Geological Characteristics And Genesis Of The Jiguanshan Molybdenum Deposit In Chifeng, Inner Mongolia

structures are complex, mainly include Subhedral-idiomorphic granular texture, residual structure,Metasomatic corrosion textures, radial structure etc.. main structures of ore are disseminated structure andvein structure. According to the characteristics of ore, we think the metallogenic period of Jiguanshanmolybdenum deposit is gas and hydrothermal mineralization period. According to the mineral assemblageand formation sequence, ore Fabric and veins interspersed relations, the Jiguanshan molybdenum depositmineralization can be divided into3stages: early stage is silicide stage, intermediate stage is the mainmetallogenic stage, late stage is quartz-carbonate stage.The ore body’s Wall rock alteration are mainly potassium, sericitization, silicification,kaolinization,fluoritization and etc., in which silicification, sericitization and fluoritization are closelyrelated to molybdenum mineralization.According to the distribution of fluid inclusions’ homogenizationtemperatures in ore bearing quartz veins in the mining area, mineralization can be divided into three stages:the early, middle and late stage, the fluid inclusions’ homogenization temperatures of differentmineralization stages are different: early stage’s homogenization temperature of fluid inclusions is morethan478.6℃, salinity is high, this study measured early stage’s salinity is11.36~60.85wt%NaCl;intermediate stage is the main metallogenic stage, in this stage, fluid inclusion homogenizationtemperature is182.6~457.6℃, salinity is between5.25~37.64wt%NaCl; late stage’s fluid inclusionhomogenization temperature is108.7℃~152.6℃, salinity is5.70~9.47wt%NaCl. By calculation,metallogenic pressure range is29MPa~146MPa, the average is91.8Mpa; depth ranged from0.99km to4.86km, with an average depth of3.06km. Jiguanshan ore forming fluid came mainly from magmaticwater, less rainfall. According to the characteristics of the lower crust source of ore-forming parent rock,we speculate that the minerals mainly from the lower crust.Jiguanshan Mo deposit belongs to Climax type porphyry molybdenum deposit, acidic porphyry is theits host rock, according the acidic porphyry tectonic environment and the magma source region of thelower crust, we think the deposit’s source region is the lower crust, forms in the extensional environmentafter Yanshan movement strong extrusion, is results of a large terrestrial shell "creeping" and "stretch" inEast Asia.