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1、第16卷第6期地学前缘(中国地质大学(北京);北京大学)Vol.16No.62009年11月EarthScienceFrontiers(ChinaUniversityofGeosciences(Beijing);PekingUniversity)Nov.2009滇西古特提斯俯冲-碰撞过程的岩浆作用记录范蔚茗,彭头平,王岳军中国科学院广州地球化学研究所同位素年代学和地球化学重点实验室,广东广州510640FanWeiming,PengTouping,WangYuejunKeyLaboratoryof
2、IsotopeGeochronologyandGeochemistry,GuangzhouInstituteofGeochemistry,ChineseAcademiyofSciences,Guan-gzhou510640,ChinaFanWeiming,PengTouping,WangYuejun.TriassicmagmatisminthesouthernLancangjiangzone,southwesternChinaanditsconstraintsonthetectonicevolut
3、ionofPaleo-Tethys.EarthScienceFrontiers,2009,16(6):291-302Abstract:TriassicmagmatismwidelydevelopedinthesouthernLancangjiangzone,southwesternChina.ThestudyoftheirpreciseU-Pbgeochronologyandcharacteristicsofrockassociationsshowsthat(1)smallamountofEarl
4、y-Triassic(～248Ma)volcanicrockswerepreservedandcroppedoutinthearea,whichconsistmainlyofthinbedofandesiticrocksintercalatedwithminorbasalticandesites;that(2)theMiddle-Triassicmag-matismwascharacterizedbyextensivefelsicigneousrockswithminorbasaltsinterb
5、eddedinthemiddleofvol-canicsectionsinpartofareas,andthelateMiddle-TriassicrhyolitesandmainbodyofLincanggraniticbatho-lithhavethesameextrusive/intrusivetimewiththeageof～230Ma;that(3)theLate-Triassicvolcanicse-quencesareprincipallycomposedofbasaltswithm
6、inorinterlayeredrhyolites,exhibitingtypicalcharacteristicsofbimodalvolcanics.Inaddition,thefeaturesofelementalgeochemistryofallsamplessuggestthat(1)theEarly-Triassicandesiticrocks,characterizedbycharacteristicnaturesofislandarcvolcanics,likelyeruptedi
7、nthesubductionsetting;that(2)thegenerationofLate-TriassicrhyoliteswithanaffinityofA-likegraniteandsynchronouslymainbodygranitesintheLincangbatholithdisplayingsimilargeochemicalfeatures,iscloselyrelatedwiththepost-collisionorlate-collisionsetting;that(
8、3)althoughtheLate-Triassicbasicrockspartlyshowislandarcvolcanicssuchashigh-AlcontentsandNb-Tadepletion,someofthempossessinghigh-Mgcontentsandmostlyhavingtrace-elementratiossimilartointraplatebasalt,whichindicatesthattheyeruptedinthepost-collis
