青藏高原东缘新构造及其对汶川地震的控制作用
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摘要
基于卫星遥感图像解译、地形起伏度分析和地面调查资料,论述了青藏高原东缘构造地貌格局、新构造演化阶段和活动断裂特征,提出青藏高原东缘不同地块在晚新生代时期有序的向东挤出过程,并划分为4个阶段:中新世早期川滇地块向北东挤出、中新世晚期川滇地块的再次强烈向东挤出、上新世至早中更新世时期川青地块的向东挤出、晚更新世以来最新构造变动阶段,青藏高原东缘地貌边界带也经历了由西向东、由南向北的有规律的迁移过程。基于活动构造的最新研究成果和现今GPS测量成果,阐述了东昆仑-岷山-龙门山走滑-逆冲断裂系统的运动学特征。根据地震破裂构造的实地调查,分析了汶川地震的地表破裂行为,提出了汶川地震的发震构造模型。研究认为,青藏高原东部地区NW向楔状条块向东运动速度的一半被鲜水河断裂及其北西延伸的构造带所吸收,而龙门山构造带向东运动受阻于四川盆地之下扬子刚性地块,使得龙门山断裂带处在低应变、高应力环境下,因长期应力-应变累积而导致向西陡倾的断裂带突然向东逆冲运动而释放能量。汶川强震发生的深部机理值得深入研究。
Based on satellite imagery interpretation, land relief amplitude analysis, and field observations, this paper discusses the tectono-morphologic background, neotectonics evolution history and active fault characteristics of eastern Tibet. It is proposed that different blocks in the eastern margin of Tibet-Qinghai Plateau successively extruded eastward during later Cenozoic and the extrusion can be divided into four stages: extrusion of the Chuan-Dian block eastward in early Miocene; intense extrusion of the Chuan-Dian block eastward again in late Miocene; eastward extrusion of the Qing-Chuan block from early Pliocene to early-middle Pleistocene; and tectonic change stage since late Pleistocene to Holocene. Accordingly, morphological boundary of east Tibet underwent change from west to east and from south to north. Latest research results on the active faults and GPS measurements display the kinematic features of East Kunlun-Mingshan-Longmen Mountain strike-slip system. Based on the field survey of earthquake rupture, combined with analysis of ground rupture features in the Wenchuan area, the study proposes a model for seismogenic structure of the Wenchuan earthquake. This study also indicates that almost half speed of movement of an NW-trending wedge-like block toward east was absorbed by the Xianshuihe fault and its westward extension structure. However, the motion of Longmenshan structural belt toward east was likely stopped by the rigid block beneath the Yangtze plate, resulting in that the Longmenshan rapture occurred in a setting of low strain and high stress; thus long-term strain-stress accumulation triggered energy releasing by abrupt thrusting of the steeply west dipping rapture eastward. Therefore, the focal mechanism for the Wenchuan catastrophic earthquake is worth further studying.
Based on satellite imagery interpretation, land relief amplitude analysis, and field observations, this paper discusses the tectono-morphologic background, neotectonics evolution history and active fault characteristics of eastern Tibet. It is proposed that different blocks in the eastern margin of Tibet-Qinghai Plateau successively extruded eastward during later Cenozoic and the extrusion can be divided into four stages: extrusion of the Chuan-Dian block eastward in early Miocene; intense extrusion of the Chuan-Dian block eastward again in late Miocene; eastward extrusion of the Qing-Chuan block from early Pliocene to early-middle Pleistocene; and tectonic change stage since late Pleistocene to Holocene. Accordingly, morphological boundary of east Tibet underwent change from west to east and from south to north. Latest research results on the active faults and GPS measurements display the kinematic features of East Kunlun-Mingshan-Longmen Mountain strike-slip system. Based on the field survey of earthquake rupture, combined with analysis of ground rupture features in the Wenchuan area, the study proposes a model for seismogenic structure of the Wenchuan earthquake. This study also indicates that almost half speed of movement of an NW-trending wedge-like block toward east was absorbed by the Xianshuihe fault and its westward extension structure. However, the motion of Longmenshan structural belt toward east was likely stopped by the rigid block beneath the Yangtze plate, resulting in that the Longmenshan rapture occurred in a setting of low strain and high stress; thus long-term strain-stress accumulation triggered energy releasing by abrupt thrusting of the steeply west dipping rapture eastward. Therefore, the focal mechanism for the Wenchuan catastrophic earthquake is worth further studying.
