南海东北部及其邻近地区地壳上地幔P波速度结构
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摘要
利用中国地震台网和ISC台站记录的P波到时数据,采用球坐标系有限差分地震层析成像方法反演了南海东北部及其邻近地区壳幔三维P波速度结构,并分析了不同地质单元的构造差异及其深部特征。结果表明:南海东北部表现出陆架地区的岩石层特性,属于华南大陆向海区的延伸,岩石层厚度较大,现今不存在大规模的地幔热流活动,推测大陆边缘张裂作用仅限于地壳内部而没有延伸进入上地幔,具有非火山型大陆边缘的深部特点。中央海盆附近上地幔P波速度明显降低,与海盆下方地幔热流活动密切相关。不同的速度异常特征表明:华南大陆暨台湾地区属于欧亚大陆的正常地壳或是与菲律宾海板块相互作用产生的增厚型地壳,冲绳海槽则是弧后扩张产生的减薄型地壳。滨海断裂带作为华南大陆高速异常和南海北部高速异常的分界,代表了一定地质时期华南地块和南海地块的拼合边界。断裂附近的上地幔低速异常揭示了闽粤沿海岩浆作用的深层动力机制。吕宋岛弧、马尼拉海沟、东吕宋海槽的速度异常与其所处的特殊构造位置有密切的关系,清晰地反映出岛弧俯冲带的地壳结构差异;台湾南部至吕宋岛弧的上地幔低速异常揭示了两个重要火山链的深部构造特征,北吕宋海脊下方100km深度的条带状高速异常有可能代表了俯冲下沉的岩石层板片。
With the P-wave arrival times from Chinese and ISC stations,we conducted the tomographic inversion for the 3D velocity structure in the crust and mantle beneath the northeastern South China Sea(SCS)and surrounding regions by using spherical finite difference technique.We analyzed the tectonic differences and deep geodynamic characteristics based on the tomographic results,which show high velocity anomalies at the uppermost mantle beneath the northeast SCS,and depict the lithospheric mantle extension from South China continent to marginal sea.Because of the low temperature and thick lithosphere beneath the northeast SCS,it seems no magma intruded from mantle,so we inferred that the rift may only occur in the crust rather than extend to the upper mantle,which shows the nature of non-volcanic continental margin.The low velocity anomalies at the central sub-basin suggest the uplift of hot materials in the mantle.The high velocities at South China continent and Taiwan region,and the low velocities at Okinawa Trough depict the different tectonics of the crust:the former ones belong to the normal crust of Eurasia continent or thickened crust caused by the collision between Philippine Sea Plate and Eurasia Plate,while the latter one belongs to the thinned crust caused by back-arc spreading.Between the high velocities of South China continent and northeast SCS,the Binhai fault belt depicts the suture of South China block and SCS block,and the low velocities at upper mantle suggest the deep-driven magma process beneath the marine of South China continent.The velocity anomalies at Luzon,Manila Trench and East Luzon Trench relate to their tectonics natures.The low velocities at the upper mantle from southern Taiwan to northern Luzon depict two volcanic chains:western volcanic chain(WVC)and eastern volcanic chain(EVC).The high velocity belt at north Luzon ridge depicts the subducted continental slab.
With the P-wave arrival times from Chinese and ISC stations,we conducted the tomographic inversion for the 3D velocity structure in the crust and mantle beneath the northeastern South China Sea(SCS)and surrounding regions by using spherical finite difference technique.We analyzed the tectonic differences and deep geodynamic characteristics based on the tomographic results,which show high velocity anomalies at the uppermost mantle beneath the northeast SCS,and depict the lithospheric mantle extension from South China continent to marginal sea.Because of the low temperature and thick lithosphere beneath the northeast SCS,it seems no magma intruded from mantle,so we inferred that the rift may only occur in the crust rather than extend to the upper mantle,which shows the nature of non-volcanic continental margin.The low velocity anomalies at the central sub-basin suggest the uplift of hot materials in the mantle.The high velocities at South China continent and Taiwan region,and the low velocities at Okinawa Trough depict the different tectonics of the crust:the former ones belong to the normal crust of Eurasia continent or thickened crust caused by the collision between Philippine Sea Plate and Eurasia Plate,while the latter one belongs to the thinned crust caused by back-arc spreading.Between the high velocities of South China continent and northeast SCS,the Binhai fault belt depicts the suture of South China block and SCS block,and the low velocities at upper mantle suggest the deep-driven magma process beneath the marine of South China continent.The velocity anomalies at Luzon,Manila Trench and East Luzon Trench relate to their tectonics natures.The low velocities at the upper mantle from southern Taiwan to northern Luzon depict two volcanic chains:western volcanic chain(WVC)and eastern volcanic chain(EVC).The high velocity belt at north Luzon ridge depicts the subducted continental slab.
