西藏冈底斯北带首例主碰撞造山期铜矿——林周县程巴矽卡岩型铜矿床地质特征、辉钼矿Re-Os同位素年龄及成矿意义  

The first Cu deposit of main collisional stage on the northern gangdese Belt:geological features and molybdenite Re-Os dating of the Chengba skarn Cu deposit in Linzhou County and their geological significance

作　　者：郑文宝[1] 丁帅 李盛俊[3] 冷秋锋 李超[1] 王豪 李茂田 戴成龙 ZHENG Wenbao;DING Shuai;LI Shengjun;LENG Qiufeng;LI Chao;WANG Hao;LI Maotian;DAI Chenglong(MLR Key Laboratory of MetaUogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing,100037;Guangxi Non ferrous Metal Group Resource Exploration Co.,Ltd.,Nanning,1530023;Sichuan Institute of Nuclear Industry Geological Survey,Chengdu,610000;College of Earth Sciences,Chengdu University of Technology,Chengdu,610059)

机构地区：[1]中国地质科学院矿产资源研究所国土资源部成矿作用与资源评价重点开发实验室,北京100037 [2]广西有色金属集团资源勘查有限公司,南宁530023 [3]四川省核工业地质调查院,成都610000 [4]成都理工大学地球科学学院,成都610059

出　　处：《地质学报》2019年第2期459-469,共11页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号41302060);中国地质调查局地质调查项目(编号12120113093700)资助的成果

摘　　要：通过近十年的地质勘查,在冈底斯北带多座具有经济价值的矿床得到开发利用,该带已经成为西藏地区矿床勘查与研究的又一热点地区。程巴铜矿是冈底斯北带近年来新发现的唯一一例中-大型规模的富铜矿床。矿床为典型的富含石榴子石的矽卡岩型矿床,铜矿体主要呈似层状、脉状产于林布宗组角岩和多底沟组大理岩的层间构造带内,矿石中富铜,伴生钼、锌、金、银、铋。本文在矿床成矿地质背景和矿床地质特征研究的基础上,用Re-Os同位素方法测试辉钼矿,获得等时线年龄为58.49±0.43 Ma(MSWD=0.61),模式年龄加权平均为58.49±0.33Ma(MSWD=0.25),确定程巴铜矿是主碰撞期成矿作用的产物,程巴铜矿的发现证明在冈底斯成矿带主碰撞造山过程能够形成铜矿床。因此,主碰撞成矿阶段由深变浅的矿床组合模型应在前人研究的基础上修改为矽卡岩型Cu(Mo)矿+矽卡岩型Fe-Pb-Zn-Mo(Cu)矿+斑岩型Mo(W)矿。此外,辉钼矿中Re含量介于84.6×10^(-6)～461.3×10^(-6)之间,平均值为252×10^(-6),暗示程巴矿区物源具有壳幔混合的特征。Through nearly ten years of geological exploration,several ore deposits with high economic values in the northern Gangdese have been developed and utilized;therefore,this belt has become another hot spot of geological exploration and research in Tibet.The Chengba deposit is the only medium-large sized Curich deposit newly discovered in the northern Gangdese belt.It is typical of a skarn depositswhich consists mainly of garnets.Cu-bearing orebodies at the Chengba deposit occur in interlayers between the Linbuzong Formation hornfels and Duodigou Formation marble as strata or veins,accompanied with secondary Mo,Zn,Au?Ag and Bi.On the basis of the geological background and geological characteristic of ore deposit,Re-Os dating of molybdenite yields a model age of 58.2~58.8Ma and an isochron age of 58.49+0.43Ma(MSWD=0.61),determining that the Chengba Cu deposit is the product of mineralization in the main collision stage.The discovery of the Chengga copper deposit confirms that copper deposits can be formed from main collisional process of the Gangdese metallgoenic belt.Therefore,the composite model of the deposits in the main collision stage should be modified into the skarn Cu(Mo)+skarn Fe-Pb-Zn-Mo(Cu)+porphyry Mo(W)from the previous study ones.In addition,Re contents of molybdenite range between 84.6×10^-6 and 461.3×10^-6(ave.252×10^-6),indicating that the ore-forming materials of the Chengba Cu deposit are characterized by mixing of the crust and mantle.

关 键 词：地质特征 辉钼矿RE-OS年龄 主碰撞造山 冈底斯北带 程巴铜矿 

分 类 号：P618.41[天文地球—矿床学]