利用远震接收函数分析三峡库区重庆段地壳厚度变化
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摘要
针对三峡库区重庆段地震监测台网和重庆区域台网2007年到2010年记录到的远震数据,利用接收函数方法,得到该区域的地壳厚度值及泊松比。结果显示27个地震台下方的地壳平均厚度为44.6km。最厚处为城口(CHK),达50.9km;最薄处为荣昌(ROC),仅38.9km,两者相差12km。研究区的地壳泊松比σ值约为0.27,三峡重庆库区东部奉节荆竹(JIZ)地壳泊松比高达0.302,武隆(WUL)地区的地壳泊松比较低,最低为0.228,两者相差0.074;研究区内泊松比的最大值偏离标准泊松体比值(0.25)20.8%以上,其最小值偏离标准泊松体比值-8.80%。布格重力异常反映了地下的密度与地壳厚度变化。文中得出的三峡库区重庆段地壳厚度变化与该区布格重力异常分析结果一致,重庆境内最小的负布格重力异常在地壳厚度最厚的城口—巫溪地区(厚49.7～50.9km),地壳最薄的荣昌—合川地区(厚38.9～41km)对应着渝西最大的负布格重力异常。
Based on teleseimic data for the period of 2007 to 2010 acquired from the Three Gorges reservoir(Chongqing section)seismic network and Chongqing regional seismic network,we obtained the crustal thickness and Possion's ratio of the area through receiver function method.The results show that the crustal thickness ranges from 38.9km to 50.9km.Station CHK in northeastern Chongqing has the largest thickness which is about 50.9km;the thinnest crust is 38.9km under the station ROC in the west of Chongqing,and Poisson's ratio is about 0.27.The results show that the maximum Posson's ratio is beneath station JIZ in the east of the Chongqing section of Three Gorges Reservoir area,and the minimum Possion's ratio is beneath the station WUL,which is 0.228.In comparison with the Poisson medium(0.25),its maximum deviates up to 20.8%,and the minimum deviates by-8.80%.The Bouguer gravity anomaly often reflects subsurface density and crustal thickness variation.In this paper,the two agree with each other.The largest negative Bouguer anomaly is between CHK(50.9km)and WUX(49.7km),where the crust is the thickest.The smallest negative Bouguer anomaly is between ROC(38.9km)and YUM(41km),where the crust is the thinnest.
Based on teleseimic data for the period of 2007 to 2010 acquired from the Three Gorges reservoir(Chongqing section)seismic network and Chongqing regional seismic network,we obtained the crustal thickness and Possion's ratio of the area through receiver function method.The results show that the crustal thickness ranges from 38.9km to 50.9km.Station CHK in northeastern Chongqing has the largest thickness which is about 50.9km;the thinnest crust is 38.9km under the station ROC in the west of Chongqing,and Poisson's ratio is about 0.27.The results show that the maximum Posson's ratio is beneath station JIZ in the east of the Chongqing section of Three Gorges Reservoir area,and the minimum Possion's ratio is beneath the station WUL,which is 0.228.In comparison with the Poisson medium(0.25),its maximum deviates up to 20.8%,and the minimum deviates by-8.80%.The Bouguer gravity anomaly often reflects subsurface density and crustal thickness variation.In this paper,the two agree with each other.The largest negative Bouguer anomaly is between CHK(50.9km)and WUX(49.7km),where the crust is the thickest.The smallest negative Bouguer anomaly is between ROC(38.9km)and YUM(41km),where the crust is the thinnest.
引文
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王峻,刘启元,陈九辉,等.2009.根据接收函数反演得到的首都圈地壳上地幔三维S波速度结构[J].地球物理学报,52(10):2472—2482.WANG Jun,LIU Qi-yuan,CHEN Jiu-hui,et al.2009.Three-dimensional S-wave velocity structure of the crust and up-per mantle beneath the Capital Circle Region from receiver function inversion[J].Chinese Journal of Geophysics,52(10):2472—2482(in Chinese).
