青藏高原板内地震震源深度分布规律及其成因
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摘要
青藏高原板内地震以浅源地震为主,下地壳基本上没有地震,地震震源多集中在15~40km的深度范围,主要在中地壳内,呈似层状弥散分布.其中30~33km深度是一个优势层,与壳内分层有关.总体上青藏高原南、北部的震源面略呈相向倾斜特征.70~100km深度区间出现了比较集中的震级较小的地震,可能与壳幔过渡带的拆离作用有关.高原内部的正断层系与板内地震密切相关,是板内浅源地震的主控构造.总之,青藏高原地震震源沿着活动的上地壳脆性层与软弱层之间的脆-韧性过渡带分布.这些板内地震活动属于大陆动力学过程,与板块碰撞和板块俯冲无关.初步认为青藏高原浅层到深层多震层的成因分别是韧性基底与脆性盖层、韧性下地壳与脆性上地壳、韧性下地壳与脆性上地幔的韧-脆性转换、拆离和解耦的产物.
The Qinghai-Tibet plateau intraplate earthquakes are mainly shallow earthquakes, and basically no earthquakes happens in the lower crust. Earthquakes mostly distribute in the range of 15-40km in depth,basically within the middle crust and concentrate at the depth of 30-33km as an advantage layer related to the crustal stratification. On the South and North of the plateau, the focal surfaces slightly dip to the center. Some earthquakes concentrate within the range of 70-100km depth, which may be associated with the detachment between crust and mantle. The intraplate earthquakes in the central Qinghai-Tibet are closely related to the normal faults which are dominant earthquake faults. In short, the Qinghai-Tibet plateau seismic activity distributes along the brittle-ductile transition zone between the brittle upper crust layer and the ductile lower crust. Intraplate seismic activity is a continental dynamic process, irrelevant to plate collision and subduction. The seismogenic layers from shallow to deep are separately the result of ductile-brittle transition, detachment and decoupling between basement and cover; ductile lower crust and brittle upper crust, and ductile lower crust and brittle upper mantle.
The Qinghai-Tibet plateau intraplate earthquakes are mainly shallow earthquakes, and basically no earthquakes happens in the lower crust. Earthquakes mostly distribute in the range of 15-40km in depth,basically within the middle crust and concentrate at the depth of 30-33km as an advantage layer related to the crustal stratification. On the South and North of the plateau, the focal surfaces slightly dip to the center. Some earthquakes concentrate within the range of 70-100km depth, which may be associated with the detachment between crust and mantle. The intraplate earthquakes in the central Qinghai-Tibet are closely related to the normal faults which are dominant earthquake faults. In short, the Qinghai-Tibet plateau seismic activity distributes along the brittle-ductile transition zone between the brittle upper crust layer and the ductile lower crust. Intraplate seismic activity is a continental dynamic process, irrelevant to plate collision and subduction. The seismogenic layers from shallow to deep are separately the result of ductile-brittle transition, detachment and decoupling between basement and cover; ductile lower crust and brittle upper crust, and ductile lower crust and brittle upper mantle.
引文
Chen,W.P.,Molnar,P.,1983.Focal depths of intraconti-nental and intraplate earthquakes and their i mplicationsfor the thermal and mechanical properties of the litho-sphere.Journal of Geophysical Research,88(B5):4183-4214.
Chen,W.P.,1988.A brief update on the focal depths of in-tracontinental earthquakes and their correlations withheat flowand tectonic age.Seismological Research Let-ters,59(4):263-272.
Chen,W.P.,Yang,Z.H.,2004.Earthquakes beneath thHi malayas and Tibet:Evidence for strong lithospherimantle.Science,304(5679):1949-1952.
Cui,Z.Z.,Yin,Z.X.,Gao,E.Y.,et al.,1990.The structureand tectonics of the crust and their relation with earth-quakes in the Qinghai-Xizang plateau.Bulletin of TheChinese Academy of Geological Sciences,21:215-225(in Chininese).
Cui,Z.Z.,Yin,Z.X.,Gao,E.Y.,et al.,1992.Velocitystructure and deep-seated structure of the Qinghai-Ti-bet plateau.Geological Publishing House,Bejing,1-112(in Chinese).
Li,D.W.,1992.On tectonic asymmetrical evolution of theHi malayan orogenic belt.Earth Science—Journal ofChina University of Geosciences,17(5):539-545(inChinese with English abstract).
Li,D.W.,1993.The style of continental structure and modelof continental dynamics.Advance in Earth Sciences,8(5):88-93(in Chinese with English abstract).
Li,D.W.,1995a.Speculations on continental tectonics.EarthScience—Journal of China University of Geosciences,20(1):10-18(in Chinese with English abstract).
