地震层析成像之密度异常驱动地幔对流模型
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摘要
地震层析成像展现了地球内部横向不均匀性 ,其描述的地幔结构正是地幔演化热动力学过程的现代表现。然而 ,如何利用这些最新的观测成果去研究地球特别是地幔的动力学过程是对地球动力学研究的挑战。建立了地幔密度异常 (温度异常 )直接驱动地幔对流的新方法 ,并利用现代地震层析成像模型计算了对应的地幔对流的格局 ,探讨了其和全球构造相关的地幔问题。结果表明 ,在单层地幔粘滞结构条件下 ,对流格局仍然以全地幔大尺度对流为主体 ;所发展的理论和方法可以适用于不同来源的地幔层析成像的数据 ,可以用于探讨不同边界条件和地幔参数对应的地幔对流模型 ,也可以用于使用大地水准面异常检验对流模型。
The data of seismic tomography shows the heterogeneity of the Earth. It is easy to understand that the mantle structure described by these data is the modern exhibit of the mantle thermal dynamics.However,how to establish a new model by using these observation data to study the mantle dynamical processes is a challenge for the geo-scientists.In this paper we establish a new mantle convection model which is drived by the density anomalies in the mantle.Using the seismic tomography data we have calculated the mantle convection patterns and investigate the plate and mantle dynamics on the basis of the computed models.The results show that the convection runs in whole mantle and has single cells.In the meantime,in this method the seismic tomography data from different resources can be used. It is suitable to discuss the mantle convection models based on different boundary conditions and different dynamical parameters of the mantle,and can be used to test the convection model with the geoid anomalies as well.
The data of seismic tomography shows the heterogeneity of the Earth. It is easy to understand that the mantle structure described by these data is the modern exhibit of the mantle thermal dynamics.However,how to establish a new model by using these observation data to study the mantle dynamical processes is a challenge for the geo-scientists.In this paper we establish a new mantle convection model which is drived by the density anomalies in the mantle.Using the seismic tomography data we have calculated the mantle convection patterns and investigate the plate and mantle dynamics on the basis of the computed models.The results show that the convection runs in whole mantle and has single cells.In the meantime,in this method the seismic tomography data from different resources can be used. It is suitable to discuss the mantle convection models based on different boundary conditions and different dynamical parameters of the mantle,and can be used to test the convection model with the geoid anomalies as well.
引文
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16 SongXDandHelmbergerDV .AnisotropyofEarth’sin nercore[J].Geophys.Res.Lett,1993,20:2591-2594.
17 SongXDandHelmbergerDV .DepthdependenceofanisotropyofEarth’sinnercore[J].J.Geophys.Res.,1995,100:9805-9816.
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20 ObayashiMandFukaoY .PandPcPtraveltimetomogra phyforthecore mantleboundary[J].J .Geophys.Res.,1997,102:17825-17841.
21 ShearerPMandMastersTG .Globalmappingoftopogra phyonthe660kmdiscontinuity[J].Nature,1992,355:791-796.
22 KelloggLH ,HagerBHandVanderHilstRD .Composi tionalstratificationindeepmantle[J].Science,1999,283:1881-1884.
23 FuRongshan,ZhengYong,ChangXiaohua,etal.Seismictomographyandtheevolutionoftheearth’smantle[J].ProgressinGeophysics,2001,16(4):85-95.(inChinese)
24 HagerBH ,ClaytonRW ,RichardsMA ,etal.Lowermantleheterogeneity,dynamictopographyandthegeoid[J].Nature,1985,313:541-545.
25 JarvisGTandPeltierWR .Convectionmodelsandgeo physicalobservations[A].Mantleconvection:Platetecton icsandglobaldynamics[C].EditedbyPeltierWR .GordonandBreachSci.Publish.,1989,480-593.
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27 RichardYandVignyC .Mantledynamicswithinducedplatetectonics[J].J.Geophys.Res.,1989,94:17543-17559.
28 ChandrasekharU .Hydrodynamicandhydromagneticsta bility[M].Oxford:ClarendonPress,1961,652.
29 MastersTG ,JordanTH ,SilverPGandGilbertF .Sphericalearthstructurefromfundmentalspherical modedata[J].Nature,1982,298:609-613.
30 FuRongshan,ChenLing,HuangJianhua,etal.Globalseis mictomography,thedensityheterogeneityofthemantleandcontinenteddynamicy[J].ProgressinGeophysics,1995,10(3):51-62.(inChinese)
2 Akik,ChristofferssonAandHusebyeES .Determinationofthethree dimensionalseismicstructureofthelithosphere[J].Geophys.J.R .Astron.Soc.,1977,82:277-296.
3 DzeiwonskiAM .Mappingthelowermantle:determinationoflateralheterogeneityinPvelocityuptodegreeandorder6[J].J.Geophys.Res.,1984,89:5929-5952.
