帕米尔地区现今大陆深俯冲——地震构造和动力学解释
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摘要
在 NEIC(UsGS)1975～1999年地震记录的基础上,补充中国新疆地震台网1975年以来的16,339个部分重新定位的有效地震记录,根据该地区地震活动时空分布规律、地壳速度结构和地表变形构造等最新研究成果,对兴都库什-帕米尔-中国西部地震活动的三维几何学及其构造联系作出了新的解释,强调沿恰曼断层的左行走滑作用对帕米尔和兴都库什地震带的制约。沿帕米尔地震带正在发生大陆深俯冲作用,是恰曼断层左行牵引的结果,深俯冲岩板为上宽下窄向恰曼断层收敛的楔形体,俯冲角度上缓(20～30°)下陡(60～70°),转变深度在80～120公里,部分下地壳物质被深俯冲作用带到200公里以下的深度。帕米尔深俯冲带上盘岩石中的多期反冲构造组合和后退俯冲作用历史,解释了该地区地壳缩短加厚和深部岩石折返的机制。与深俯冲作用相关的双地震剪切带和3个地震群的构造联系,提供了大陆深俯冲作用的动力学信息。
Besides the NEIC (USGS) 1975～1999 seismic records,16,339 other earthquakes occur since 1975,some of them are relocated,are added from records of Chinese Xinjiang seismic network.A 3-D geometry of the seismicity in Hindu kush-Pamir-Western China area and their structural relationship are illustrated according to the recent studies on the space-time distribution of the above earthquakes,velocity structure in the crust and surface deformation pattern in this area.An emphasize is given to the left-leteral movement along Chaman strike-slip fault which is restricting the Pamir and Hindu Kush seismic zones.The ongoing deep-subducting in the Pamir seismic zone is thought to be resulted in a traction from the left-leteral movement,where a subducting slab appears as a wedge disappearing towards to Chaman fault,and become steeper downwards from 20～30°at the upper part to 60～70°at the lower part,changing at 80～120 km.Some of lower crust material have been carried down into a depth more than 200 km.An answer about the shortening and thickening of the crust,and the returning upwards of the deep-seated rocks in the area is obtained from a facts that a multiple stage ramp thrusting and roll-back thrusting are recorded in the hanging wall of the deep-subduction zone.Tectonic relationships of the double seismic shear zones and three seismic swarms in response to the deep-subducting give new light to the dynamics about the deep-subduction of continent crust.
Besides the NEIC (USGS) 1975～1999 seismic records,16,339 other earthquakes occur since 1975,some of them are relocated,are added from records of Chinese Xinjiang seismic network.A 3-D geometry of the seismicity in Hindu kush-Pamir-Western China area and their structural relationship are illustrated according to the recent studies on the space-time distribution of the above earthquakes,velocity structure in the crust and surface deformation pattern in this area.An emphasize is given to the left-leteral movement along Chaman strike-slip fault which is restricting the Pamir and Hindu Kush seismic zones.The ongoing deep-subducting in the Pamir seismic zone is thought to be resulted in a traction from the left-leteral movement,where a subducting slab appears as a wedge disappearing towards to Chaman fault,and become steeper downwards from 20～30°at the upper part to 60～70°at the lower part,changing at 80～120 km.Some of lower crust material have been carried down into a depth more than 200 km.An answer about the shortening and thickening of the crust,and the returning upwards of the deep-seated rocks in the area is obtained from a facts that a multiple stage ramp thrusting and roll-back thrusting are recorded in the hanging wall of the deep-subduction zone.Tectonic relationships of the double seismic shear zones and three seismic swarms in response to the deep-subducting give new light to the dynamics about the deep-subduction of continent crust.
