University of Tasmania, Australia

This project focuses on pyrite textures, geochemistry and isotopes in a wide range of gold deposits, to elucidate the origin, sources and timing of pyrite and gold using LA-ICP-MS analyses and mapping. A portion of this work forms AMIRA project P1041: The application of new technologies to gold deposits.

The following deposits were studied as part of this overall project in 2011:

• Witwatersrand Carbon Leader Reef in the West Wits district (part of AMIRA P1041 – Research is addressing the question: “What are the potential sources of the various pyrite types and related gold?” A keynote address on the results of this research was delivered at the Fermor Conference.
• Wafi high sulfidation epithermal gold deposit, PNG – The focus for this project with Newcrest is on the pyrite textures, mineralogy and timing of gold, and the geochemical fingerprint of the gold event.
• McPhillamys volcanic/sediment hosted disseminated gold deposit in NSW – Work in collaboration with Newmont is determining the pyrite-gold mineralogy, timing of gold, S and Pb isotope characteristics of pyrite and the alteration mineralogy/geochemistry.
• Kumtor gold deposit in Central Asia – In this collaboration with Valeriy Maslennikov, pyrite has been studied in both the black shale wall rocks and the ore zones. It has been discovered that nodular diagenetic pyrite in the carbonaceous shale host sequence is enriched in gold and tellurium, and may be the original source of these elements in the ores.
• Bendigo gold mine, Victoria – S-isotope studies of sediment–hosted and vein pyrite have been written for publication.
• • Northern Carlin Trend, Nevada – Ross Large and Stuart Bull published a paper on the results from AMIRA P923 research.
• Otago Gold Province, New Zealand – In a collaboration with Dave Craw and Simon Henderson, a paper has been submitted for publication on the importance of diagenetic pyrite as a source for gold in the Otago Province.
• St Ives gold camp, Yilgarn, WA – This PhD study by Dan Gregory is a collaboration with the CSIRO MDU Flagship and Goldfields. The research, focussing on the Kapai Slate, demonstrated that early diagenetic pyrite is enriched in Au and Te, which could have been a factor in the genesis of the Au-Te deposits in the camp.
• Homestake gold mine, USA – PhD student, Jeff Steadman, is undertaking a study of the carbonaceous pyrrhotite-pyrite-bearing shales in the footwall of this deposit. His research is focused on understanding the metamorphic transition from pyrite to pyrrhotite in the shales, and how this may relate to the concentration of gold in the overlying carbonate facies BIF.
• Randalls gold-BIF deposits, Kalgoorlie District – PhD student, Jeff Steadman, is also studying the mineralogy, mineral chemistry and source of gold in the BIFs, hosted in sedimentary rocks equivalent to the Black Flag Beds.
• Hope Bay greenstone-hosted gold camp, Canada – Helen Thomas and Sebastien Meffre have been studying pyrite and gold paragenesis in the structurally controlled Madrid deposit (part of AMIRA P1041) to assist Newmont in the development of a model for the discovery of further deposits in the camp.
• Geita Hill BIF-hosted gold deposit, Tanzania – This study with AngloGold Ashanti is focused on pyrite-magnetite-gold relations and paragenesis in the complex lodes at Geita.

Research on sediment-hosted and greenstone-hosted gold has resulted in a new genetic model for Carlin type and orogenic gold deposits, which has major relevance in mineral exploration. A paper on the topic has been recently published in Economic Geology.