引文
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邓起东,陈社发,赵小麟.1994.龙门山及其邻区的构造和地震活动及动力学.地震地质,16(4):389~402.
李勇,周荣军,Densmore A L,Ellis M A,黎兵.2006a.青藏高原东缘龙门山晚新生代走滑挤压作用的沉积响应.沉积学报,24(2):153~165.
李勇,周荣军,Densmore A L,Ellis M A.2006b.青藏高原东缘龙门山晚新生代走滑-逆冲作用的地貌标志.第四纪研究,26(1):40~52.
~52.刘树文,王宗起,阎全人,李秋根,张德惠,王建国.2006.折多山花岗岩时代、成因及其动力学意义.岩石学报,22(2):343~352.
卢华复,贾东,王良书,王胜利.2008.关于汶川地震发震机制.高校地质学报,14(2):133~138.
马寅生,施炜,张岳桥,杨农,张春山,张会平.2005.东昆仑活动断裂带玛曲段活动特征及其东延.地质通报,24(1):30~35.
青海省地震局,中国地震局地壳应力研究所.1999.东昆仑活动断裂系.北京:地震出版社,186.
四川省地质矿产局.1989.四川省地质志.北京:地质出版社.
唐荣昌,韩渭宾.1993.四川活动断裂与地震.北京:地震出版社.
唐荣昌,黄祖智,马声浩,龚宇,周荣军.1995.四川活动断裂带的基本特征.地震地质,17(4):390~396.
徐锡伟,闻学泽,叶建青,马报起,陈杰,周荣军,何宏林,田勤俭,河玉林,王志才,孙昭民,冯希杰,于贵华,陈立春,陈桂华,于慎鄂,冉勇康,李细光,李陈侠,安艳芬.2008.汶川MS8.0地震地表破裂及其发震构造.地震地质,30(3):597~629.
许志琴,索书田,韩郁菁,傅小方,黄明华.1992.中国松潘-甘孜造山带的造山过程.北京:地质出版社,1~190.
许志琴,李化启,侯立炜,付小芳,陈文,曾令森,蔡志慧,陈方远.2007.青藏高原东缘龙门-锦屏造山带的崛起——大型拆离断层和挤出机制.地质通报,26(10):1262~1276.
张岳桥,杨农,陈文,马寅生,孟晖.2003.中国东西部地貌边界带晚新生代构造变形历史与青藏高原隆升过程初步研究.地学前缘,10(4):599~612.
张岳桥.2004.晚新生代青藏高原构造挤出及其对中国东部裂陷盆地晚期油气成藏的影响.石油与天然气地质,25(2):162~169.
张岳桥,杨农,孟晖,陈文.2004a.四川攀西地区晚新生代构造变形历史与隆升过程初步研究.中国地质,31(1):23~33.
张岳桥,陈文,杨农.2004b.川西鲜水河断裂带晚新生代剪切变形40Ar/39Ar测年及其构造意义.中国科学(D辑),34(7):613~621.
张岳桥,马寅生,杨农,张会平,施炜.2005.西秦岭地区东昆仑-秦岭断裂系晚新生代左旋走滑历史及其向东扩展.地球学报,26(1):1~8.
周荣军,李勇,Densmore A L,Ellis M A,何玉林,王凤林,黎小刚.2006.青藏高原东缘活动构造.矿物岩石,26(2):40~51.
唐文清,陈智梁,刘宇平,张清志,赵济湘.2005.青藏高原东缘鲜水河断裂与龙门山断裂交会区现今的构造活动.地质通报,24(12):1169~1172.
Arne D,Worley B,Wilson C,Chen S F,Foster D,Luo Z L,Liu S G,Dirks P.1997.Differential exhumation in response to episodicthrusting along the eastern margin of the Tibetan Plateau.Tectonophysics,280:239~256.
Avouac J P,Tapponnier P.1993.Kinematic model of activedeformationin Central-Asia.Geophysical Research Letters,20:895~898.
Burchfiel B C,Chen Z,Liu Y,Royden,L H,1995.Tectonics of theLongmen Shan and adjacent regions,central China.International Geological Review,37(8):661~735.
Chen S F,Wilson C J L,Deng Q D,Zhao X L,Luo Z L.1994.Active faulting and block movement associated with largeearthquakes in the Minshan and Longmen Mountains,northeastern Tibetan plateau.Journal of Geophysical Research,99:24025~24038.
CENC(China Earthquake Net Center).http://www.csi.ac.cn/sichuan/index080512.ht m.
