Study On Ore Genesis Of The Tianbaoshan Pb-Zn Deposit And The Regional Metallogenetic Geodynamical Setting

The Tianbaoshan Pb-Zn deposit is located at the southwestern margin of the Yangtze plate,which is an important part of Sichuan-Yunnan-Guizhou Zn-Pb ore concentration area.This study was carried out through field investigation,microscope observation,and geochemical analyses.The aim of the research is to explore the ore genesis of Tianbaoshan Pb-Zn deposite and the regional metallogenetic geodynamical setting.The Tianbaoshan Pb-Zn deposite is formed in Sinian Denying Formation,which has epigenetic metallization characteristics.Its ore body is obviously controlled by fracture.There are not many magmatic rocks in the mining area.It has no intermediate-acid pluton and only developments diabase dikes.Based on the mineral association and intercalated relationship,the ore-forming process can be divided into chalcopyrite-sphalerite-tetrahedrite-arsenopyrite stage and sphalerite-galena-pyritecalcite stage.The ore-forming temperatures of chalcopyrite-sphalerite-tetrahedritearsenopyrite stage range from 300? to 370?,belong to medium-high temperature hydrothermal fluid.The ore-forming temperatures of sphalerite-galena-pyrite-calcite stage range from 150? to 250?,belong to medium-low temperature hydrothermal fluid.The sulfur isotope ?34S of sulfide indicates that the sulfur in ore-forming fluid comes from magmatic hydrothermal.The carbon and oxygen isotope of late-stage calcite veins indicates that the carbon and oxygen in ore-forming fluid come from the formation water dissolved marine carbonate rocks and magmatic hydrothermal.The characteristics of trace elements of sphalerite from different mineralization stage indicates that chalcopyrite-sphalerite-tetrahedrite-arsenopyrite stage has magmatic hydrothermal ore-forming characteristics and sphalerite-galena-pyrite-calcite stage has low temperature hydrothermal ore-forming characteristics.Therefore,this study considers that the Tianbaoshan Pb-Zn deposit belongs to mesothermal hydrothermal vein Pb-Zn deposit.The previous research data of the mineralization age of Pb-Zn deposit inSichuan-Yunnan-Guizhou ore concentration area ranges 190 Ma from 230 Ma.This study conducts comprehensive research on Triassic detrital rock and redefines the regional Pb-Zn mineralization geodynamic setting.The results show that the Triassic basin sedimentary background consistents to tectonic dynamic setting of Pb-Zn mineralization in Sichuan-Yunnan-Guizhou ore concentration area.They occur simultaneity under the Indosinian orogeny background.The Indosinian orogeny causes the plate collision and leads to the uplift-denudation of Jiangnan paleocontinent and Yuebei paleocontinent.The material sources of the elastic rocks is transported to inland,meanwhile,the basin fluid flows into inland and the deep fluid rises along the structural fault.The ore-bearing fluid finally mineralizes in Sichuan-Yunnan-Guizhou area.