新疆萨热克砂砾岩型铜矿床成矿流体碳、氢-氧同位素组成及其意义  

Carbon,hydrogen and oxygen isotopic compositions from ore-forming fluids of Sareke sediment-hosted copper deposit,Xinjiang

作　　者：贾润幸[1,2] 方维萱[1,2] 王寿成 杨自安[1] JIA RunXing;FANG WeiXuan;WANG ShouCheng;YANG ZiAn(China Non-ferrous Metals Resource Geological Survey,Beijing 100012,China;Innovation Laboratory of Mine,Environment and Mineral,China Non-ferrous Metals Resource Geological Survey,Beijing 100012,China)

机构地区：[1]有色金属矿产地质调查中心,北京100012 [2]有色金属矿产地质调查中心矿山生态环境资源创新实验室,北京100012

出　　处：《矿床地质》2021年第6期1299-1311,共13页Mineral Deposits

基　　金：新疆乌恰县萨热克地区铜多金属矿整装勘查区矿产调查与找矿预测项目(编号:121201004000150017-47、121201004000160901-67)资助。

摘　　要：新疆萨热克铜矿为砂砾岩型铜矿床,赋矿地层为上侏罗统库孜贡苏组砂砾岩。矿体以层状为主,并有裂隙、碎裂构造岩相伴生,常见辉铜矿等金属硫化物与石英、方解石和白云石等胶结物沿砾石间隙或岩石裂隙充填分布。为了揭示成矿流体的性质、来源,文章对矿体中呈脉状产出的石英和碳酸盐矿物(方解石和白云石)中的流体包裹体和碳、氢-氧同位素进行了测定。研究表明:石英和方解石中流体包裹体的气相分数通常为5%~15%,均一温度变化范围88~249□,平均为172□;盐度变化范围为6.30%~12.51%,平均为9.46%,为中低温、中低盐度成矿流体。脉状方解石中的δD变化范围为-72‰~-62‰,平均-67.3‰;δ^(18)O变化范围为3.9‰~8.0‰,平均5.3‰,脉状石英中δD变化范围为-101.7‰~-87.1‰,平均-93.3‰;δ^(18)O变化范围5.1‰~7.5‰,平均6.6‰,氢-氧同位素组成主要落在岩浆水和变质水重叠区及其附近。方解石(白云石)中的δ^(18)O变化范围为-15.1‰~-9.5‰,平均为-12.9‰;δ^(13)C变化范围为-2.5‰~-2.0‰,平均为-0.8‰。同位素组成显示其位于海相碳酸盐岩区左侧附近,与研究区石炭系等碳酸盐岩的碳、氧同位素相似,表明铜矿石中的脉状方解石脉(无机碳)主要与海相碳酸盐岩的溶解作用有关。综合考虑上述结果,文章推测在萨热克铜矿的北矿段深部可能存在隐伏岩体,成矿流体为变质流体与岩浆热液叠加形成的具中、低温,中、低盐度特征的混合流体,该研究区深部存在具有进一步找矿的潜力。The Sareke copper deposit in Xinjiang is a sediment-hosted copper deposit,the orebodies are mainly hosted in glutenite of the Upper Jurassic Kuzigongsu Formation.The orebodies are mainly stratiform,accompanied by fissures and fragmentation breccias.Metal sulfides such as chalcocite are cemented by quartz,calcite and dolomite and commonly distributed in pores among gravels or rock fissures.In order to reveal the nature and origin of ore-forming fluids,fluid inclusions and C、H-O isotopes of quartz and carbonate minerals (calcite and dolomite)occurred as veins in orebodies have been measured.The results show that the gas-liquid ratio of fluid inclusions in quartz and calcite is usually in the range of 5%~15%,and the homogenization temperature ranges from 88℃ to 249℃,with an average of 172□.The salinity varies from 6.30%to 12.51%,with an average of 9.46%,indicating moderate to low temperature as well as moderate to low salinity.TheδD in vein calcite ranges from -72‰to -62‰with an average of-67.3‰,and δ^(18)O ranges from 3.9‰to 8.0‰with an average of 5.3‰.The δD in vein quartz ranges from -101.7‰to-87.1‰with an average of-93.3‰.δ^(18)O varied from 5.1‰to 7.5‰with an average of 6.6‰.In the δ^(18)O-δD diagram,the above samples mainly fall in and around the overlap region of magmatic water and metamorphic water.Theδ^(18)O in calcite (dolomite) ranges from -15.1‰to -9.5‰,with an average of-12.9‰.The δ^(13)C ranges from -2.5‰to-2.0‰,with an average of -0.8‰;In the δ^(18)O-δ^(13)C diagram,most of the above samples fall near the left side of the marine carbonate rocks,which is similar to the carbon and oxygen isotopes of the Carboniferous carbonate rocks in this area,indicating that the vein calcite (inorganic carbon)in copper ores are mainly related to the dissolution of marine carbonate rocks.Considering the above results,it is speculated that there may be concealed intrusive rock mass in the deep northern zone of the Sareke copper deposit,and the ore-forming fluid is t

关 键 词：地球化学 成矿流体 碳、氢-氧同位素 流体来源 成矿作用 砂砾岩型铜矿 萨热克铜矿 

分 类 号：P618.82[天文地球—矿床学]