云南地区地壳速度结构的层析成像研究
详细信息 本馆镜像全文    |  推荐本文 | | 获取馆网全文
摘要
利用地震波到时和体波层析成像方法反演了云南地区的P波速度结构,根据不同深度的速度异常分析了主要断裂和区域动力作用的深部效应,揭示出壳内低速层的分布范围以及与下地壳流动的联系.研究结果表明,哀牢山红河断裂两侧的地壳速度结构存在明显的差异,滇中地区的速度异常分布与小江断裂、元谋断裂、程海断裂等南北走向的断裂一致,反映了青藏东部地壳块体顺时针旋转产生的构造效应;滇西南的速度异常分布与哀牢山红河断裂、无量山断裂、澜沧江等断裂的走向平行,显示了印支块体朝东南方向挤出产生的影响;沿着南汀河断裂分布的低速异常则与印缅块体侧向挤压引起的构造活动有关.壳内低速异常具有分层和分区特征:在哀牢山红河断裂西侧和澜沧江之间主要分布在地壳中上部,在小江断裂和元谋断裂附近分布在地壳中下部,在滇中地区则广泛分布于地壳底部至莫霍面附近,东、西两侧分别受到小江断裂和哀牢山红河断裂的限制.其中攀西地区的低速异常与小江断裂和元谋断裂在此附近交汇形成的热流传输通道以及张裂时期强烈的壳幔热交换有关;在哀牢山—红河和澜沧江地区,除了印支块体向东南方向的挤出之外,印缅块体的侧向挤压和向东俯冲也对地壳深部的构造变形产生了一定的影响,由此引发的地幔上涌将导致热流物质沿着断裂通道进入地壳形成低速层.因此,哀牢山红河断裂不仅在地壳浅部是分隔印支块体和华南块体的地质界限,也是控制两侧区域深部构造变形和壳内韧性流动的分界.
We studied P-wave velocity structures of the Yunnan region through a seismic tomography using arrival data from permanent and temporary stations. Our objective is to analyze velocity anomalies that can reflect fault shearing and regional dynamic process at depths. We also like to locate low-velocity zones within the crust that are associated with lower crustal flows. The results reveal a prominent difference of crustal velocity structures across the Ailao Shan-Red River Fault. Bordered by the fault zone, velocity anomalies in the central Yunnan are parallel to the N—S trending faults like the Xiaojiang fault, the Yuanmou Fault and the Chenghai Fault, which reflect the deep effect of the clockwise rotation of the eastern Tibetan crust. Velocity anomalies in the southeastern Yunnan are parallel to the NW—SE trending faults like the Ailao Shan—Red River Fault, the Wuliang Shan Fault and the Lancang River Fault, which show the effect of the southeastward extrusion of the Indochina Block; whereas low-velocity anomalies along the Nanting River Fault are related to tectonic activities of the eastward motion of the Indo-Burma Block. The low-velocity anomalies within the crust are distributed at various depths and in different regions. They are observed in the upper-mid crust between the Ailao Shan—Red River Fault and the Lancang River Fault, and in the mid-lower crust near the Xiaojiang Fault and the Yuanmou Fault. In the lowermost crust and near the Moho, they are distributed throughout the central Yunnan, but limited by the Xiaojiang Fault to the east and by the Ailao Shan-Red River Fault to the west. We estimate that the low velocities in the Panxi region is related to the intersection of the Xiaojiang Fault and the Yuanmou Fault, that would provide heat flow channels for the crust-mantle thermal exchange in the rifting period. In the Ailao Shan-Red River region, besides the southeastward extrusion of the Indochina Block, the collision and eastward subduction of the Indo-Burma Block has also played a certain role in deep crustal deformation. The induced mantle upwelling would lead to a penetration of heat flows into the crust through the fault systems and to create the low-velocity layers within the crust. Therefore, the Ailao Shan-Red River Fault is not only a simple geological boundary between the Indochina Block and the South China Block, but also a border to control the deep crustal deformation and the ductile flow in the eastern and western sides.
引文
[1]Zhang X,Wang Y H.Crustal and upper mantle velocitystructure in Yunnan,Southwest China.Tectonophysics,2009,471(3-4):171-185.
    [2]Bai D H,Unsworth M J,Meju M A,et al.Crustaldeformation of the eastern Tibetan plateau revealed bymagnetotelluric imaging.Nature Geoscience,2010,3(5):358-362,doi:10.1038/ngeo830.
    [3]Huang J L,Zhao D P,Zheng S H.Lithospheric structureand its relationship to seismic and volcanic activity insouthwest China.J.Geophys.Res.,2002,107(B10):ESE13-1-ESE13-14,doi:10.1029/2000JB000137.
    [4]Wang C Y,Chan W W,Mooney W D.Three-dimensionalvelocity structure of crust and upper mantle in southwesternChina and its tectonic implications.J.Geophys.Res.,2003,108(B9):2442,doi:10.1029/2002JB001973.
