.D. Lambert, J.G. Foster, L.R. Frick, and E.M. Ripley Ore Systems Metallogenesis in Continental Margins: J. Ruiz and R. Mathur Re-Os Evidence from Deposits in Chile 40Ar/39Ar of Processes in Ore Deposits P.M. Vasconcelos Integrative Geochronology of Ore Deposits: J.T. Chesley New Insights into the Duration and Timing of Isotopic Dating of Diamonds D.G. Pearson and S.B. Shirey In Situ Analysis of Radiogenic Isotopes with Emphasis on R.A. Stern Ion Microprobe Techniques and Applications

Editors D.D. Lambert and P.E. Brown

SOCIETY OF ECONOMIC , INC. Society of Economic Geologists, Inc.

Reviews in , Vol. 12 Application of Radiogenic Isotopes to Ore Deposit Research and Exploration D.D. Lambert and P.E. Brown, Editors

Additional copies of this publication can be obtained from

Society of Economic Geologists, Inc. 7811 Shaffer Parkway Littleton, CO 80127 www.segweb.org

ISBN: 978-1-629495-70-5 The Authors:

Robin M. Bouse D. Graham Pearson Paulo Vasconcelos U.S. Department of Geological Sciences Department of Sciences 345 Middlefield Road Durham University University of Queensland Menlo Park, CA 94025 South Road Brisbane, QLD 4072 USA Durham DH1 3LE Australia Telephone: 650.329.4448 U.K. Telephone: 61.7.3365.2297 Email: [email protected] Telephone: 44.191.374.4701 Email: Email: [email protected] [email protected] John Chesley Department of Geosciences Edward M. Ripley Joseph L. Wooden University of Arizona Department of Geological Sciences U.S. Geological Survey Tucson, AZ 85721 Indiana University 345 Middlefield Road USA Bloomington, IN 47405-5101 Menlo Park, CA 94025 Telephone: 520.621.6024 USA USA Email: [email protected] Telephone: 812.855.5581 Telephone: 650.725.9237 Email: [email protected] Email: [email protected] Jeffrey G. Foster BHP Discovery Joaquin Ruiz 40 McDougall Street Department of Geosciences Brisbane, QLD 4064 University of Arizona Australia Tucson, AZ 85721 Telephone: 61.7.3278.5733 USA Email: [email protected] Telephone: 520.621.6024 Email: [email protected] Louise R. Frick Victorian Institute of Earth and Steven B. Shirey Planetary Sciences Department of Terrestrial Magnetism Department of Carnegie Institution of Washington Monash University 5241 Broad Branch Road, N.W. Melbourne, VIC 3168 Washington, D.C. 20015 Australia USA Telephone: 61.3.9905.4893 Telephone: 202.686.4370 Email: Email: [email protected] [email protected] Richard A. Stern David D. Lambert J.C. Roddick Ion Microprobe Victorian Institute of Earth and Laboratory Planetary Sciences Geological Survey of Canada Department of Earth Science 601 Booth St. Monash University Ottawa, ON K1A 0E8 Melbourne, VIC 3168 Canada Australia Telephone: 613.995.8935 Telephone: 61.3.9905.5767 Email: [email protected] Email: [email protected] Richard M. Tosdal Deposit Research Unit Ryan Mathur Department of Earth and Ocean Department of Geosciences Sciences University of Arizona University of British Columbia Tucson, AZ 85721 Vancouver, BC V6T 1Z4 USA Canada Telephone: 520.621.6024 Telephone: 604.822.6136 Email: [email protected] Email: [email protected]

