Genetic Mineralogy And Metallogenic Environment Characteristics Of Jingren–Hutouya–Kendekeke Deposit

Jingren-Hutouya-Kendekeke Deposit,located in the southern margin of Qaidam Basin closely,as a typical iron-copper-lead-zinc polymetallic deposit in Qimantage metallogenic belt.Jingren Deposit is the west periphery of Hutouya Deposit,with a distance of about 10 km and the same stratigraphic position.Regional faults pass between Hutouya and Kendekeke Deposit,which is about3km apart.In this way,the genes is and metallogenic environment may be different among these deposits.Since the discovery of Kendekeke Deposit in the last century,although great progress has been made in geological background and prospecting after decades of geological in veatigation and mineral exploration,there is still no agreement about the genesis and mineralization of deposits.Besides,Jingren Deposit was discovered relatively later and a comprehensive and systematic study is also needed.This paper takes Jingren-Hutouya-Kendekeke Deposit as the research area,summarizing relevant data about the regional geological background and ore deposit geological characteristics,through thin section and polished section microscope observation,EPMA,in-s itu sulfur isotope test and Re content analysis from molybdenite and other methods to analyze genetic mineralogy typomorphic characteristics of main ore minerals?pyrite,chalcopyrite,sphalerite,magnetite,pyrrhotine,galena and arsenopyrite,etc.?,combined with metallogenic age and metallogenic material sources to analyze the ore genesis comprehensively.Jingren-Hutouya-Kendekeke Deposit is the product of the metallogenic process in the late indochinese epoch,with the metallogenic age ranging from220 to 240 Ma.The fault of Jingren-Hutouya-Kendekeke Deposit developed in NWW direction due to the Caledonian cracking-c losure and Indosinian continental margin collision-orogeny,which provided a channel for the migration of ore-forming fluid.?³⁴S_Py and?³⁴S_Po value obtained by in-situ sulfur isotope test was3.19‰?5.40‰and 0.11‰?2.47‰respectively,with a small variation range,and the?³⁴S was no significant change from the middle to the edge of pyrite and magnetopyrite samples,reflecting the stability of sulfur source in the study area.Based on the analys is of sulfur isotope data of pyrite,magnetite,chalcopyrite and galena,it was found that fractiation equilibrium was reached among sulfide minerals in the study area,and the?³⁴S_totalotal was from-1.66‰to 9.9‰,with an average of 3.67‰,indicating that the sulfur source was characterized by mixing of mantle sulfur and small amounts of other genetic sulfur.The?value of lead isotope?9.410?9.880?of Hutouya and Kendeke Deposits lies between the original mantle and the crust,and is characterized by crust-mantle mixed source lead.Mineralization temperature in the study area was judged to be medium temperature by?Cu+Fe?/S value of chalcopyrite,pyrrhotite exists,Zn/Fe and Zn/Cd value of sphalerite.Besides,the FeS content of sphalerite indicates the metallogenic temperature and pressure among Jingren,Hutouya 2 and 7 series and Kendekeke Deposit are 175?200?,148?223?,148?262?,145?260?and 1618.79?2039.77bar,1410.86?2341.90bar,294.75?3198.12bar,594.43?2809.71bar,respectively,which is consistent with the mineralization temperature?225.14??calculated from the sulfur isotope equilibrium fractionation equation.The metallogenic temperature of Jingren Deposit in the study area is slightly higher than that of Hutouya and Kendeke deposit through geothermometer of sphalerite,arsenopyrite and chalcopyrite mineralogy.The Co/Ni value of pyrite in Jingren Deposit is 10.75?18.034,and the Co/Ni ratio of pyrite in Kendekeke Deposit is 0.87?28.667,which is close to that of magmatic hydrothermal origin and volcanic origin pyrite.The Zn/Cd values of the sphalerite in the study area are in good agreement with the Zn/Cd values?104?214?of the hydrothermal deposit,showing hydrothermal mineralization characteristics.According to the genes is mineralogy of magnetite,the characteristics of hydrothermal mineralization and skarn mineralization exist in the study area.The formation of magnetite in the early stage of Kendekeke Deposit is mainly influenced by magmatic hydrothermal,while the late magnetite has obvious contact metasomatism,which reflects the transition process from magmatic hydrothermal mineralization to skarn hydrothermal mineralization.On the whole,Jingren-Hutouya-Kendekeke Deposit is mineralized in a medium-low temperature metallogenic environment and there's a metallogenic process from magmatic hydrothermal mineralization to metasomatic hydrothermal mineralization which can be summarized as four evolutionary processes:magmatic intrusion,hydrothermal alteration,contact metasomatism and precipitation.