2015-INAEYN-UCAS-3-OIBSource

我们继续吧！牛耀龄(YaolingNiu)EarthSciences英国杜伦大学（DurhamUniversity）地球科学系Theme:GlobalTectonicsandGeodynamics–APetrologicalandGeochemicalApproachTopics:0-Selfintroduction&magmatism1-Geologicalunderstandingofglobaltectonics:Basicconcepts,illustrations,examplesandnewperspectives2-Globalmid-oceanridgedynamics-apetrologicalperspective3-Debateonthesourcesofoceanislandbasalts(OIB)4-Lid-effectonthecompositionofoceanislandbasalts(OIB)5-Apetrologicalperspectiveonmantleconvection6-Whatdrivesplume-ridgeinteractions?7-Thenatureofthelithosphere-asthenosphereboundary(LAB)8-Tectonicsettingandmechanismofcontinentalcrustaccretion9-Testingmantleplumehypothesis用岩石学、元素和同位素地球化学、矿物物理等基本概念证明广泛接受的“地幔柱OIB源区物质是再循环洋壳”解释的错误ConvergentPlateBoundary(Mariana,Tonga)IslandArcMid-OceanRidgeOceanIslandContinentalMarginArcIntraplate/DivergentPlateBoundary(EastAfrica,CFBofDeccan)RiftDivergentPlateBoundary(EPR,MAR)Intraplate(Hawaii,Reunion)ConvergentPlateBoundary(AndesinSouthAmerica)110100BaThULaPrPbSmHfGdTbHoErYbRbNbTaCeSrNdZrEuTiDyYTmLuPrimitiveMantleNormalizedIABC.CrustOIBE-MORBN-MORB10100LaCePrNdSmEuGdTbDyHoErTmYbLuChondrite(C1)NormalizedIABC.CrustOIBE-MORBN-MORBWhyareOIBenriched?WhyareMORBdepleted?WhyareIABdepletedinHFSEsandenrichedinotherLILEs?Wethinkweknow!?Theprevailinginterpretationsfor:MORB–reasonableIAB–reasonableOIB–flawed!![Notaboutopinion,buthowtothinkandreason,andtoapply]Niu,Y.L.&M.J.O’Hara,Originofoceanislandbasalts:Anewperspectivefrompetrology,geochemistryandmineralphysicsconsiderations,JournalofGeophysicalResearch,108,2209,doi:10.1029/2002JB002048,2003,19pp（pagesECV51-19).Niu,Y.L.,M.Regelous,J.I.Wendt,R.Batiza&M.J.O’Hara,Geochemistryofnear-EPRseamounts:Importanceofsourcevs.processandtheoriginofenrichedmantlecomponent,EarthandPlanetaryScienceLetters,199,327-345,2002.Niu,Y.L.,Theoriginofalkalinelavas,Science,320,883-884,2008.Humphreys,E.R.&Y.L.Niu,Onthecompositionofoceanislandbasalts(OIB):Theeffectsoflithosphericthicknessvariationandmantlemetasomatism,Lithos,112,118-136,2009.Niu,Y.L.,Somebasicconceptsandproblemsonthepetrogenesisofintra-plateoceanislandbasalts(OIB),ChineseScienceBulletin,54,ppp-ppp,2009.(doi:10.1007/s11434-009-0668-3).://://://://’Hara,2011.Theoriginofintra-plateoceanislandbasalts(OIB):Thelideffectanditsgeodynamicimplications,JournalofPetrology,52,1443-1468.mantlewedge:K,Rb,Cs,Ba,Pb,Sr&U;toalesserextentTh,LREEsetc.Waterinsolubleorimmobileelementsretainintheslab:Nb,Ta,Zr,Hf,Ti;toalesserextentHREEsAboutthefirst-orderpetrogenesisofIAB110100BaThULaPrPbSmHfGdTbHoErYbRbNbTaCeSrNdZrEuTiDyYTmLuPrimitiveMantleNormalizedIABC.CrustOIBE-MORBN-MORB10100LaCePrNdSmEuGdTbDyHoErTmYbLuChondrite(C1)NormalizedIABC.CrustOIBE-MORBN-MORBWhyareIABdepletedinHFSEsandenrichedinotherLILEs?110100BaThULaPrPbSmHfGdTbHoErYbRbNbTaCeSrNdZrEuTiDyYTmLuPrimitiveMantleNormalizedIABC.CrustOIBE-MORBN-MORB10100LaCePrNdSmEuGdTbDyHoErTmYbLuChondrite(C1)NormalizedIABC.CrustOIBE-MORBN-MORBWhyareCCenriched?WhyareMORBdepleted?Aboutthefirst-orderpetrogenesisofMORB110100BaThULaPrPbSmHfGdTbHoErYbRbNbTaCeSrNdZrEuTiDyYTmLuPrimitiveMantleNormalizedIABC.CrustOIBE-MORBN-MORB10100LaCePrNdSmEuGdTbDyHoErTmYbLuChondrite(C1)NormalizedIABC.CrustOIBE-MORBN-MORBWhyareCCenriched?WhyareMORBdepleted?MantlePlumesexpressedas“hotspots”onthesurfaceHowaboutthe“enriched”OIB?(Foulger,2012)Oneoftheadvancesinmoderngeochemistry-Recognitionofmantlecompositionalheterogeneitythroughstudiesofoceanicbasalts:MORBandOIBFrom:JianLin[Hittingthehotspots,Oceanus,41,34-37,1998]DMMHIMUEM1EM1PMMORBHawaiiSt.HelenaIcelandEasterAscentionCanariesGuadalupeAzoresReunionBouvetTahitiSamoaWalvisRidgeKerguelen0.7020.7030.7040.7050.7060.7071620211817192287Sr/86Sr=f(Rb/Sr,t)FOZOC?206Pb/204Pb=f(U/Pb,t)?EM2DMMHIMUEM1EM2PMFOZOC??Rb/SrU/PbLowU/PbHighRb/Sr()VeryhighU/PbLowRb/Sr()LowU/PbLowRb/Sr()HighU/PbVeryhighRb/Sr()•SolidstateP/Dfractionationindeepmantleisunlikely-slowdiffusion!•TheserockswithfractionatedP/Dratiosintroducedinthesourceregionsofoceanicbasaltsviasubductionzones•P/Dfractionation-bysurface(e.g.,weathering)ornearsurfaceprocesses(melting,meltdifferentiation,hydrothermalalteration,highgrademetamorphismetc.);SourcesheterogeneitiesP/D(in)+SZMP/D(out)1.2.PeridotitemeltingP/D(out)P/D(in)P/D=Rb/Sr,U/Pb,Th/Pb,Sm/Nd,Lu/Hf,Re/OsNiu,Y.L.,ChineseScienceBulletin,54,4148-4160,2009.DMM,EM1,EM2,HIMUetc.(1)RecycledOceanCrust(ROC)(2)RecycledsedimentsorUCC(3)MantlemetasomatismHofmann,A.W.&W.M.White,Mantleplumesfromancientoceaniccrust,EarthPlanet.Sci.Lett.,57,421-436,1982.LaCePrNdSmEuGdTbDyHoErTmYbLuChondrite(C1)NormalizedOIBMORB10100BaThULaPrPbSmHfGdTbHoErYbRbNb