The Geological Characteristics And Prospecting Directionof The Bujinhei Pb-Zn Deposit In West Ujimqin,Inner Mongolia

Bujinhei Pb-Zn deposit, a representative hydrothermal vein-type, is tectioncally located at the southern Daxinganling Mountains and belongs to Haerchulutu-Bairendaba-Shabuleng metallogenic belt. The hydrothermal ore-forming epoch of the deposit is classified into three stages: pyrite-arsenopyrite-pyrrhotite-quartz phase(I),polymetallic sulfide-quartz(Ⅱ)and polymetallic sulfide- calcite phase(Ⅲ). Ore bodies mainly occur in Shoushangouzu Formation and the chief constitute are metamorphic sandstone and slate. The primary ore is produced in shape with lenticular and veined ore body.The ore strikes almost EW, dips northwardly, which are controlled by strata, magmatism and tectonism.Fluid-inclusion observations and microthermometric datas suggest that the ore-forming fluid of Istage develops aqueous two-phase,CO2-CH4 three-phase and minor gas-rich CO2-CH4 one-phase fluid inclusions,which is of the immiscible medium-high temperature,medium-high salinity CO2-CH4-H2O-Nacl system.the ore-forming fluid of Ⅱstage develops aqueous two-phase and gas-rich fluid inclusions,which is of the medium temperature,medium salinity-H2O-Nacl system.the ore-forming fluid of Ⅲ stage develops aqueous two-phase and minor gas-rich fluid inclusions,which is of the medium-low temperature,low salinity H2O-Nacl system.according to D-O isotope research,the sources of ore-forming fluid were the mixture of meteoric water and magmatic water.Dates of S isotope(5.4~13.7‰) and C isotope(-18.4~-26.45‰) suggest that the sources of metallogenic material were strata and magmatism. Respectively, using arsenopyrite geothermometer the author calculates the metallogenic temperature in the Ⅰ, Ⅱ and Ⅲ state which are about to 350~400 ℃,280~330 ℃ and 250~270 ℃ respectively.The corresponding pressure are about to 21~80Mpa,9.5~70Mpa and 4~40Mpa respectively.The corresponding depths are about to 3.7km,2.86 km and 1.70 km respectively.The shallow,metallogenic depth of states suggests a good potential of mineralization.In this paper on the basis of ore genesis,by research drilling,geophysical and geochemical information,further invest on the ore control factors and regularity of mineralization and enrichment.Applications of Trend Analysis Method and structure interpretation of magnetic abnormal in fracture surface show that under the controlling of strata,magmatism and tectonism,Ore bodies mainly occur in superposition and inflection point of teconic,which have physical property characteristics of low resistivity,high chargeability and high magnetic susceptibility. Based on the factors,combined with geological, geophysical, and engineering information to help guid the direction of prospecting and deep prediction.Finalliy, 3 targets of regional metallogenetic prediction are given. And 1 and 3 targets of the deep prognosis ofⅠandⅡores are given.This paper can show clearly direction of prospecting.