The Geological And Geochemical Characteristics And The Study On The Genesis Of The Xiying Gold Deposit, Shanshan, Xinjiang

The belt, consisting of the Ural mountain of Central Asia, Zarafshan Mountains which is southeast of Aral Sea, and then extending to South Tianshan of Xinjiang, is known as "the Asian gold belt". There is Sawayaerdun gold deposit, Dashankou gold deposit, Sahentuohai gold deposit, Bulong, Xiying gold deposit in the south Tianshan Mountains in Xinjiang, a giant gold ore belt which is most concerned in Asia. As part of "the Asian gold belt", Xiying gold deposit, having the same or similar Regional geological setting and geological environment with other large orogenic gold deposit, has a great potential.Based on the study of regional geological background and the research of geological characteristics, the relationship between the ore-controlling factors in mining area , including stratum, structure and magmatite and mineralization are deeply studied the source of metallogenic material and ore-forming fluids are analyzed by the method of mineragraphy, stable isotope geochemistry and fluid inclusion and finally Genesis of the deposit are put forward and metallogenic model is established. Therefore, we generalize a few conclusions as follows:The stratum bearing Xiying gold deposit is Lower Carboniferous Gan cao hu Group, whose regional background has a high level of Au, so it provides a good foundation for mineralization.Xiying gold deposit is spatially controlled by multi-level structure system obviously, and every vein is founded in the same alteration zone north of ductile-brittle Yiertuogushibulake shear belt. Therefore the gold deposit is controlled by great ductile-brittle shear zone, occurring in secondary fault system.Based on the feature of isotopic composition of carbon, hydrogen, oxygen, sulfur and lead and the regional geological setting, we conclude that the metallogenic material is mainly from mantle. Ore-forming fluids absorb or extract part of the metallogenic material from wall rock when it goes into fault system of supracrust. That is to say, the source of the metallogenic material mainly mantle-derived, has the characteristics of mixing mantle-derived and crust-derived sources. The ore-forming fluids is magmatic water mainly, mixed with part of metamorphic water.The main types of fluid inclusions are aqueous inclusions, CO₂-H₂O inclusions, CO₂-rich inclusions. The ore-forming fluids is CO₂-H₂O-NaCl system with high temperature(mainly in the range of 150-390℃), low-middle salinity(mainly in the range of 3-13%) , low density(mainly in the range of 0.7-0.99g/cm3). The precipitation mechanism of fluid is mainly water - rock interaction and immiscibility of fluid.The type of Xiying gold deposit is orogenic gold deposit which is closely related with collision orogeny of the two plates in Middle Hercynian, extensional of late collision in Late Hercynian and activities and evolution of the fluid in depth in the same period. Therefore, the age of mineralization may be in Late Hercynian to Early Indo-China.