引文
Aki K.1992． Higher-order interpretations between seismogenetic structures and earthquake processes.Tectonophysics,211:1-12
Benioff H.1954． Orogenesis and deep crustal structure:additional evidence from seismology.Geol.Soc.Am.Bull.,65:385-400
Billington S,Isacks LB & Barazangi M.1977． Spatial distribution and focal mecanisms of mantle earthquakes in the Hindu Kush-Pamir region;a eontored Benioff zone.Geology,5:699-704
Burtman VS & Molnar P.1993． Geological and geophysical evidence for deep subduction of continental crust beneath the Pamir.Tech.Rept.Spec.Pap.,281,Geological Society
Chaterlain JL,Roecker SW,Hatzfeld D & Molnar P.1980． Microerathquake seismicity and fault plane solutions in the Hindo Kush region anti their tectonic implications.J.Geophys.Res.,85:1365-1387
Clarke GL and Norman AR.1993． Generation of pseudotachylite under granulite facies conditions,and its preservation during cooling.J.Metamorphic Geol.,11:319-335
Fan G,Ni JF & Wallace TC.1994． Active tectonics of the Pamirs and Karakoram.J.Geophys.Res.,99:7131-7160
Hamburger MW,Sarewitz DR,Pavlis TL & Popandopulo GA.1992． Structural and seismic evidence for intracontinental subduction in the Peter the first range,central Asia.Geol.Soc.Am.Bull.,104:397-408
Hobbs BE.1986． Earthquakes in the ductile regime?Pure and Applied Geophysics,124:309-336
Katok AP.1988． On the deepest earthquake in the Pamir-Hindu Kush zone,Izv.Acad.Sci.USSR Phys.Solid Earth,Transl.,24:649-653
Li Jianhua,Zhang Jiasheng and Shan Xinjian.2002． Faulting in the Western Kunlun-southwestern Tianshan area.Acta Geologica Sinica,76(3) :347-353
Lei JS,Zhou HL and Zhao DP.2002． 3-D velocity structure of P-wave in the crust and upper-mantle beneath Pamir and adjacent region.Chinese J.Geophysics,45(6) :802-811
Nowroozi AA.1971． Seismotectonics of the Pakistan plateau,eastern Turkey,Caucasus,and Hindu Kush regions.Bull.Seism.Soc.Am.,61:317-341．
Pegler G and Das S.1998． An enhanced imagge of the Pamir-Hindu Kush seismic zone from relocated earthquake hypocentres.Geophys.J.Int.,134:573-595
Reigber Ch,Michel GW,Galas R,Angermann D,Klotz J,Chen JY,Papschev A,Arslanov R,Tzurkov VE,Ishanov MC.2001． New space geodetic constraints on the distribution of deformation in Central Asia.Earth and Planetary Science Letters,191:157-165
Roecker SW,Soboleva V,Nersesov IL,Lukk AA,Hatzfeld D,Chatelain JL & Molnar P.1980． Seismicity and fault plane solutions of intermediate depth earthquakes in the Pamir-Hindu Kush region.J.Geophys.Res.,85:1358-1364
Roecker SW.1982． Velocity structure of the Pamir-Hindu Kush region:possible evidence of subducted crust.J.Geophys.Res.,87:945-959
Sibson RH.1980． Transient discontinuities in ductile shear zone.J.Struct.Geol.,2(1/2) :165-171
Sibson RH.1992． Implications of fault-valve behaviour for rupture nucleation and recurrence.Tectonopbysics,211:283-293
Vinnik LP,Lukk AA & Nersesov IL.1977． Nature of the intermediate seismic zone in the mantle of the Pamir-Hindu Kush.Tectonophysics,38:T9-T14．
Vinnik LP,Lukk AA & Mirzokurbonov M.1978． Quantitative analysis of velocity inhomogeneities of the Pamir-Hindu Kush upper mantle,Izv.Acad.Sci.USSR Phys.Solid Earth,Transl.,14:319-328
Zhang Jiasheng.1987． Two-phase deformation in the fault zone and related earthquake generation.Seismology and Geology,9(4) :63-70
Zhang Jiasheng,Xiongnan Huang and Jianmin Liu.2004． Tectonic implication of stockwork microbreccias.Chinese Science Bulletin,49(24) :2580-86
Zhang Jiasheng,Jiang Laili and Xu Jiandong.2003． Progressive deformation of Precambrian adamellitic gneisses ewsponse to an uplift-related cooling in eastern Dabie mountains,central China.Chinese J.of Geology.38(1) :114-127
Zhang Xiankang,Zhou Jinren,Zhang Chengke et al.2002． Crustal structure at the Northeast side of the Pamir.Chinese J.of Geophysics.45(5) :665-671
李建华,张家声,单新建.2002． 西昆仑-西南天山地区断裂活动性研究.地质学报,76(3) :347-353
雷建设,周蕙兰,赵大鹏.2002． 帕米尔及邻区地壳上地幔 P 波三维速度结构的研究.地球物理学报,45(6) :802-81
张家声.1987． 断裂带中的二相变形与地震成因讨论.地震地质,9(4) :63-70
张家声,黄雄南.刘建民.2004． 网脉状微角砾岩构造意义.科学通报,49(24) :2580-2586
张家声,江来利,许建东.2003． 大别山东麓前寒武纪二长花岗质片麻岩在抬升冷却过程的递进变形.地质科学,38(1) :114-127