    [5]Xu Y,Liu J H,Liu F T,et al.Crust and upper mantlestructure of the Ailao Shan-Red River fault zone and adjacentregions.Sci.China Ser.D:Earth Sci.,2005,48(2):156-164.
    [6]Lei J S,Zhao D P,Su Y J.Insight into the origin of theTengchong intraplate volcano and seismotectonics insouthwest China from local and teleseismic data.J.Geophys.Res.,2009,114(B5):B05302,doi:10.1029/2008JB005881.
    [7]Liu Y K,Chang X,He J K,et al.Three-dimensionalvelocity images of the crust and upper mantle beneath thenorth-south zone in China.Bull.Seism.Soc.Am.,2005,95(3):916-925.
    [8]Yao H J,Beghein C,Van der Hilst R D.Surface wave arraytomography in SE Tibet from ambient seismic noise and two-station analysis-II.Crustal and upper-mantle structure.Geophys.J.Int.,2008,173(1):205-219.
    [9]Huang R Q,Wang Z,Pei S P,et al.Crustal ductile flow andits contribution to tectonic stress in Southwest China.Tectonophysics,2009,473(3-4):476-489.
    [10]Xu Z J,Song X D.Joint inversion for crustal and Pnvelocities and Moho depth in Eastern Margin of the TibetanPlateau.Tectonophysics,2010,491(1-4):185-193.
    [11]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 velocitystructure beneath digital seismic stations of Yunnan provinceinferred from teleseismic receiver function modelling.ChineseJ.Geophys.(in Chinese),2001,44(2):228-237.
    [12]Hu J F,Su Y J,Zhu X G,et al.S-wave velocity andPoisson’s ratio structure of crust in Yunnan and itsimplication.Sci.China Ser.D:Earth Sci.,2005,48(2):210-218.
    [13]Xu L L,Rondenay S,Van der Hilst R D.Structure of thecrust beneath the southeastern Tibetan Plateau fromteleseismic receiver functions.Phys.Earth Planet.Int.,2007,165(3-4):176-193.
    [14]Li Y H,Wu Q J,Zhang R Q,et al.The crust and uppermantle structure beneath Yunnan from joint inversion ofreceiver functions and Rayleigh wave dispersion data.Phys.Earth Planet.Int.,2008,170(1-2):134-146.
    [15]Gao X,Su Y L,Wang W M,et al.Lower-crust S-wavevelocity beneath western Yunnan Province from waveforminversion of dense seismic observations.Terra Nova,2009,21(2):105-110.
    [16]张晓曼,胡家富,胡毅力等.云南壳幔S波速度结构与强震的构造背景.地球物理学报,2011,54(5):1222-1232.Zhang X M,Hu J F,Hu Y L,et al.The S-wave velocitystructure in the crust and upper mantle as well as the tectonicsetting of strong earthquake beneath Yunnan region.ChineseJ.Geophys.(in Chinese),2011,54(5):1222-1232.
    [17]常利军,王椿镛,丁志峰.云南地区SKS波分裂研究.地球物理学报,2006,49(1):197-204.Chang L J,Wang C Y,Ding Z F.A study on SKS splittingbeneath the Yunnan region.Chinese J.Geophys.(inChinese),2006,49(1):197-204.
    [18]Huang Z C,Wang L S,Xu M J,et al.Shear wave splittingacross the Ailao Shan-Red River fault zone,SW China.Geophys.Res.Lett.,2007,34(20):L20301.
    [19]Hu S B,He L J,Wang J Y.Heat flow in the continentalarea of China:a new data set.Earth Planet.Sci.Lett.,2000,179(2):407-419.
    [20]Wang Y.Heat flow pattern and lateral variations oflithosphere strength in China mainland:constraints on activedeformation.Phys.Earth Planet.Int.,2001,126(3-4):121-146.
    [21]胡家富,丛连理,苏有锦等.云南及周边地区Lg尾波Q值的分布特征.地球物理学报,2003,46(6):809-813.Hu J F,Cong L L,Su Y J,et al.Distribution characteristicsof Qvalue of the Lg coda in Yunnan and its adjacent regions.Chinese J.Geophys.(in Chinese),2003,46(6):809-813.
    [22]马宏生,汪素云,裴顺平等.川滇及周边地区地壳横波衰减的成像研究.地球物理学报,2007,50(2):465-471.Ma H S,Wang S Y,Pei S P,et al.Q0tomography of S waveattenuation in Sichuan-Yunnan and adjacent regions.ChineseJ.Geophys.(in Chinese),2007,50(2):465-471.
    [23]Lev E,Long M D,Van der Hilst R D.Seismic anisotropy inEastern Tibet from shear wave splitting reveals changes inlithospheric deformation.Earth Planet.Sci.Lett.,2006,251(3-4):293-304.
