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西昆仑库地蛇绿岩的二辉辉石岩和玄武岩锆石LA-ICP-MSU - 岩石学报.PDF

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10000569/2014/030(08)239301 ActaPetrologicaSinica 岩石学报 西昆仑库地蛇绿岩的二辉辉石岩和玄武岩锆石 LAICPMSUPb年龄及其意义 李天福 张建新 LITianFuandZHANGJianXin 大陆构造与动力学国家重点实验室,中国地质科学院地质研究所,北京 100037 StateKeyLaboratoryofContinentalTectonicsandDynamics,InstituteofGeology,ChineseAcademyofGeologicalSciences,Beijing100037,China 20140310收稿,20140514改回 LiTFandZhangJX2014ZirconLAICPMSUPbagesofwebsteriteandbasaltinKudiophioliteandtheimplication, WestKunlunActaPetrologicaSinica,30(8):2393-2401 Abstract  WestKunlunorogenissubdividedintonorthterreneandsouthterreneTheknownKudiophioliteinsouthterreneof WestKunlunorogeniscomposedofultramaficbodyinBuziwanvalleyandextrusiverocksinYixiekevalleyfromthebottomupThere hasbeenahotdebatingaboutageofKudiophioliteThisstudyhascollectedsamplesandobtainedzirconLAICPMSUPbagesof 49428±086Maand50030±80MarespectivelyforwebsteritefromBuziwanvalleyultramaficbodyanddoleritefromlowerpartof YixiekevalleyextrusiverocksinKudiophioliteThesetwoagesareverysimilarandindicatethattheultramaficbodyandlowerpartof theextrusiverocksarecomposingmembersofLateCambrianEarlyOrdovicianophiolite,ie,Kudiophiolitewastheresidueof PrototethysOceanPreviousstudiesbyotherresearchersgotthevariousagedataforultramaficrocksandextrusiverocksThereasonof largevarietyofageisthatdifferentauthorsuseddifferentdatingmethods(includingRadiolarian)ondifferentsamplescollectedat differentlocalities(especiallyforextrusiverocksofupperunitoftheophiolit),nottosaymostofthedatingmethodsusedwerenot fairlyreliableOurreliableinsitumethodage(50030±80Ma)ofdoleritefromlowermostpartofextrusivestratumisdifferentfrom theanotherpreviouslypublishedinsituagedatum(alsoreliable)formassivebasalt,whichamplydemonstratethatthereasonofage differenceisbecauseofdifferentlocalityofsamplingThus,theYishakeGroupshouldbedismemberedbecauseitmightbetectonicly superimposedstratum Keywords  Age;Zircon;Websterite;Dolerite;Ophiolite;Kudi;WesternKunlun 摘 要  西昆仑造山带划分为北昆仑地体和南昆仑地体,关于西昆仑造山带中库地蛇绿岩的形成时代一直存在争议。本
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