利用地震面波频散重建川滇地区壳幔S波速度
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摘要
利用适配滤波频时分析技术分析覆盖川滇地区的长周期面波记录,计算了周期10～100 s内的面波群速度频散,对研究区进行划分尺度大小1.5°×1.5°分格后,采用射线追踪方法求取各分段射线的长度和时间,得到各个格子的纯路径频散.继而采用阻尼最小二乘法求解,反演得到该研究区壳幔S波速度分布.研究结果表明,川滇地区表现出地壳增厚和缩短,在地壳和上地幔顶部,川滇菱形块体内部与其外部相比,虽然存在局部速度负异常,总体上呈相对高速,其周边的走滑断裂带呈现深至上地幔顶部的负速度异常,这有助于地壳块体沿断裂的侧向挤出;此外,云南西部和四川西部壳内和上地幔高导层的存在被认为是与部分熔融的物质或与滑脱构造相关联;从纬向剖面和经向剖面可以得到四川盆地莫霍面平均深度大约为45 km,云南地区莫霍面深度南北方向不一致,云南地区最北端深度达到49 km,南端莫霍面深度大约为36 km,这说明不同构造块体在构造运动过程中受到影响的程度不同.
We apply the technique of matched filter frequency time analysis to process long period surface wave data covering Sichuan and Yunnan regions,and then obtain the surface wave group velocity dispersion in the period range 10～100s.Then we use the grid inversion method to extract pure path dispersion in the grid of 1.5°×1.5°after getting the distance and time in the grid of the study area by ray tracing,at the same time,we employ the damped least-square method to determine the crust-mantle S wave velocity structure in the Sichuan and Yunnan region.The result shows that the crust of the region is thickened and shortened.In spite of some local low velocity anomalies,the crust and uppermost mantle of the rhombic Chuan-Dian block as a whole have relatively high velocity as compared with the surrounding areas.The peripheral strike-slipping faults display negative velocity anomalies down to the top of upper mantle,which facilitates the lateral extrusion of crustal blocks along the faults.The high conductivity layer in the crust and upper mantle in western Yunnan and Sichuan is connected with partial melting or detachment structure.The average depth of Moho of Sichuan basin is about 48 km.The Moho in Yunnan reaches 58 km in the north end and is about 51 km in the south end,which proves that different blocks are affected differently by tectonic movement.
We apply the technique of matched filter frequency time analysis to process long period surface wave data covering Sichuan and Yunnan regions,and then obtain the surface wave group velocity dispersion in the period range 10～100s.Then we use the grid inversion method to extract pure path dispersion in the grid of 1.5°×1.5°after getting the distance and time in the grid of the study area by ray tracing,at the same time,we employ the damped least-square method to determine the crust-mantle S wave velocity structure in the Sichuan and Yunnan region.The result shows that the crust of the region is thickened and shortened.In spite of some local low velocity anomalies,the crust and uppermost mantle of the rhombic Chuan-Dian block as a whole have relatively high velocity as compared with the surrounding areas.The peripheral strike-slipping faults display negative velocity anomalies down to the top of upper mantle,which facilitates the lateral extrusion of crustal blocks along the faults.The high conductivity layer in the crust and upper mantle in western Yunnan and Sichuan is connected with partial melting or detachment structure.The average depth of Moho of Sichuan basin is about 48 km.The Moho in Yunnan reaches 58 km in the north end and is about 51 km in the south end,which proves that different blocks are affected differently by tectonic movement.
