南秦岭刘岭群砂岩碎屑锆石LA-ICP-MS U-Pb年龄及其构造意义.pdf

《南秦岭刘岭群砂岩碎屑锆石LA-ICP-MS U-Pb年龄及其构造意义.pdf》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。

1、第33卷第9期地质通报Vo1．33．No．92014年9月GEoLoGICALBULLETIN0FCHINASep．，2014南秦岭刘岭群砂岩碎屑锆石LA—ICP-MSU-Pb年龄及其构造意义陈龙耀，罗玉凌，刘晓春，曲玮，胡娟CHENLong—yao，LUOYfi—ling2，LIUXiao—chun，QUWei，HUJuan1．中国地质科学院地质力学研究所，北京100081；2．中国海洋石油总公司规划计划部，北京1000101．InstituteofGeomechanics，ChineseAcademyofGeologicalSciences，Beqing

2、100081，China；2．PlanningDepartment，ChinaNationalOffshoreOilCorporation,B4iing100010，China摘要：秦岭造山带的构造演化是理解华北与扬子陆块缝合过程的关键，位于商丹断裂带以南的刘岭群是揭示秦岭造山带晚古生代构造演化历史的重要窗口。采用LA～ICP—MS对刘岭群3个变质砂岩样品中的碎屑锆石进行了U-Th—pb同位素测定，获得最年轻的一组年龄区间为377~395Ma，主要年龄峰值约为442Ma、780~850Ma和900-970Ma，表明刘岭群沉积时代可以持续到晚泥盆世，物质来源于

3、北秦岭构造带。结合刘岭群北侧武关杂岩的最新研究成果可以确定，刘岭群和武关杂岩共同构成了华北陆块南缘中一晚泥盆世弧前盆地的沉积序列，暗示古秦岭洋的最终闭合发生在泥盆纪之后，而华北与扬子陆块碰撞的主缝合线应位于刘岭群的南侧。关键词：z4屑锆石；LA—ICP-MSU-Pb年龄；物质来源；晚古生代；古秦岭洋；刘岭群；秦岭造山带中图分类号：P588．212．3；P597~．3文献标志码：A文章编号：1671—2552(2014)09—1363—16ChenLY，LuoYL，LiuXC，QuW，HuJ．LA-ICP—MSU—Pbgeochronologyofdetrit

4、alzirconsfromtheLiulingGroupintheSouthQinlingtectonicbeltanditstectonicsignificance．GeologicalBulletinofChina，2014，33(9)：1363—1378Abstract：ThetectonicevolutionoftheQinlingorogenisthekeytounderstandingtheassemblyoftheNorthChinaandSouthChi—nablocks．TheLiulingGroupinthesouthoftheShang

5、danfaultcanprovideanimportantwindowfordetectingtheLatePaleozoicevolutionaryprocessoftheQinlingorogen．TheLA—ICP—MSU—PbagesofdetritalzirconsfromthreemetasandstonesamplesfromtheLiMingGroupshowaagespectrumwithmajorpopulationsatca．442Maandintherangeof780～850Maand900-970Ma，withtheyounges

6、tpopulationbeingca．377~395Ma．ThesedatasuggestthatthedepositionoftheLiulingGroupmighthavelastedtotheLateDevonian．andsedimentswereprobablyde6vedfromtheNorthQiulingtectonicbelt．Incombinationwi出therecentinvestiga—tionoftheWuguancomplexinthenorthoftheLiulingGroup，theauthorsinferthataMid

7、dletoLateDevonianturbiditesequencemighthaveformedinafore—arcbasinonthesouthernmarginoftheNorthChinablock，andtheclosureofthePaleo—QiulingoceanmighthaveoccurredafterDevonian．Hence，thecollisionalboundaryoftheNorthandSouthChinablocksshouldbelocatedinthesouthoftheLiulingGroup．Keywords：D

8、etritalzircons；LA—ICP—MSU—