西藏聂荣微陆块变质基底新元古代—侏罗纪构造–岩浆事件:来自LA-ICP-MS锆石U-Pb定年的启示  

Neoproterozoic-Jurassic Tectonic-Magmatic Events of the Metamorphic Basement in the Nyainrong Microcontinent of Tibet:Implications from Zircon LA-ICP-MS Geochronology

作　　者：陆露[1,2] 钱程 赵珍[4] 吴珍汉[4] LU Lu;QIAN Cheng;ZHAO Zhen;WU Zhenhan(Paleontological College of Shenyang Normal University,Shenyang 110034,China;Key Laboratory of Evolution of Past Life in Northeast Asia,Ministry of Natural Resources,Shenyang 110034,China;Shenyang Institute of Geology and Mineral Resources,Shenyang 110000,China;Chinese Academy of Geological Sciences,Beijing 100037,China)

机构地区：[1]沈阳师范大学古生物学院,辽宁沈阳110034 [2]自然资源部东北亚古生物演化重点实验室,辽宁沈阳110034 [3]沈阳地质矿产研究所,辽宁沈阳110000 [4]中国地质科学院,北京100037

出　　处：《沉积与特提斯地质》2023年第4期734-746,共13页Sedimentary Geology and Tethyan Geology

基　　金：中国地质调查局项目“羌塘盆地隆鄂尼-鄂斯玛地区油气地质构造调查”(DD20160161);辽宁省教育厅项目“西藏聂荣微陆块片麻岩年代格架重建”(LQN201915);沈阳师范大学博士引进人才科技项目启动基金项目“西藏聂荣微陆块侏罗纪花岗岩类研究”(BS201705)。

摘　　要：本文选择聂荣微陆块变质基底中正片麻岩进行了详细的年代学研究,通过LA-ICP-MS锆石U-Pb测年获得的年龄结果分别为502.8±1.2 Ma、532.7±3.4 Ma、833.2±2.8 Ma、734.8±3.3 Ma、495.3±1.7 Ma、496.6±2.0 Ma、495.1±1.2 Ma、803.8±2.8 Ma、811.7±2.8 Ma。综合上述片麻岩锆石U-Pb测年数据结果发现,聂荣微陆块变质基底中正片麻岩的锆石U-Pb年龄大致可以分为三组:830~730 Ma、580~470 Ma、185~160 Ma,说明聂荣微陆块变质基底从新元古代—侏罗纪经历了三期构造–岩浆事件,这三期构造事件分别发生于新元古代早期、新元古代晚期—早古生代、早—中侏罗世。综合前人研究结果,认为聂荣微陆块存在新元古代的基底,并经历了罗迪尼亚超大陆的裂解,于新元古代晚期—早古生代时期发生了泛非—早古生代构造事件,到了侏罗纪,受班公湖–怒江洋壳俯冲和大洋关闭的影响,变质基底发生了早—中侏罗世的岩浆作用和变质作用。In order to further research the Nyainrong microcontinent and the regional geological conditions of the Tibet Plateau,this paper systematically studied the geochronology of orthogneisses from the Nyainrong microcontinent in Tibet.We obtained the zircon U-Pb ages of nine samples by LA-ICP-MS,which were 502.8±1.2 Ma,532.7±3.4 Ma,833.2±2.8 Ma,734.8±3.3 Ma,495.3±1.7 Ma,496.6±2.0 Ma,495.1±1.2 Ma,803.8±2.8 Ma,811.7±2.8 Ma.To analyze these age results,we could divide these ages into three groups:830-730 Ma,580-470 Ma,185-160 Ma.It concludes that the metamorphic basement of Nyainrong microcontinent underwent three tectonic-magmatic events which occurred in the early Neoproterozoic,the late Neoproterozoic to the early Paleozoic,and the early-middle Jurassic.Combined with previous studies,it suggests that the Nyainrong microcontinent has Neoproterozoic basement and occurred the breakup of the Rodinia Supercontinent.The metamorphic basement underwent Pan-African and early Paleozoic tectonic events.Then it underwent early-middle Jurassic magmatic-metamorphic events which were related to the Bangong-Nujiang suture zone subduction and closure.

关 键 词：聂荣微陆块 正片麻岩 锆石U-PB年龄 新元古代—侏罗纪 青藏高原 

分 类 号：P597.3[天文地球—地球化学]