引文
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[2]England P C,Houseman G A.Finite strain calculation of continental deformation,Comparison with the India-Asia collision zone.J Geophys Res,1986,91:3664～3676
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[6]Zhang Z J,Li Y K,Wang G J,et al.East-west crustal structure and“down-bowing”Moho under the northern Tibet revealed by wide-angle seismic profile.Science in China (Series D),2002,45(6):550～558
[7]张中杰，秦义龙，陈赟等．由宽角反射地震资料重建壳幔反射结构的相似性剖面．地球物理学报，2004，47(3)：469～474 Zhang Z J,Qin Y L,Chen Y,et al.Reconstruction of the semblance section for the crust and mantle reflection structure by wide-angle reflection seismic data.Chinese J.Geophys. (in Chinese),2004,47(3):469～474
[8]林中洋，胡鸿翔．张文彬等．滇西地区地壳上地幔速度结构特征的研究．地震学报，1993，15(4)：427～440 Lin Z Y,Hu H X,Zhang W B,et al.A study on velocity structure of the crust and upper mantle in Dianxi region.Acta Seismologica Sinica(in Chinese),1993,15(4):427～440
[9]尹周勋，滕吉文．熊绍柏等．渡口及其邻近地区地壳浅层结构的研究．地球物理学报，1987，30(1)：22～30 Yin Z X,Teng J W,Xiong S B,et al.Study on crustal shallow structure in Dukou and the surrounding region. Chinese J.Geophys.(in Chinese),1987,30(1):22～30
[10]孙若昧，刘福田，刘建华．四川地区的地震层析成像．地球物理学报，1991，25(6)：708～716 Sun R M,Liu F T,Liu J H.Seismic tomography of Sichuan. Chinese J.Geophys.(in Chinese),1991,25(6):708～716
[11]滕吉文，王绍舟，姚振兴等．青藏高原及其邻近地区的地球物理场特征与大陆板块构造．地球物理学报，1980．23(3)：254～268 Teng J W,Wang S Z,Yao Z X,et al.The geophysical character and continental block structure in Tibetan and the surrounding regions.Chinese J.Geophys.(in Chinese), 1980,23(3):254～268
[12]王椿镛，Mooney W D，王溪莉等．川滇地区地壳上地幔三维速度结构研究．地震学报．2002，24(1)：1～16 Wang C Y,Mooney W D,Wang X L,et al.Study on 3-D velocity structure of crust and upper mantle in Sichuan- Yunnan region,China.Acta Seismologica Sinica(in Chinese),2002,24(1):1～16
[13]胡家富，朱雄关．夏静瑜，陈赟．利用面波和接收函数联合反演滇西地区壳幔速度结构．地球物理学报．2005，8(5)：1069～1076 Hu J F,Zhu X G,Xia J Y,Chen Y.Using surface wave and receiver function to jointly inverse the crust-mantle velocity structure in the West Yunnan area.Chinese J.Geophys.(in Chinese),2005,48(5):1069～1076
[14]陈培善，刘福田．李强等．云南地区速度结构的横向不均匀性．中国科学(B)辑．1990，20(4)：431～458 Chen P S,Liu F T,Li Q,et al.Transverse inhomogeneous of the velocity structure in Yunnan region.Science in China (Series B),1990,20(4):431～458
[15]刘瑞丰．陈培善．李强．云南及其邻近地区三维速度图像．地震学报，1993，15(1)：61～67 Liu R F,Chen P S,Li Q.Three dimension velocity pictures in Yunnan and the surrounding regions.Acta Seismologica Sinica(in Chinese),1993,15(1):61～67
[16]吴建平．明跃红，王椿镛．云南数字地震台站下方的S波速度结构研究．地球物理学报．2001，44(2)：228～237 Wu J P,Ming Y H,Wang C Y.The S wave velocity structure beneath digital seismic stations of Yunnan province inferred from teleseismic receiver function modeling.Chinese J.Geophys.(in Chinese),2001,44(2):228～237
[17]张中杰，白志明．王椿镛等．冈瓦纳型和扬子型地块地壳结构：以滇西孟连—马龙宽角反射剖面为例，中国科学(D辑)，2005，34(5)：387～392 Zhang Z J,Bai Z M,Wang C Y,et al.The crustal structure of Gondawana and Yangtze blocks:An example by wide angle seismic reflection profiling between Menglian and Malong. Sciencein China(Serial D),2005,48(11):1828～1836
[18]张中杰，白志明，王椿镛等．三江地区地壳结构及动力学意义：云南遮放—宾川地震反射/折射剖面的启示．中国科学(D辑)．2005，35(4)：314～319 Zhang Z J,Bai Z M,Wang C Y,et al.The crustal structure under Sanjiang and its dynamic implications:Revealed by seismic reflection/refraction profiling between Zhefang and Binchuan,Yunnan.Science in China(Series D),2005,48 (9):1329～1336