Li,D.W.,1995b.On continental tectonics and its dynamics.Earth Science—Journal of China University of Geo-sciences,20(1):19-26(in Chininese with English ab-stract).
Li,D.W.,Ji,Y.L.,2000.Laminar flowin the lower conti-nental crust and its significance for continental dynam-ics.Seismology and Geology,22(1):89-96(in Chin-inese with English abstract).
Li,D.W.,Wang,J.Y.,2001.Geological anomaly of conti-nental lower crust and its tectonic significance.Geolog-ical Science and Technology Information,20(3):11-15(in Chinese with English abstract).
Li,D.W.,2003.A new model for uplifting mechanism ofQinghai-Tibet Plateau.Earth Science—Journal of Chi-na University of Geosciences,28(6):593-600(inChininese with English abstract).
Li,D.W.,2005.Intraplate active faults and earthquakemechanismin the Qinghai-Tibet plateau.In:Wu,Z.H.,Zhao,Z.Z.,Yang,M.L.,et al.,eds.,Geologicalprocess andits effect onthe environment and disaster ofthe Tibetan plateau.Seismic Press,Beijing,118-124(in Chinese).
Li,Q.S.,Peng,S.P.,Gao,R.,2004.Areview on the Mohodiscontinuity beneath the Tibetan plateau.GeologicalReview,50(6):598-612(in Chininese).
Ma,Z.J.,Zhang,J.S.,Liu,G.D.,et al.,1990.Current stateof research on continental seismogenic layer-internation-al workshop held in Beijing,April27-30,1990.Seis-mology and Geology,12(3):262-264(in Chininese).
Maggi,A.,Jackson,J.A.,McKenzie,D.,et al.,2000.Earth-quake focal depths,effective elastic thickness,and thestrength of the continental lithosphere.Geology,28(6):495-498.
Molnar,P.,1988.Continental tectonics in the aftermath ofplate tectonics.Nature,335(186):131-137.
Pan,G.T.,Wang,P.S.,Xu,Y.R.,et al.,1990.CenozoicTectonic Evolution of the Qinghai-Tibet Plateau.Geo-logical publishing House,Bejing,1-163(in Chin-inese).
Ranalli,G.,Murphy,D.C.,1987.Rheological stratificationof the lithosphere.Tectonophysics,132:281-295.
Wang,C.Y.,Wang,X.L.,Su,W.,et al.,2006.Seismologi-cal evidence of the crust flowing under the easternboundary part of Qinghai-Tibet plateau.Earthquake Re-search in Sichuan,4:1-4(in Chininese with Englishabstract).
Wong,I.G.,Chapman,D.S.,1990.Deep intraplate earth-quakes in the Western United States and their relation-ship to lithospheric temperatures.Bulletin of the Seis-mological Society of America,80(3):589-599.
Zeng,R.S.,Zhu,J.S.,Zhou,B.,et al.,1992.3D seismicwave velocity structure of easten Qinghai-Tibet plateauand its adjacent areas and continental collision model.Acta Seismologica Sinica,14(Suppl.):523-533(inChininese with English abstract).
Zhang,G.M.,Wang,S.Y.,Li,L.,et al.,2002.Focal depthresearch of earthquakes in Mainland China:I mplicationfor tectonics.Chinese Science Bulletin,47(9):663-668(in Chininese with English abstract).
Zhao,J.L.,Yuan,Y.M.,Li,D.W.,et al.,2007.Geophysi-cal anomaly of lower crust of Qinhai-Tibet plateau andits adjacent regions.Geological Science and TechnologyInformation,26(2):13-18,29(in Chininese withEnglish abstract).
Zhou,F.H.,Yao,Z.X.,Liu,Z.J.,et al.,2002.The originand i mplication of the NNE-trendingdeep negative mag-netic anomaly zonein central Qinghai-Tibet plateau.Ge-ophysical&Geochemical Exploration,26(1):12-16(in Chininese with English abstract).
崔作舟,尹周勋,高恩元,等,1990.青藏高原地壳结构构造及其与地震的关系.中国地质科学院院报,21:215-225.
崔作舟,尹周勋,高恩元,等,1992.青藏高原速度结构和深部构造.北京:地质出版社,1-112.
李德威,1993.大陆构造样式及大陆动力学模式初探.地球科学进展,8(5):88-93.
李德威,1995a.关于大陆构造的思考.地球科学——中国地质大学学报,20(1):10-18.
李德威,1995b.再论大陆构造与动力学.地球科学——中国地质大学学报,20(1):19-26.
