纵波速度模型约束的首都圈地壳横波速度结构成像
|
摘要
通过搜集首都圈地震台网记录到的634个地震事件的近三万条地震射线,并从中挑选出274条信噪比高、发育良好的面波频散曲线,并将已有的纵波速度转换为横波速度,作为横波速度反演的初始模型,利用最小二乘反演方法进行面波频散层析成像,得到了研究区地壳S波速度结构和地壳的厚度分布以及一些初步结论:地壳可分为地表、基底、上地壳、中地壳、下地壳五层,中地壳整体横波速度表现为弱梯度,局部出现负速度梯度,下地壳横波速度均呈现不同程度的异常,证实了中地壳低速层的存在;研究区内速度存在明显横向不均匀性,这是复杂的地质构造特征在地球物理场中的响应;各构造单元表现明显不同的速度结构变化,中地壳层位速度变化范围较小;同一构造单元在不同深度的层位上速度变化明显,出现高低速异常交替现象,特别是在张渤断裂带上地壳层位以上,高速和低速异常块体交替明显;地壳平均厚度29～40km,并且从东南向西北逐渐变厚加深,其中张北地区地壳最厚达40km,华北裂陷盆地地壳厚度为29～32km,华北裂陷盆地中部的深浅交叉的异常块体内的冀中坳陷构造最薄。
We picked up 274 well-developed and high signal to noise performance surface wave ray-paths recorded by 38 seismic stations in the Capital Seismic station Network and study the crust of the Capital region by surface wave tomography method through the original velocity model from P velocity transformation.Then we obtain,analyze and interpret the depth section and S wave velocity structure.Here are some preliminary results: firstly,the area crust could be divided into five layers: surface,basement,upper crust,mid-crust and lower crust.The mid-crust S velocity structure shows low gradient,even negative velocity gradient partly,and S velocity shows different degree anomaly in lower crust.So this further proved the truth of mid-crust exist.Secondly,S wave velocity profile shows obvious lateral heterogeneity in the Capital region,for this is the response of the complex geological structural characteristic in the geophysical field;Every tectonic unit shows obvious different velocity structures,and the velocity changes less in mid-crust layer;the same tectonic unit has clear different velocity changes in different depth,and the high velocity and low velocity alternate abnormally,particularly,above the crust layer of the fault zone.Because of Zhangjiakou-bohai sea rift broken belt,higher velocity and low velocity abnormal block alternate obviously.thirdly,the crust average thickness in the Capital region is from 29 to 40 kilometers,and presents the distinguishing feature that the thickness more thicker and deeper from southeast to northwest,the most thick area is Zhangbei area around Zhangjiakou,in the North China rift depression basin,the crust thickness is from 29 to 32 kilometers,and the most thin place is located in North China basin.
We picked up 274 well-developed and high signal to noise performance surface wave ray-paths recorded by 38 seismic stations in the Capital Seismic station Network and study the crust of the Capital region by surface wave tomography method through the original velocity model from P velocity transformation.Then we obtain,analyze and interpret the depth section and S wave velocity structure.Here are some preliminary results: firstly,the area crust could be divided into five layers: surface,basement,upper crust,mid-crust and lower crust.The mid-crust S velocity structure shows low gradient,even negative velocity gradient partly,and S velocity shows different degree anomaly in lower crust.So this further proved the truth of mid-crust exist.Secondly,S wave velocity profile shows obvious lateral heterogeneity in the Capital region,for this is the response of the complex geological structural characteristic in the geophysical field;Every tectonic unit shows obvious different velocity structures,and the velocity changes less in mid-crust layer;the same tectonic unit has clear different velocity changes in different depth,and the high velocity and low velocity alternate abnormally,particularly,above the crust layer of the fault zone.Because of Zhangjiakou-bohai sea rift broken belt,higher velocity and low velocity abnormal block alternate obviously.thirdly,the crust average thickness in the Capital region is from 29 to 40 kilometers,and presents the distinguishing feature that the thickness more thicker and deeper from southeast to northwest,the most thick area is Zhangbei area around Zhangjiakou,in the North China rift depression basin,the crust thickness is from 29 to 32 kilometers,and the most thin place is located in North China basin.
