利用共转换点叠加方法研究华北地区地壳结构
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摘要
利用华北地震台阵L测线的35个台站记录的895个远震数据进行了接收函数的计算,并利用H-κ叠加方法得到华北克拉通西部陆块东侧和中部陆块内基岩台站下方的地壳结构.利用得到的基岩台站下方的地壳结构和通过波形模拟方法得到的渤海湾盆地的沉积层结构作为背景模型对测线进行共转换点(CCP)叠加成像.在渤海湾盆地,通过增大CCP叠加方法中的共转换点单元,使得由于沉积层基底反射信号过强而难以识别的Ps转换波信号得以增强,获得渤海湾盆地下方的地壳结构.由CCP叠加的结果可以看出:华北克拉通地壳西厚东薄.西部陆块东侧的吕梁山下方地壳出现了地壳的突然减薄,减薄幅度约3 km.在减薄处的西侧,地壳逐渐加深,由44 km左右加深至46 km左右,之后在减薄处突然减薄至43 km左右,推测该减薄处可能是西部和中部陆块在深部的分界点;中部造山带地区的重力梯度带的西侧,地壳较为平缓,厚约42 km左右,山西断陷盆地下的地壳出现了略微的上升,幅度为2 km左右.大同盆地东侧下方的台站出现了Moho面的不连续,可能是地幔物质上涌的通道.在太行山前缘的重力梯度带内地壳迅速变浅至33 km左右,渤海湾盆地内地壳厚约32 km左右,冀中坳陷带下方地壳变浅,最浅可达29 km.沉积层基底的深度与地壳厚度呈负相关关系,可能与渤海湾盆地受到的拉张剪切作用力相关.
895 teleseismic data recorded by the 35 stations located on North China Craton (NCC) as a line are used to calculate the receiver functions which are used to obtain the crustal structure under the stations installed on bedrock by H-k stacking method. The image of the crust along the 550 km-long profile is obtained by the common conversion point (CCP) stacking method using the crustal model calculated from the H-k stacking and the sedimentary structure calculated before. Because some stations are located on sediments, the size of the bin used in the CCP stacking is enlarged to strengthen the amplitude of the P to S conversion phases. Then the crustal structure of the Bohai Bay Basin (BBB) can be imaged by CCP stacking. The result shows that the crust thickness of the west NCC is much thicker than that of the east NCC. The thickness of the Western Block is about 45 km. The crustal thickness reduces to 43 km under the Liiliangshan which may be the boundary between the Western Block and the Trans-North China Orogen (TNCO) in the depth of Moho. In the west of the North-South Gravity Lineament, the average crustal thickness is about 42 km while the Moho rises slightly under the Shanxi fault depression zone. There is a discontinuity under east of Datong Basin, which may be the channel of the mantle-derived material. In the North-South Gravity Lineament belt, the crustal thickness reduced obviously to 33 km. The average crustal thickness of the Bohai Bay Basin (BBB) is about 32 km, which is much thinner than the one of the Central Block. The Moho depth under the Jizhong depression is the shallowest, which can reach to 29 km in the thinnest area along the profile. The thick sedimentary layer corresponds to the thin crust, which can be explained by the extension of the basin.
895 teleseismic data recorded by the 35 stations located on North China Craton (NCC) as a line are used to calculate the receiver functions which are used to obtain the crustal structure under the stations installed on bedrock by H-k stacking method. The image of the crust along the 550 km-long profile is obtained by the common conversion point (CCP) stacking method using the crustal model calculated from the H-k stacking and the sedimentary structure calculated before. Because some stations are located on sediments, the size of the bin used in the CCP stacking is enlarged to strengthen the amplitude of the P to S conversion phases. Then the crustal structure of the Bohai Bay Basin (BBB) can be imaged by CCP stacking. The result shows that the crust thickness of the west NCC is much thicker than that of the east NCC. The thickness of the Western Block is about 45 km. The crustal thickness reduces to 43 km under the Liiliangshan which may be the boundary between the Western Block and the Trans-North China Orogen (TNCO) in the depth of Moho. In the west of the North-South Gravity Lineament, the average crustal thickness is about 42 km while the Moho rises slightly under the Shanxi fault depression zone. There is a discontinuity under east of Datong Basin, which may be the channel of the mantle-derived material. In the North-South Gravity Lineament belt, the crustal thickness reduced obviously to 33 km. The average crustal thickness of the Bohai Bay Basin (BBB) is about 32 km, which is much thinner than the one of the Central Block. The Moho depth under the Jizhong depression is the shallowest, which can reach to 29 km in the thinnest area along the profile. The thick sedimentary layer corresponds to the thin crust, which can be explained by the extension of the basin.
