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Gold and trace element zonation in pyrite using a laser imaging technique: implications for the timing of gold in orogenic and carlin-style sediment-hosted deposits

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Large, RR and Danyushevsky, LV and Hollit, Chris and Maslennikov, VV and Meffre, S and Gilbert, SE and Bull, SW and Scott, RJ and Emsbo, Poul and Thomas, HV and Singh, Bob and Foster, Jeffery (2009) Gold and trace element zonation in pyrite using a laser imaging technique: implications for the timing of gold in orogenic and carlin-style sediment-hosted deposits. Economic Geology, 104 (5). pp. 635-668. ISSN 0361-0128

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Abstract

Laser ablation ICP-MS imaging of gold and other trace elements in pyrite from four different sedimenthosted gold-arsenic deposits has revealed two distinct episodes of gold enrichment in each deposit: an early synsedimentary stage where invisible gold is concentrated in arsenian diagenetic pyrite along with other trace elements, in particular, As, Ni, Pb, Zn, Ag, Mo, Te, V, and Se; and a later hydrothermal stage where gold forms as either free gold grains in cracks in overgrowth metamorphic and/or hydrothermal pyrite or as narrow goldarsenic rims on the outermost parts of the overgrowth hydrothermal pyrite. Compared to the diagenetic pyrites, the hydrothermal pyrites are commonly depleted in Ni, V, Zn, Pb, and Ag with cyclic zones of Co, Ni, and As concentration. The outermost hydrothermal pyrite rims are either As-Au rich, as in moderate- to highgrade deposits such as Carlin and Bendigo, or Co-Ni rich and As-Au poor as in moderate- to low-grade deposits such as Sukhoi Log and Spanish Mountain. The early enrichment of gold in arsenic-bearing syngenetic to diagenetic pyrite, within black shale facies of sedimentary basins, is proposed as a critical requirement for the later development of Carlin-style and orogenic gold deposits in sedimentary environments. The best grade sediment- hosted deposits appear to have the gold climax event, toward the final stages of deformation-related hydrothermal pyrite growth and fluid flow.

Item Type: Article
Keywords: syngenetic gold, diagenitic gold, orogenic, Carlin, sukhoi log, Bandigo, Spanish Mountain, pyrite
Journal or Publication Title: Economic Geology
Page Range: pp. 635-668
ISSN: 0361-0128
Identification Number - DOI: 10.2113/gsecongeo.104.5.635
Additional Information: © 2009 The Society of Economic Geologists
Date Deposited: 07 Sep 2009 23:44
Last Modified: 30 Apr 2014 05:37
URI: http://eprints.utas.edu.au/id/eprint/9167
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