新疆肯登高尔铜钼矿地质和S、Pb、O、H同位素组成及Re-Os测年

Geology,S,Pb,O and H isotopic compositions and Re-Os chronology of Kendenggaoer Cu-Mo deposit in Xinjiang

肯登高尔是新疆西天山备受关注的一处铜钼矿,它处于博罗霍洛古生代岛弧带。矿体呈板状、不规则脉状和透镜状产在晚石炭世花岗闪长岩与上石炭统碳酸盐岩外接触带矽卡岩中,矿石中金属矿物以黄铜矿、辉钼矿为主,脉石矿物以透辉石、钙铁榴石为主;硫化物矿物呈自形晶或他形结构,网脉状、浸染状分布于矽卡岩中。内生成矿作用明显经历了矽卡岩和石英-硫化物2期。肯登高尔铜钼矿石中辉钼矿、黄铜矿的δ34SV-CDT值介于-0.55‰～1.90‰,集中在零值附近;206Pb/204Pb=17.963～18.256,207Pb/204Pb=15.549～15.605,208Pb/204Pb=36.802～38.271;成矿物质显示上地幔与下地壳混合来源特点。石英-硫化物铜钼矿石中石英的δ18OH2O(V-SMOW)=-2.82‰～3.65‰,δDH2O(V-SMOW)=-96‰～-82‰,显示成矿流体为岩浆水并有大气降水的混合。铜钼矿石中辉钼矿的w(Re)介于11.13～59.72μg/g,Re-Os等时线测年获得(313.9±2.5)Ma的晚石炭世成矿年龄。铜钼成矿与早石炭世中期依连哈比尔尕小洋盆向南俯冲有关。

Located in Bolohuoluo palaeozoic arc belt,the Kendenggaoer Cu-Mo deposit has aroused much attention among geologists.The ore bodies,in the tabular,laminated and lenticular forms,occur in the outer contact zone between Late Carboniferous granodiorite and Upper Carboniferous carbonate rocks.Metallic minerals in the ore include mainly chalcopyrite and molybdenite,while gangue minerals are mainly diopside and andradite.Sulfide minerals,existing as euhedral or xenomorphic crystals with stockwork and dissemination structures,are distributed in the skarn rocks.Endogenic ore-forming process has obviously experienced two stages of mineralization i.e.,skarn and quartz-sulfide.δ34SV-CDT values of molybdenite and chalcopyrite in the ore vary from-0.55‰ to 1.90‰,concentrated around zero.The ratios of 206Pb/204Pb,207Pb/204Pb and 208Pb/204Pb are from 17.963 to 18.256,15.549 to 15.605,and 36.802 to 38.271,respectively,suggesting that metallogenic materials are derived from both upper mantle and lower crust.δ18OH2O V-SMOW and δDH2O V-SMOW values of quartz as well as the water in the inclusions from the Cu-Mo ores of the quartz-sulfide stage are from-2.82‰ to 3.65‰ and from-96‰ to 82‰,respectively,implying that ore-forming fluids were mainly magmatic water,with the mixture of small quantities of precipitate water.Re content of molybdenite in Cu-Mo ores is in the range of 11.13～59.72 μg/g.Isochron dating of Re-Os is（313.9 ± 2.5）Ma,indicating that the metallogenic age is Late Carboniferous.Therefore,the ore-forming process was related to the southward subduction of the Yilianhabierga oceanic basin in the middle of Early Carboniferous.