引文
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[19] Zhu L P.Crustal structure across the San Andreas Fault,southern California from teleseismic converted waves.Earth and Planetary Science Letters,2000,179(1) :183～190
[20] 王俊,刘启元,陈九辉等.首都圈地区的地壳厚度及泊松比.地球物理学报,2009,52(1) :57～66 Wang J,Liu Q Y,Chen J H,et al.The crustal thickness and Poisson's ratio beneath the Capital Circle Region.Chinese Journal of Geophysics (in Chinese),2009,52 (1) :57～66
[21] 李永华,吴庆举,田小波等.用接收函数方法研究云南及其邻区地壳上地幔结构.地球物理学报,2009,52(1) :67～80 Li Y H,Wu Q J,Tian X B,et al.Crustal structure in the Yunnan region determined by modeling receiver functions.Chinese J.Geophys.(in Chinese),2009,52(1) :67～80
[22] 徐强,赵俊猛,崔仲雄等.利用接收函数研究青藏高原东南缘的地壳上地幔结构.地球物理学报,2009,52(12) :3001～3008 Xu Q,Zhao J M,Cui Z X,et al.Structure of the crust and upper mantle beneath the southeastern Tibetan Plateau by P and S receiver functions.Chinese J.Geophys.(in Chinese),2009,52(12) :3001～3008
[23] Christensen N I,Fountain D M.Constitution of the lower continental crust based on experimental studies of seismic velocities in granulite.Bulletin of the Geological Society of America,1975,86(2) :227～236
[24] 徐义刚.太行山重力梯度带的形成与华北岩石圈减薄的时空差异性有关.地球科学-中国地质大学学报,2006,31(1) :14～22 Xu Y G.Formation of the Taihangshan Gravity Lineament by the diachronous lithospheric thinning of the North China Craton.Earth Science-Journal of China University of Geosciences (in Chinese),2006,31(1) :14～22
[25] 张建师,祝治平,张先康等.山西高原北部地壳上地幔地震波速结构与深部构造.地震地质,1997,19(3) :220～226 Zhang J S,Zhu Z P,Zhang X K,et al.The seismic velocity structure of crust and upper mantle and deep structure feature in north Shanxi Plateau.Seismology and Geology (in Chinese),1997,19(3) :220～226
[26] 马杏垣,刘昌铨,刘国栋.江苏响水至内蒙古满都拉地学断面.地质学报,1991,65(3) :199～215 Ma X Y,Liu C Q,Liu G D.Xiangshui(Jiangsu Province) to Mandal (Nei Monggol) geoscience transect.Acta Geologica Sinica (in Chinese),1991,65(3) :199～215
[27] 赵金仁,张先康,张成科等.山西五台山地区地壳深部结构特征研究.地球物理学报,2006,49(1) :123～129 Zhao J R,Zhang X K,Zhang C K,et al.Features of deep crustal structure beneath the Wutai Mountain area of Shanxi province.Chinese J.Geophys.(in Chinese),2006,49(1) :123～129
[28] Li S L,Mooney W D.Crustal structure of China from deep seismic sounding profiles.Tectonophysics,1998,288(1 4) :105～113
[29] Zhang Z J,Chen Q F,Bai Z M,et al.Crustal structure and extensional deformation of thinned lithosphere in Northern China.Tectonophysics,2010,508(1-4) :62～72,doi:10． 1016/j.tecto.2010． 06． 021
[30] 马宗晋,邓起东,刘国勋等.山西临汾地震研究与系统减灾.北京:地震出版社,1993 Ma Z J,Deng Q D,Liu G X,et al.Research on Earthquake and Systematic Hazard Reducing in Linfen City,Shanxi Province (in Chinese).Beijing:Seismological Press,1993
[31] Ding Z F,Zhou X F,Wu Y,et al.Tomographic imaging of P wave velocity structure beneath the region around Beijing.Earthquake Science,2009,22(4) :403～408
[2] Yin A,Nie S Y.An indentation model for the North and South China collision and the development of the Tan Lu and Honam Fault Systems,eastern Asia.Tectonics,1993,12(4) :801～813
