A new understanding of Demala Group complex in Chayu Area, southeastern Qinghai- Tibet Plateau: Evidence from zircon U-Pb and mica ^(40)Ar/^(39)Ar dating
A new understanding of Demala Group complex in Chayu Area, southeastern Qinghai-Tibet Plateau: Evidence from zircon U-Pb and mica 40Ar/39Ar dating作者机构：Institute of GeologyChinese Academy of Geological SciencesBeijing 100037China Chengdu CenterChina Geological SurveyChengdu 610081China
出 版 物：《China Geology》 (中国地质（英文）)
年 卷 期：2021年第4卷第1期
页 面：77-94页
学科分类：0709[理学-地质学] 0819[工学-矿业工程] 0908[农学-水产] 07[理学] 0710[理学-生物学] 070902[理学-地球化学] 070901[理学-矿物学、岩石学、矿床学] 0707[理学-海洋科学] 0818[工学-地质资源与地质工程] 0708[理学-地球物理学] 0815[工学-水利工程] 0705[理学-地理学] 0816[工学-测绘科学与技术] 0813[工学-建筑学] 0814[工学-土木工程] 0812[工学-计算机科学与技术（可授工学、理学学位）]
基 金：a project of National Natural Science Foundation of China(41773026) two geological survey projects initiated by the China Geological Survey(DD20190053,DD20160021)
主 题：Demala Group complex Zircon U-Pb dating 40Ar/39Ar dating Jiali fault zone Geological survey engineering Tibet-Qinghai Plateau China
摘 要：The Chayu area is located at the southeastern margin of the Qinghai-Tibet *** region was considered to be in the southeastward extension of the Lhasa Block,bounded by Nujiang suture zone in the north and Yarlung Zangbo suture zone in the *** Demala Group complex,a set of high-grade metamorphic gneisses widely distributed in the Chayu area,is known as the Precambrian metamorphic basement of the Lhasa Block in the *** to field-based investigations and microstructure analysis,the Demala Group complex is considered to mainly consist of banded biotite plagiogneisses,biotite quartzofeldspathic gneiss,granitic gneiss,amphibolite,mica schist,and quartz schist,with many leucogranite *** zircon U-Pb ages of two granitic gneiss samples are 205±1 Ma and 218±1 Ma,respectively,representing the ages of their *** zircons from two biotite plagiogneisses samples show core-rim *** U-Pb ages of the cores are mainly 644–446 Ma,1213–865 Ma,and 1780–1400 Ma,reflecting the age characteristics of clastic zircons during sedimentation of the original *** U-Pb ages of the rims are from 203±2 Ma to 190±1 Ma,which represent the age of *** zircon U-Pb ages of one sample taken from the leucogranite veins that cut through granitic gneiss foliation range from 24 Ma to 22 Ma,interpreted as the age of the anatexis in the Demala Group *** and muscovite separates were selected from the granitic gneiss,banded gneiss,and leucogranite veins for 40Ar/39Ar *** plateau ages of three muscovite samples are 16.56±0.21 Ma,16.90±0.21 Ma,and 23.40±0.31 Ma,and the plateau ages of four biotite samples are 16.70±0.24 Ma,16.14±0.19 Ma,15.88±0.20 Ma,and 14.39±0.20 *** mica Ar-Ar ages can reveal the exhumation and cooling history of the Demala Group *** with the previous research results of the Demala Group complex,the authors refer that the Demala Group complex should be a set of metamorphic *** complex in
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