The Spatial Structure Of Metallogenic In Zhaishang Gold Deposit, Western Qinling

Located in the northern part of the Western Qinling Orogen, Zhaishang gold deposit is ranked as the largest independent gold deposit in the light of proved gold resouces in this belt. However, many key issues of this deposit still remains unclear, such as the existance of concealed intrusion, the relationship between magmatism and ore-forming process, metallogenic dynamic setting, source of ore-forming fluid and material, deposit geology and ore-forming physicial-chemical condition and age. This thesis focused on the spatial structure of ore-forming process. The main conclusions are reached on the ground of systematic filed observation, remote sensing and aeromagnetic interpretation, kinematic survey and dynamic calculation, appraisal of polished thin section, temperature and composition of fluid inclusion and other geochemical testing.1. According to remote sensing and aeromagnetic interpretation and the revealed vein rock, it is inferred that there exists concealed intrusion in the deep of the mining area. Vein rock belongs to the peraluminous S-type granite, which formed by melting of the lower crust in the volcanic arc setting.2. Distinguished discrepancies have been recognized between the southern and the northern metallogenic belt in the aspect of spatial architecture of geological feature by geological survey and comprehensive research.3. The mechanical property and evolution of ore-bearing structure have been determined on the basis of kinematic observation and dynamic calculation: N-S oriented compression prior to ore-forming process, left-lateral compresso-shear before the ore-forming stage, right-lateral tensile-shear during the structural-hydrothermal stage, right-lateral compresso-shear after the ore-forming process.4. Fluid inclusion and isotope analysis have been used to study the geochemical spatial architecture of the ore-forming process. Discrepancies exist among the southern, the northern metallogenic belt and the deep of the southern metallogenic belt. In general, the ore-forming fluid exhibits the characteristics of medium-low temperature, low pressure and shallow. The northern metallogenic belt is lower than that of the southern while the southern is lower than the deep. Ore-forming fluid derived from the mixture of meterio water and magmatic water.5. It is inferred that ore-forming materials derived from the middle and upper Devonian strata and the deep magma in the light of contrasting Au abundance in strata between mining area and the region, extraction of mobile Au, hydrothermal alteration transfer calculation and S and Pb isotopes.6. Based on 40Ar/39 Ar dating and secondary development of previous dating data, it is determined that Vein rock Formed in the range of 212 to 221 Ma and Mineralization occurred in the range of 125 to 130 Ma。7. The united metallogenic model of stratum-structure-concealed magma has been established.