滇西高黎贡山群变质岩的锆石年龄及其构造意义.pdf

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1、1000-0569／2012／028(05)一1529-41ActaPetrologicaSinica岩石学报滇西高黎贡山群变质岩的锆石年龄及其构造意义李再会林仕良丛峰谢韬邹光富LIZaiHui，LINShiLiang，CONGFeng，XIETa0andZ0UGuangFu成都地质矿产研究所，成都610081ChengduInstituteofGeologyandMindralResources，Chengdu610081，China2012-01—11收稿．2012—04—16改回．LiZH，LinSL，CongF，XieTandZouGF．2012．U-Pba

2、gesofzirconfrommetamorphicrocksoftheGaoHgongshanGroupinwesternYunnananditstectonicsignificance．ActaPetrologicaSinica。28(5)：1529—1541AbstractTheGaoligongshanGroup，whichhaslongbeeninterpretedasPrecambrianbasementoftheTengchong—LiangheblockinwesternYunnan，buttheformingagesoftheirprotolith

3、andsubsequentdeformedandmetamorphicageshasbeenanissueoflittleconsensne．Petrograpicandgeochemicalanalysesindicatesthatbiotitemonzonitegneiss，biotiteamphibolic—plagioclasegneissandfeldsparfelswhichconsistingoftheGaoligongshanGroupmetamorphosedrocksareorthometamorphites．U—PbSHRIMPandLA-IC

4、P—MSzirconsdatingofthesemetamorphosedrockswerecarriedoutfirstlyandyieldsages497．8±7．2Ma～500±14Ma．83．5±0．9Maasthetimingoftheiremplacementand459±5Ma，55．2±1．1Maasthatofmetamorphism，respectively．Basedontheseresults，togetherwiththeregionalcomparisonanddetritalzirconsagesobtainedfromadjacent

5、metamorphicrocks，itisconcludedthatthesedimentarybodyoftheGaoligongshanGrouphadbeenformedduringtheNeoproterozoicandthenintrudedbyCambriangranitesformedduringthecircum—Gondwanaorogeny．TheGaoligongshanGroupinitiallyexperiencedanAndean-typeorogenesisthroughthesubductionoftheNeo-Tethysocean

6、iclithosphereduringLateMesozoicandthentheIndia--EurasiacontinentalcollisionintheCenozoicandthestrike—slipshearingduringtheextrusionoftheIndochinaBlock．TheIndochinaBlockhasresembleswiththeLhasaBlockintermsofPaleozoictoMesozoicmagmatismanddetritalzirconages．KeywordsGaoligongshanGroup；Hig

7、h—amphibolitetogranulite-faciesmetamorphicgrade；ZirconU—Pbdating；Metamorphicevolution；WesternYunnan摘要被认为是腾冲一梁河地块前寒武纪结晶基底的滇西高黎贡山群变质岩系，其原岩及变质时代长期争论不休。岩相学和地球化学表明，组成高黎贡山群的黑云二长片麻岩、黑云角闪斜长片麻岩和变粒岩的原岩均为岩浆岩。首次对这些变质岩进行原位锆石U—Ph定年，分别获得497．8±7．2Ma～500±14Ma、83．5±0．9Ma的岩浆结晶年龄和459±5Ma、55．2±1．1Ma的变质年龄