Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Mustard, R. Articles by Mernagh, T. Search for Related Content GeoRef GeoRef Citation

Gold and metal enrichment in natural granitic melts during fractional crystallization

¹ Predictive Mineral Discovery Cooperative Research Centre, Economic Geology Research Unit, School of Earth Sciences, James Cook University, Townsville, QLD 4811, Australia
² Earth and Marine Science Department, Australian National University, Canberra, ACT 0200, Australia
³ School of Earth Sciences and Centre for Ore Deposit Research, University of Tasmania, GPO Box 252-79, Hobart, TAS 7001, Australia
⁴ Geoscience Australia, GPO Box 378, Canberra, ACT 0200, Australia

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.

Key Words: gold • metal enrichment • LA-ICP-MS • melt inclusions • fractional crystallization • intrusion-related Au deposit

This article has been cited by other articles:

				J. D. Webster and C. W. Mandeville Fluid Immiscibility in Volcanic Environments Reviews in Mineralogy and Geochemistry, July 1, 2007; 65(1): 313 - 362. [Full Text] [PDF]