[19]任纪舜，姜春发，张正坤等．中国大地构造及其演化．北京：科学出版社，1980 Ren J X,Jiang C F,Zhang Z K,et al.The Geotectonic Evolution of China(in Chinese).Beijing:Science Press, 1980
[20]Allen C R,Luo Z,Qian H,et al.Field study of a high active fault zone:the Xianshuihe fault of southwestern China.Geol Soc Amer Bull,1991,103:1178～1190
[21]Tapponnier P,Lacassin R,Leloup P H,et al.The Ailao Shan/Red River metamorphic belt:Tertiary left-lateral shear between Indo-China and South China.Nature,1990,343: 431～437
[22]Fan P,Outline of the tectonic evolution of southwestern China.Tectonophysics,1978,45:261～267
[23]Jeffreys H.On compressional waves in two superposed layers.Proceedings of the Cambridge Philosophical Society,1926,23:472～481
[24]Holbrook W S,Mooney W D,Christensen N J.The seismic velocity structure of the deep continental crust.In:Fountain D M,Arculusr,Kayaw eds.Continental Lower Crust. Amsterdam:Elsevier Science Publishers,1992.1～34
[25]张智，赵兵，张晰等．云南思茅—中甸地震剖面的地壳结构．地球物理学报，2006，49(5)：1377～1384 Zhang Z,Zhao B,Zhang X,et al.Crustal structure beneath the wide-angle seismic profile between Simao and Zhongdian in Yunnan.Chinese J.Geophys.(in Chinese),2006,49 (5):1377～1384
[26]白志明，王椿镛．云南遮放—宾川和孟连—马龙宽角地震剖面的层析成像研究．地球物理学报．2004，47(2)：257～267 Bai Z M,Wang C Y.Tomography research of the Zhefang- Binchuan and Menglian-Malong wide-angle seismic profiles in Yunnan.Chinese J.Geophs.(in Chinese),2004,47(2):257～267
[2]England P C,Houseman G A.Finite strain calculation of continental deformation,Comparison with the India-Asia collision zone.J Geophys Res,1986,91:3664～3676
[3]Zhang Z J,Simon L Klemperer.West-east variation in crustal thickness in northern Lhasa block,central Tibet, from deep seismic sounding data.J.Geophys.Res.,2005, 110(B9),B090403
[4]刘建华，刘福田，吴华等．中国南北带地壳和上地幔的三维速度成像．地球物理学报，1989，32(2)：143～151 Liu J H,Liu F T,Wu H,et al.Three dimension velocity tomography of the crustal and mantle on the Chinese north- south belt.Chinese J.Geophys.(in Chinese),1989,32(2): 143～151
[5]丁志峰．何正勤，孙为国．青藏高原东部及其边缘地区的地壳上地幔三维速度结构．地球物理学报，1999．42(2)：197～205 Ding Z F,He Z Q,Sun W G.Three dimension velocity structure of the crustal and upper mantle in eastern Tibetan and the surrounding region.Chinese J.Geophys.(in Chinese),1999,42(2):197～205
[6]Zhang Z J,Li Y K,Wang G J,et al.East-west crustal structure and“down-bowing”Moho under the northern Tibet revealed by wide-angle seismic profile.Science in China (Series D),2002,45(6):550～558
[7]张中杰，秦义龙，陈赟等．由宽角反射地震资料重建壳幔反射结构的相似性剖面．地球物理学报，2004，47(3)：469～474 Zhang Z J,Qin Y L,Chen Y,et al.Reconstruction of the semblance section for the crust and mantle reflection structure by wide-angle reflection seismic data.Chinese J.Geophys. (in Chinese),2004,47(3):469～474
[8]林中洋，胡鸿翔．张文彬等．滇西地区地壳上地幔速度结构特征的研究．地震学报，1993，15(4)：427～440 Lin Z Y,Hu H X,Zhang W B,et al.A study on velocity structure of the crust and upper mantle in Dianxi region.Acta Seismologica Sinica(in Chinese),1993,15(4):427～440
[9]尹周勋，滕吉文．熊绍柏等．渡口及其邻近地区地壳浅层结构的研究．地球物理学报，1987，30(1)：22～30 Yin Z X,Teng J W,Xiong S B,et al.Study on crustal shallow structure in Dukou and the surrounding region. Chinese J.Geophys.(in Chinese),1987,30(1):22～30
[10]孙若昧，刘福田，刘建华．四川地区的地震层析成像．地球物理学报，1991，25(6)：708～716 Sun R M,Liu F T,Liu J H.Seismic tomography of Sichuan. Chinese J.Geophys.(in Chinese),1991,25(6):708～716