引文
[1]Liu G D.The characteristics of geophysical fields on the Chi-na seas[J].Progress in Geophysics,2002,17(1):1-12(in Chinese).
[2]Nissen S S,Hayes D E,Buhl P,et al.Deep penetration seis-mic soundings across the northern margin of the South China Sea[J].J Geophys Res,1995,100(B11):22407-22433.
[3]Qiu X L,Ye S Y,Wu S M,et al.Crustal structure across the Xisha Trough,northwestern South China Sea[J].Tec-tonophysics,2001,341:179-193.
[4]Yan P,Zhou D,Liu Z S.Acrustal structure profile across the northern continental margin of the South China Sea[J].Tectonophysics,2001,338:1-21.
[5]Qiu X L,Zeng G P,Xu Y,et al.The crustal structure be-neath the Shidao station on Xisha islands of South China Sea[J].Chinese J Geophys,2006,49(6):1720-1729(in Chi-nese).
[6]Wang T K,Chen M K,Lee C S,et al.Seismic imaging of the transitional crust across the northeastern margin of the South China Sea[J].Tectonophysics,2006,412:237-254.
[7]Bautista B C,Bautista ML P,Oike K,et al.Anewinsight on the geometry of subducting slabs in northern Luzon,Phil-ippines[J].Tectonophysics,2001,339:279-310.
[8]Besana G M,Shibutani T,Hirano N,et al.The shear wave velocity structure of the crust and upper mantle beneathTagaytay,Philippinesinferredfromreceiver function analysis[J].Geophys Res Lett,1995,22(23):3143-3146.
[9]Lallemand S,Font Y,Bij waard H,et al.Newinsights on3-D plates interaction near Tai wan fromtomography and tec-tonic implication[J].Tectonophysics,2001,335:229-253.
[10]Kim K H,Qiu J M,Pujol J,et al.Three dimensional Vp and Vs structural models associated with the active subduction and collision tectonics in the Tai wan region[J].Geophys J Int,2005,162:204-220.
[11]Rau R J,Wu F T.Tomographic imaging of lithospheric structures under Tai wan[J].Earth Planet Sci Lett,1995,133(3):517-532.
[12]Liu J H,Wu H,Liu F T.Features of3-D velocity distribu-tion and lithosphere structure in South China andits contigu-ous sea area[J].Chinese J Geophys,1996,39(4):483-492(in Chinese).
[13]Liu J H,Xu Y,Hao T Y,et al.Three dimensional velocity structure feature in the crust and upper mantle beneath Chi-nese marginal seas and adjacent regions[J].Progress in Geo-physics,2005,20(3):594-599(in Chinese).
[14]Zheng YJ,Huang Z X,Liu F T,et al.Rayleigh wave veloc-ity and structure of the crust and upper mantle beneath the seas in eastern China[J].Chinese J Geophys,2000,43(4):480-487(in Chinese).
[15]Cao X L,Zhu J S,Zhao L F,et al.Three dimensional shear wave velocity structure of crust and upper mantle in South China Sea andinits adjacent regions surface waveforminver-sion[J].Acta Seismologica Sinica,2002,23(2):113-124(in Chinese).
[16]Xu Y,Liu J H,Hao T Y,et al.P wave velocity structure and tectonic analysis of lithospheric mantle in eastern China seas and adjacent regions[J].Chinese J Geophys,2006,49(4):1053-1061(in Chinese).
[17]Xu Y,Li Z W,Hao T Y,et al.Pn wave velocity and anisot-ropy in the northeastern South China Sea and adjacent region[J].Chinese J Geophys,2007,50(5):1473-1479(in Chi-nese).
[18]Li Z W,Xu Y,Hao T Y,et al.Inversion of P-wave velocity structure of lithosphere in the Ryukyu-Tai wan-Luzon area by nonlinear algorithm[J].Progress in Geophysics,2007,22(5):1345-1351(in Chinese).
