云南_三江_变质杂岩带多期花岗质岩浆事件及其构造意义_王舫

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1、1000-0569/2013/029(06)-2141-60ActaPetrologicaSinica岩石学报云南“三江”变质杂岩带多期花岗质岩浆事件及其*构造意义王舫刘福来刘平华WANGFang，LIUFuLaiandLIUPingHua中国地质科学院地质研究所，北京100037InstituteofGeology，ChineseAcademyofGeologicalSciences，Beijing100037，China2013-02-02收稿，2013-04-20改回.WangF，LiuFLandLiuPH.2013.Multiplegraniti

2、cmagmaeventsinSanjiangcomplexbelt，YunnanProvince:Implicationsfortectonicevolution.ActaPetrologicaSinica，29(6):2141－2160AbstractSanjiangareaisconsideredasthemarginbetweenIndianandEurasianplates，recordingmultiplemagmaticandmetamorphicevents.EightgranitoidrockswerecollectedfromDianc

3、angShanandGaoligongShancomplexforinsituzirconU-Pbdatingandwhole-rockgeochemistryanalysis.Basedongeochronologyresults，sixepisodesofmagmatismwererecognized:Mid-Cambrian(501.2±5.0Ma)，LateOrdovician(456±2.1Ma)，LatePermiantoEarlyTriassic(251～246Ma)，EarlyPaleocene(55±0.62Ma)andLateEoce

4、ne(38±0.52Ma).AbundantPaleoproterozoicandMid-Neoproterozoicinheritedzirconswerealsoindentified.GeochemistryresultsshowthatSiO2，Al2O3，Na2OandK2Ocontentsrangeform60.41%to77.41%，11.57%to17.54%，2.05%to4.16%and2.09%～6.31%，respectively.EarlyTriassicgranitoidrocksarecharacterizedbyperal

5、uminouswithA/CNK≥1，predominantly，whileothersarecharacterizedbymetaluminouswithA/CNK≥1.Theyshowobviousfractionationof143144ＲEE，negativeEuanomalyand(La/Yb)Nrangefrom5.22to19.56.FiveofthemhaveNd/Ndratiosof0.51195to0.51255，εNd(t)valuesof0to－11.11andNdmodelages(tDM)of1071Mato1969Ma.Th

6、epresencesoftwooldersamplessuggestMid-CambrianandLateOrdovicianmagmatism.TheclosureofPaleo-TethyswasresponsibleforLatePermiantoEarlyTriassicmagmatism.TheGaoligongEarlyCretaceousgranitoidrocksarethemagmaticexpressionofcrustalthickening.Cenozoicgranitoidrocksarerelatedtosubduction-

7、collisionbetweentheIndianandEurasianplates.Inheritedzirconyieldmajorageclustersat1100～800Ma，indicatingNeoproterozoicmagmaticevent.AfewPaleo-Midproterozoiczirconsimplytheexistenceofolderbasementrocks.NdmodelagesalsosupportthatthePaleoproterozoicandMid-Neoproterozoicoccurredinthisa

8、rea.KeywordsZirconU-Pbdating;Geochemistr