[11]滕吉文，王绍舟，姚振兴等．青藏高原及其邻近地区的地球物理场特征与大陆板块构造．地球物理学报，1980．23(3)：254～268 Teng J W,Wang S Z,Yao Z X,et al.The geophysical character and continental block structure in Tibetan and the surrounding regions.Chinese J.Geophys.(in Chinese), 1980,23(3):254～268
[12]王椿镛，Mooney W D，王溪莉等．川滇地区地壳上地幔三维速度结构研究．地震学报．2002，24(1)：1～16 Wang C Y,Mooney W D,Wang X L,et al.Study on 3-D velocity structure of crust and upper mantle in Sichuan- Yunnan region,China.Acta Seismologica Sinica(in Chinese),2002,24(1):1～16
[13]胡家富，朱雄关．夏静瑜，陈赟．利用面波和接收函数联合反演滇西地区壳幔速度结构．地球物理学报．2005，8(5)：1069～1076 Hu J F,Zhu X G,Xia J Y,Chen Y.Using surface wave and receiver function to jointly inverse the crust-mantle velocity structure in the West Yunnan area.Chinese J.Geophys.(in Chinese),2005,48(5):1069～1076
[14]陈培善，刘福田．李强等．云南地区速度结构的横向不均匀性．中国科学(B)辑．1990，20(4)：431～458 Chen P S,Liu F T,Li Q,et al.Transverse inhomogeneous of the velocity structure in Yunnan region.Science in China (Series B),1990,20(4):431～458
[15]刘瑞丰．陈培善．李强．云南及其邻近地区三维速度图像．地震学报，1993，15(1)：61～67 Liu R F,Chen P S,Li Q.Three dimension velocity pictures in Yunnan and the surrounding regions.Acta Seismologica Sinica(in Chinese),1993,15(1):61～67
[16]吴建平．明跃红，王椿镛．云南数字地震台站下方的S波速度结构研究．地球物理学报．2001，44(2)：228～237 Wu J P,Ming Y H,Wang C Y.The S wave velocity structure beneath digital seismic stations of Yunnan province inferred from teleseismic receiver function modeling.Chinese J.Geophys.(in Chinese),2001,44(2):228～237
[17]张中杰，白志明．王椿镛等．冈瓦纳型和扬子型地块地壳结构：以滇西孟连—马龙宽角反射剖面为例，中国科学(D辑)，2005，34(5)：387～392 Zhang Z J,Bai Z M,Wang C Y,et al.The crustal structure of Gondawana and Yangtze blocks:An example by wide angle seismic reflection profiling between Menglian and Malong. Sciencein China(Serial D),2005,48(11):1828～1836
[18]张中杰，白志明，王椿镛等．三江地区地壳结构及动力学意义：云南遮放—宾川地震反射/折射剖面的启示．中国科学(D辑)．2005，35(4)：314～319 Zhang Z J,Bai Z M,Wang C Y,et al.The crustal structure under Sanjiang and its dynamic implications:Revealed by seismic reflection/refraction profiling between Zhefang and Binchuan,Yunnan.Science in China(Series D),2005,48 (9):1329～1336
[19]任纪舜，姜春发，张正坤等．中国大地构造及其演化．北京：科学出版社，1980 Ren J X,Jiang C F,Zhang Z K,et al.The Geotectonic Evolution of China(in Chinese).Beijing:Science Press, 1980
[20]Allen C R,Luo Z,Qian H,et al.Field study of a high active fault zone:the Xianshuihe fault of southwestern China.Geol Soc Amer Bull,1991,103:1178～1190
[21]Tapponnier P,Lacassin R,Leloup P H,et al.The Ailao Shan/Red River metamorphic belt:Tertiary left-lateral shear between Indo-China and South China.Nature,1990,343: 431～437
[22]Fan P,Outline of the tectonic evolution of southwestern China.Tectonophysics,1978,45:261～267
[23]Jeffreys H.On compressional waves in two superposed layers.Proceedings of the Cambridge Philosophical Society,1926,23:472～481
[24]Holbrook W S,Mooney W D,Christensen N J.The seismic velocity structure of the deep continental crust.In:Fountain D M,Arculusr,Kayaw eds.Continental Lower Crust. Amsterdam:Elsevier Science Publishers,1992.1～34
[25]张智，赵兵，张晰等．云南思茅—中甸地震剖面的地壳结构．地球物理学报，2006，49(5)：1377～1384 Zhang Z,Zhao B,Zhang X,et al.Crustal structure beneath the wide-angle seismic profile between Simao and Zhongdian in Yunnan.Chinese J.Geophys.(in Chinese),2006,49 (5):1377～1384
[26]白志明，王椿镛．云南遮放—宾川和孟连—马龙宽角地震剖面的层析成像研究．地球物理学报．2004，47(2)：257～267 Bai Z M,Wang C Y.Tomography research of the Zhefang- Binchuan and Menglian-Malong wide-angle seismic profiles in Yunnan.Chinese J.Geophs.(in Chinese),2004,47(2):257～267
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