[19]Laske G,Masters G,Reif C.Crust2.0:Anewglobal crustal model at2×2degrees.http:∥mahi.ucsd.edu/Gabi/rem.dir/crust2.ht ml.
[20]Kennett B L N,Engdahl E R.Travel times for global earth-quake location and phase identification[J].Geophy J Int,1991,105(2):429-465.
[21]Li Z W.Seismic Tomography and the Crust and Upper Man-tle Structure Beneaththe Tien Shan[D].Beijing:Institute of Geology and Geophysics,Chinese Academy of Sciences,2008(in Chinese).
[22]Lees J M,Crosson R S.Tomographic inversion for three di-mensional velocity structure at Mount St.Helens using earthquake data[J].J Geophys Res,1989,94:5716-5728.
[23]He L,Wang K,Xiang L,et al.Heat flowandthermal histo-ry of the South China Sea[J].Phys Earth Planet Int,2001,126:211-220.
[24]Zhang J,Wang J Y.Geodynamic characteristics of tectonic extensionin the northern margin of South China Sea[J].Sci-ence in China:Series D,2001,31(5):437-445.
[25]Zou H P.The Meso-Cenozoic crust-mantle interactions and the tectonic evolutionin the north part of south china sea and its coastal areas—To the memory of Professor Chen Guoda,the advocate of the concept of continental marginal extension-al belt[J].Geotectonica et Metallogenia,2005,29(1):78-86(in Chinese).
[26]Taylor B,Hayes D E.The tectonic evolution of South China Basin[C]∥Hayes D E.The Tectonic and Geologic Evolution of Southeast Asian Seas and Islands.Washington DC:Geo-phys Monogr Ser AGU,1980,23:89-104.
[27]Taylor B,Hayes D E.Origin and history of the South China Sea Basin[C]∥Hayes D E.The Tectonic and Geologic Evo-lution of Southeast Asian Seas and Islands.Washington DC:Geophys Monogr Ser AGU,1983,27:23-56.
[28]Hao T Y,Liu J H,Song H B,et al.Geophysical evidences of some important faults in Huanan block and adjacent mar-ginal sea region[J].Progress in Geophysics,2003,17(1):13-23(in Chinese).
[29]Zhao M H,Qiu X L,Ye C M,et al.Analysis on deep crustal structure alongthe onshore-offshore seismic profile across the Binhai(Littoral)Fault Zone in northeastern South China Sea[J].Chinese J Geophys,2004,47(5):845-852(in Chinese).
[1]刘光鼎.中国海地球物理场特征[J].地球物理学进展,2002,17(1):1-12.
[5]丘学林,曾钢平,胥颐,等.南海西沙石岛地震台下的地壳结构研究[J].地球物理学报,2006,49(6):1720-1729.
[12]刘建华,吴华,刘福田.华南及其海域三维速度分布特征与岩石层结构[J].地球物理学报,1996,39(4):483-492.
[13]刘建华,胥颐,郝天珧,等.中国边缘海及邻区地壳和上地幔速度结构特征[J].地球物理学进展,2005,20(3):594-599.
[14]郑月军,黄忠贤,刘福田,等.中国东部海域地壳上地幔瑞利波速度结构研究[J].地球物理学报,2000,43(4):480-487.
[15]曹小林,朱介寿,赵连锋,等.南海及邻区地壳上地幔三维S波速度结构的面波波形反演[J].地震学报,2001,23(2):113-124.
[16]胥颐,刘建华,郝天珧,等.中国东部海域及邻区岩石层地幔的P波速度结构与构造分析[J].地球物理学报,2006,49(4):1053-1061.
[17]胥颐,李志伟,郝天珧,等.南海东北部及其邻近地区的Pn波速度结构和各向异性[J].地球物理学报,2007,50(5):1473-1479.
[18]李志伟,胥颐,郝天珧,等.利用非线性方法反演琉球—台湾—吕宋地区的岩石层P波速度结构[J].地球物理学进展,2007,22(5):1345-1351.
[21]李志伟.地震层析成像与天山地区的壳幔深部结构研究[D].北京:中国科学院地质与地球物理研究所,2008.
[25]邹和平.南海北部及其沿岸中、新生代壳幔相互作用与构造演化——纪念“陆缘扩张带”概念的倡导者陈国达教授[J].大地构造与成矿学,2005,29(1):78-86.