ii PREFACE

The concept for Reviews in Economic Geology: Application included is one chapter devoted to the isotopic dating of di- of Radiogenic Isotopes to Ore Deposit Research and Exploration amonds. This study has profound implications for diamond grew out of discussions between scientists at several cen- genesis, the longevity of portions of the Earth’s upper man- ters for ore deposit studies in the United States, Canada, tle, and diamond exploration strategies in Archean cratonic and Australia. We recognized that there was a need for a settings. book that illustrates the diverse applications of radiogenic We sincerely hope that this volume makes members of in the mineral exploration arena. the economic geology community more aware of the The purpose of this volume and of the Society of Eco- broad field of radiogenic isotope geochemistry and the nomic Geologists short course is to provide economic geol- potential applications to their own research and explo- ogists, and the students of economic geology, with the fun- ration problems. The volume editors/short course con- damentals of the most commonly used radiogenic isotope venors and SEG editors are indebted to all of the authors systems and up-to-date information on applications of these for their efforts in the production of the short course and important tools to understanding ore-forming processes. the resulting volume. The editors would especially like to The volume covers the fundamentals of the more tradi- thank Lisa Laird of SEG for her extreme patience during tional (Pb, Rb-Sr, Sm-Nd) as well as the more exotic (Re-Os) the final stages of production of this Reviews volume. isotope systems in both magmatic and hydrothermal min- eral deposits. Unique new applications of Ar-Ar geochronol- David D. Lambert ogy in understanding supergene processes are also pre- Joaquin Ruiz sented, as are the latest in situ U-Pb geochronology techniques using SHRIMP microbeam technology. Finally,

iii BIOGRAPHIES ROBIN M. BOUSE received her BS degree from Duke DAVID D. LAMBERT received his PhD degree in geo- University and an MS degree from the University of Rhode chemistry from the Colorado School of Mines in 1982. He Island. In 1995, she received a PhD from the University of has worked for the Branch of Isotope Geology (U.S. Geo- Arizona. As a doctoral candidate, Bouse studied ore de- logical Survey) in Denver; Texas Christian University in posits and isotope geochemistry, with emphasis on por- Fort Worth; and the Department of Terrestrial Magnetism phyry copper deposits in Arizona. She is interested in the at Carnegie Institution of Washington in Washington, origin of in ore deposits and their use, fate, and D.C. In 1990, he joined the Department of Earth Sciences transport in the environment. Since 1994, Bouse has been at Monash University (Melbourne, Australia), where he with the USGS Water Resources Division in Menlo Park, the Research Group. The prime focus California, where she has concentrated on isotope geo- of this group is the study of igneous processes that are chemistry and its application to tracing sources of metals recorded in ultramafic- intrusions, mantle xenoliths, in the environment. and flood successions, ultrapotassic rocks, and porphyry system—in particular, those JOHN T. CHESLEY began his career in exploration with processes that concentrated strategic mineral resources of a BSc degree in geology from Oregon State University. He , , copper, , the -group ele- received his MSc degree from OSU in 1986 and spent the ments, and diamonds. His research and teaching is cen- next two years helping set up the 40Ar/39Ar facility at the tered on the role of lithospheric in the pet- U.S. Geological Survey in Denver. A continuing interest in rogenesis of giant ore deposits and in new applications of ore deposits led to his completion of a PhD degree at the trace element and radiogenic isotope geochemistry in University of