Metal evolution in a composite granitic pluton was tracked by analyzing melt inclusions in 11 quartz samples from 7 zones at the Timbarra gold deposit, Australia. We present the first quantitative microanalyses of gold (Au) in granitic silicate melt inclusions using laser ablation inductively coupled plasma mass-spectrometry and show how Au and other metals become enriched during fractional crystallization in a granite intrusion. Au was enriched during fractionation from a monzogranite to a highly fractionated alkali-feldspar granite. Similar enrichment behavior for other metals implies that no gold-enriched precursor melt is required and fractional crystallization can enrich the Au concentration to economic levels. The low content of accessory oxides and sulfides, the absence of early Cl-bearing fluids, the volatile content in the melt, and a prolonged crystallization constitute important factors for extensive metal enrichment during crystal fractionation. These characteristics play a crucial role in felsic, highly fractionated plutons and their associated deposits such as intrusion-related Au deposits. The gold enrichment during fractionation also implies that Au is directly sourced from the granites. © 2006 Geological Society of America.

Item Type:	Refereed Article
Research Division:	Earth Sciences
Research Group:	Geology
Research Field:	Resource geoscience
Objective Division:	Mineral Resources (Excl. Energy Resources)
Objective Group:	Mineral exploration
Objective Field:	Precious (noble) metal ore exploration
UTAS Author:	Kamenetsky, VS (Professor Vadim Kamenetsky)
ID Code:	43376
Year Published:	2006
Web of Science® Times Cited:	94
Deposited By:	Centre for Ore Deposit Research - CODES CoE
Deposited On:	2006-08-01
Last Modified:	2007-05-02
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