[28]郝天珧,刘建华,宋海滨,等.华南及其相邻边缘海域一些重要断裂的地球物理证据[J].地球物理学进展,2003,17(1):13-23.
[29]赵明辉,丘学林,叶春明,等.南海东北部深地震联测与滨海断裂带两侧地壳结构分析[J].地球物理学报,2004,47(5):845-852.
[2]Nissen S S,Hayes D E,Buhl P,et al.Deep penetration seis-mic soundings across the northern margin of the South China Sea[J].J Geophys Res,1995,100(B11):22407-22433.
[3]Qiu X L,Ye S Y,Wu S M,et al.Crustal structure across the Xisha Trough,northwestern South China Sea[J].Tec-tonophysics,2001,341:179-193.
[4]Yan P,Zhou D,Liu Z S.Acrustal structure profile across the northern continental margin of the South China Sea[J].Tectonophysics,2001,338:1-21.
[5]Qiu X L,Zeng G P,Xu Y,et al.The crustal structure be-neath the Shidao station on Xisha islands of South China Sea[J].Chinese J Geophys,2006,49(6):1720-1729(in Chi-nese).
[6]Wang T K,Chen M K,Lee C S,et al.Seismic imaging of the transitional crust across the northeastern margin of the South China Sea[J].Tectonophysics,2006,412:237-254.
[7]Bautista B C,Bautista ML P,Oike K,et al.Anewinsight on the geometry of subducting slabs in northern Luzon,Phil-ippines[J].Tectonophysics,2001,339:279-310.
[8]Besana G M,Shibutani T,Hirano N,et al.The shear wave velocity structure of the crust and upper mantle beneathTagaytay,Philippinesinferredfromreceiver function analysis[J].Geophys Res Lett,1995,22(23):3143-3146.
[9]Lallemand S,Font Y,Bij waard H,et al.Newinsights on3-D plates interaction near Tai wan fromtomography and tec-tonic implication[J].Tectonophysics,2001,335:229-253.
[10]Kim K H,Qiu J M,Pujol J,et al.Three dimensional Vp and Vs structural models associated with the active subduction and collision tectonics in the Tai wan region[J].Geophys J Int,2005,162:204-220.
[11]Rau R J,Wu F T.Tomographic imaging of lithospheric structures under Tai wan[J].Earth Planet Sci Lett,1995,133(3):517-532.
[12]Liu J H,Wu H,Liu F T.Features of3-D velocity distribu-tion and lithosphere structure in South China andits contigu-ous sea area[J].Chinese J Geophys,1996,39(4):483-492(in Chinese).
[13]Liu J H,Xu Y,Hao T Y,et al.Three dimensional velocity structure feature in the crust and upper mantle beneath Chi-nese marginal seas and adjacent regions[J].Progress in Geo-physics,2005,20(3):594-599(in Chinese).
[14]Zheng YJ,Huang Z X,Liu F T,et al.Rayleigh wave veloc-ity and structure of the crust and upper mantle beneath the seas in eastern China[J].Chinese J Geophys,2000,43(4):480-487(in Chinese).
[15]Cao X L,Zhu J S,Zhao L F,et al.Three dimensional shear wave velocity structure of crust and upper mantle in South China Sea andinits adjacent regions surface waveforminver-sion[J].Acta Seismologica Sinica,2002,23(2):113-124(in Chinese).
[16]Xu Y,Liu J H,Hao T Y,et al.P wave velocity structure and tectonic analysis of lithospheric mantle in eastern China seas and adjacent regions[J].Chinese J Geophys,2006,49(4):1053-1061(in Chinese).
[17]Xu Y,Li Z W,Hao T Y,et al.Pn wave velocity and anisot-ropy in the northeastern South China Sea and adjacent region[J].Chinese J Geophys,2007,50(5):1473-1479(in Chi-nese).
[18]Li Z W,Xu Y,Hao T Y,et al.Inversion of P-wave velocity structure of lithosphere in the Ryukyu-Tai wan-Luzon area by nonlinear algorithm[J].Progress in Geophysics,2007,22(5):1345-1351(in Chinese).
[19]Laske G,Masters G,Reif C.Crust2.0:Anewglobal crustal model at2×2degrees.http:∥mahi.ucsd.edu/Gabi/rem.dir/crust2.ht ml.
[20]Kennett B L N,Engdahl E R.Travel times for global earth-quake location and phase identification[J].Geophy J Int,1991,105(2):429-465.
