Composition and sulfur isotope characteristics of pyrite and their implications from duolanasayi gold deposit, Xinjiang

Duo lanasayi gold deposit in Xinjiang is located in the west of suture between Siberian and Kazakhstan plate, controlled by ductile shear zone. Pyrite is the main metal minerals of this gold deposit. Based on detail field investigation and indoor appraisal, this paper divided pyrites of the deposit into four periods, and the third one is mainly fine grains and broken crystals, which is an important period of gold mineralization. Different periods of pyrites were carried out electron microprobe and sulfur isotopic analysis, and study systematically typomorphic composition and sulfur composition of pyrite of important period of gold mineralization. This paper gets the chemical formula for the period of pyrite: FeS_1.98, and it is poor in sulfur. The average ratio of Co/Ni is 1.488, inferred that the genesis of this period of pyrites is hydrothermal. δ³⁴S(‰) values range from -3.8‰ -2.0‰, concentrated in the vicnity of the mantle-derived sulfur. It is indicated that sulfur of pyrite which is closely accompanyed with gold is mainly from the deep crust. (authors)