东昆仑西段阿确墩地区白沙河岩组锆石U-Pb年龄——对前寒武纪基底演化的约束  

Zircon U-Pb geochronology of the Baishahe Formation in the western part of East Kunlun Orogenic Belt:Constraints on Precambrian basement evolution

作　　者：李猛[1,2] 查显锋 胡朝斌[1,2] 高晓峰 李婷[1,2] 姚志亮 LI Meng;ZHA Xianfeng;HU Chaobin;GAO Xiaofeng;LI Ting;YAO Zhiliang(Xi’an Center of Geological Survey,CGS/Orogen Research Center of China Geological Survey,Xi'an 710054,Shaanxi,China;Key Laboratory for the Study of Focused Magmatism and Giant Ore Deposits,MNR,Xi'an 710054,Shaanxi,China;Xi'an Northwest Nonferrous Chemical Exploration Team,Co.,Ltd.,Xi'an 710000,Shaanxi,China)

机构地区：[1]中国地质调查局西安地质调查中心/中国地质调查局造山带地质研究中心,陕西西安710054 [2]自然资源部岩浆作用成矿与找矿重点实验室,陕西西安710054 [3]西安西北有色物化探总队有限公司,陕西西安710000

出　　处：《地质通报》2021年第1期41-57,共17页Geological Bulletin of China

基　　金：国家自然科学基金项目《华北克拉通西南缘豫西地区汝阳群微体化石研究》(批准号:41602005);中国地质调查局项目《东昆仑成矿带木孜塔格铅锌铜金多金属矿调查评价区地质矿产调查》(编号:DD2016002)、《东天山昌吉—双沟山地区区域地质调查》(编号:DD20190065)。

摘　　要：对东昆仑西段阿确墩地区金水口岩群白沙河岩组片麻岩进行了LA-ICP-MS锆石U-Pb年代学研究。结果显示,片麻岩中锆石的年龄范围为2400~410 Ma,峰值范围为1650~1400 Ma,其中存在少量新元古代(1.0~0.9 Ga)和早古生代(410M a)的变质锆石,从而限定了原岩的最早沉积时代,为中元古代末期,指示片麻岩先后经历了新元古代和早古生代变质作用。片麻岩锆石含有大量早古生代变质的信息,考虑到片麻岩中的榴辉岩形成于早古生代(450~410 Ma),推测该地区片麻岩也经历了早古生代榴辉岩相变质作用,片麻岩与榴辉岩为原地关系。结合区域研究资料,表明东昆仑早古生代可能存在1条上千千米的高压变质岩带,可能为俯冲折返后的产物。The geochronology of the detrital zircons of the gneiss in the Aquedun region,western part of the East Kunlun Mountains was studied by LA-ICP-MS method.The ages of the detrital zircons of the gneiss vary between 2400 Ma and 410 Ma with a peak ranging from 1650 Ma to 1400 Ma.Minor metamorphic zircons was dated as 1.0 ~ 0.9 Ga( Neoproterozoic) and 410 Ma( Early Paleozoic). The dating results imply that the protolith of the gneiss was deposited in Late Mesoproterozoic,and had undergone Neoproterozoic and Early Paleozoic metamorphism.Based on eclogite in gneisses formed in Early Paleozoic( 450 ~ 410 Ma).Combined with a lot of Early Paleozoic metamorphic information from zircons in gneiss,it is speculated that the gneiss in this region also underwent Early Paleozoic eclogitefacies metamorphism,and gneiss and eclogite is in situ relationship.Combined with regional studies,it is suggested that there may exists a high pressure metamorphic belt of nearly 1000 km long in Early Paleozoic in East Kunlun,which may be the product of subduction and reentry.

关 键 词：金水口群 白沙河岩组 锆石U-PB年龄 东昆仑 

分 类 号：P534.3[天文地球—古生物学与地层学] P597.3[天文地球—地质学]