天津—北京高分辨地震折射剖面初至波走时成像
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摘要
利用走时成像中的正则化反演方法对天津—北京的高分辨地震折射剖面获得的初至波资料进行成像。分析了不同的初始模型和参数变化对反演结果的影响,并采用检测板方法对最终模型的分辨进行评估,得到了天津-北京剖面的上地壳精细速度结构,给出了该地区的隐伏断层。结果显示,最终模型分辨达到5km×1km,部分地区更加细致;研究区域坳陷区与隆起区相间,大坳陷内部有小坳陷;结晶基底的深度变化约2～8km,其起伏形态符合地质构造情况;断裂活动和第三系以来的壳内运动对速度结构影响较大。
The traveltimes tomography of first arrive waves along Tianjin-Beijing profile with high resolution is done using regularization inversion method.The impacts on the inversion results from very different starting models and inversion parameters are analyzed,the resolution of the final model is assessed by the checkboard method,and the upper crust fine structure with blind faults in the study area is obtained finally.The results show that the resolution of the final model is up to 5 km×1 km with some are more fine.The study region is alternate by depressed areas with upheaval areas,and small sags are within big ones.The depths of crystalline basement change in the range of 2-8 km and its fluctuant pattern complies with the geological tectonic characteristics.The fault activity and crustal moment since Tertiary have greater impact on the velocity structure of this region.
The traveltimes tomography of first arrive waves along Tianjin-Beijing profile with high resolution is done using regularization inversion method.The impacts on the inversion results from very different starting models and inversion parameters are analyzed,the resolution of the final model is assessed by the checkboard method,and the upper crust fine structure with blind faults in the study area is obtained finally.The results show that the resolution of the final model is up to 5 km×1 km with some are more fine.The study region is alternate by depressed areas with upheaval areas,and small sags are within big ones.The depths of crystalline basement change in the range of 2-8 km and its fluctuant pattern complies with the geological tectonic characteristics.The fault activity and crustal moment since Tertiary have greater impact on the velocity structure of this region.
引文
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[15]王椿庸,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[J].地球物理学报.1997,40(4):459-501.
[2]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[J].地球物理学报,2002,45(3):362-369.
[3]嘉世旭,张成科,赵金仁,等.华北东北部裂陷盆地与燕山隆起地壳结构[J].地球物理学报,2009,52(1):99-110.
[4]嘉世旭,齐诚,王夫运,等.首都圈地壳网格化三维结构[J].地球物理学报,2005,48(6):1316-1324.
[5]王帅军,张先康,张成科,等.武清—北京—赤城二维地壳结构和构造[J].地球物理学报,2007,50(6):1769-1777.
[6]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.
[7]Colin A Zelt,P J Barton.3Dseismic refraction tomography:A comparison of two methods applied to data from the FaeroeBasin[J].J.Geophys.Res.,1998,103,7187-7210.
[8]Priyank Jaiswal,Colin A Zelt,et al.2-D traveltime and wave-form inversion for improved seismic imaging:Naga Thrust andFold Belt,India[J].Geophys.J.Int.,2008,173,642-658.
[9]Hole J A.Nonlinear High-Resolution Three-DimensionalSeismic Travel Time Tomography[J].J.Geophys.Res.,1992,97(B5):6553-6562.
[10]Vidale John.Finite-difference calculation of travel times[J].Bulletin of the Seismological Society of America,1988,78(6):2062-2076.
[11]Vidale John.Finite-difference calculation of traveltimes inthree dimensions[J].Geophysics,1990:55,521-526.
[12]Toomey D R,Solomon S C,Purdy G M.Tomographic ima-ging of the shallow crustal structure of the East Pacific Riseat9°30N[J].J.geophys.Res.,1994,99,24135-24157.
[13]张元生,徐果明.联合利用走时与波形反演技术研究地壳三维速度结构(Ⅰ):理论与方法[J].西北地震学报,1998,20(2):8-15.
[14]张元生,徐果明.联合利用走时与波形反演技术研究地壳三维速度结构(Ⅱ):应用[J].西北地震学报,1998,20(3):44-51.
[15]王椿庸,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[J].地球物理学报.1997,40(4):459-501.
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