西藏班公湖-怒江成矿带西段富铁矿与铜(金)矿C、Si、O、S和Pb同位素特征及地质意义  

Characteristics of C,Si,O,S and Pb Isotopes of the Fe-rich and Cu(Au) Deposits in the Western Bangong-Nujiang Metallogenic Belt,Tibet,and Their Geological Significance

作　　者：吕立娜[1] 赵元艺[1] 宋亮[2] 田毅[3] 辛洪波[1] 

机构地区：[1]中国地质科学院矿产资源研究所,北京100037 [2]中国地质大学(北京),北京100083 [3]吉林大学,长春130026

出　　处：《地质学报》2011年第8期1291-1304,共14页Acta Geologica Sinica

基　　金：国家"973"计划项目(编号2011CB403103);国家科技支撑课题(编号2006BAB01A05);中国地质调查局青藏专项(编号1212010818097)共同资助成果

摘　　要：本文在大量的野外地质调查与室内研究的基础上,对班公湖-怒江成矿带西段的4个典型矿床———材玛矽卡岩型铁矿床、弗野矽卡岩型铁矿床、尕尔穷矽卡岩型铜金矿床和多不杂斑岩型铜金矿床的C、Si、O、S和Pb同位素特征进行了研究。δ30Si、δ18O的研究结果表明,石英主要为岩浆热液成因,δ13C、δ18O同位素的研究结果表明,与成矿有关的矽卡岩、磁铁矿大理岩中的碳除部分来源于海相碳酸盐岩的溶解外,主要来源于地幔,多不杂矿区的硫同位素研究结果表明成矿物质主要来自岩浆流体。多不杂和尕尔穷矿区岩石样品中的铅同位素研究显示其属于造山带构造环境,部分接近下地壳。因此,尕尔穷和多不杂矿区的铅同位素组成主要是班公湖-怒江成矿带在弧-陆碰撞造山过程中形成的。班公湖-怒江成矿带西段的区域成矿模式初步总结为早白垩世深源岩浆流体与二叠纪、三叠纪和白垩纪的海相碳酸盐岩接触的外接触带形成了矽卡岩型矿体,在与中侏罗统和下白垩统砂岩、粉砂岩接触处的内外接触带形成了斑岩型矿体。Based on geological surveys and researches,the study discussed four typical deposits distributed on the western Bangonghu-Nujiang metallogenic belt（Caima skarn-type iron deposit,Fuye skarn-type iron deposit,Garqiong skarn-type copper-gold deposit and Duobuza porphyry-type copper-gold deposit）,and their C,Si,O,S and Pb isotope characteristics.The δ30Si-δ18O results suggest that quartzes are magmatic hydrothermal in origin.The δ18O-δ13C isotope results show that carbon of skarn and magnetite marble related with mineralization was mainly from mantle,except that partial carbon resulted from solution of marine carbonate.Study of sulfur isotopes for the Duobuza deposit suggests that ore-forming material derived mainly from magmatic fluid.Pb isotope analysis of the samples from the Duobuza and Garqiong mines shows that both of them formed in a structural environment of orogen,with part of mines approaching lower crust.Therefore,Pb isotopic compositions of the Duobuza and Garqiong mines indicate that the Bangonghu-Nujiang metallogenic belt resulted from arc-continent collisional orogeny.It can be concluded that the metallogenic mode of the western section of the Banggonghu-Nujiang metallogenic belt is that the skarn-type orebodies formed along the exocontact zone between Early Cretaceous magmatic fluid and Permian,Triassic and Cretaceous marine carbonatic rocks,and the porphyry-type orebodies formed along the endocontact and exocontact zones between the magmatic fluid and Mid-Jurassic and Lower Cretaceous sandstone and siltstone.

关 键 词：西藏 班公湖-怒江成矿带西段 C-Si-O-S-Pb同位素 成矿模式 

分 类 号：P597[天文地球—地球化学] P618.31[天文地球—地质学]