Chen Z,Burchfiel B C,Liu Y,King R W,Royden L H,Tang W,Wang E,Zhao J,Zhang X.2000.Global Positioning Systemmeasurements from eastern Tibet and their i mplications forIndia/Eurasia intercontinental deformation.J.Geophys.Res.,105:16215~16228.
Clark M K,Royden L H.2000.Topographic ooze:building theeastern margin of Tibet by lower crustal flow.Geology,28:703~706.
Densmore A L,Ellis M A,Li Y,Zhou R,Hancock G S,Richardson N.2007.Active tectonics of the Beichuan andPengguan faults at the eastern margin of the Tibetan Plateau.Tectonics,26(4):1~17.
Dong Shuwen,Zhang Yueqiao,Wu Zhenhan,Yang Nong,MaYinsheng,Shi Wei,Chen Zhengle,Long Changxing,AnMeijian.2008.Surface ruptures and co-seismic displacementproduced bytheMS8Wenchuan earthquake on12thMay,2008,Sichuan,China:eastward growth of Qinghai-Tibet Plateau.Acta Geologica Sinica(English Edition),82(5):938~948.
Jia D,Wei G Q,Chen Z X,Li B L,Zen Q,Yang G.2006.Longmen Shan fold-thrust belt and its relation to the westernSichuan Basinin central China:Newinsights fromhydrocarbonexploration.AAPG Bulletin,90:1425~1447.
Kirby E,Whipple K X,Burchfiel B C,et al.2000.Neotectonics ofthe Min Shan,China:I mplications for mechanisms drivingQuaternary deformation alongthe eastern margin of the TibetanPlateau.Geological Society of America Bulletin,112(3):375~393.
Kirby E,Reiners P W,Krol M A,Whipple K X,Hodges K V,Farley K A,Tang W Q,Chen Z L.2002.Late Cenozoicevolution of the eastern margin of the Tibetan Plateau:inferences from40Ar/39Ar and(U-Th)/He thermochronology.Tectonics,21(1):1~19.
Lin A M,Fu B H,Guo J M,Zeng Q L,Dang G M,He WG,ZhaoY.2002.Co-seismic strike-slip and rupture length produced bythe2001MS8.1Central Kunlun earthquake.Science,296:2015~2017.
Roger F,Calassou S,Lancelot J,Malavieille J,Mattauer M,Xu ZQ,Hao Z W,Hou L W.1995.The presently active sinistraXianshui He strike-slip fault(XSH)is a lithospheric scalestrike-slip fault in the eastern Tibet.Earth and PlanetaryScience Letters,130(1~4):201~216.
Shen Z,Lu J,Wang M,Burgmann R.2005.Contemporary crustaldeformation around the southeast borderland of the TibetanPlateau.J.Geophys.Res.,110:1~17.
Tapponnier P,Xu Z Q,Roger F,Meyer B,Arnaud N,WittlingerG,Yang J S.2001.Oblique stepwise rise and growth of theTibet plateau.Science,294:1671~1677.
USGS(United States Geological Survey).Magnitude7.9-easternSichuan,China.(http://earthquake.usgs.gov/eqcenter/eqinthenews/2008/us2008ryan).
van der Woerd J,Tapponnier P,Ryeson F J,Meriaux A S,MeyerB,Gaudemer Y,Finkel R C,Caffee M W,Zhao G,Xu Z.2002.Uniforme post-glacial slip-rate along the central600kmof the Kunlun Fault(Tibet),from26Al,10Be and14C dating ofrise offsets,and cli matic origin of the regional morphology.Geophy.J.Inter.,148:356~388.
Wang E,Burchfiel B C.2000.Late Cenozoic to Holocenedeformation in southwestern Sichuan and adjacent Yunnan,China,andits role in formation of the southeastern part of theTibetan Plateau.GSA Bulletin,112(3):412~423.
Zhang P Z,Shen Z,Wang M,Gan WJ,Burgmann R,Molnar P.2004.Continuous deformation of the Tibetan Plateau fromglobal positioning systemdata.Geology,32:809~812.
Zhao Zhizhong,Qiao Yansong,Wang Shubing,Yao Haitao,WangYan,Li Chaozhu,Fu Jianli,Liu Zongxiu,Li Mingze,MiaoQi,Jiang Fuchu.2008.Late Cenozoic Geology and Paleo-environment change in the eastern edge of Qinghai-TibetPlateau.Acta Geologica Sinica(English Edition),82(5):959~966.