4 WoodhouseJHandDeiewonskiAM .Mappingtheuppermantle:Three dimensionalmodellingofearthstructurebyinversionofseismicwaveforms[J].J.Geophys.Res.,1984,89:5953-5986.
5 TanimotoT .Long wavelengthS wavevelocitystructurethroughoutthemantle[J].geophys.J.Int.,1990,100:327-336.
6 SuW ,WoodwardRLandDziewonskiAM .Degree12modelofshearvelocityheterogeneityinthemantle[J].J.Geophys.Res.,1994,99:6945-6980.
7 MastersTG ,JohnsonS ,LaskeG ,etal.Ashear velocitymodelofthemantle[J].Phios,Trans.R .Soc.LondonSer.A ,1996,354:1385-1411.
8 VascoDWandJohnsonLR .Wholeearthstructureesti matedfromseismicarrivaltimes[J].J .Geophy.Res.,1998,103:2633-2671.
9 vanderHilstRD .Complexmorphologyofsubductedlitho sphereinthemantlebeneaththeTongatrench[J].Nature,1995,374:154-157.
10 vanderHilstRD ,WidiyantoroSandEngdahlER .Evi dencefordeepmantlecirculationfrom globaltomography[J].Nature,1997,386:578-584.
11 GrandSP .Mantleshearstructurebeneaththeamericasandsurroundingoceans[J].J .Geophys.Res.,1994,99:11591-11621.
12 GrandSP ,vanderHilstRDandWidiyantoroS .Globalseismictomography:asnapshotofconvectionintheEarth[J].GSAToday,1997,(7):1-7.
13 LiuFutian,QuKexin,WuHua,etal.SeismictomographyoftheChinesecontinentadjacentregion[J].ActaGeophys icaSinica,1989,32(3):281-291.(inChinese)
14 LiuFT ,ZhongJH ,HeDL ,etal.ThesubductedslabofYangtzecontineitalblockbeneaththeTethyanorogeninwesternYunnan[J].ChineseSci.Bull.,2000,45(5):466-471.(inChinese)
15 ShearerPM ,ToyKMandOrcuttJA .Axi symmetricearthmodelsandinner coreanisotropy[J].Nature,1988,333:228-232.
16 SongXDandHelmbergerDV .AnisotropyofEarth’sin nercore[J].Geophys.Res.Lett,1993,20:2591-2594.
17 SongXDandHelmbergerDV .DepthdependenceofanisotropyofEarth’sinnercore[J].J.Geophys.Res.,1995,100:9805-9816.
18 SuWJandDziewonskiAM .Innercoreanisotropyinthreedimensions[J].J.Geophys.Res.,1995,100:9831-9852.
19 MorelliAandDziewonskiAM .Topographyofthecore mantleboundaryandlateralhomogeneityoftheliquidcore[J].Nature,1987,325:678-683.
20 ObayashiMandFukaoY .PandPcPtraveltimetomogra phyforthecore mantleboundary[J].J .Geophys.Res.,1997,102:17825-17841.
21 ShearerPMandMastersTG .Globalmappingoftopogra phyonthe660kmdiscontinuity[J].Nature,1992,355:791-796.
22 KelloggLH ,HagerBHandVanderHilstRD .Composi tionalstratificationindeepmantle[J].Science,1999,283:1881-1884.
23 FuRongshan,ZhengYong,ChangXiaohua,etal.Seismictomographyandtheevolutionoftheearth’smantle[J].ProgressinGeophysics,2001,16(4):85-95.(inChinese)
24 HagerBH ,ClaytonRW ,RichardsMA ,etal.Lowermantleheterogeneity,dynamictopographyandthegeoid[J].Nature,1985,313:541-545.
25 JarvisGTandPeltierWR .Convectionmodelsandgeo physicalobservations[A].Mantleconvection:Platetecton icsandglobaldynamics[C].EditedbyPeltierWR .GordonandBreachSci.Publish.,1989,480-593.
26 HagerBHandClaytonRW .Constraintsonthestructureofmantleconvectionusingobservations,flowmodelsandthegeoid[A].Mantleconvection:Platetectonicsandglobaldynamics[C].EditedbyPeltierWR ,GordonandBreachSci.Publish.,1989,657-763.
27 RichardYandVignyC .Mantledynamicswithinducedplatetectonics[J].J.Geophys.Res.,1989,94:17543-17559.
28 ChandrasekharU .Hydrodynamicandhydromagneticsta bility[M].Oxford:ClarendonPress,1961,652.
29 MastersTG ,JordanTH ,SilverPGandGilbertF .Sphericalearthstructurefromfundmentalspherical modedata[J].Nature,1982,298:609-613.
30 FuRongshan,ChenLing,HuangJianhua,etal.Globalseis mictomography,thedensityheterogeneityofthemantleandcontinenteddynamicy[J].ProgressinGeophysics,1995,10(3):51-62.(inChinese)
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