Michigan in 1993. Chesley’s thesis was enti- tracing elemental pathways in magmatic and hydrother- tled, “Geochronology of Hydrothermal Ore Deposits.” For mal systems. He is a Fellow of the Society of Economic Ge- this, he used Sm-Nd in fluorite for direct dating of ore de- ologists and a member of the American Geophysical posits; he was the first person to do so. In conjunction with Union, Geochemical Society, and the Geological Societies other researchers at the University of Michigan and the of America and Australia. University of Arizona, Chesley has shown the importance of directly dating ore deposits and the application of mul- D. GRAHAM PEARSON is a graduate of the Royal School tiple isotopic dating methods toward understanding the of Mines, Imperial College, London. He completed a PhD overall lifetime of hydrothermal systems. He has worked at Leeds University in 1989, studying graphitised dia- with the U-Pb, Ar-Ar, Rb-Sr, Sm-Nd and Re-Os systems. monds in the Beni Bousera peridotite massif, north Mo- Currently he is a Research Associate at the University of rocco. He then undertook postdoctoral work at the De- Arizona, where he helped set up the Re-Os facility and partment of Terrestrial Magnetism (DTM), Carnegie continues his research on the geochronology of ore de- Institution of Washington, applying the Re-Os isotope sys- posits. His research horizons have broadened to include tem to dating mantle xenoliths in kimberlites. This work the timing of formation of Archean cratons, /mantle continued back in the UK, where he established an Re-Os interaction, Himalayan , and Sr in . isotope laboratory at the Open University. Moving to Durham in 1995, as a lecturer, he began applying the LOUISE R. FRICK graduated with a PhD in geochemistry Re-Os isotope system to dating diamond inclusions, col- from Monash University in 1999. As a graduate student, laborating with Steve Shirey and Rick Carlson at DTM. she spent three months as a predoctoral fellow at the De- Current research is focused on diamond genesis, plat- partment of Terrestrial Magnetism at Carnegie Institution inum-group-element geochemistry and applications of of Washington in Washington, D.C. Her specialty is the ap- Re-Os isotopes to Earth sciences, among other things. He plication of Re-Os isotope geochemistry to the petrogene- has been awarded the 1999 Lindgren Award for his work sis and geochronology of Archean terranes. For the past on anomalous diamonds and the application of the Re-Os three years she has been manager of the Victorian Insti- isotope system to diamond dating. tute of Earth and Planetary Sciences (VIEPS) Trace Analy- sis Laboratory. Facilities at VIEPS include a high-resolu- EDWARD M. RIPLEY is professor of geochemistry at In- tion inductively coupled plasma-mass spectrometer diana University, Bloomington, where his research and (Finnigan MAT ELEMENT), a platinum-group-element teaching have focused on the genesis of metallic mineral geochemistry laboratory and an Re-Os isotope geochem- deposits and stable isotope geochemistry. His BS degree is istry facility. In 1999, she spent four months establishing from Illinois State University (1971), MS work was done at an Re-Os isotope geochemistry facility for the Centro de the University of Minnesota-Duluth (1973), and PhD study Pesquisas Geochronólogicas, Instituto de Geosciências, was completed at Pennsylvania State University (1976). Universidade de São Paolo, Brazil. She has collaborated Ripley’s studies of mineral deposits have ranged from on a number of international Re-Os isotope studies, in- those produced as a result of low-temperature, syngenetic cluding the metallogenesis of the Duluth Complex, to diagenetic processes, through hydrothermal base and United States; Voisey’s Bay Ni-Cu-Co deposit, Canada; and precious deposits, to magmatic Cu-Ni-PGE occur- the Skaergaard Intrusion, Greenland. rences. Recent studies have emphasized the interaction of

