银川盆地深地震断层的三维透射成像
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摘要
为了获得三维地震透射成像技术在活断层探测中的有效性和应用价值的评价,在银川盆地中北部布设了一个三维地震透射台阵,利用该台阵获得的基底初至折射波和莫霍界面反射波资料,采用有限差分反演、时间项反演和连续速度模型反演方法,对台阵区域基底及上地壳结构进行了分析.结果表明:研究区基底呈东西浅、中部深的界面形态,且西陡东缓,最深处大致位于芦花台至西大滩一带,埋深达7 km.芦花台断层、银川平罗断层、黄河断层在研究区内均表现为北北东走向的速度差异条带,且断层两侧基底及沉积界面埋深存在显著变化.芦花台断层东倾,倾角较陡,延伸至研究区基底之下;银川—平罗断层倾向西,是一条超基底的隐伏断层;黄河断层西倾,延伸深度超过研究区基底.本探测结果证明,初至折射波与莫霍面反射波探测相结合的三维地震透射台阵技术能够给出研究区上地壳三维细结构图像,不仅可以揭示主要断裂的展布位置、浅部空间形态和特征,而且可以揭示断裂向基底之下的延伸状况.
In order to prove the validity and application value of three-dimensional seismic transmission technology in active fault detection,a three-dimensional seismic transmission array was deployed in the middle north of Yinchuan basin,The basement and upper crust structure under the seismic array were reconstructed based on first-arrival refraction traveltimes and reflection traveltimes from Moho at critical distances by using finite difference method,time-term method and the inversion method without model blocks.The results show that the basement of the studied area is shallow in the east and west and deep in the centre and it is steeper in the west than in the east.The greatest depth of the basement occurs between Luhuatai to Xidatan,and its depth reaches 7 km there.Luhuatai fault,Yinchuan-Pingluo fault and Huanghe fault all behave as velocity difference strip of NNE direction and there is significant variation in the depth of the sediment interface.The east-dipping,high-angle Luhuatai fault extends under the basement.The west-dipping Yinchuan-Pingluo fault is a buried fault penetrating the basement.Huanghe fault dips toward the west and penetrates the basement as well.These exploration results prove that the three-dimensional seismic transmission technology,which combines first-arrival refraction wave exploration with Moho reflection wave exploration,is applicable in the reconstruction of fine upper crustal image of the studied area.With this technology,we can not only reveal distribution and shallow features of the major faults,but also their extension under the basement.
In order to prove the validity and application value of three-dimensional seismic transmission technology in active fault detection,a three-dimensional seismic transmission array was deployed in the middle north of Yinchuan basin,The basement and upper crust structure under the seismic array were reconstructed based on first-arrival refraction traveltimes and reflection traveltimes from Moho at critical distances by using finite difference method,time-term method and the inversion method without model blocks.The results show that the basement of the studied area is shallow in the east and west and deep in the centre and it is steeper in the west than in the east.The greatest depth of the basement occurs between Luhuatai to Xidatan,and its depth reaches 7 km there.Luhuatai fault,Yinchuan-Pingluo fault and Huanghe fault all behave as velocity difference strip of NNE direction and there is significant variation in the depth of the sediment interface.The east-dipping,high-angle Luhuatai fault extends under the basement.The west-dipping Yinchuan-Pingluo fault is a buried fault penetrating the basement.Huanghe fault dips toward the west and penetrates the basement as well.These exploration results prove that the three-dimensional seismic transmission technology,which combines first-arrival refraction wave exploration with Moho reflection wave exploration,is applicable in the reconstruction of fine upper crustal image of the studied area.With this technology,we can not only reveal distribution and shallow features of the major faults,but also their extension under the basement.
