The structure, stability, and potential instability of ancient continental 的结构，稳定性，和古大陆的潜在不稳定性.ppt

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1、GLOBALTOPOGRAPHYCONTINENTAL&OCEANICLITHOSPHEREAgeTopographyHeatFlowmidoceanridgemantleCONTINENTAL&OCEANICLITHOSPHEREtectothermalageofplate(ta)mantleheatloss(q)mantleflowtMORthermalThermalboundarylayerofmantleconvectiontTTsot=0t=0_+zTTsotimezRegionofTgradientisaTherma

2、lBoundaryLayermmantleheatloss(q)mantleflowMORthermalThermalboundarylayerofmantleconvectiontmechanical:Layeroflongtermstrengthmcchemical/mechanical:DehydratedLayer(dry=hiviscsoity)m(cold=hiviscosity)ttectothermalageofplate(ta)OceanicThermalLithospheredefinesconvec

3、tionpattern-itisthecold,overturningboundarylayer.ContinentalChemicalLithospheredoesnotparticipateinconvectivemantleoverturn(inherentlybuoyant).ContinentOceanicChemicalLithospheresubducts-overturningportionsoftheEarthseeaconstanttemperatureboundarycondition.Providesamorecomp

4、lexthermalcouplingconditionforcovectingmantlebelow.“subducting”lithosphereviscosity=10Pas25warmmantleviscosity=10Pas21hotcoldconvectingmantlefailedregionextensionfailedregioncompressioncratonicrootlowercrustuppercrustbulkmantlelocalgeothermCooperetal.2004Cooperetal.2004cCh

5、emical/MechanicalLithospheretThermalLithosphereDynamicMantleSub-LayerctmantleheatflowsurfaceheatflowUpperCrustLowerCrustChemicalLithosphereAverageThermalLithosphereTemperature(Celsius)0200400600800100012001400Depth(km)050100150200250300Thermal/ChemicalBLThicknessRatio4.5

6、433.522.511.5ChemicalBoundaryLayerThickness(km)406080100120140160180200TemperatureDropAcrossSub-Layer(C)700600500400300200100RadiogenicallyDepletedRootRadiogenicallyEnrichedRootYuan&Romanowicz2010ThermChemChemicalLithosphere(km)Latitudedepth(km)50100150200432400Thermal/Chem

7、icalRatio300200100065355545605040Preserving&DestroyingCratonicLithosphereTheStructureofPreserving&DestroyingCratonicLithosphereCRATONSTABILITYCRATONINSTABILITYUNDERSTANDSTABILITYTOUNDERSTANDINSTABILITYMODELINGCRATONSTABILITYchemicallylightmaterial-root(ownrheology)chemicall

8、yreallightmaterial-crust(hasownrheology)coldhotmantlebaseofthermallithosphereconti