邓起东,陈社发,赵小麟.1994.龙门山及其邻区的构造和地震活动及动力学.地震地质,16(4):389~402.
李勇,周荣军,Densmore A L,Ellis M A,黎兵.2006a.青藏高原东缘龙门山晚新生代走滑挤压作用的沉积响应.沉积学报,24(2):153~165.
李勇,周荣军,Densmore A L,Ellis M A.2006b.青藏高原东缘龙门山晚新生代走滑-逆冲作用的地貌标志.第四纪研究,26(1):40~52.
~52.刘树文,王宗起,阎全人,李秋根,张德惠,王建国.2006.折多山花岗岩时代、成因及其动力学意义.岩石学报,22(2):343~352.
卢华复,贾东,王良书,王胜利.2008.关于汶川地震发震机制.高校地质学报,14(2):133~138.
马寅生,施炜,张岳桥,杨农,张春山,张会平.2005.东昆仑活动断裂带玛曲段活动特征及其东延.地质通报,24(1):30~35.
青海省地震局,中国地震局地壳应力研究所.1999.东昆仑活动断裂系.北京:地震出版社,186.
四川省地质矿产局.1989.四川省地质志.北京:地质出版社.
唐荣昌,韩渭宾.1993.四川活动断裂与地震.北京:地震出版社.
唐荣昌,黄祖智,马声浩,龚宇,周荣军.1995.四川活动断裂带的基本特征.地震地质,17(4):390~396.
徐锡伟,闻学泽,叶建青,马报起,陈杰,周荣军,何宏林,田勤俭,河玉林,王志才,孙昭民,冯希杰,于贵华,陈立春,陈桂华,于慎鄂,冉勇康,李细光,李陈侠,安艳芬.2008.汶川MS8.0地震地表破裂及其发震构造.地震地质,30(3):597~629.
许志琴,索书田,韩郁菁,傅小方,黄明华.1992.中国松潘-甘孜造山带的造山过程.北京:地质出版社,1~190.
许志琴,李化启,侯立炜,付小芳,陈文,曾令森,蔡志慧,陈方远.2007.青藏高原东缘龙门-锦屏造山带的崛起——大型拆离断层和挤出机制.地质通报,26(10):1262~1276.
张岳桥,杨农,陈文,马寅生,孟晖.2003.中国东西部地貌边界带晚新生代构造变形历史与青藏高原隆升过程初步研究.地学前缘,10(4):599~612.
张岳桥.2004.晚新生代青藏高原构造挤出及其对中国东部裂陷盆地晚期油气成藏的影响.石油与天然气地质,25(2):162~169.
张岳桥,杨农,孟晖,陈文.2004a.四川攀西地区晚新生代构造变形历史与隆升过程初步研究.中国地质,31(1):23~33.
张岳桥,陈文,杨农.2004b.川西鲜水河断裂带晚新生代剪切变形40Ar/39Ar测年及其构造意义.中国科学(D辑),34(7):613~621.
张岳桥,马寅生,杨农,张会平,施炜.2005.西秦岭地区东昆仑-秦岭断裂系晚新生代左旋走滑历史及其向东扩展.地球学报,26(1):1~8.
周荣军,李勇,Densmore A L,Ellis M A,何玉林,王凤林,黎小刚.2006.青藏高原东缘活动构造.矿物岩石,26(2):40~51.
唐文清,陈智梁,刘宇平,张清志,赵济湘.2005.青藏高原东缘鲜水河断裂与龙门山断裂交会区现今的构造活动.地质通报,24(12):1169~1172.
Arne D,Worley B,Wilson C,Chen S F,Foster D,Luo Z L,Liu S G,Dirks P.1997.Differential exhumation in response to episodicthrusting along the eastern margin of the Tibetan Plateau.Tectonophysics,280:239~256.
Avouac J P,Tapponnier P.1993.Kinematic model of activedeformationin Central-Asia.Geophysical Research Letters,20:895~898.
Burchfiel B C,Chen Z,Liu Y,Royden,L H,1995.Tectonics of theLongmen Shan and adjacent regions,central China.International Geological Review,37(8):661~735.
Chen S F,Wilson C J L,Deng Q D,Zhao X L,Luo Z L.1994.Active faulting and block movement associated with largeearthquakes in the Minshan and Longmen Mountains,northeastern Tibetan plateau.Journal of Geophysical Research,99:24025~24038.
CENC(China Earthquake Net Center).http://www.csi.ac.cn/sichuan/index080512.ht m.