李德威,纪云龙,2000.大陆下地壳层流作用及其大陆动力学意义,地震地质,22(1):89-96.
李德威,王家映,2001.大陆下地壳地球物理异常及其构造意义.地质科技情报,20(3):11-15.
李德威,2003.青藏高原隆升机制新模式.地球科学——中国地质大学学报,28(6):593-600.
李德威,2005.青藏高原板内活动断层与地震成因.吴珍汉,赵志中,杨美玲,等.青藏高原地质过程与环境灾害效应文集.北京:地震出版社,118-124.
李秋生,彭苏萍,高锐,2004.青藏高原莫霍面的研究进展.质论评,50(6):598-612.
马宗晋,张家声,刘国栋,等,1990.大陆多震层研究现状和讨论.地震地质,12(3):262-264.
潘桂棠,王培生,徐耀荣,等,1990.青藏高原新生代构造演化.北京:地质出版社,1-163.
王椿镛,王溪莉,苏伟,等,2006.青藏高原东缘下地壳流动的地震学证据.四川地震,4:1-4.
曾融生,朱介寿,周兵,等,1992.青藏高原及其东部邻区的三维地震波速度结构与大陆碰撞模型.地震学报,14(增刊):523-533.
张国民,汪素云,李丽,等,2002.中国大陆地震震源深度及其构造含义.科学通报,47:663-668.
赵继龙,袁晏明,李德威,等,2007.青藏高原及周边地区下地壳地球物理异常及成因.地质科技情报,26(2):13-18,29.
周伏洪,姚正煦,刘振军,等,2002.青藏高原中部北北东向深部负磁异常带的成因及其意义.物探与化探,26(1):12-17.
Chen,W.P.,1988.A brief update on the focal depths of in-tracontinental earthquakes and their correlations withheat flowand tectonic age.Seismological Research Let-ters,59(4):263-272.
Chen,W.P.,Yang,Z.H.,2004.Earthquakes beneath thHi malayas and Tibet:Evidence for strong lithospherimantle.Science,304(5679):1949-1952.
Cui,Z.Z.,Yin,Z.X.,Gao,E.Y.,et al.,1990.The structureand tectonics of the crust and their relation with earth-quakes in the Qinghai-Xizang plateau.Bulletin of TheChinese Academy of Geological Sciences,21:215-225(in Chininese).
Cui,Z.Z.,Yin,Z.X.,Gao,E.Y.,et al.,1992.Velocitystructure and deep-seated structure of the Qinghai-Ti-bet plateau.Geological Publishing House,Bejing,1-112(in Chinese).
Li,D.W.,1992.On tectonic asymmetrical evolution of theHi malayan orogenic belt.Earth Science—Journal ofChina University of Geosciences,17(5):539-545(inChinese with English abstract).
Li,D.W.,1993.The style of continental structure and modelof continental dynamics.Advance in Earth Sciences,8(5):88-93(in Chinese with English abstract).
Li,D.W.,1995a.Speculations on continental tectonics.EarthScience—Journal of China University of Geosciences,20(1):10-18(in Chinese with English abstract).
Li,D.W.,1995b.On continental tectonics and its dynamics.Earth Science—Journal of China University of Geo-sciences,20(1):19-26(in Chininese with English ab-stract).
Li,D.W.,Ji,Y.L.,2000.Laminar flowin the lower conti-nental crust and its significance for continental dynam-ics.Seismology and Geology,22(1):89-96(in Chin-inese with English abstract).
Li,D.W.,Wang,J.Y.,2001.Geological anomaly of conti-nental lower crust and its tectonic significance.Geolog-ical Science and Technology Information,20(3):11-15(in Chinese with English abstract).
Li,D.W.,2003.A new model for uplifting mechanism ofQinghai-Tibet Plateau.Earth Science—Journal of Chi-na University of Geosciences,28(6):593-600(inChininese with English abstract).
Li,D.W.,2005.Intraplate active faults and earthquakemechanismin the Qinghai-Tibet plateau.In:Wu,Z.H.,Zhao,Z.Z.,Yang,M.L.,et al.,eds.,Geologicalprocess andits effect onthe environment and disaster ofthe Tibetan plateau.Seismic Press,Beijing,118-124(in Chinese).
Li,Q.S.,Peng,S.P.,Gao,R.,2004.Areview on the Mohodiscontinuity beneath the Tibetan plateau.GeologicalReview,50(6):598-612(in Chininese).
Ma,Z.J.,Zhang,J.S.,Liu,G.D.,et al.,1990.Current stateof research on continental seismogenic layer-internation-al workshop held in Beijing,April27-30,1990.Seis-mology and Geology,12(3):262-264(in Chininese).
