藏北羌塘荣玛地区新生代火山岩锆石LA-ICP-MS U-Pb测龄及其地质意义  

LA-ICP-MS U-Pb dating of zircons and geological implication for Cenozoic volcanic rocks in Rongma area,Qiangtang terrane,North Tibet,China

作　　者：冉皞[1] 王根厚[1] 梁晓[1] 郑艺龙[1] 王梁[1,2] 

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]武警黄金地质研究所,河北廊坊065000

出　　处：《成都理工大学学报（自然科学版）》2014年第1期102-112,共11页Journal of Chengdu University of Technology: Science & Technology Edition

基　　金：中国地质调查局项目(1212011221115;1212011221081)

摘　　要：通过羌塘荣玛地区新生代火山岩锆石的LA-ICP-MS U-Pb年代学研究,探讨羌塘地块的构造演化.结果表明,其年龄跨越的时代从新太古代到新生代（2 651～24 Ma B.P.）,并且具有明显的阶段性,可分为12个年龄组：2 651～1 381 Ma、1 182～1 147 Ma、921～911 Ma、832～741 Ma、659 Ma、562～535 Ma、423～414 Ma、320～291 Ma、243～200 Ma、156～140Ma、127～117Ma、24 Ma,记录了羌塘地块与超级大陆演化相关的构造热事件、泛非运动、加里东运动、古特提斯洋与中特提斯洋的发展演化和新生代岩浆活动,并指示羌塘地块存在前寒武纪年龄记录,但这不是结晶基底存在的充分条件,只是必要条件.将其与拉萨地块和特提斯喜马拉雅地区锆石的前寒武纪年龄对比发现,三者均具有泛非运动记录,暗示羌塘地块、拉萨地块和特提斯喜马拉雅地区均起源于冈瓦纳大陆.Tectonic evolution of Qiangtang terrane is studied by LA-ICP-MS U-Pb geochronology of zircons from the Cenozoic volcanic rocks in the Rongma area,Qiangtang terrane,northern Tibet.The result suggests that the ages of zircons range from Late Archean to Cenozoic （2651～24 Ma B.P.）with evident stage characteristics and fall into twelve groups：2651～1381 Ma,1182～1147 Ma,921～911 Ma,832～741 Ma,659 Ma,562～535 Ma,423～14 Ma,320～291 Ma,243～200 Ma,156～140Ma,127～117 Ma and 24 Ma.These age groups record the tectonic thermal events of supercontinent,Pan-African Movement and Caledonian Movement.The development and evolution of the PaleoTethyan Ocean and Meso-Tethyan Ocean and the Cenozoic magmatism in the Qiangtang terrane are also recorded.They imply that there is the record of the Precambrian age.This is not the sufficient condition but the necessary condition for the existence of crystalline basement in Qiangtang terrane.There are the records of Pan-African Movement which indicate that the Qiangtang terrane,Lhasa terrane and Tethyan Himalaya are derived from Gondwana.

关 键 词：羌塘 锆石 LA-ICP-MS U-Pb测龄 构造热事件 

分 类 号：P588.1[天文地球—岩石学] P597[天文地球—地质学]