Characteristics Of Fluid Inclusions And Genesis Of Asiha Gold Deposit, Qinghai Province

The Asiha gold deposit is located in Polymetallic Deposits in the Eastern Kunlun metallogenic belt. The deposit has a short discovering history, the low levels of fundamental geological work and scientific research. With field study of geological features, wall rock alteration characteristics, ore-controlling structures and characteristics of the fluid inclusions, and then discussed the geologic structure background, ore genesis and mineralization mechanism.The strata outcropped in the mining area is simple, just the Palaeoproterozoic Jinshuikou group only. Fault is the main structure in the mining area, nearly EW trending faults and different grades of secondary faults widely distributed in the area, while the NNE and NW trending extension fractures are the mainly ore-controlling structure and ore-controlling structure. Intrusive rocks are widely distributed, mainly for the late Varisean to Indosinian granodiorites. The magmatism is low variable and characterized by high potassium, metaluminous and calc-alkaline.There are more than ten orebodies found in the three altered fractured zone of granodiorite in the mine. Mineralization can be divided into hydrothermal ore-forming period and hypergene weathering period. And hydrothermal ore-forming period can be divided into three stages:quartz sulfide stage, ankerite sulfide stage, quartz ankerite stage.Fluid inclusions of quartz crystals can be classified into three-phased CO2-aqueous fluid inclusion and two-phase aqueous. Ore-forming fluids are characterized by low salinities, middle-low temperature and rich arbon dioxide. The mineralization temperature ranges from280℃to320℃, and calculates pressure range from85MPa to154MPa, corresponding to depths of7.5～10.4km, indicating that this mineral deposit formed in mesogene mineralization environment. The immiscibility of ore-forming fluid played an important role in the metallogenetic process of Asiha gold deposit.In the aspect of ore genesis, Asiha gold deposit’s characteristics are similar to the orogenic gold deposits, the metallotectonic setting is intracontinental orogeny. The genetic type of ore deposit is mesozonal orogenic gold deposit.