大别山双河超高压榴辉岩中变质锆石：离子探针和微区结构研究.pdf

维普资讯 1000一O569／2O02／O18(O3)一0369—77 ActaPetrologicaSinica 岩石学报 大别山双河超高压榴辉岩 中变质锆石 离子探针和微区结构研究 陈道公 EtienneDEIOUIE 夏群科 吴元保 程昊 CHENDa0G0ng，EtienneDEIOUIE ，XIAQunKe，WUYueBa0andCHENGHa0 1．中国科学技术大学地球和空间科学系，合肥 230026 2，岩石地球化学研 究中心 ，南锡 54501，法 国 1．DepartmentofEarthandSpaceSciences，Universityof ScienceandTechnologyofChina，Hefei230026，China 2．CRPG—CNRS ．Nancy 54501，France 2001—11-30收稿 ，2002—05—28改 回． ChenDG，DelouleE，XiaQK ，WuYBandChengH．2002．Metamorphiczirconfrom Shuangheultra—highpressureeclogite， Dabieshan：ion microprobeandinternalm icro—structurestudy．ActaPetrologicaSinica，18(3)：369— 377 Abstract Zircon from Shuanghe UHP eclogite·Southern Dabieshan wasanalysed forobservation and determ ination of cathodoluminscenceimage，Raman spectrometer，SIMS U—Pbandoxygen isotopes．Mostofzircongrainsshow core—mantle— ringstructurewithdifferentU ，ThandPbconcentrations．Th／U ratios． 。Pb／。U agesand艿 O values．Theringsshow characteristicsofm etamorphiczircon structureandchem icalcompositions．W hereasthecoresshow transitionfrom magmatic to m etamorphic zircon．M ostof 17 m easured SIM S ages are discordant． and discordia line obtained from 14 positive discordantdatapointsyieldtheir1owerandupperinterceptagesof2489土 25M aand 248土 16M a，respectively．The upper interceptagerepresentstheprotolithformationandlowerinterceptrepresentsthetimeofre—crystallizationofmagmaticzircon and metamorphiczircon overgrow th during prograde to peak UHP metamorphism ．The genesisofmetamorphic zircon of Dabieshan isquitecomplicated．Itcouldbenew zircongrowthofeitherformingan independentgrainorasaringofprotoloth zircon，andalsoaproductofre—crystallizationofmagmaticzirconundersolidstateand／orfluidexistence．Differentdegreeof re—-crystallizationisamajorphysico——chemicalphenomenonhappenedforprotolithzirconofShuangheeclogiteduringthewhole UHPstage．ItcausedreduceofU ，Th，Pbcontent