简介：PlatesubductiondrivesboththeinternalconvectionandthesurfacegeologyofthesolidEarth.Despitetherapidincreaseofcomputationalpower,itremainschallengingforgeodynamicmodelstoreproducethehistoryofEarth-likesubductionandassociatedmantleflow.Here,basedonanadaptiveapproachofsequentialdataassimilation,wepresentahigh-resolutionglobalmodelsincethemid-Mesozoic.ThismodelincorporatesthethermalstructureandsurfacekinematicsoftectonicplatesbasedonarecentplatereconstructiontoreproducetheobservedsubductionconfigurationandEarth-likeconvection.Introductionoftemperature-andcomposition-dependentrheologyallowsforincorporationofmanynaturalcomplexities,suchasinitiationofsubductionzones,reversalofsubductionpolarity,anddetailedplate-boundarydynamics.Theresultantpresent-dayslabgeometrywellmatchesBenioffzonesandseismictomographyatdepths<1500km,makingitpossibletohindcastpastsubductiondynamicsandmantleflow.Forexample,themodelproducesaflatFarallonslabbeneathNorthAmericaduringtheLateCretaceoustoEarlyCenozoic,afeaturethathasbeengeodynamicallychallengingtoreproduce.Thishigh-resolutionmodelcanalsocapturedetailsofthe4-Devolutionofslabsandtheambientmantle,suchastemporallyandspatiallyvaryingmantleflowassociatedwithevolvingslabgeometryandbuoyancyflux,aswellastheformationofshallowslabtearsduetosubductionofyoungseafloorsandtheresultingcomplexmantledeformation.Suchageodynamicframeworkservestofurtherconstrainuncertainplatereconstructioninthegeologicalpast,andtobetterunderstandtheoriginofenigmaticmantleseismicfeatures.

简介：TheTibetanPlateau,knownas“theroofoftheworld”and“thethirdpoleoftheearth”,isaproductofthecollisionbetweenIndiaandAsiaduringthelast~50Ma.Theregionaltectonics–inparticular,growthandexpansionoftheplateau–hasbeenattributedprimarilytodeformationwithinthelithosphere.Theroleandpatternoftheunderlyingasthenosphericflow,however,remainmostlyunaddressed.Inlightofrecentseismictomographicimagesandpublishedseismicanisotropicdescriptionsoftheuppermantle,hereweproposethatanentrainedmantleflowislikelytoexistunderTibet,inducedbythenorthwardadvancingIndianplate.ThedirectionofmantleflowischaracterizedbyagradualrotationfromnorthwardinthesouthtoeastwardinthenorthasaresultofdeflectionbythedeeprootoftheTarimblock.Thepresenceofanunderlyingmantleflowisnotonlyabletoaccountforthewest-eastorientedfast-axisofseismicanisotropyinnorthernTibet,butcanalsoadequatelyexplainthesporadicnullsplittinginsouthernTibet.Specifically,thenullsplittingresults,atleastinpart,fromupwellingsofasthenosphericflowthroughtearsoftheunderthrustingIndianplatethathavebeenrevealedbyvariousseismicobservations.ThemantleflowmayinturnpromotetheblockextrusionunderTibetthathasbeenobservedinGPSmeasurements;hotasthenosphericupwellingsmayalsoleadtowidespreadpost-collisionalmagmatisminsouthernTibet.

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简介：Amapoftheaverageatomicnumberoflunarrockandsoilcanbeusedtodifferentiatelithologyandsoiltypeonthelunarsurface.Thispaperestablishesalinearrelationshipbetweentheaverageatomicnumberoflunarrockorsoilandthefluxofpositionannihilationradiation(0.512-MeVgamma-ray)fromthelunarsurface.TherelationshipisconfirmedbyMonteCarlosimulationwithdatafromlunarrockorsoilsamplescollectedbyLuna(Russia)andApollo(USA)missions.AmapoftheaverageatomicnumberofthelunarrockandsoilonthelunarsurfacehasbeenderivedfromtheGamma-RaySpectrometerdatacollectedbyChang’e-1,anunmannedChineselunar-orbitingspacecraft.Inthemap,thehigheraverageatomicnumbers(ZA>12.5),whicharerelatedtodifferenttypesofbasalt,areinthemariaregion;thehighestZA(13.2)readingsareassociatedwithSinusAestuum.ThemiddleZA(~12.1)regions,intheshapeofirregularovalrings,areinWestOceanusProcellarumandMareFrigoris,whichseemstobeconsistentwiththedistributionofpotassium,rareearthelements,andphosphorusasauniquefeatureonthelunarsurface.Theloweraverageatomicnumbers(ZA<11.5)arefoundtobecorrelatedwiththeanorthositeonthefarsideoftheMoon.