A synmetamorphic lateral fluid flow model for gold mineralization in the Archean southern Kalgoorlie and Norseman terranes, Western Australia

摘要: Gold deposits are widely distributed in the Archean southern Kalgoorlie and Norseman greenstone terranes, Eastern Goldfields superterrane, Western Australia, which have collectively produced more than 1,850 metric tons (t) of gold. occur a variety host rocks structural settings, but all associated with quartz veins and/or shear zones that formed during latest stages regional compression. Available data indicate similar H 2 O-CO (-CH 4 ) ore fluid at each deposit. Alteration assemblages vary metamorphic grade manner indicates late tectonic gradients were still place when gold was deposited from hydrothermal fluids. These thermal related to differential uplift deep hot crust, margin belt, accompanied by intrusion voluminous monzogranite magma. At this time, western belt zone high heat flow, as intrusive centers northern part terrane. spatial temporal relationships, combination apparent absence viable local source for most deposits, suggest small number large, synmetamorphic systems. Published models predict up-temperature, lateral flow toward under these circumstances. A model involving fluids overcomes some problems deeply sourced conventional is consistent features terranes. Potassium metasomatism radiogenic isotope signatures mineralization ascribed modified exchange biotite-bearing felsic (granitoids, volcanic volcaniclastic rocks) course flow.