引文
[1]曾融生.固体地球物理学导论[M].北京:科学出版社,1984.
[2]滕吉文,张中杰,白武明,等.岩石圈物理学[M].北京:科学出版社,2004.
[3]刘树才.煤矿底板突水机理及破坏裂隙带演化动态探测技术[D].徐州:中国矿业大学,2008.
[4]李松林,张先康,宋占隆,等.地震测深剖面资料联合反演首都圈三维地壳结构[J]地球物理学报,2001,44(5):360～369.
[5]王夫运,张先康,陈棋福,等.北京地区上地壳三维细结构层析成像[J].地球物理学报,2005,48(2):359～366.
[6]赵贤任,刘树才,李富,等.煤层底板破坏带电阻率法异常特征研究[J].工程地球物理学报,2008,5(2):164～168.
[7]刘保金,胡平,孟勇奇,等.北京地区地壳精细结构的深地震反射剖面探测研究[J].地球物理学报,2009,52(9):2264～2272.
[8]金安蜀,刘福田,孙永智,等.北京地区地壳和上地幔的三维P波速度结构[J].地球物理学报,1980,23(2):172～182.
[9]刘福田,曲克信,吴华,等.华北地区的地震层面成像[J].地球物理学报,1986,29(5):442～449.
[10]朱露培,曾融生,刘福田.京津唐张地区地壳与上地幔三维P波速度结构[J].地球物理学报,1990,33(3):253～269.
[11]孙若昧,刘福田.京津唐地区地壳结构与强震的发生_I_P波速度结构[J].地球物理学报,1995,38(5):599～607.
[12]孙若昧,赵燕来,吴丹.京津唐地区地壳结构与强震的发生——Ⅱ.S波速度结构[J].地球物理学报,1996,39(3):347～355.
[13]丁志峰.近震层析成像的理论及应用[J].国际地震动态,2000(10):37～38.
[14]于湘伟,陈运泰,王培德.京津唐地区中上地壳三维P波速度结构[J].地震学报,2003,25(1):1～14.
[15]黄金莉,赵大鹏.首都圈地区地壳三维P波速度细结构与强震孕育的深部构造环境[J].科学通报,2005,50(4):348～355.
[16]齐诚,赵大鹏,陈顒.首都圈地壳P波和S波三维速度结构及其与大地震的关系[J].地球物理学报,2006,49(3):805～815.
[17]张亚明,孟朴在,滕吉文,等.京津唐及邻区地壳结构的中新生代构造运动响应[J].地球物理学报,2008,51(4):1123～1134.
[18]罗艳,崇家军,倪四道,等.首都圈地区莫霍面起伏及沉积层厚度[J].地球物理学报,2008,51(4):1135～1145.
[19]Z J Zhang,X Zhang,JoséBadal.Composition ofthe crust beneath southeastern China derived from anintegrated geophysical data set[J].Journal of physi-cal Research,2008,113:25.doi:10.1029/2006JB004503.
[20]张金清,梁青,陈超.软弱夹层瑞雷面波频散曲线特征[J].工程地球物理学报,2005,2(3):208～215.
[21]陈健,杨永波,张永.瑞雷波在块石强夯地基质量检测中的应用[J].工程地球物理学报,2005,2(5):365～368.
[22]M Choura,J Badal,V Corchete.A survey of theshallow structure beneath the Alboran Sea using Rg-waves and 3Dimaging[J].Tectonophysics,2001,335(19):255～273.
[23]徐锡伟.首都圈地区地壳最新构造变动与地震[M].北京:科学出版社,2002.
[24]史海霞.首都圈地区地震动场地效应研究[D].北京:中国地震局地震预测研究所,2008.
[25]胡中民,王夫运,刘明军.用DSS资料研究首都圈地区的地壳结[J].华南地震,2008,28(1):41～51.