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王小平,朱元清,于海英.2006.用远震接收函数反演上海及其邻区地壳速度结构[J].地震研究,29(3):239—244.WANG Xiao-ping,ZHU Yuan-qing,YUHai-ying.2006.Crust velocity structure in Shanghai and its neighboring area in-versed by teleseismic receiver function[J].Journal of Seismological Research,29(3):239—244(in Chinese).
许卫卫,郑天愉.2002.接收函数方法及研究进展[J].地球物理学进展,17(4):605—613.XU Wei-wei,ZHENG Tian-yu.2002.The receiver function method and its progress[J].Progress in Geophysics,17(4):605—613(in Chinese).
赵军龙,毛锁明,胡建平.2007.综合地球物理在三峡重庆库区深部断裂构造特征研究中的应用[J].西安石油大学学报(自然科学版),22(3):52—56.ZHAO Jun-long,MAO Suo-ming,HUJian-ping.2007.Application of integrated geophysics in the study of the character-istics of the deep faulted structures in Chongqing reservoir area of Three Gorges[J].Journal of Xi an Shiyou Uni-versity(Natural Science Edition),22(3):52—56(in Chinese).
Christensen N I,Fountain D M.1975.Constitution of the lower continental crust based on experimental studies of seis-mic velocities in granulite[J].Geol Soc Am Bull,86(2):227—236.
Fountain D M,Christensen NI.1989.Composition of the continental crust and upper mantle[A].In:Pakiser L Cet al(eds).Geophisical Framework of the Continental United States.Boulder,Colorado.711—742.
Wang HL,Zhu L,Chen HW.2009.Moho depth variation in Taiwan from teleseismic receiver functions[J].Journal ofAsian Earth Sciences,37(3):286—291.
Zhu L,Kanamori H.2000.Moho depth variation in southern California from teleseismic receiver functions[J].Journalof Geophysical Research,105(B2):2969—2980.
段永红,张先康,刘志,等.2005.长白山-镜泊湖火山区地壳结构接收函数研究[J].地球物理学报,48(2):352—358.DUAN Yong-hong,ZHANG Xian-kang,LIU Zhi,et al.2005.A study on crustal structures of Changbaishan Jingpohuvolcanic area using receiver functions[J].Chinese J Geophys,48(2):352—358(in Chinese).
贺传松,王椿镛,吴庆举.2003.接收函数方法及其新的进展[J].地球物理学进展,18(2):224—228.HE Chuan-song,WANG Chun-yong,WU Qing-ju.2003.The receiver function method and its new progress[J].Pro-gress in Geophysics,18(2):224—228(in Chinese).
胡建平,赵军龙,汪文秉.2005.三峡重庆库区深部二维构造剖面的建立和分析[J].地震研究,28(1):71—77.HU Jian-ping,ZHAO Jun-long,WANG Wen-bing.2005.Establishing and analyzing of deep2-D structure section atChongqing,Three Gorges reservoir area[J].Journal of Seismological Research,28(1):71—77(in Chinese).
贾丽华,崇加军,刘渊源,等.2010.利用远震接收函数研究辽宁地区的地壳厚度及泊松比[J].地震地质,32(2):260—268.JIA Li-hua,CHONG Jia-jun,LIU Yuan-yuan,et al.2010.Crustal thickness and Poisson ratio of Liaoning Province fromreceiver function study[J].Seismology and Geology,32(2):260—268(in Chinese).
刘春,崇加军,倪四道,等.2009.利用远震接收函数反演陕西地震台站下方的地壳厚度[J].地震地质,31(2):313—320.LIUChun,CHONG Jia-jun,NI Si-dao,et al.2009.Study on the crustal thickness beneath stations of seismic network inShaanxi Province by teleseismic receiver function[J].Seismology and Geology,31(2):313—320(in Chinese).
李永华,吴庆举,安张辉,等.2006.青藏高原东北缘地壳S波速度结构与泊松比及其意义[J].地球物理学报,49(5):1359—1368.LI Yong-hua,WUQing-ju,AN Zhang-hui,et al.2006.The Poisson ratio and crustal structure across the NE Tibetan Plateaudetermined from receiver functions[J].Chinese Journal of Geophysics,49(5):1359—1368(in Chinese).