iv BIOGRAPHIES (continued) fluids and with country rocks, and the application pendent , he has worked on geologic, tectonic, of various isotopic tracers which help to monitor reaction, and metallogenic problems in the North American mixing, isotopic exchange, and decoupling. Cordillera, the central Andes of South America, and the shield of Brazil. His principal interests include JOAQUIN RUIZ received his PhD in geology from the the role of structure and tectonics in ore genesis, structural University of Michigan in 1983. After a year at the Univer- controls on ore formation, and the source of metal in ore sity of Miami (Florida), where he was an assistant profes- deposits. He currently is the Director of the Mineral De- sor, he moved to the University of Arizona, where he is posit Research Unit at the University of British Columbia. now professor and department head. He has also been a visiting scientist at Lawrence Livermore National Labora- PAULO VASCONCELOS is a Senior Lecturer in economic tories and a visiting Fellow at the University of California geology and low-temperature geochemistry at the Univer- at Berkeley. He is a Fellow of the Geological Society of sity of Queensland, Australia. He has a BS degree from the America and the Society of Economic Geologists. His re- University of Kansas, an MA degree from the University of search involves the dating of ore deposits with an empha- Texas at Austin, and a PhD degree from the University of sis on constraining the duration and size of the hy- California at Berkeley. His research interests include the drothermal systems responsible for mineralization; the influence of surficial processes on the formation and the evolution of the crust and mantle; and the tectonic evolu- supergene enrichment of ore deposits. Dr. Vasconcelos tion of Mexico. At the University of Arizona he teaches in- and his research group are currently engaged in develop- troductory geochemistry and geology. ing new geochronological methodologies for determining the age and duration of events on continental STEVEN SHIREY received his AB degree from Dart- landscapes. mouth College, New Hampshire, his MSc degree from the University of Massachusetts, Amherst, and his PhD degree JOSEPH L. WOODEN received a BS degree in 1970 from from the State University of New York at Stony Brook. He the University of Tennesee at Knoxville, with a major in ge- is currently on the scientific staff of the Department of ology and a minor in chemistry. He received a PhD degree Terrestrial Magnetism of the Carnegie Institution of Wash- in geology from the University of North Carolina, Chapel ington. His research interests include early Earth differ- Hill, in 1975. His work at UNC focused on the geochem- entiation processes, chemical evolution of the mantle, and istry and geochronology of Precambrian mafic dikes in formation of the continents, especially as constrained by southwestern Montana. As a postdoctoral fellow, from 1974 radiogenic isotopes. Most recently, his work has focused to 1976, Wooden worked with Sam Goldich on the geo- on the application of the Re-Os isotope system to these re- chemistry and geochronology of the Archean rocks of the search areas. Minnesota Valley. Afterward, from 1976 to 1983, he was located at Johnson Space Center, Houston, Texas, with RICHARD STERN received a BSc degree in geology from Lockheed, working for the Planetary Sciences Division of the University of Waterloo, Canada, and a PhD from the NASA on geochemistry and geochronology of lunar rocks, State University of New York at Stony Brook (1989). For meteorites, and Archean terrestrial rocks. From 1983 to his doctoral studies, Stern worked with Gilbert Hanson on the present, he has been with the U.S. Geological Survey in the geochemistry and petrogenesis of Archean granitic Menlo Park, California. His work has focused on the U-Pb rocks, focusing on trace element systematics. Stern subse- geochronology and Pb isotope studies in the western quently joined the Geological Survey of Canada (GSC) as United States, with emphasis on regional geologic, mineral a postdoctoral fellow, and later as a staff scientist within resource, and volcanic hazard studies. In addition, the Geochronology Laboratory (headed by R. Parrish, and Wooden currently serves as codirector of the cooperative later, Otto van Breemen), specializing in radiogenic iso- ion microprobe laboratory run by the U.S. Geological Sur- tope geochemistry and geochronological studies of vey and Stanford University at Stanford, California. Archean and Proterozoic rocks. In 1995, Stern was charged with establishing a SHRIMP II ion microprobe fa- cility at the GSC, and by mid-1996 the J.C. Roddick Ion Mi- croprobe Laboratory was officially opened in honor of his colleague and mentor. Stern is currently the manager of this facility, where his research is directed at ion micro- probe analytical technique development and applications.

