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

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1、1000-0569/2002/018(03)-0369-77ActaPetrologicaSinica岩石学报大别山双河超高压榴辉岩中变质锆石:X离子探针和微区结构研究12111陈道公EtienneDELOULE夏群科吴元保程昊12111CHENDaoGong,EtienneDELOULE,XIAQunKe,WUYueBaoandCHENGHao1.中国科学技术大学地球和空间科学系,合肥2300262.岩石地球化学研究中心,南锡54501,法国1.DepartmentofEarthandSpaceScien

2、ces,UniversityofScienceandTechnologyofChina,Hefei230026,China2.CRPG-CNRS,Nancy54501,France2001-11-30收稿,2002-05-28改回.ChenDG,DelouleE,XiaQK,WuYBandChengH.2002.MetamorphiczirconfromShuangheultra-highpressureeclogite,Dabieshan:ionmicroprobeandinternalmicro-str

3、ucturestudy.ActaPetrologicaSinica,18(3):369-377AbstractZirconfromShuangheUHPeclogite,SouthernDabieshanwasanalysedforobservationanddeterminationofcathodoluminscenceimage,Ramanspectrometer,SIMSU-Pbandoxygenisotopes.Mostofzircongrainsshowcore-mantle-20623818r

4、ingstructurewithdifferentU,ThandPbconcentrations,Th/Uratios,Pb/UagesandDOvalues.Theringsshowcharacteristicsofmetamorphiczirconstructureandchemicalcompositions.Whereasthecoresshowtransitionfrommagmatictometamorphiczircon.Mostof17measuredSIMSagesarediscordan

5、t,anddiscordialineobtainedfrom14positivediscordantdatapointsyieldtheirlowerandupperinterceptagesof2489±25Maand248±16Ma,respectively.Theupperinterceptagerepresentstheprotolithformationandlowerinterceptrepresentsthetimeofre-crystallizationofmagmaticzirconand

6、metamorphiczirconovergrowthduringprogradetopeakUHPmetamorphism.ThegenesisofmetamorphiczirconofDabieshanisquitecomplicated.Itcouldbenewzircongrowthofeitherforminganindependentgrainorasaringofprotolothzircon,andalsoaproductofre-crystallizationofmagmaticzirco

7、nundersolidstateand/orfluidexistence.Differentdegreeofre-crystallizationisamajorphysico-chemicalphenomenonhappenedforprotolithzirconofShuangheeclogiteduringthewholeUHPstage.ItcausedreduceofU,Th,PbcontentandTh/Uratio,andremovingofmagmaticoscillatoryzoning.K

8、eywordsZircon,Metamorphicre-crystallization,Overgrowth,Ionmicroprobedating,UHPM,Dabieshanchronology摘要对南大别双河超高压岩板榴辉岩中锆石进行了阴极发光、喇曼光谱、U-Pb和氧同位素离子探针微区分析。发现大部分锆石具有核边结构,其核和边有明显不同的U,Th,Pb含量、Th/U比、20623818Pb/U年龄和DO值。