[3] Zheng T Y,Chen L,Zhao L,et al.Crust mantle structure difference across the gravity gradient zone in North China Craton:Seismic image of the thinned continental crust.Physics of the Earth and Planetary Interiors,2006,159(1-2) :43～58
[4] Chen L,Tao W,Zhao L,et al.Distinct lateral variation of lithospheric thickness in the Northeastern North China Craton.Earth and Planetary Science Letters,2008,267 (1-2) :56～68
[5] Li Y H,Wu Q J,Zhang R Q,et al.The lithospheric thinning of the North China Craton inferred from Rayleigh waves inversion.Geophys.J.Int.,2009,177(3) :1334～ 1442
[6] 邓晋福,苏尚国,刘翠等.关于华北克拉通燕山期岩石圈减薄的机制与过程的讨论:是拆沉,还是热侵蚀和化学交代?地学前缘,2005,13(2) :105～119 Deng J F,Su S G,Liu C,et al.Discussion on the lithospheric thinning of the North China craton:delamination or thermal erosion and chemical metasomatism? Earth Science Frontier (in Chinese),2006,13(2) ,105～119
[7] 于慎谔.山西断陷带北部块体构造活动样式及强震构造背景.地震学报,2004,26(4) :379～386 Yu S E.A study on characteristics of tectonic block motion and tectonic setting of strong earthquakes in northern part of the Shanxi Fault Depression Zone.Acta Seismologica Sinica (in Chinese),2004,26(4) :379～386
[8] Allen M B,Macdonald D I M,Zhao X,et al.Early Cenozoic two phase extension and late Cenozoic thermal subsidence and inversion of the Bohai Basin,northern China.Mar.Pet. Geol.,1997,14(7-8) :951～972
[9] Oreshin S,Kiselev S,Vinnik L,et al.Crust and mantle beneath western Himalaya,Ladakh and western Tibet from integrated seismic data.Earth and Planetary Science Letters,2008,271(1-4) :75～87
[10] Savage B,Silver P G.Evidence for a compositional boundary within the lithospheric mantle beneath the Kalahari craton from S receiver functions.Earth and Planetary Science Letters,2008,272(3-4) :600～609
[11] Sodoudi F,Kind R,Hatzfeld D,et al.Lithospheric structure of the Aegean obtained from P and S receiver functions.Journal of Geophysical Research,2006,111:B12307,doi:10． 1029/2005JB003932
[12] Chen L,Zheng T Y,Xu W W.A thinned lithospheric image of the Tanlu Fault Zone,eastern China:Constructed from wave equation based receiver function migration.Journal of Geophysical Research,2006,111:B09312,doi:10． 1029/2005JB003974
[13] Chen L.Lithospheric structure variations between the eastern and central North China Craton from S-and Preceiver function migration.Physics of the Earth and Planetary Interiors,2009,173(3-4) :216～227
[14] Zhu L P,Mitchell B J,Akyol N,et al.Crustal thickness variations in the Aegean region and implications for the extension of continental crust.Journal of Geophysical Research,2006,111:B01301,doi:10． 1029/2005JB003770
[15] 邓起东主编.中国活动构造图(1:4000000) .北京:地震出版社,2007 Deng Q D,ed.Distribution of Active Faults in China (1:4000000) (in Chinese).Beijing:Earthquake Publishing Company,2007
[16] 汪一鹏,邓起东,朱世龙.华北地区岩石圈动力学特征.见:马杏垣主编.中国岩石动力学地图集.北京:中国地图出版社,1989 Wang Y P,Deng Q D,Zhu S L.Lithospheric Dynamics of North China.In:Ma X Y,ed.Lithospheric Dynamics Atlas of China (in Chinese).Beijing:China Cartographic Publishing House,1989
[17] Zhu L P,Kanamori H.Moho depth variation in southern California from teleseismic receiver functions.Journal of Geophysical Research,2000,105(B2) :2969～2980
