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1、辽东营口一辽阳地区古元古代花岗岩和变质基性岩形成时代及意义摘要:?
2、东地区保存有较为完好的古元古代地质记录。对位于辽东营口一辽阳地区古元古代花岗岩(建一花岗岩)和变质基性岩(隆昌变质辉绿岩和蒜盘峪变质辉长岩)进行了错石UPb定年、地球化学和岩石成因学研究。结果表明:建一花岗岩形成于(2322土18)Ma,隆昌变质辉绿岩形成于(2335±21)Ma,蒜盘峪变质辉长岩形成于(2353±22)Ma;建一花岗岩源自太古宙古老地壳部分熔融,属于准铝质钙碱性I型花岗岩,富集Rb、Ba.U等大离子亲石元素,亏损Nb、Ta.Zr>Hf等高场强元素,具有俯冲带岩浆特
3、征;隆昌变质辉绿岩和蒜盘峪变质辉长岩均具有富集型洋中脊玄武岩(EMORB)特点,并显示岛弧地球化学特征;隆昌变质辉绿岩源自新太古代富集程度不高的地幔部分熔融,并在上升过程中受到年轻地壳的改造,蒜盘峪变质辉长岩是古太古代一中太古代富集地幔部分熔融的产物;古元古代早期,辽吉地区处于大陆弧后盆地构造环境,弧后伸展作用导致大陆岩石圈部分熔融产生花岗岩和基性岩,在后期的地体拼贴过程中,两者遭受到不同程度的变质变形,进而形成了条痕状花岗岩和变质基性岩。关键词:花岗岩;基性岩;古元古代;铅石UPb年龄;地球化学;弧后盆地;胶辽吉带;华北克拉通中图分类号:P588
4、.12文献标志码:APalcoprotcrozoicGranitesandMotamaficRocksfromYingkouLiaoyangAreaoftheEasternLiaoningandTheirSignificanceLIChaol,SUNKekel,CHENBini,2(1.SchoolofEarthandSpaceSciences,PekingUniversity,Beijing100871,China;2.SchoolofResourcesandEnvironmentalEngineering,HefeiUniversityofTe
5、chnology,Hefei230009,Anhui,China)Abstract:Paleoproterozoicgeologicalrecordsarewe11preservedintheeasternLiaoning.ThezirconUPbdating,geochemicalandpetrogenesisofPaleoproterozoicgranites(Jianyigranite)andmetamaficrocks(LongchangmetadiabaseandSuanpanyumetagabbro)inYingkouLiaoyanga
6、reaoftheeasternLiaoningwerestudied.TheresultsshowthatLAICPMSzirconUPbagesofJianyigranite,LongchangmetadiabaseandSuanpanyumotagabbroarc(2322±18),(2335±21),(2353±22)Ma,respectively;JianyiGraniteformsfrompartialmeltingofArcheancrust,andbelongstometaluminouscalcalkalineItypegranit
7、e,andisenrichedinlargeionlithophileelement(LILE),andisdepletedinhighfieldstrengthelement(HFSE),showingthecharacteristicsofmagmainsubduetionzones;LongchangmetadiabaseandSuanpanyumetagabbrobelongtocnrichedmidoceanridgebasalts(EMORB)andhavethegeochemicalcharacteristicsofislandarc
8、;LongchangmetadiabaseisgeneratedfrompartialmeltingofNeoarcheanmantlewhichisnotveryenriched,andthediabaseiscontaminatedbyjuvenilecrustduringupwelling;SuanpanyumetagabbroisproducedfrompartialmeltingofPaleoarchoanMcsoarchcanenrichedmantle;Liaoningjilinregionisacontinentaibackarcb
9、asininEarlyPaleoproterozoic,andthestrongextensioninthebackarc