地球岩石的化学组成.pptx

地球岩石的化学组成作者：卡卡西

地球中微子?地球科学问题 CompositionoftheBulkSilicateEarth(BSE)CompositionoftheEarth’smantleCompositionoftheEarth’scrustUThK??岩石密度元素丰度结构信息U和Th元素在地球中的总量和分布

CompositionoftheBSEchondrite（球粒陨石）Cosmochemistrymodel

CompositionoftheBSEGeochemistrymodel

CompositionoftheBSEGeochemistrymodel

CompositionoftheBSEGeochemistrymodelTheKconcentrationintheEarthisprobablyonlycertaintoaboutafactoroftwo.

CompositionoftheBSE?ThematterfromwhichtheEarthformedwasNOTchondritic;OrtheEarthhaslostmatterbycollisionalerosion.Massbalancerequiresthatamissingreservoir,whichwouldhosttheequivalentofthemoderncontinents’budgetofradioactiveheat-producingelements(U,ThandK),yethasnotbeendiscovered.Wearguethatthisreservoircouldhavebeenlosttospace.

CompositionoftheEarth’smantleUppermantle,MORBperidotite（橄榄岩）Lowermantle,OIBbasalt（玄武岩）

CompositionoftheEarth’smantleCi=CM*[F+D*(1-F)]-1Ci=CM*F/[1-(1-F)1/D]DepletedMantleEnrichedMantle(Srameketal.,2013)

HeterogeneouscompositionoftheEarth’smantle(HuangZhao,2006)

EnrichedMantle?

CompositionoftheEarth’scrustOceaniccrust:Sediment（沉积物）Basalt（玄武岩）Gabbro（辉长岩）Continentalcrust:Complex

CompositionoftheEarth’scrustContinentalcrust–uppercrustJUNO岩浆岩和变质岩高SiO2=高U,Th(Gaoetal.,2020)

CompositionoftheEarth’scrustContinentalcrust–lowercrustMetamorphicterranes（地体）Xenoliths（捕掳体）挤压环境相对高SiO2拉张环境相对低SiO2U(ppm)(Huangetal.,2013)

CompositionoftheEarth’scrust

HowtoformthecompositionoftheEarth’scrust?低SiO2熔体高SiO2陆壳高SiO2,U,Th低SiO2,U,Th拆沉模型风化模型高SiO2岩石更抗风化(Lietal.,2016)

CompositionoftheBulkSilicateEarth(BSE)HeterogeneouscompositionoftheEarth’smantleHowtoformthecompositionoftheEarth’scrustConclusionsUThK?

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18华南的岩浆岩具有更高的平均U丰度

19华南、特提斯构造域和中亚造山带的岩浆岩具有更高的平均Th丰度这些不同既与不同构造环境下的主要产出的岩性不同有关，也与不同构造环境下相同岩性的U-Th丰度特征不同有关