张先康,赵金仁,张成科等.2002． 帕米尔东北侧地壳结构研究.地球物理学报,45(5) :665-671
Benioff H.1954． Orogenesis and deep crustal structure:additional evidence from seismology.Geol.Soc.Am.Bull.,65:385-400
Billington S,Isacks LB & Barazangi M.1977． Spatial distribution and focal mecanisms of mantle earthquakes in the Hindu Kush-Pamir region;a eontored Benioff zone.Geology,5:699-704
Burtman VS & Molnar P.1993． Geological and geophysical evidence for deep subduction of continental crust beneath the Pamir.Tech.Rept.Spec.Pap.,281,Geological Society
Chaterlain JL,Roecker SW,Hatzfeld D & Molnar P.1980． Microerathquake seismicity and fault plane solutions in the Hindo Kush region anti their tectonic implications.J.Geophys.Res.,85:1365-1387
Clarke GL and Norman AR.1993． Generation of pseudotachylite under granulite facies conditions,and its preservation during cooling.J.Metamorphic Geol.,11:319-335
Fan G,Ni JF & Wallace TC.1994． Active tectonics of the Pamirs and Karakoram.J.Geophys.Res.,99:7131-7160
Hamburger MW,Sarewitz DR,Pavlis TL & Popandopulo GA.1992． Structural and seismic evidence for intracontinental subduction in the Peter the first range,central Asia.Geol.Soc.Am.Bull.,104:397-408
Hobbs BE.1986． Earthquakes in the ductile regime?Pure and Applied Geophysics,124:309-336
Katok AP.1988． On the deepest earthquake in the Pamir-Hindu Kush zone,Izv.Acad.Sci.USSR Phys.Solid Earth,Transl.,24:649-653
Li Jianhua,Zhang Jiasheng and Shan Xinjian.2002． Faulting in the Western Kunlun-southwestern Tianshan area.Acta Geologica Sinica,76(3) :347-353
Lei JS,Zhou HL and Zhao DP.2002． 3-D velocity structure of P-wave in the crust and upper-mantle beneath Pamir and adjacent region.Chinese J.Geophysics,45(6) :802-811
Nowroozi AA.1971． Seismotectonics of the Pakistan plateau,eastern Turkey,Caucasus,and Hindu Kush regions.Bull.Seism.Soc.Am.,61:317-341．
Pegler G and Das S.1998． An enhanced imagge of the Pamir-Hindu Kush seismic zone from relocated earthquake hypocentres.Geophys.J.Int.,134:573-595
Reigber Ch,Michel GW,Galas R,Angermann D,Klotz J,Chen JY,Papschev A,Arslanov R,Tzurkov VE,Ishanov MC.2001． New space geodetic constraints on the distribution of deformation in Central Asia.Earth and Planetary Science Letters,191:157-165
Roecker SW,Soboleva V,Nersesov IL,Lukk AA,Hatzfeld D,Chatelain JL & Molnar P.1980． Seismicity and fault plane solutions of intermediate depth earthquakes in the Pamir-Hindu Kush region.J.Geophys.Res.,85:1358-1364
Roecker SW.1982． Velocity structure of the Pamir-Hindu Kush region:possible evidence of subducted crust.J.Geophys.Res.,87:945-959
Sibson RH.1980． Transient discontinuities in ductile shear zone.J.Struct.Geol.,2(1/2) :165-171
Sibson RH.1992． Implications of fault-valve behaviour for rupture nucleation and recurrence.Tectonopbysics,211:283-293
Vinnik LP,Lukk AA & Nersesov IL.1977． Nature of the intermediate seismic zone in the mantle of the Pamir-Hindu Kush.Tectonophysics,38:T9-T14．
Vinnik LP,Lukk AA & Mirzokurbonov M.1978． Quantitative analysis of velocity inhomogeneities of the Pamir-Hindu Kush upper mantle,Izv.Acad.Sci.USSR Phys.Solid Earth,Transl.,14:319-328
Zhang Jiasheng.1987． Two-phase deformation in the fault zone and related earthquake generation.Seismology and Geology,9(4) :63-70
Zhang Jiasheng,Xiongnan Huang and Jianmin Liu.2004． Tectonic implication of stockwork microbreccias.Chinese Science Bulletin,49(24) :2580-86
Zhang Jiasheng,Jiang Laili and Xu Jiandong.2003． Progressive deformation of Precambrian adamellitic gneisses ewsponse to an uplift-related cooling in eastern Dabie mountains,central China.Chinese J.of Geology.38(1) :114-127
Zhang Xiankang,Zhou Jinren,Zhang Chengke et al.2002． Crustal structure at the Northeast side of the Pamir.Chinese J.of Geophysics.45(5) :665-671
李建华,张家声,单新建.2002． 西昆仑-西南天山地区断裂活动性研究.地质学报,76(3) :347-353
雷建设,周蕙兰,赵大鹏.2002． 帕米尔及邻区地壳上地幔 P 波三维速度结构的研究.地球物理学报,45(6) :802-81
张家声.1987． 断裂带中的二相变形与地震成因讨论.地震地质,9(4) :63-70
张家声,黄雄南.刘建民.2004． 网脉状微角砾岩构造意义.科学通报,49(24) :2580-2586
张家声,江来利,许建东.2003． 大别山东麓前寒武纪二长花岗质片麻岩在抬升冷却过程的递进变形.地质科学,38(1) :114-127
张先康,赵金仁,张成科等.2002． 帕米尔东北侧地壳结构研究.地球物理学报,45(5) :665-671
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