Chen Z,Burchfiel B C,Liu Y,King R W,Royden L H,Tang W,Wang E,Zhao J,Zhang X.2000.Global Positioning Systemmeasurements from eastern Tibet and their i mplications forIndia/Eurasia intercontinental deformation.J.Geophys.Res.,105:16215~16228.
Clark M K,Royden L H.2000.Topographic ooze:building theeastern margin of Tibet by lower crustal flow.Geology,28:703~706.
Densmore A L,Ellis M A,Li Y,Zhou R,Hancock G S,Richardson N.2007.Active tectonics of the Beichuan andPengguan faults at the eastern margin of the Tibetan Plateau.Tectonics,26(4):1~17.
Dong Shuwen,Zhang Yueqiao,Wu Zhenhan,Yang Nong,MaYinsheng,Shi Wei,Chen Zhengle,Long Changxing,AnMeijian.2008.Surface ruptures and co-seismic displacementproduced bytheMS8Wenchuan earthquake on12thMay,2008,Sichuan,China:eastward growth of Qinghai-Tibet Plateau.Acta Geologica Sinica(English Edition),82(5):938~948.
Jia D,Wei G Q,Chen Z X,Li B L,Zen Q,Yang G.2006.Longmen Shan fold-thrust belt and its relation to the westernSichuan Basinin central China:Newinsights fromhydrocarbonexploration.AAPG Bulletin,90:1425~1447.
Kirby E,Whipple K X,Burchfiel B C,et al.2000.Neotectonics ofthe Min Shan,China:I mplications for mechanisms drivingQuaternary deformation alongthe eastern margin of the TibetanPlateau.Geological Society of America Bulletin,112(3):375~393.
Kirby E,Reiners P W,Krol M A,Whipple K X,Hodges K V,Farley K A,Tang W Q,Chen Z L.2002.Late Cenozoicevolution of the eastern margin of the Tibetan Plateau:inferences from40Ar/39Ar and(U-Th)/He thermochronology.Tectonics,21(1):1~19.
Lin A M,Fu B H,Guo J M,Zeng Q L,Dang G M,He WG,ZhaoY.2002.Co-seismic strike-slip and rupture length produced bythe2001MS8.1Central Kunlun earthquake.Science,296:2015~2017.
Roger F,Calassou S,Lancelot J,Malavieille J,Mattauer M,Xu ZQ,Hao Z W,Hou L W.1995.The presently active sinistraXianshui He strike-slip fault(XSH)is a lithospheric scalestrike-slip fault in the eastern Tibet.Earth and PlanetaryScience Letters,130(1~4):201~216.
Shen Z,Lu J,Wang M,Burgmann R.2005.Contemporary crustaldeformation around the southeast borderland of the TibetanPlateau.J.Geophys.Res.,110:1~17.
Tapponnier P,Xu Z Q,Roger F,Meyer B,Arnaud N,WittlingerG,Yang J S.2001.Oblique stepwise rise and growth of theTibet plateau.Science,294:1671~1677.
USGS(United States Geological Survey).Magnitude7.9-easternSichuan,China.(http://earthquake.usgs.gov/eqcenter/eqinthenews/2008/us2008ryan).
van der Woerd J,Tapponnier P,Ryeson F J,Meriaux A S,MeyerB,Gaudemer Y,Finkel R C,Caffee M W,Zhao G,Xu Z.2002.Uniforme post-glacial slip-rate along the central600kmof the Kunlun Fault(Tibet),from26Al,10Be and14C dating ofrise offsets,and cli matic origin of the regional morphology.Geophy.J.Inter.,148:356~388.
Wang E,Burchfiel B C.2000.Late Cenozoic to Holocenedeformation in southwestern Sichuan and adjacent Yunnan,China,andits role in formation of the southeastern part of theTibetan Plateau.GSA Bulletin,112(3):412~423.
Zhang P Z,Shen Z,Wang M,Gan WJ,Burgmann R,Molnar P.2004.Continuous deformation of the Tibetan Plateau fromglobal positioning systemdata.Geology,32:809~812.
Zhao Zhizhong,Qiao Yansong,Wang Shubing,Yao Haitao,WangYan,Li Chaozhu,Fu Jianli,Liu Zongxiu,Li Mingze,MiaoQi,Jiang Fuchu.2008.Late Cenozoic Geology and Paleo-environment change in the eastern edge of Qinghai-TibetPlateau.Acta Geologica Sinica(English Edition),82(5):959~966.
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