Conditions of the Formation of Disseminated Gold-Sulfide Ores

摘要

Disseminated gold-sulfide ores are known in metal-logenic provinces of different ages. They are primarily located in carbonaceous (terrigenous and terrigenous-carbonate) sequences and are confined to deep fault zones. The ores are characterized by a high Au : Ag ratio (up to 10 : 1 or more) and relatively homogeneous distribution of Au. Gold is primarily present as fine-dispersed inclusions in As-pyrite (As 1-5%) and arse-nopyrite. The total content of As-pyrite and arsenopy-rite is 5-10%. Gold-bearing sulfides are disseminated in shear and foliation zones. The fine sulfide dissemination extends to a depth of more than 1 km without any significant changes in composition or Au content. Lateral and vertical mineral zonations are also absent. Ore bodies include numerous quartz veins and veinlets that are older (or younger) than the major productive dissemination. Metamorphogenic quartz veins predated the productive stage. Late gold-quartz, quartz-silver-base metal, and Au-bearing quartz-antimonite veins are more abundant.