Study On The Minerlization Stages And Ore-genesis Of The De'erni Copper Deposit

De'erni Cu deposit, located in the southern slope of De'erni middle of Jishi mountain,Maqin country,Qinhai Province, is a comprehensive utilization deposit which dominanted by Cu. According to previous data, De'erni deposit contains a large scale of S and huge serpentinite resource reserve. De'erni deposit has considerable economic value.Predecessors did not well know about the ore minerals, mineralization stages and ore-genesis of the deposit, especially its ore-genesis has been disputed since it is found, for its high altitude and special geological location. I have studied in detail on its mineralization stages and ore-genesis by macro-observation, mineralogical studies and electron macro probe analysis. Some conclusions can be drawn as following:1.By the mineralogical studies of De'erni Cu deposit, the main minerals such as pyrite, chalcopyrite and sphalerite are divided into three stages, the other minerals only have one stage.2.This is the first time that barite and gypsum was discovered.They insert early stage pyrite, magnetite and carbonate and others.Quartz-carbonate-barite-gypsum is Low-temperature mineral assemblage and also is the typical mineral composition of submarine hydrothermal deposit. Chalcopyrite-sphalerite-pyrrhotite-galena is low-temperature mineral assemblage and similar to the typical hydrothermal ore mineral assemblage Cyprus-type massive sulfide deposit.3.According to the geological features, ore types, ore structures and contextures and mineral composition of De'erni copper deposit. The mineralization of this deposit includes endogenesis stage (serpentinized stage,hydrothermal stage and overlap stage) and supergene stage (Limonite-malachite-chessylite formative stage).4.By calculating the FeS molecule percentage content in the sphalerite,the main ore mineral, results show that the maximum mineralization temperature is less than 400℃and the minimum one lower than 100℃.5.Co-Ni diagram shows that the most samples plot in the neighborhood of Sossego copper-gold deposit, Brazil, which indicates that the pyrite is formed in hydrothermal stage.6.Previous research combination with these mentioned above show De'erni Cu deposit maybe a hydrothermal exhalative-sedimentary deposit in the seafloor environment.