引文
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[12] 徐朝繁,张先康,段永红等.新疆伽师强震群区上部地壳细结构的高分辨折射地震探测研究.地震学报,2006,28(1) :60～69Xu Z F,Zhang X K,Duan Y H,et al.Fine upper crustal structure of Jiashi strong earthquake swarm region in Xirtjiang inferred from high resolution seismic refraction profile data.Acta Seismologica Sinica,2006,19 (1) :62～71
[13] 张先康,杨卓欣,徐朝繁等.阿尼玛卿缝合带上地壳结构-马尔康-碌曲-古浪深地震测深剖面结果.地震学报,2007,29 (6) :592～602Zhang X K,Yang Z X,Xu Z F,et al.Upper crust structure of eastern A'nyemaqn suture zone:results of Barkam-Luqu-Gulang deep seismic sounding profile.Acta Seismologica Sinica,2007,20(6) :628～640
[14] 张先康,杨玉春,赵 平等.唐山滦县震区三维地震透射研究--中、上地壳速度层析成像.地球物理学报,1994,37(6) :759～766Zhang X K,Yang Y C,Zhao P,et al.Three-dimensional seismic transmission experiment in the Luanxian earthquake region of North China:tomographic determination of the upper and middle crust structure.Chinese J.Geophys.(Acta Geophysica Sinica) (in Chinese),1994,37(6) :759～766
[15] 张先康,杨卓欣,杨玉春等.地壳三维结构的层析成像方法-爆炸和地震资料的联合反演.地震学报,1995,17(4) :422～431Zhang X K,Yang Z X,Yang Y C,et al.Tomographic determination of 3 D crustal structure-Joint inversion of explosion and earthquake data.Acta Seismologica Sinica,1995,8(4) :519～529
[16] 张先康,张成科,赵金仁等.长白山天池火山岩浆系统的深地震测深研究.地震学报,2002,24(2) :135～143Zhang X K,Zhang C K,Zhao J R,et al.Deep seismic sounding investigation into the deep structure of the magma system in Changbaishan-Tianchi volcanic region.Acta Seismologica Sinica,2002,15(2) :143～151
[17] 杨卓欣,赵金仁,张先康等.伽师强震群区上地壳三维速度层析成像.地震学报,2002,24(2) :153～161Yang Z X,Zhao J R,Zhang X K,et al.Tomographic determination of the upper crustal structure in the Jiashi strong earthquake swarm region.Acta Seismologica Sinica,2002,15(2) :162～170
[18] 王夫运,张先康,陈棋福等.北京地区上地壳结构层析成像.地球物理学报,2005,48(2) :359～366Wang F Y,Zhang X K,Chen Q F,et al.Fine tomographic inversion of the upper crust 3-D structure around Beijing.Chinese J.Geophys.(Acta Geophysica Sinica) (in Chinese),2005,48(2) :359～366
[2] Hole J A.Nonlinear high resolution three-dimensional seismic travel time tomography.J.Geophys.Res.,1992,97 (B5) :6553～6562
[3] Scheidegger A E,Willmore P L.The use of a least square method for the interpretation of data from seismic surveys.Geophysics,1957,22(1) :9～22
[4] Tarantola A,Nercessian A.Three dimensional inversion without blocks.Geophys.J.R.Astr.Soc.,1984,76:299～306
[5] Nercessian A,Him A,Tarantola A.Three-dimensional seismic transmission prospecting of the Mont Dore volcano,France.Geophys.J.R.Astr.Soc.,1984,76:307～315
[6] 艾伯特·塔兰托拉著.反演理论-数据拟合和模型参数估算方法.张先康等译.北京:学术书刊出版社,1989． 418～444Tarantola A.Inverse Problem Theory,Methods for Data Fitting and Model Parameter Estimation (in Chinese).Zhang X K,et al.Trans.Beijing:Academic Book and Periodical Press,1989． 418～444
[7] 国家地震局鄂尔多斯周缘活动断裂系课题组.鄂尔多斯周缘活动断裂系.北京:地震出版社,1988． 20～38The Research Group on Active Fault System around Ordos Massif,SSB.Active Fault System around Ordos Massif (in Chinese).Beijing:Seismological Press,1988． 20～38
