Study On Geological Characteristics And Metallogenesis Of Kangjiawan Lead-zinc Deposit,Hunan

The Kangjiawan deposit is a large-scale lead-zinc deposit,located in the northeast of the Shuikoushan polymetallic ore field in southern Hunan.Based on field geological investigation,this paper presents a comprehensive study of the mineralization geological background,geological features,characteristics of ore body morphology,geological characteristics of breccia,and combined with geochemical detection of mineral deposits,to explore he source of ore-forming material and the origin of ore deposit,and the metallogenic model of ore deposits are established.This paper has achieved the following main understanding:Through the analysis of the characteristics of ore body morphology and metallogenic structure of the Kangjiawan ore body,it is believed that the main ore bodies of VI and VII in Kangjiawan belong to breccia-metallotectonical type;The main ore bodies of I to V are karstmetallotectonical type.The analysis of the breccia and genetic characteristics in the area shows that the closeness of various types of breccia and mineralization is:interlayer silicified breccia> karsl breccia>collapse breccia>tecto breccia.It is found that the formation of all kinds of breccia is synchronous with the formation process of the mineral deposits,and they have experienced two stages of underground hot water activities and magmatic hydrothermal activities by comparing with the geochemical characteristics of ore.Besides the breccia formed in the early stage offer the source of ore-forming material and essential space for the ore-forming in the later mineralizing process.The ore originate of sulphur in the Kangjiawan lead-zinc deposit are relatively complex,mainly from deep magma,while contaminating the organic matter,crust,the Earth's mantle material,and atmospheric precipitation in ancient karst deposits according to the analysis of the characteristic of the composition of sulfur isotope and the judge of the balance of sulfur isotope fractionation.Based on the analysis of the characteristics of the composition of lead isotopes,it is further concluded that magmatic fluid offered principal hydrothermal source for mineralization,and the radiogenic lead in the early formation of wall-rock breccias are mixed in.It can be seen that the early formation of wall-rock breccias also provided material source for the later mineralization,which in turn confirmed the close relationship between the surrounding rock breccia and metallogenesis.The ore fluid consist of the mixture of volcano water and rainwater,while organic matter,groundwater and brine are also involved in metallogenesis by analyzing the characters of fluid inclusions and the data of the carbon and hydrogen and oxygen isotopic compositions.Therefore,it was concluded that there was a metallogenic epoch of hydrothermal depositions in the process of early karst development and sedimentary filling in the area.On the basis of the above analysis,the Kangjiawan lead-zinc deposit is considered to be a hydrothermal karst type deposit,and has gone through five stages:the formative stages of Faults and folds,the formative stages of paleokarst,the stages of mineralization of hot brine,the stages of construction collapse,the formative stages of Mixed hydrothermal solutions.