[21]Li Z W.Seismic Tomography and the Crust and Upper Man-tle Structure Beneaththe Tien Shan[D].Beijing:Institute of Geology and Geophysics,Chinese Academy of Sciences,2008(in Chinese).
[22]Lees J M,Crosson R S.Tomographic inversion for three di-mensional velocity structure at Mount St.Helens using earthquake data[J].J Geophys Res,1989,94:5716-5728.
[23]He L,Wang K,Xiang L,et al.Heat flowandthermal histo-ry of the South China Sea[J].Phys Earth Planet Int,2001,126:211-220.
[24]Zhang J,Wang J Y.Geodynamic characteristics of tectonic extensionin the northern margin of South China Sea[J].Sci-ence in China:Series D,2001,31(5):437-445.
[25]Zou H P.The Meso-Cenozoic crust-mantle interactions and the tectonic evolutionin the north part of south china sea and its coastal areas—To the memory of Professor Chen Guoda,the advocate of the concept of continental marginal extension-al belt[J].Geotectonica et Metallogenia,2005,29(1):78-86(in Chinese).
[26]Taylor B,Hayes D E.The tectonic evolution of South China Basin[C]∥Hayes D E.The Tectonic and Geologic Evolution of Southeast Asian Seas and Islands.Washington DC:Geo-phys Monogr Ser AGU,1980,23:89-104.
[27]Taylor B,Hayes D E.Origin and history of the South China Sea Basin[C]∥Hayes D E.The Tectonic and Geologic Evo-lution of Southeast Asian Seas and Islands.Washington DC:Geophys Monogr Ser AGU,1983,27:23-56.
[28]Hao T Y,Liu J H,Song H B,et al.Geophysical evidences of some important faults in Huanan block and adjacent mar-ginal sea region[J].Progress in Geophysics,2003,17(1):13-23(in Chinese).
[29]Zhao M H,Qiu X L,Ye C M,et al.Analysis on deep crustal structure alongthe onshore-offshore seismic profile across the Binhai(Littoral)Fault Zone in northeastern South China Sea[J].Chinese J Geophys,2004,47(5):845-852(in Chinese).
[1]刘光鼎.中国海地球物理场特征[J].地球物理学进展,2002,17(1):1-12.
[5]丘学林,曾钢平,胥颐,等.南海西沙石岛地震台下的地壳结构研究[J].地球物理学报,2006,49(6):1720-1729.
[12]刘建华,吴华,刘福田.华南及其海域三维速度分布特征与岩石层结构[J].地球物理学报,1996,39(4):483-492.
[13]刘建华,胥颐,郝天珧,等.中国边缘海及邻区地壳和上地幔速度结构特征[J].地球物理学进展,2005,20(3):594-599.
[14]郑月军,黄忠贤,刘福田,等.中国东部海域地壳上地幔瑞利波速度结构研究[J].地球物理学报,2000,43(4):480-487.
[15]曹小林,朱介寿,赵连锋,等.南海及邻区地壳上地幔三维S波速度结构的面波波形反演[J].地震学报,2001,23(2):113-124.
[16]胥颐,刘建华,郝天珧,等.中国东部海域及邻区岩石层地幔的P波速度结构与构造分析[J].地球物理学报,2006,49(4):1053-1061.
[17]胥颐,李志伟,郝天珧,等.南海东北部及其邻近地区的Pn波速度结构和各向异性[J].地球物理学报,2007,50(5):1473-1479.
[18]李志伟,胥颐,郝天珧,等.利用非线性方法反演琉球—台湾—吕宋地区的岩石层P波速度结构[J].地球物理学进展,2007,22(5):1345-1351.
[21]李志伟.地震层析成像与天山地区的壳幔深部结构研究[D].北京:中国科学院地质与地球物理研究所,2008.
[25]邹和平.南海北部及其沿岸中、新生代壳幔相互作用与构造演化——纪念“陆缘扩张带”概念的倡导者陈国达教授[J].大地构造与成矿学,2005,29(1):78-86.
[28]郝天珧,刘建华,宋海滨,等.华南及其相邻边缘海域一些重要断裂的地球物理证据[J].地球物理学进展,2003,17(1):13-23.
[29]赵明辉,丘学林,叶春明,等.南海东北部深地震联测与滨海断裂带两侧地壳结构分析[J].地球物理学报,2004,47(5):845-852.
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