We report sulfur isotopic compositions of sulfides of various paragenetic stages in the giant Sukhoi Log sediment-hosted orogenic Au deposit in Russia. The overall mean value and the significant variability in early pyrite indicate that the sulfur was from the reduction of seawater sulfate. The later generations of sulfide have δ34S values in successively smaller ranges, coincident with the mode that is around the median value of the whole data set. Together with textural evidence, sulfide trace element data, and gold occurrence, the data demonstrate that metamorphism has gradually homogenized the early sulfur, accompanied by the segregation of quartz and the release of Au from the lattice of early pyrite and its reprecipitation as inclusions in later pyrite. The S isotopic compositions of sulfides in Sukhoi Log, and many other major orogenic Au deposits hosted in sedimentary rocks of various ages, show a pattern generally parallel to the seawater sulfate curve through geologic time, indicating that the sulfur in most sediment-hosted orogenic Au deposits was probably also originally from the reduction of seawater sulfate. We conclude that sulfidation and gold mineralization in many sediment-hosted orogenic gold deposits was early during basin evolution when seawater was the principal active fluid, rather than later, during or after basin inversion, as proposed in current models. © 2008 The Geological Society of America.

Item Type:	Refereed Article
Research Division:	Earth Sciences
Research Group:	Geochemistry
Research Field:	Isotope geochemistry
Objective Division:	Mineral Resources (Excl. Energy Resources)
Objective Group:	Mineral exploration
Objective Field:	Precious (noble) metal ore exploration
UTAS Author:	Chang, Z (Dr Zhaoshan Chang)
UTAS Author:	Large, RR (Professor Ross Large)
ID Code:	52993
Year Published:	2008
Web of Science® Times Cited:	162
Deposited By:	Centre for Ore Deposit Research - CODES CoE
Deposited On:	2008-10-18
Last Modified:	2010-06-01
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