    [24]Flesch L,Holt W,Silver P,et al.Constraining the extent ofcrust–mantle coupling in central Asia using GPS,geologic,and shear wave splitting data.Earth Planet.Sci.Lett.,2005,238(1-2):248-268.
    [25]胥颐,钟大赉,刘建华.滇西地区壳幔解耦与腾冲火山区岩浆活动的深部构造研究.地球物理学进展,2012,27(3):846-855,doi:10.6038/j.issn.1004-2903.2012.03.003.Xu Y,Zhong D L,Liu J H.Constraints of deep structureson the crust-mantle decoupling in the western Yunnan and themagma activity in the Tengchong volcanic area.Progress inGeophys.(in Chinese),2012,27(3):846-855.doi:10.6038/j.issn.1004-2903.2012.03.003.
    [26]Zhong D L,Ding L,Liu F T,et al.Multi-oriented andlayered structures of lithosphere in orogenic belt and theireffects on Cenozoic magmatism—A case study of westernYunnan and Sichuan,China.Sci.China,Ser.D:Earth Sci.,2000,43(Supp):122-133.
    [27]Royden L H,Burchfiel B C,King R W,et al.Surfacedeformation and lower crustal flow in eastern Tibet.Science,1997,276(5313):788-790.
    [28]Wang C Y,Lou H,Silver P G,et al.Crustal structurevariation along 30°N in the eastern Tibetan Plateau and itstectonic implications.Earth Planet.Sci.Lett.,2010,289(3-4):367-376.
    [29]Liang C T,Song X D,Huang J L.Tomographic inversion ofPn travel times in China.J.Geophys.Res.,2004,109(B11):B11304,doi:10.1029/2003JB002789.
    [30]Kennett B L N,Engdahl E R,Buland R.Constraints onseismic velocities in the Earth from traveltimes.Geophys.J.Int.,1995,122(1):108-124.
    [31]Bassin C,Laske G,Masters G.The current limits ofresolution for surface wave tomography in North America.EOS Trans.AGU,2000,81:F897.
    [32]Paige C C,Saunders M A.LSQR:An algorithm for sparselinear equations and sparse least squares.ACM Trans.Math.Softw.,1982,8(1):43-71.
    [33]滕吉文.康滇构造带岩石圈物理与动力学.北京:科学出版社,1994.Teng J W.Lithospheric Physics and Dynamics of the Kang-Dian Tectonic Zone.Beijing:Science Press(in Chinese),1994.
    [34]Shen Z K,LüJ G,Wang M,et al.Contemporary crustaldeformation around the southeast borderland of the TibetanPlateau.J.Geophys.Res.,2005,110:B11409,doi:10.1029/2004JB003421.
    [35]Gan W J,Zhang P Z,Shen Z K,et al.Present-day crustalmotion within the Tibetan Plateau inferred from GPSmeasurements.J.Geophys.Res.,2007,112(B8):B08416,doi:10.1029/2005JB004120.
    [36]Schoenbohm L M,Burchfiel B C,Chen L Z.Propagation ofsurface uplift,lower crustal flow,and Cenozoic tectonics ofthe southeast margin of the Tibetan Plateau.Geology,2006,34(10):813-816,doi:10.1130/G22679.1.
    [37]钱晓东,秦嘉政,刘丽芳.云南地区现代构造应力场研究.地震地质,2011,33(1):91-106.Qian X D,Qin J Z,Liu L F.Study on recent tectonic stressfield in Yunnan region.Seismology and Geology(in Chinese),2011,33(1):91-106.
    [38]徐鸣洁,王良书,刘建华等.利用接收函数研究哀牢山红河断裂带地壳上地幔特征.中国科学(D辑:地球科学),2005,35(8):729-737.Xu M J,Wang L S,Liu J H,et al.Crust and uppermostmantle structure of the Ailaoshan-Red River fault fromreceiver function analysis.Sci.China,Ser.D:Earth Sci.,2005,49(10):1043-1052.
    [39]Pan W,Wang L S,Mi N,et al.Crustal thickness andaverage Vp/Vsratio variations in southwest Yunnan,China,from teleseismic receiver functions.J.Geophys.Res.,2010,115(B11):B11308,doi:10.1029/2009JB006651.
    [40]Tapponnier P,Lacassin R,Leloup P H,et al.The AilaoShan/Red River metamorphic belt:Tertiary left-lateral shearbetween Indochina and south China.Nature,1990,343(6257):431-437.
    [41]Leloup P H,Harrison T M,Ryerson F J,et al.Structural,petrological and thermal evolution of a Tertiary ductile strike-slip shear zone,Diancang Shan,Yunnan.J.Geophys.Res.,1995,98(B4):6175-6743.

版权所有:© 2023 中国地质图书馆 中国地质调查局地学文献中心