Discussion On The Characteristics And Genesis Of Kangjiawan Pb-Zn-Au-Ag Deposit,Hunan

The Kangjiawan Pb-Zn-Au-Ag polymetallic deposit is located in the depression of southeastern Hunan province,the middle sector of the Oinhang metallogenic belt between Yangtze and Cathaysia Plates.It's an important part of Shuikoushan Orefield.Combining with achievements done by former scientists and the detailed results of field geological survey,both fluid inclusion and isotope geochemical characteristics of this very deposit have been further studied,meanwhile the properties of ore-forming fluids and the source of ore-forming materials.At last the genesis of this ore deposit has been discussed while the metallogenic model has also been initially established on account of specifically regional tectonic evolution and geochronological data.Within the mining area,there are not exposed igneous rock body(pulse)in the surface.Combined with the Kangjiawan geological characteristics and its surrounding environment,earth chemical profile elements ratio and fluid inclusion geochemical,puts forward the metallogenic geologic body of the Kangjiawan ore deposit is the Laoyachao 4th granodiorite.we concluded that Shuikoushan Orefield of diagenetic and mineralization occurred continuously over the same period.Kangjiawan Pb-Zn-Au-Ag polymetallic deposit is a concealed deposits under cretaceous red gritstone.The main orebodies occurred in the Kangjiawan between concealed overturned anticline and F22 nappe fault phase cutting of the Dangchong formation of the Permian lower memeber mudstone and Qixia formation carbonate rocks of interlayer silicide fracture zone.The morphology of orebody is stratoid,lenticular,vein outputs.Metallic minerals are dominantly galena,sphalerite,pyrite.Gangue minerals are mainly quartz,chalcedony and subordinately calcite.The ores are mostly disseminated,breccia,banding and massive in structure,while their textures are mainly idiomorphic-subhedral,crushing,metasomatic residual textures.The alterations of wall rocks related with mineralization are basically silicification,carbonatation,a little adularization,sericitization,chloritization,exhibiting a regular zonation.The major ore-forming stage can be divided into three stages,that is,pyrite-quartz stage,galena-sphalerite-quarze stage,gold and sliver sulphide-carbonate stage.The study of fluid inclusion indicated that the metallogenic process is under mid-low temperature conditions and ore-forming fluid is mid-low salinity and mid density type.The ore-forming fluid of the temperature,salinity and pressure decrease as the ore-forming continuing.The characteristics of hydrogen and oxygen isotope indicated that the ore-forming fluid was the magmatic fluid,with the deposit was forming,more and more meteoric water mixed into the ore-forming fluid and increased gradually.The characteristics of carbon?sulfur and lead isotope indicated that the ore-forming material was mostly from magma and partly from wall-rock.Through comprehensive analysis in geological characteristics and the deposit geochemistry characteristics,it shows that Kangjiawan Pb-Zn-Au-Ag deposit is a mesothermal and epithermal deposit,which is related to the magmatic fliud and controlled by the lithologic interface.