RICHARD TOSDAL received a BA degree from the Uni- versity of California at Santa Barbara, an MSc degree from Queen’s University, Kingston, Ontario, and a PhD degree from the University of California at Santa Barbara. As a geologist with the U.S. Geological Survey and as an inde-

v CONTENTS

Chapter 1—Pb Isotopes, Ore Deposits, and Metallogenic FIELD IDENTIFICATION OF MINERALS SUITABLE Terranes FOR GEOCHRONOLOGY...... 101 Richard M. Tosdal, Joseph L. Wooden, and Robin M. Bouse CASE STUDIES...... 101 WHAT DOES THIS CHAPTER DESCRIBE?...... 1 DISCUSSION...... 108 A PRIMER ON PB ISOTOPE GEOCHEMISTRY ...... 1 CONCLUSIONS ...... 110 PB ISOTOPES IN ORE DEPOSITS ...... 5 ACKNOWLEDGMENTS...... 111 PB ISOTOPE RECORD OF FLUID- INTERACTION REFERENCES ...... 111 IN MAGMATIC HYDROTHERMAL SYSTEMS ...... 8 METALLOGENIC TERRANE CHARACTERIZATION...... 13 Chapter 5—Integrative Geochronology of Ore CRUSTAL INFLUENCES ON TRACE METAL CONTENTS Deposits: New Insights into the Duration and IN MAGMATIC-RELATED ORE DEPOSITS ...... 17 Timing of Hydrothermal Circulation TECTONIC INFLUENCE ON PB ISOTOPE COMPOSITIONS John T. Chesley NTRODUCTION IN ORE DEPOSITS...... 22 I ...... 115 ENERAL VERVIEW SUMMARY ...... 25 G O ...... 115 ENERAL SOTOPE YSTEMATICS ACKNOWLEDGMENTS...... 25 G I S ...... 117 ASE TUDIES REFERENCES ...... 25 C S ...... 125 FINAL COMMENTS ...... 137 Chapter 2—Re-Os Isotope Geochemistry of Magmatic ACKNOWLEDGMENTS...... 138 Sulfide Ore Systems REFERENCES ...... 138 D.D. Lambert, J.G. Foster, L.R. Frick, and E.M. Ripley INTRODUCTION ...... 29 Chapter 6—Isotopic Dating of Diamonds FUNDAMENTALS OF THE RE-OS ISOTOPE SYSTEM ...... 29 D.G. Pearson and S.B. Shirey SAMPLING STRATEGIES AND ANALYTICAL METHODOLOGY...36 INTRODUCTION: WHY AND HOW TO DATE GEODYNAMIC MODELING OF MAGMATIC SULFIDE DIAMONDS ...... 143 ORE GENESIS USING RE-OS ISOTOPES ...... 37 INCLUSIONS IN DIAMONDS ...... 143 KOMATIITE-ASSOCIATED NI SULFIDE ORE SYSTEMS ...... 40 ISOTOPIC SYSTEMS ...... 145 BASALT-ASSOCIATED CU-NI-CO SULFIDE ORE SYSTEMS ...... 46 DATING SILICATE INCLUSIONS...... 147 SUMMARY ...... 52 DATING SULFIDE INCLUSIONS IN DIAMONDS ...... 156 ACKNOWLEDGMENTS...... 52 SYNTHESIS OF AGE INFORMATION ...... 166 REFERENCES ...... 53 FUTURE DIRECTION...... 167 ACKNOWLEDGMENTS...... 168 Chapter 3—Metallogenesis in Continental Margins: REFERENCES ...... 168 Re-Os Evidence from Porphyry Copper Deposits in Chile Chapter 7—In Situ Analysis of Radiogenic Isotopes Joaquin Ruiz and Ryan Mathur with Emphasis on Ion Microprobe Techniques INTRODUCTION ...... 59 and Applications BACKGROUND...... 59 Richard A. Stern GEOCHRONOLOGY WITH RE-OS ISOTOPES ...... 60 INTRODUCTION ...... 173 SOURCES OF ORE-FORMING COMPONENTS BASED RADIOGENIC ISOTOPES IN MINERALS ...... 174 ON RE-OS ISOTOPES ...... 61 SHRIMP INSTRUMENTATION...... 175 ANALYTICAL TECHNIQUES...... 62 SHRIMP ISOTOPIC RATIO MEASUREMENTS ...... 180 PORPHYRY COPPER DEPOSITS ...... 62 MICROANALYTICAL APPLICATIONS OF RE-OS STUDIES OF BASE METAL PORPHYRY DEPOSITS...... 64 RADIOGENIC ISOTOPES ...... 184 GEOCHRONOLOGY OF CHILE DEPOSITS...... 66 CONCLUSIONS ...... 196 SOURCE OF ORE-FORMING COMPONENTS BASED ACKNOWLEDGMENTS...... 196 ON RE-OS ISOTOPES ...... 67 REFERENCES ...... 197 CONCLUSIONS ...... 70 ACKNOWLEDGMENTS...... 70 REFERENCES ...... 70 Chapter 4—40Ar/39Ar Geochronology of Supergene Processes in Ore Deposits P.M. Vasconcelos INTRODUCTION ...... 73 DATING METHODS...... 73 METHODOLOGY FOR WEATHERING GEOCHRONOLOGY ...... 75 MINERALS SUITABLE TO WEATHERING GEOCHRONOLOGY...... 91

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