In Xinjiang Altai Region Halasu, The Copper Deposit Minerageny

The Halasu copper deposite in Xinjiang Aertai area is situated in the famouscopper belt of Lalaxiangeer, where fault structures widely developed and magmaticactivity is very strong, this area has abundant copper, nickel and gold mineralresources. Therefore this area has good ore prospects.This paper is based on field geological work, researched Halasu copper depositgeologic background, ore-forming geologic condition, rock mineralization andalteration characteristics. As well as applying many kinds of meehods such astypomorphic pecularities of pyrite, sulfur isotopic composition, study on fluidinclusions and together with analysis and comparison.Field obserbation and laboratory study indicate the main type of rock alterationwere K-feldsparization, biotitization, sericitization, silication, epidotization,chloritization and carbonatization. From early to late, these alteration could dividedinto three epochs: early-stage was K-feldsparization-biotitization, middle-stage wasquartzification -sericitization, late-stage was silication, carbonatization, epidotizationand chloritization. In ore body, K-feldsparization is widely distributed, silication ispockety, the other alterations have obvious vertical zoning, from upper to lower is:biotite zoneâ†'sericite zoneâ†'propylitic zone (epidote-chlorite-calcitization zone).According to mineral associated characteristics and intersection relationships,mineralization and alteration epochs, the pyrite can be divided into three generations,correlation to mineralization is secondly and thirdly epochs. The data analysis of mainelements and trace elements compositions of pyrites show that comparision withstandard value, sulphur is less deficiency and iron is similar in main elements. Theprimarily trace elements are Co, Ni, Se, Te, Cu., of which high Co content couldachieve to 1020ppm, Co/Ni is 1.918～15.549,S/Se is 0.564×104～1.251×104,Se/Te is 为 0.826～9.479,that indicates the genetic of pyrite in this deposit ishydrothermal alteration.The research of sulfur isotopic composition in pyrite and copper showsδ34S‰has narrow variable ranged which from -2.9 to 1.1, so the sulfur should derive frommantle. Research of fluid inclusions in quartz vein and quartz phenocrysts indicate thethree main types fluid inclusions are carbon dioxide inclusions, gas-liquidinclusions(gas-liquid ratio under 25 percents) and crystal-bearing multiphaseinclusions(greater than or equal). By the means of temperature measurement, analyzethe ore-forming fluid temperature, salinity and density, estimate the range ofore-forming pressure is 132.9～436.9Mpa,average value is 237.3 Mpa,ore-formingdepth is about 747m。This deposit should be porphyry copper deposit, the magmatic rocks related tomineralization mainly include quartz diorite porphyry and granodiorite porphyry. Thedeposit developed in the environment of epi-middle-low temperture.