Maggi,A.,Jackson,J.A.,McKenzie,D.,et al.,2000.Earth-quake focal depths,effective elastic thickness,and thestrength of the continental lithosphere.Geology,28(6):495-498.
Molnar,P.,1988.Continental tectonics in the aftermath ofplate tectonics.Nature,335(186):131-137.
Pan,G.T.,Wang,P.S.,Xu,Y.R.,et al.,1990.CenozoicTectonic Evolution of the Qinghai-Tibet Plateau.Geo-logical publishing House,Bejing,1-163(in Chin-inese).
Ranalli,G.,Murphy,D.C.,1987.Rheological stratificationof the lithosphere.Tectonophysics,132:281-295.
Wang,C.Y.,Wang,X.L.,Su,W.,et al.,2006.Seismologi-cal evidence of the crust flowing under the easternboundary part of Qinghai-Tibet plateau.Earthquake Re-search in Sichuan,4:1-4(in Chininese with Englishabstract).
Wong,I.G.,Chapman,D.S.,1990.Deep intraplate earth-quakes in the Western United States and their relation-ship to lithospheric temperatures.Bulletin of the Seis-mological Society of America,80(3):589-599.
Zeng,R.S.,Zhu,J.S.,Zhou,B.,et al.,1992.3D seismicwave velocity structure of easten Qinghai-Tibet plateauand its adjacent areas and continental collision model.Acta Seismologica Sinica,14(Suppl.):523-533(inChininese with English abstract).
Zhang,G.M.,Wang,S.Y.,Li,L.,et al.,2002.Focal depthresearch of earthquakes in Mainland China:I mplicationfor tectonics.Chinese Science Bulletin,47(9):663-668(in Chininese with English abstract).
Zhao,J.L.,Yuan,Y.M.,Li,D.W.,et al.,2007.Geophysi-cal anomaly of lower crust of Qinhai-Tibet plateau andits adjacent regions.Geological Science and TechnologyInformation,26(2):13-18,29(in Chininese withEnglish abstract).
Zhou,F.H.,Yao,Z.X.,Liu,Z.J.,et al.,2002.The originand i mplication of the NNE-trendingdeep negative mag-netic anomaly zonein central Qinghai-Tibet plateau.Ge-ophysical&Geochemical Exploration,26(1):12-16(in Chininese with English abstract).
崔作舟,尹周勋,高恩元,等,1990.青藏高原地壳结构构造及其与地震的关系.中国地质科学院院报,21:215-225.
崔作舟,尹周勋,高恩元,等,1992.青藏高原速度结构和深部构造.北京:地质出版社,1-112.
李德威,1993.大陆构造样式及大陆动力学模式初探.地球科学进展,8(5):88-93.
李德威,1995a.关于大陆构造的思考.地球科学——中国地质大学学报,20(1):10-18.
李德威,1995b.再论大陆构造与动力学.地球科学——中国地质大学学报,20(1):19-26.
李德威,纪云龙,2000.大陆下地壳层流作用及其大陆动力学意义,地震地质,22(1):89-96.
李德威,王家映,2001.大陆下地壳地球物理异常及其构造意义.地质科技情报,20(3):11-15.
李德威,2003.青藏高原隆升机制新模式.地球科学——中国地质大学学报,28(6):593-600.
李德威,2005.青藏高原板内活动断层与地震成因.吴珍汉,赵志中,杨美玲,等.青藏高原地质过程与环境灾害效应文集.北京:地震出版社,118-124.
李秋生,彭苏萍,高锐,2004.青藏高原莫霍面的研究进展.质论评,50(6):598-612.
马宗晋,张家声,刘国栋,等,1990.大陆多震层研究现状和讨论.地震地质,12(3):262-264.
潘桂棠,王培生,徐耀荣,等,1990.青藏高原新生代构造演化.北京:地质出版社,1-163.
王椿镛,王溪莉,苏伟,等,2006.青藏高原东缘下地壳流动的地震学证据.四川地震,4:1-4.
曾融生,朱介寿,周兵,等,1992.青藏高原及其东部邻区的三维地震波速度结构与大陆碰撞模型.地震学报,14(增刊):523-533.
张国民,汪素云,李丽,等,2002.中国大陆地震震源深度及其构造含义.科学通报,47:663-668.
赵继龙,袁晏明,李德威,等,2007.青藏高原及周边地区下地壳地球物理异常及成因.地质科技情报,26(2):13-18,29.
周伏洪,姚正煦,刘振军,等,2002.青藏高原中部北北东向深部负磁异常带的成因及其意义.物探与化探,26(1):12-17.
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