Geochemistry Chacteristic Of Yongping Copper-polymetallic Deposit In Jiangxi Province

The Yongping Copper-Polymetallic deposit, located in the south of Shi-Hang Rift zone,is a porphyry-skarn type deposit related to the late Jurassic monzogranite intrusions. On the basis of the detailed study of field geological, using by inductively coupled plasma masspectrometry, microthermometry, and isotope mass spectrometry, We do some studies included lithogeochemistry, U-Pb geochronology, fulid inclusion and stable isotope etc. several conclusions are proposed as follow:(1) The mineralization types at Yongping can be divided into two: porphyry type and skarn type. The zoning of minerlization type in space is remarkable. Porphyry Mo minerlization exist in the magmatic rock core or near the contact zone. Skarn Cu minerlization develop in the carbonate formation. The fomation of porphyry Mo deposit experienced two stages: quartz-sulfide stage and quartz-carbonate-sulfide stage. The process of Skarn Cu minerlization include three stages: skarn stage, quartz-sulfide stage and carbonate stage.(2) The geochemistry research of element indicate that granitic rock in Yongping is named quartz monzonite porphyry which has the characteristics of high silica and high cakali content. It belongs to peraluminous-peraluminous and high-K calc-alkaline series magmatite. Its Aluminum saturation index(ASI) is between 0.97 and 1.38. Ligh rare earth elements(LREE) are highly enriched, large ion lithophile elements(Rb, Ba, U, Th, K, Pb) are generally enriched, high field srength elements(Nb, Ta, Ti) are deoleted. This show that monzonite porphyry is connected with island arc magmatism. Zircon U-Pb dating yields concordant age of 155.7±2.7Ma which belongs to late Jurassic epoch.(3) Fluid inclusions study indicate that the ore-forming fulid in Cu deposit and Mo deposit expericenced similar evolutionary processes of natural cooling. Raman microspectroscopic studies of the fluid inclusions of skarn deposit and porphyry deposit show that the main component are CO2 and H2 O, and the ore-forming fluid belongs to H2O-CO2-Na Cl system.(4) Sulfur isotope research shows that values of δ34S vary from-0.2‰ to +1.9‰, indicating a predominant sulfur origin of deep-seated magma.(5) We suggest that Yongping Copper-Polymetallic deposit is a typical Porphyry-Skarn type deposit which is resulted from the emplacement of the Late Jurassic monzogranite intrusions. From instrusion through contact zone to host rocks, the mineralization is demonstrated by Mo-Cu-W-PbZn.