CHEMICAL COMPOSITION OF FLUID INCLUSIONS OF THE SAWAYARDUN GOLD DEPOSIT, XINJIANG: IMPLICATIONS FOR OREGENESIS AND PREDICTION

Abstract

Both barren and Au-bearing quartz veins occur in exploration area of the Sawayardun gold deposit, Xinjiang. Fluids extracted from the barren and Au-bearing quartz separates and pyrite separates roughly represent the characteristics of the fluids of preore-, early ore- and main ore-stages, and show contrasted chemical compositions. In early ore-forming stage, fluid immiscibility was the main mechanism resulting in precipitation of ore-metals; and associated Au-bearing quartz, albite and pyrite were formed. In the main ore-forming stage, fluid condensing and/or mixing was the major origin of metallic precipitation, causing formation of a great deal of Au-bearing minerals such as pyrite. Chemical compositions and the evolution of ore-forming fluids of the Sawayardun deposit are similar to those of the orogenic type mesothermal gold lodes in the world, especially similar to those of the Muruntau giant gold deposit in South Tianshan, Uzbekistan. This strongly suggests the Sawayardun gold deposit is an example of Muruntau-like orogenic type. This paper predicts that lodes XI and II are potential for further prospecting because their fluid compositions are similar to those of lode IV which has been evidenced to the best mineralized in the area by previous prospecting. Whereas the lode I is not recommended because its fluid compositions contrast to those of lode IV.