藏北羌塘地块中部蓝片岩中捕获锆石SHRIMP U-Pb定年及其意义  

SHRIMP U-Pb dating of zircons from blueschist in the central part of the Qiangtang block,northern Tibet,China,and its implications

作　　者：邓希光[1] 张进江[2] 张玉泉[3] 刘敦一[4] 

机构地区：[1]国土资源部广州海洋地质调查局,广东广州510760 [2]北京大学地球与空间科学学院,北京100871 [3]中国科学院广州地球化学研究所,广东广州510640 [4]中国地质科学院地质研究所北京离子探针中心,北京100037

出　　处：《地质通报》2007年第6期698-702,共5页Geological Bulletin of China

基　　金：国家自然科学基金项目(编号:40202023);国家重点基础研究发展规划项目(编号:G1998040800);高等学校全国优秀博士学位论文作者专项资金项目(编号:200022)资助

摘　　要：羌塘中部2个蓝片岩样品中锆石的SHRIMp U-Pb定年结果表明,锆石属于残留锆石,不是蓝片岩相变质作用形成的新生锆石,这些年龄代表源区原岩的年龄或原岩捕获锆石的年龄,是不同构造-热事件的响应。首次在藏北羌塘地区获得了锆石SHRIMP U-Pb年龄2533Ma,说明这颗锆石来自新太古代,虽然不一定源自本地,但至少暗示羌塘地区新太古代曾经可能发生过构造-热事件。SHRIMP U-Pb dating of zircons from two blueschist samples in central Qiangtang, northern Tibet, suggests that the zircons in blueschist are relict ones rather than neogenic ones formed by blueschist facies metamorphism. These ages stand for those of protoliths in source regions or those of zircons captured by protoliths and are responses to different tectonothermal events. The SHRIMP U-Pb zircon age of 2533 Ma obtained for the first time in the central Qiangtang area, northern Tibet, indicates that the zircon originated from the Late Archean rocks, and although the zircon may not necessarily have originated in the study area, its age at least implies that a tectonothermal event may have occurred in the Qiangtang area in the late Archean.

关 键 词：钻石 SHRIMP U—Pb年龄 蓝片岩 羌塘地块中部 西藏 

分 类 号：P588.344[天文地球—岩石学] P597.3[天文地球—地质学]