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本文利用人工地震探测剖面获得的E-W向S波数据,参考P波资料,利用正演算法对该条剖面获得的Sg、Sc1、Sc2、SmS及Sn波波组信息进行了相关计算与处理,获得了沿剖面S波的地壳二维速度结构,结果显示:银川盆地及其两侧区域的地壳速度结构和壳内界面分层都显示出较大的差异.银川盆地及其以西区段呈现四层地壳结构,鄂尔多斯块体内部由西向东C2界面逐渐缺失,显示三层地壳结构特征.且壳内界面及速度等值线变化相对平缓,显示出稳定的地壳结构特征.剖面中段的银川盆地沉积盖层埋深最深达到7.6 km,盆地下方Moho界面的隆起与基底的凹陷呈镜像关系,隆起最浅处深度为38.5 km左右.银川盆地西缘至阿拉善块体边缘中下地壳内出现局部低速异常,横向影响范围达到120 km左右,速度值明显比周围介质低0.15~0.28 km/s个量级,壳内界面起伏变化剧烈,与两侧块体接触及其耦合部位速度结构异常紊乱,显示出断陷活动、地壳不稳定的特征.阿拉善块体壳内速度等值线变化较为平缓,Moho界面相对其他块体显示出较深的深度.沿剖面从获得的S波二维速度结构特征可以看出各块体地壳速度结构特征、深部构造环境、以及深部介质物性差异,揭示了银川盆地在周围块体相互运动、碰撞、挤压背景下的应力变形特征.
In this paper, the EW-S wave data obtained by the artificial seismic exploration section are used to calculate and process the Sg, Sc1, Sc2, SmS and Sn wave group information obtained by using the forward algorithm with reference to P-wave data. The crustal two-dimensional velocity structure along the S-wave profile shows that the crustal velocity structure and the interfacial delamination of the crust in the Yinchuan basin and the two sides show great differences. The Yinchuan basin and its west section show four layers Crustal structure, the Ordos block gradually disappears from west to east C2 interface, showing the characteristics of the three layers of crustal structure, and the variation of the in-shell interface and velocity contour is relatively gentle, showing a stable crustal structure characteristics.The mid-section of the Yinchuan Basin sedimentary cover The depth of the deepest layer reaches to 7.6 km, and the uplift of the Moho interface beneath the basin is mirror image of the basement depression with a depth of 38.5 km at the shallowest of the uplift. Local low-velocity anomalies occur in the middle and lower crust of the margin of the Alxa Block in the Yinchuan Basin , The horizontal influence range reaches about 120 km, the velocity value is obviously lower than the surrounding medium by 0.15 ~ 0.28 km / s, and the fluctuation of the interface in the shell changes violently. The contact with the two blocks and the coupling part The velocity structure is anomalous disorder, showing the characteristics of tectonic movement and unstable crust.However, the velocity contours of the Alashan block change more moderately and the Moho interface shows a deeper depth than the other blocks.With the S The characteristics of crustal velocity structure, deep tectonic environment and the difference of physical properties in deep media can be seen from the two-dimensional structural features of wave velocity. The stress-strain characteristics of the surrounding blocks in the context of mutual motion, collisions and extrusion are revealed.