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Invisible gold in arsenian pyrite and arsenopyrite from a multistage Archaean gold deposit: Sunrise Dam, Eastern Goldfields Province, Western Australia

Citation

Sung, YH and Brugger, J and Ciobanu, CL and Pring, A and Skinner, W and Danyushevsky, LV and Nugus, M, Invisible gold in arsenian pyrite and arsenopyrite from a multistage Archaean gold deposit: Sunrise Dam, Eastern Goldfields Province, Western Australia, Mineralium Deposita: International Journal of Geology, Mineralogy, and Geochemistry of Mineral Deposits, 44, (7) pp. 765-791. ISSN 0026-4598 (2009) [Refereed Article]

DOI: doi:10.1007/s00126-009-0244-4

Abstract

The Sunrise Dam gold mine (11.1 Moz Au) is the largest deposit in the Archaean Laverton Greenstone Belt (Eastern Goldfields Province, Yilgarn Craton, Western Australia). The deposit is characterized by multiple events of fluid flow leading to repeated alteration and mineralization next to a major crustal-scale structure. The Au content of arsenian pyrite and arsenopyrite from four mineralizing stages (D1, D3, D4a, and D4b) and from different structural and lithostratigraphic environments was measured using in situ laser ablation inductively coupled plasma mass spectrometry. Pyrite contains up to 3,067 ppm Au (n=224), whereas arsenopyrite contains up to 5,767 ppm (n=19). Gold in arsenopyrite (D4a stage) was coprecipitated and remained as ※invisible gold§ (nanoparticles and/or latticebound) during subsequent deformation events. In contrast, gold in pyrite is present not only as ※invisible gold§ but also as micrometer-size inclusions of native gold, electrum, and Au(Ag)每tellurides. Pristine D1 and D3 arsenian pyrite contains relatively low Au concentrations (≒26 ppm). The highest Au concentrations occur in D4a arsenian-rich pyrite that has recrystallized from D3 pyrite. Textures show that this recrystallization proceeded via a coupled dissolution每 reprecipitation process, and this process may have contributed to upgrading Au grades during D4a. In contrast, Au in D4b pyrite shows grain-scale redistribution of ※invisible§ gold resulting in the formation of micrometer-scale inclusions of Au minerals. The speciation of Au at Sunrise Dam and the exceptional size of the deposit at province scale result from multiple fluid flow and multiple Auprecipitating mechanisms within a single plumbing system.

Item Details

Item Type:Refereed Article
Keywords:gold, arsenian pyrite, Sunrise Dam, Eastern Goldfields
Research Division:Earth Sciences
Research Group:Geology
Research Field:Ore Deposit Petrology
Objective Division:Mineral Resources (excl. Energy Resources)
Objective Group:Mineral Exploration
Objective Field:Precious (Noble) Metal Ore Exploration
Author:Danyushevsky, LV (Professor Leonid Danyushevsky)
ID Code:61798
Year Published:2009
Web of Science® Times Cited:71
Deposited By:Centre for Ore Deposit Research - CODES CoE
Deposited On:2010-03-05
Last Modified:2010-04-14
Downloads:0

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