[8] 严烈宏,王利,张黎等.银川盆地地热系统.宁夏:宁夏人民出版社,2002． 39～52Yan L H,Wang L,Zhang L,et al.Geothermal System in Yinchuan Basin (in Chinese).Ningxia:Ningxia People's Publishing House,2002． 39～52
[9] 王椿镛,张先康,丁志峰等.大别造山带上部地壳结构的有限差分层析成像.地球物理学报,1997,40(4) :459～501Wang C Y,Zhang X K,Ding Z F,et al.Finite-difference tomography of upper crustal structure in Dabieshan orogenic belt.Chinese J.Geophys.(Acta Geophysica Sinica) (in Chinese),1997,40(4) :459～501
[10] Fuis G S,Ryberg T,Lutter W J,et al.Seismic mapping of shallow fault zones in the San Gabriel Mountains from the Los Angeles region seismic experiment,Southern California.J.Geophys.Res.,2001,106(B4) :6549～6568
[11] 段永红,张先康,方盛明.华北地区上部地壳结构的三维有限差分层析成像.地球物理学报,2002,45(3) :362～369Duan Y H,Zhang X K,Fang S M.Three-dimensional finite- difference tomography of velocity structure of the upper crust in North China.Chinese J.Geophys.(Acta Geophysica Sinica) (in Chinese),2002,45(3) :362～369
[12] 徐朝繁,张先康,段永红等.新疆伽师强震群区上部地壳细结构的高分辨折射地震探测研究.地震学报,2006,28(1) :60～69Xu Z F,Zhang X K,Duan Y H,et al.Fine upper crustal structure of Jiashi strong earthquake swarm region in Xirtjiang inferred from high resolution seismic refraction profile data.Acta Seismologica Sinica,2006,19 (1) :62～71
[13] 张先康,杨卓欣,徐朝繁等.阿尼玛卿缝合带上地壳结构-马尔康-碌曲-古浪深地震测深剖面结果.地震学报,2007,29 (6) :592～602Zhang X K,Yang Z X,Xu Z F,et al.Upper crust structure of eastern A'nyemaqn suture zone:results of Barkam-Luqu-Gulang deep seismic sounding profile.Acta Seismologica Sinica,2007,20(6) :628～640
[14] 张先康,杨玉春,赵 平等.唐山滦县震区三维地震透射研究--中、上地壳速度层析成像.地球物理学报,1994,37(6) :759～766Zhang X K,Yang Y C,Zhao P,et al.Three-dimensional seismic transmission experiment in the Luanxian earthquake region of North China:tomographic determination of the upper and middle crust structure.Chinese J.Geophys.(Acta Geophysica Sinica) (in Chinese),1994,37(6) :759～766
[15] 张先康,杨卓欣,杨玉春等.地壳三维结构的层析成像方法-爆炸和地震资料的联合反演.地震学报,1995,17(4) :422～431Zhang X K,Yang Z X,Yang Y C,et al.Tomographic determination of 3 D crustal structure-Joint inversion of explosion and earthquake data.Acta Seismologica Sinica,1995,8(4) :519～529
[16] 张先康,张成科,赵金仁等.长白山天池火山岩浆系统的深地震测深研究.地震学报,2002,24(2) :135～143Zhang X K,Zhang C K,Zhao J R,et al.Deep seismic sounding investigation into the deep structure of the magma system in Changbaishan-Tianchi volcanic region.Acta Seismologica Sinica,2002,15(2) :143～151
[17] 杨卓欣,赵金仁,张先康等.伽师强震群区上地壳三维速度层析成像.地震学报,2002,24(2) :153～161Yang Z X,Zhao J R,Zhang X K,et al.Tomographic determination of the upper crustal structure in the Jiashi strong earthquake swarm region.Acta Seismologica Sinica,2002,15(2) :162～170
[18] 王夫运,张先康,陈棋福等.北京地区上地壳结构层析成像.地球物理学报,2005,48(2) :359～366Wang F Y,Zhang X K,Chen Q F,et al.Fine tomographic inversion of the upper crust 3-D structure around Beijing.Chinese J.Geophys.(Acta Geophysica Sinica) (in Chinese),2005,48(2) :359～366
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