[18] Zhu L P.Lateral variation of the Tibetan lithospheric structure inferred from teleseismic waveforms.In:Chen Y T,et al.eds.Advancements in Seismology and Physics of the Earth Interior in China.Beijing:Seismological Press,2004． 295～310
[19] Zhu L P.Crustal structure across the San Andreas Fault,southern California from teleseismic converted waves.Earth and Planetary Science Letters,2000,179(1) :183～190
[20] 王俊,刘启元,陈九辉等.首都圈地区的地壳厚度及泊松比.地球物理学报,2009,52(1) :57～66 Wang J,Liu Q Y,Chen J H,et al.The crustal thickness and Poisson's ratio beneath the Capital Circle Region.Chinese Journal of Geophysics (in Chinese),2009,52 (1) :57～66
[21] 李永华,吴庆举,田小波等.用接收函数方法研究云南及其邻区地壳上地幔结构.地球物理学报,2009,52(1) :67～80 Li Y H,Wu Q J,Tian X B,et al.Crustal structure in the Yunnan region determined by modeling receiver functions.Chinese J.Geophys.(in Chinese),2009,52(1) :67～80
[22] 徐强,赵俊猛,崔仲雄等.利用接收函数研究青藏高原东南缘的地壳上地幔结构.地球物理学报,2009,52(12) :3001～3008 Xu Q,Zhao J M,Cui Z X,et al.Structure of the crust and upper mantle beneath the southeastern Tibetan Plateau by P and S receiver functions.Chinese J.Geophys.(in Chinese),2009,52(12) :3001～3008
[23] Christensen N I,Fountain D M.Constitution of the lower continental crust based on experimental studies of seismic velocities in granulite.Bulletin of the Geological Society of America,1975,86(2) :227～236
[24] 徐义刚.太行山重力梯度带的形成与华北岩石圈减薄的时空差异性有关.地球科学-中国地质大学学报,2006,31(1) :14～22 Xu Y G.Formation of the Taihangshan Gravity Lineament by the diachronous lithospheric thinning of the North China Craton.Earth Science-Journal of China University of Geosciences (in Chinese),2006,31(1) :14～22
[25] 张建师,祝治平,张先康等.山西高原北部地壳上地幔地震波速结构与深部构造.地震地质,1997,19(3) :220～226 Zhang J S,Zhu Z P,Zhang X K,et al.The seismic velocity structure of crust and upper mantle and deep structure feature in north Shanxi Plateau.Seismology and Geology (in Chinese),1997,19(3) :220～226
[26] 马杏垣,刘昌铨,刘国栋.江苏响水至内蒙古满都拉地学断面.地质学报,1991,65(3) :199～215 Ma X Y,Liu C Q,Liu G D.Xiangshui(Jiangsu Province) to Mandal (Nei Monggol) geoscience transect.Acta Geologica Sinica (in Chinese),1991,65(3) :199～215
[27] 赵金仁,张先康,张成科等.山西五台山地区地壳深部结构特征研究.地球物理学报,2006,49(1) :123～129 Zhao J R,Zhang X K,Zhang C K,et al.Features of deep crustal structure beneath the Wutai Mountain area of Shanxi province.Chinese J.Geophys.(in Chinese),2006,49(1) :123～129
[28] Li S L,Mooney W D.Crustal structure of China from deep seismic sounding profiles.Tectonophysics,1998,288(1 4) :105～113
[29] Zhang Z J,Chen Q F,Bai Z M,et al.Crustal structure and extensional deformation of thinned lithosphere in Northern China.Tectonophysics,2010,508(1-4) :62～72,doi:10． 1016/j.tecto.2010． 06． 021
[30] 马宗晋,邓起东,刘国勋等.山西临汾地震研究与系统减灾.北京:地震出版社,1993 Ma Z J,Deng Q D,Liu G X,et al.Research on Earthquake and Systematic Hazard Reducing in Linfen City,Shanxi Province (in Chinese).Beijing:Seismological Press,1993
[31] Ding Z F,Zhou X F,Wu Y,et al.Tomographic imaging of P wave velocity structure beneath the region around Beijing.Earthquake Science,2009,22(4) :403～408
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