Magmatic And Mineralization Of Diaoquan Skating Silver - Copper Deposit In Shanxi Province

The Taihang orogenic belt, which is located in the center of the North China platform, has been activated and transformed by the Yanshanian activity since Jurrassic. Widespread and intense tectonic–magmatism events results in formation of an important metallogenic belt in eastern China. The Diaoquan copper-silver deposit is a typical example to study mineralization in this district. In order to study magmatic origin, evolutional sequence and its control on mineralization, systemic investigations on ore deposit geology, petrochemistry and geochemistry have been carried out. Several major conclusions are draw as follows:(1) The Diaoquan complex consists of biotite quartz monazite and granite porphyry. petrology and major elements show that they both belong to high-K, alkaline-rich, subaluminous to weakly-peraluminous calc-alkline granites. Trace elements, rare earth elements and isotopes suggest that they derive from the lower crust. Biotite quartz monazite and granite porphyry are formed in 140 Ma and 132 Ma, respectively, using zircon U-Pb dating method. They are both formed by partial melting of mid-high metamorphic materials from the lower crust at different stage during the middle Yanshsnian continental orogenic event, which coincide with the tectonic system transformation from compression to extension.(2) The Diaoquan silver-copper mineralization occur in 132 Ma(molybdenite Re-Os dating), which is consistent with the age of granite porphyry(132 Ma, zircon U-Pb dating). Sulfur isotopes show that the ore materials originate from magmatic rock. Ore and magmatic rock are characterized by similar Pb isotopes, which indicate that ore-forming materials are mainly derived from magmatic rocks. The obtained temperature, salinity, composition, H, O and C isotopes of fluid inclusions are consistent with magmatic hydrothermal fluids, which suggest that the fluid primarily originates from the magma. Ore-forming fluid belongs to the H2O-Na Cl-CO2 system. The above studies collectively demonstrate that the mineralization has a close genetic relationship with the granitic porphyry, which may provide ore materials, fluid and heat for the mineralization.(3) Besides skarn silver-copper mineralization, There may be porphyric molybdnite mineralization in Diaoquan silver-copper deposit, which belong to one magma-hydrothermal system. Based on ore deposit geology and geochemistry, mineralization model of the Diaoquan copper-silver deposit is established.