[26]王峻,刘启元,陈九辉.首都圈地区的地壳厚度及泊松比[J].地球物理学报,2009,52(1):57～66.
[2]滕吉文,张中杰,白武明,等.岩石圈物理学[M].北京:科学出版社,2004.
[3]刘树才.煤矿底板突水机理及破坏裂隙带演化动态探测技术[D].徐州:中国矿业大学,2008.
[4]李松林,张先康,宋占隆,等.地震测深剖面资料联合反演首都圈三维地壳结构[J]地球物理学报,2001,44(5):360～369.
[5]王夫运,张先康,陈棋福,等.北京地区上地壳三维细结构层析成像[J].地球物理学报,2005,48(2):359～366.
[6]赵贤任,刘树才,李富,等.煤层底板破坏带电阻率法异常特征研究[J].工程地球物理学报,2008,5(2):164～168.
[7]刘保金,胡平,孟勇奇,等.北京地区地壳精细结构的深地震反射剖面探测研究[J].地球物理学报,2009,52(9):2264～2272.
[8]金安蜀,刘福田,孙永智,等.北京地区地壳和上地幔的三维P波速度结构[J].地球物理学报,1980,23(2):172～182.
[9]刘福田,曲克信,吴华,等.华北地区的地震层面成像[J].地球物理学报,1986,29(5):442～449.
[10]朱露培,曾融生,刘福田.京津唐张地区地壳与上地幔三维P波速度结构[J].地球物理学报,1990,33(3):253～269.
[11]孙若昧,刘福田.京津唐地区地壳结构与强震的发生_I_P波速度结构[J].地球物理学报,1995,38(5):599～607.
[12]孙若昧,赵燕来,吴丹.京津唐地区地壳结构与强震的发生——Ⅱ.S波速度结构[J].地球物理学报,1996,39(3):347～355.
[13]丁志峰.近震层析成像的理论及应用[J].国际地震动态,2000(10):37～38.
[14]于湘伟,陈运泰,王培德.京津唐地区中上地壳三维P波速度结构[J].地震学报,2003,25(1):1～14.
[15]黄金莉,赵大鹏.首都圈地区地壳三维P波速度细结构与强震孕育的深部构造环境[J].科学通报,2005,50(4):348～355.
[16]齐诚,赵大鹏,陈顒.首都圈地壳P波和S波三维速度结构及其与大地震的关系[J].地球物理学报,2006,49(3):805～815.
[17]张亚明,孟朴在,滕吉文,等.京津唐及邻区地壳结构的中新生代构造运动响应[J].地球物理学报,2008,51(4):1123～1134.
[18]罗艳,崇家军,倪四道,等.首都圈地区莫霍面起伏及沉积层厚度[J].地球物理学报,2008,51(4):1135～1145.
[19]Z J Zhang,X Zhang,JoséBadal.Composition ofthe crust beneath southeastern China derived from anintegrated geophysical data set[J].Journal of physi-cal Research,2008,113:25.doi:10.1029/2006JB004503.
[20]张金清,梁青,陈超.软弱夹层瑞雷面波频散曲线特征[J].工程地球物理学报,2005,2(3):208～215.
[21]陈健,杨永波,张永.瑞雷波在块石强夯地基质量检测中的应用[J].工程地球物理学报,2005,2(5):365～368.
[22]M Choura,J Badal,V Corchete.A survey of theshallow structure beneath the Alboran Sea using Rg-waves and 3Dimaging[J].Tectonophysics,2001,335(19):255～273.
[23]徐锡伟.首都圈地区地壳最新构造变动与地震[M].北京:科学出版社,2002.
[24]史海霞.首都圈地区地震动场地效应研究[D].北京:中国地震局地震预测研究所,2008.
[25]胡中民,王夫运,刘明军.用DSS资料研究首都圈地区的地壳结[J].华南地震,2008,28(1):41～51.
[26]王峻,刘启元,陈九辉.首都圈地区的地壳厚度及泊松比[J].地球物理学报,2009,52(1):57～66.
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