海南岛地壳厚度与泊松比结构
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摘要
地壳厚度和泊松比是了解地球内部介质的重要参数,研究二者之间的关系能够为揭示深部地壳结构特征提供重要信息。本文提取了海南岛固定地震台站记录到的远震接收函数波形,通过在地壳厚度和波速比域对壳-幔间断面的Ps转换波及其多次波震相进行振幅叠加,同时参考人工地震探测结果,获得了海南岛地区的地壳厚度和泊松比分布。结果显示:海南岛地区地壳厚度为26—31km;受普遍发育的花岗岩以及火山作用影响,其泊松比值基本小于0.26,地壳厚度与泊松比之间存在正消长关系,表明该区的构造伸展作用主要造成富含镁铁成分的下地壳的明显减薄;部分地区的上地壳可能存在褶皱或逆冲推覆构造,其泊松比出现低值异常。
Crustal thickness(H) and Poisson's ratio(v) are two important parameters to understand the interior of the Earth. Correlation between the two can reveal important information of the character of the crustal structure.Teleseismic receiver functions recorded by the permanent seismic stations distributed around Hainan Island are extracted to search the Ps converted wave and its multiples from discontinuities in the crust and mantle,and some artificial earthquake probing results are taken for references to determine the average thickness and the Poisson's ratio beneath Hainan Island.The results show that the crust thickness of Hainan is 26 31km and the Poisson's ratio is lower than 0.26 beneath the island for the widespread granite and volcano activities.This area seems to display a positive correlation between H and v,which indicates that the tectonic extension function is mainly caused the obvious reduction of lower crustal thickness;Poisson's ratios in some zones are extremely low,possibly due to fold-thrust belts of the upper crust.
Crustal thickness(H) and Poisson's ratio(v) are two important parameters to understand the interior of the Earth. Correlation between the two can reveal important information of the character of the crustal structure.Teleseismic receiver functions recorded by the permanent seismic stations distributed around Hainan Island are extracted to search the Ps converted wave and its multiples from discontinuities in the crust and mantle,and some artificial earthquake probing results are taken for references to determine the average thickness and the Poisson's ratio beneath Hainan Island.The results show that the crust thickness of Hainan is 26 31km and the Poisson's ratio is lower than 0.26 beneath the island for the widespread granite and volcano activities.This area seems to display a positive correlation between H and v,which indicates that the tectonic extension function is mainly caused the obvious reduction of lower crustal thickness;Poisson's ratios in some zones are extremely low,possibly due to fold-thrust belts of the upper crust.
引文
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[17]QIU XUELIN,YE SANYU,WU SHIMIN,et al.Crustalstructure across the Xisha Trough,northwestern South ChinaSea[J].Tectonophysics,2001,341(1):179-193.
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[19]嵇少丞,王茜,杨文采.华北克拉通泊松比与地壳厚度的关系及其大地构造意义[J].地质学报,2009,83(3):324-330.
[20]JI SHAOCHENG,WANG QIAN,SALISBURY M H.Composition and tectonic evolution of the Chinesecontinental crust constrained by Poisson's ratio[J].Tectonophysics,2009,463(1-4):15-30.
[2]李建生.海南岛地区断裂构造体系与区域稳定性[J].海洋科学,1991,(3):19-21.
[3]BULAND R,CHAPMAN C H.The computation of seismictravel times[J].Bulletin of the Seismological Society ofAmerica,1983,73(5):1271-1302.
[4]OWENS T J,TAYLOR S R,ZANDT G.Crustal structure atRegional Seismic Test Network stations determined frominversion of broadband teleseismic P waveforms[J].Bulletinof the Seismological Society of America,1987,77(2):631-662.
[5]刘启元,KIND R,李顺成.中国数字地震台网的接收函数及其非线性反演[J].地球物理学报,1997,40(3):356-368.
[6]YUAN X,SOBOLEV S V,KIND R,et al.Subduction andcollision processes in the Central Andes constrained byconverted seismic phases[J].Nature,2000,408:958-961.
[7]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.
[8]ZHU LUPEI,KANAMORI H.Moho depth variation insouthern California from teleseismic receiver functions[J].Journal of Geophysical Research,2000,105(B2):2969-2980.
[9]KENNETT B L N.Seismic wave propagation in stratifiedmedia[M].New York:Cambridge University Press,1983:231-274.
[10]LANGSTON C A.Structure under Mount Rainier,Washington,inferred from teleseismic body waves[J].Journal of Geophysical Research,1979,84(B9):4749-4762.
[11]AMMON C J,RANDALLl G E.On the nonuniqueness ofreceiver function inversions[J].Journal of GeophysicalResearch,1990,95(B10):15303-15318.
[12]陈九辉.远震体波接收函数方法:理论与应用[D].北京:中国地震局地质研究所,2007:16-20.
[13]QIU XUELIN,PRIESTLEY K,MCKENZIE D.TeleseismicP-waveform receiver function analysis and its application toQiongzhong station(QIZ)of Hainan Island,NW South ChinaSea[J].Journal of Geosciences of China,2002,4(1):1-8.
[14]李志雄,雷建设,赵大鹏,等.海南岛及邻区地壳三维P波速度结构[J].地震学报,2008,30(5):441-448.
[15]吴庆举,曾融生.用宽频带远震接收函数研究青藏高原的地壳结构[J].地球物理学报,1998,41(5):669-679.
[16]姚伯初.南海北部陆缘的地壳结构及构造意义[J].海洋地质与第四纪地质,1998,18(2):1-16.
[17]QIU XUELIN,YE SANYU,WU SHIMIN,et al.Crustalstructure across the Xisha Trough,northwestern South ChinaSea[J].Tectonophysics,2001,341(1):179-193.
[18]熊小松,高锐,李秋生,等.深地震探测揭示的华南地区莫霍面深度[J].地球学报,2009,30(6):774-786.
[19]嵇少丞,王茜,杨文采.华北克拉通泊松比与地壳厚度的关系及其大地构造意义[J].地质学报,2009,83(3):324-330.
[20]JI SHAOCHENG,WANG QIAN,SALISBURY M H.Composition and tectonic evolution of the Chinesecontinental crust constrained by Poisson's ratio[J].Tectonophysics,2009,463(1-4):15-30.
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