Geochemical Characteristics And Metallogenic Mechanism Of Copper Polymetallic Deposit In Kungaishan Mountain

Kungaishan mountain belongs to West Kunlun Mountains which is located in the northwestern of Pamir Plateau.In the north slope of Kungaishan,a set of Carboniferous bimodal volcanic rocks,characterized by basic and acidic rock components,is widely developed.At present,there are more than ten VMS type deposits and mineralization sites discovered in this set of volcanic rocks,forming a narrow metallogenic belt in space.In this study,the Saluoyi copper deposit and the Aketashi copper deposit in the metallogenic belt are selected as typical deposits to analyze.Based on the previous research results and comprehensive analysis of the metallogenic geological conditions in this area,using the geochemical and isotope methods of the deposit,researches and analyzes the metallogenetic enviroment,material sources,and the formation age of the deposit,etc.The metallogenic mechanism of the deposit is discussed,the understanding of the ore deposit is deepened and the regional metallogenic theory is enriched.The Saluoyi and Aketashi deposits are produced in the Lower Carboniferous Wuluate formation and the Upper Carboniferous Keziliqiman formation,respectively.The formation rock combinations are dominated by basic and acidic marine volcanic rocks,respectively.The geochemical characteristics of the rocks indicate that the Wuluate formation volcanic rocks are a set of sodium low-potassium and calcium-alkaline transitional series of bimodal volcanic rocks with N-MORB characteristics and formed in the early stages of the Carboniferous rift extension.The rock combination of Keziliqiman group is a bimodal volcanic rock characterized by low-potassium tantalum and calcium-alkaline transition characteristics.It is characterized by N-MORB and formed in the late stage of rift extension.The?³⁴S value of the Saluoyi deposit(average 4.0‰)and Aketashi deposit(average 2.7‰)indicate that the sulphur source may be a mixed sulphur formed from the magma and seawater;and the Pb isotope indicates that it is a mixture of mantle and crust source.Combined with the geological characteristics of the ore deposit and the geochemical characteristics of the rock(ore),the study found that the ore-forming materials of the Aketashi-Saluoyi metallogenic belt mainly come from ore-bearing volcanic rocks and magmatic hydrothermal fluids.The characteristics of fluid inclusions suggests that the Saluoyi deposit has a higher ore-forming temperature and a slightly deeper ore-forming depth than the Aketashi.The zircon U-Pb ages shows that the age of the bottom and top of the Wuluate group(353.9±1.6Ma and 337.7±4.9Ma),which are close to the H.H mode age(337.94Ma)of the Pb isotopes of the Saluoyi deposit and the age of the Aketashi deposit(314.63Ma).It is assumed that the Saluoyi deposit was formed in the Early Carboniferous,and the Aketashi was formed in the Late Carboniferous.Compared with the typical VMS deposits in the world,it is believed that the genesis of the Saluoyi deposit is similar to the Cyprus type,and that the Aetashi deposit is similar to the Kuroko type deposits.Compared with deposit characteristics,it is similar to Ashele copper deposit which formed in the bimodal volcanic rock,in Xinjiang.