西藏曲水县达布斑岩铜(钼)矿床成岩成矿年代学研究  

A Study of Diagenetic and Metallogenic Geochronology of the Dagbo Cu(Mo) Deposit in Quxur County of Tibet and Its Geological Implications

作　　者：高一鸣[1] 陈毓川[2] 唐菊兴[1] 罗茂澄[3] 冷秋锋[4] 王立强[1] 杨海锐[4] 普布次仁 

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实验室,北京100037 [2]中国地质科学院,北京100037 [3]中国地质大学(北京),北京100083 [4]成都理工大学,四川成都610059 [5]西藏自治区地质矿产勘查开发局,西藏拉萨850000

出　　处：《地球学报》2012年第4期613-623,共11页Acta Geoscientica Sinica

基　　金：973项目"青藏高原南部增生造山成矿系统发育机制"(编号:2011CB403103);青藏专项"西藏冈底斯东段中新生代斑岩成矿系统与找矿预测"(编号:1212011085529)联合资助

摘　　要：本文采用锆石LA-ICP-MS微区U-Pb测年技术,对冈底斯成矿带东段曲水县达布斑岩Cu(Mo)矿床北部达布矿区含矿斑岩体、南部显角囊含矿花岗闪长斑岩岩体进行了年代学研究,通过对3件岩体样品中单颗粒锆石的分析,达布主矿体花岗闪长斑岩样品206Pb/238U年龄加权平均值为16.5±0.05Ma(n=15,MSWD=3),达布主含矿体二长花岗斑岩样品年龄为16.1±0.13Ma(n=15,MSWD=1.03),南部显角囊矿体花岗闪长斑岩年龄为16.2±0.04Ma(n=13,MSWD=0.0064)。对达布矿床斑岩Cu(Mo)矿床主矿体中4件辉钼矿样品,显角囊矿体中6件辉钼矿样品,分别进行了Re-Os同位素测试,等时线年龄分别为14.6±0.50Ma(MSWD=0.35,主矿体)、14.8±0.23Ma(MSWD=1.3,显角囊)。结合前人研究以及本次测年结果认为:1)达布斑岩铜(钼)矿床岩体侵位的年龄应限定在16Ma左右,成矿时代为14Ma左右,成矿时间差小于0.86Ma,与区域上"成矿瞬时发生"的成矿规律是一致的;2)矿床产出于印度-亚洲大陆板块后碰撞伸展环境。Located in Quxu County of Tibet, the Dabu porphyry Cu-Mo deposit lies in the eastern part of the Gangdise belt. The authors made high-precision magmatic zircon dating of the granodiorite from the Dabu deposit The U-Pb dating analyses show that the weighted mean ages of the porphyry from the main ore body are 16.5±0.05 Ma（n=13, MSWD=3, granodiorite） and 16.1±0.13 Ma（n=15, MSWD=1.03, monzonitic granite-porphyry） respectively. The U-Pb dating analyses indicate that the granodiorite from the Xianjiaonang ore body has the weighted mean age of 16.2±0.04 Ma（n=13, MSWD=0.0064）. For the purpose of determining the mineralization time of the deposit, 4 south were selected to conduc molyb t Re- denite samples from the north and 6 molybdenite samples from the Os dating. The Re-Os dating yielded isochron age of 14.6±0.50 Ma（MSWD=0.35, N） for the samples from the northern part and 14.8±0.23 Ma（MSWD=1.3, S） for the samples from the southern part of the deposit, respectively. Based on the results mentioned above in association with data availab mineralization age let of it is proposed that crystallization of the porphyry occurred at about 16Ma, and the the deposits is about 14Ma, in a short period with time span shorter than 0.86Ma, implying the speciality of paroxysmal mineralization in the post-collision extension environment .

关 键 词：西藏 冈底斯 达布斑岩Cu(Mo)矿床 锆石U—Pb年龄 辉钼矿RE-OS年龄 后碰撞伸展 

分 类 号：P618.41[天文地球—矿床学] P597[天文地球—地质学]