西昆仑康西瓦断裂西段斜长片麻岩LA-ICP-MS锆石U-Pb定年及其构造意义  

LA-ICP-MS zircon U-Pb dating of garnet-bearing muscovite-biotite plagioclase gneiss in western Kangxiwar fault of Western Kunlun and its tectonic significance

作　　者：康磊[1] 校培喜[1] 高晓峰[1] 董增产[1] 过磊[1] 奚仁刚[1] 

机构地区：[1]中国地质调查局西安地质矿产研究所,陕西西安710054

出　　处：《地质通报》2012年第8期1244-1250,共7页Geological Bulletin of China

基　　金：中国地质调查局项目<西昆仑-阿尔金成矿带基础地质综合研究>(编号:1212011085034);陕西省自然科学基金项目<岩浆混合各阶段产物的锆石微区分析:对西准噶尔花岗岩和铜钼矿的成因以及地壳生长的启示>(编号:2012JM5004)

摘　　要：在康西瓦断裂西段发育着一套含石榴子石二云斜长片麻岩。根据锆石的阴极发光图像和Th、U、REE等特征,锆石可分为岩浆成因和变质热液成因2类。利用LA-ICP-MS法进行锆石U-Pb定年,测得含石榴子石斜长片麻岩的源岩形成年龄为254.5Ma±4.2Ma(MSWD=0.16),变质年龄为242.7Ma±2.3Ma(MSWD=0.11)。结合区域地质资料,含石榴子石二云斜长片麻岩的变质作用与古特提斯碰撞造山有关,表明西昆仑造山带在中三叠世早期(243Ma)仍处于古特提斯碰撞造山期。There exists garnet-bearing muscovite-biotite plagioclase gneiss in western kangxiwar fault.According to cathodoluminescence（CL） images and Th,U,REE characteristics,the zircons can be classified into magmatic zircons and metamorphic-hydrothermal ones.Zircon LA-ICP-MS U-Pb dating shows that the age of the protolith of the garnet-bearing plagioclase gneiss is 254.5Ma±4.2Ma（MSWD=0.16）,and the age of its metamorphism is 242.7Ma±2.3Ma（MSWD=0.11）.In combination with regional geological information,the authors hold that the metamorphism of garnet-bearing plagioclase gneiss was related to the collision and orogeny of Paleo-Tethys,suggesting that the Western Kunlun orogenic belt was still in the period of Paleo-Tethys collision in early Middle Triassic.

关 键 词：西昆仑 含石榴子石二云斜长片麻岩 LA-ICP-MS锆石U-PB测年 构造意义 

分 类 号：P588.34[天文地球—岩石学] P597[天文地球—地质学]