刘启元,Rainerkind,李顺成.1997.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,40(3):356—368.LIUQi-yuan,Rainerkind,LI Shun-cheng.1997.Receiver functions at the stations of the Chinese Digital Seismic Network(CD-SN)and their nonlinear inversion[J].Chinese Journal of Geophysics,40(3):356—368(in Chinese).
田宝峰,李娟,王卫民,等.2008.华北太行山区地壳各向异性的接收函数证据[J].地球物理学报,51(5):1459—1467.TIAN Bao-feng,LI Juan,WANG Wei-min,et al.2008.Crust anisotropy of Taihangshan Mountains in North China in-ferred from receiver functions[J].Chinese Journal of Geophysics,51(5):1459—1467(in Chinese).
王椿镛,楼海,姚志祥,等.2010.龙门山及其邻区的地壳厚度和泊松比[J].第四纪研究,30(4):652—661.WANG Chun-yong,LOU Hai,YAO Zhi-xiang,et al.2010.Crustal thicknesses and Poisson s ratios in LongmenshanMountains and adjacent regions[J].Quaternary Sciences,30(4):652—661(in Chinese).
王峻,刘启元,陈九辉,等.2009.根据接收函数反演得到的首都圈地壳上地幔三维S波速度结构[J].地球物理学报,52(10):2472—2482.WANG Jun,LIU Qi-yuan,CHEN Jiu-hui,et al.2009.Three-dimensional S-wave velocity structure of the crust and up-per mantle beneath the Capital Circle Region from receiver function inversion[J].Chinese Journal of Geophysics,52(10):2472—2482(in Chinese).
吴庆举,曾融生.1998.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,41(5):669—679.WUQing-ju,ZENG Rong-sheng.1998.The crustal structure of Qinghai-Xizang plateau inferred from broadband teleseis-mic waveform[J].Chinese Journal of Geophysics,41(5):669—679(in Chinese).
王小平,朱元清,于海英.2006.用远震接收函数反演上海及其邻区地壳速度结构[J].地震研究,29(3):239—244.WANG Xiao-ping,ZHU Yuan-qing,YUHai-ying.2006.Crust velocity structure in Shanghai and its neighboring area in-versed by teleseismic receiver function[J].Journal of Seismological Research,29(3):239—244(in Chinese).
许卫卫,郑天愉.2002.接收函数方法及研究进展[J].地球物理学进展,17(4):605—613.XU Wei-wei,ZHENG Tian-yu.2002.The receiver function method and its progress[J].Progress in Geophysics,17(4):605—613(in Chinese).
赵军龙,毛锁明,胡建平.2007.综合地球物理在三峡重庆库区深部断裂构造特征研究中的应用[J].西安石油大学学报(自然科学版),22(3):52—56.ZHAO Jun-long,MAO Suo-ming,HUJian-ping.2007.Application of integrated geophysics in the study of the character-istics of the deep faulted structures in Chongqing reservoir area of Three Gorges[J].Journal of Xi an Shiyou Uni-versity(Natural Science Edition),22(3):52—56(in Chinese).
Christensen N I,Fountain D M.1975.Constitution of the lower continental crust based on experimental studies of seis-mic velocities in granulite[J].Geol Soc Am Bull,86(2):227—236.
Fountain D M,Christensen NI.1989.Composition of the continental crust and upper mantle[A].In:Pakiser L Cet al(eds).Geophisical Framework of the Continental United States.Boulder,Colorado.711—742.
Wang HL,Zhu L,Chen HW.2009.Moho depth variation in Taiwan from teleseismic receiver functions[J].Journal ofAsian Earth Sciences,37(3):286—291.
Zhu L,Kanamori H.2000.Moho depth variation in southern California from teleseismic receiver functions[J].Journalof Geophysical Research,105(B2):2969—2980.
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