Study On Petrogeochemistry,Chronology And Metallogenic Potential Of Hongshigang Mafic-ultramafic Intrusion In Eastern Tianshan

Eastern Tianshan area of Xinjiang is one of the main Cu-Ni ore deposits in China.There are almost 30 mafic-ultramafic intrusions in Kanghuer-Huangshan shear zone,Suchas:Hongling,Tudun,Erhongwa,Huangshan,Hongshigang,Hulu,Tulaergen,Sidingheishan and so on.Most these intrusions distribute along the Kanger–Huangshanshear zone and its adjacent,with the characteristics ofeast-westband and part-concentration.In the previous research work,the study of the Eastern Tianshan mafic-ultramafic rock belt is mainly focused on the geological and geochemical characteristics of typical deposits such as Tulaergen,Huangshan,Xiangshan and Hulu,relatively speaking,The relative research on geological character and Ore Evaluation of typical rock such asSidingheishan,Tulaergennan,mati,hongshigang is not high.This study is based on the above to select Hongshigang for further discuss.Focus on petrology,mineralogy and geochemical study on the basis of field research,and combined with modern technology analysis to demonstrate the geological background,rock formation age,tectonic environment,magma source and evolution,Deep dissolution of sulfide.Finally constrain process of magma in diagenetic and mineralization of Hongshigang intrusion.Mainly achieved the following progress and results:(1)The lithofacies sequence of Hongshigang are diorite? gabbro? peridotite.The main rock-forming minerals are olivine,pyroxene,amphibole and plagioclase.The main metal minerals are chromite,pyrite,chalcopyrite,pyrrhotite,nickel pyrite,magnetite,ilmenite.Combined with the characteristics of the mineral microscope and crystallization temperature,It can be learned that the crystallization sequence of the main rock-forming minerals is:(chrome)spinel?olivine?clinopyroxene?orthopyroxene,basic plagioclase? hornblende,neutral plagioclase.(2)Hongshigang intrusion is the product of different evolution stages of homogeneous magma,The contents of Al2O3,CaO,Na2 O and ?REE decrease with the increase of rock base degree and TFeO?MgO?m/f?Mg# increase.The diagonal degree of rare earth elements decreases in turn From diorite-peridotite-gabbro,In addition to diorite,Fractionation of rare earth elements between the light and heavy,inner light,inner heavy is weak,and loss of high field strength elements Nb,Ta,the same as most mineralized rock mass in eastern Tianshan.(3)The results of LA-ICP-MS zircon U-Pb dating show that the hornblende gabbro harmonious age is 280.2±1.1Ma,which is formed during stretch after collision in Early Permian.(4)The content of MgO in parental magma of Hongshigang is 10.38 wt.% and the FeO content is 9.06 wt.%.The mantle material in the source area is subjected to the metasomatism of subduction fluid and the sediments,during the magma uplift,it suffered mixed from the surrounding rock or crust material,mainly the middleand lower crust.(5)Most ore-forming indicator of Hongshigang are good,and only a few is different from typical deposits.According to its mineralization,there is a potential for polymetallic deposits in addition to Cu-Ni good prospects in this region,further work needs to be carried out.