Geological, Geochemical Characteristica And Genesis Of The Baoshan Copper-molybdenum Deposit, Heilongjiang

The baoshan deposit is located in the north of Xiaoxing′anlin-zhangguangcailin metallogenic belt, which was mineralized by Iron, copper, molybdenum and gold, and it is a skarn deposit. Baoshan Copper-molybdenum skarn deposit is newly discovered which is researched in a low level. This study is based on field survey combining with research on microscopic identification, geochemical analysis and testing of fluid inclusion, we established the genesis of the deposit.Baoshan Copper-molybdenum deposit occurred in the contact zone granidiorite and Lower Cambrian strata qinashan group, the deposit possesses the characteristics of typical Skarn deposit. There are two stage of intrusive rock. The early intrusive rock is gneissic granites, which is belong to peraluminous-slightly, high-K calc-alkaline series, subduction type and I-type granites. The later stage intrusive rock are syengranite and granidiorite, which are metaluminous to high-K cacl-alkaline series, peraluminous-slightly, shoshonite, collision and I-type granites.Gneissic granites formed in a subduction environment, which is produced by oceanic crust between Songnen-zhangguangcai block and Jiamusi block subduct to Songnen-zhangguangcai block. Syengranite and granidiorite belong to continental collision environment, which may related to Jiamusi-Mongolia block and the eastern segment of the northern margin of the North China Plate.Skarn type is mainl ore types. Ore structures contains disseminated and vein disseminated structure. Ore textures contains xenomorphic granular texture, ramentum texture, reaction rim texture and separation texture. We divided into three periods and four stages about Baoshan deposit, such as skarn period(dry skarn stage, wet skarn stage), quartz-sulfide period(quartz-sulfide stage, carbonate stage) and exogenous period.The study results of fluid inclusions from Baoshan Copper-molybdenum deposit indicate the deposit was produced in middle-deep environment, ore-forming fluids belong to medium-high temperature, medium-high salinity and medium density system. With the process of mineralization, the ore-forming fluid shows some evolution regular. Metallogenic pressure, depth, homogenization temperatures show decreasing trend, the salinity of the ore-forming fluids with the evolution trend from high salinity to low salinity and metallogenic denity increasing slightly. We can find some evidence which would prove the fluid boiling.Baoshan Copper-molybdenum deposit suggest that the deposit is a typical Skarn deposit. The ore characteristics, minerals coexisting relationship and ore textures and structures is the best evidences.