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本文利用华北地震科学台阵、鄂尔多斯及周缘地震台网和区域地震台网记录的62736个远震P波走时数据,获得了鄂尔多斯块体中部与华北地区之间400km深度范围内的P波三维速度结构.考虑到研究区的复杂地质结构,本文采用FMM算法和子空间反演算法进行地震层析成像.成像结果表明:1)研究区的地壳速度分布与地质构造格局的相关性显著,随着深度的增加相关性减弱;断裂带多为高速异常区和低速异常区的分界线.2)研究区东部的速度结构与鄂尔多斯块体相比存在明显的不均一性,上地幔高速异常具有南北不均匀性.表明华北克拉通破坏时东、西部的岩石圈可能经历了不同的构造变形过程,东部岩石圈受到大规模破坏,破坏后的上地幔物质呈南北向不均匀分布,西部鄂尔多斯块体岩石圈保持着相对稳定的克拉通特征,不存在大规模破坏的证据.3)华北克拉通的岩石圈厚度由东向西整体逐渐增加.东部在100km深度附近出现大范围的低速异常,表明在该深度已进入软流圈,西部鄂尔多斯块体的岩石圈厚度约为250km.4)鄂尔多斯块体的东边界在黄河以东的离石断裂带.
In this paper, 62736 teleseismic P-wave travel time records recorded by North China Seismological Science Array, Ordos and its peripheral seismographs and regional seismograph networks are used to obtain the P-wave three-dimensional velocities in the depth of 400 km between the central Ordos block and North China In view of the complicated geological structure of the study area, we use the FMM algorithm and the subspace inversion algorithm to do seismic tomography. The imaging results show that: 1) the correlation between the crustal velocity distribution and the geological structure pattern is significant; with the depth The fault zone mostly demarcates the high-speed anomalous zone and the low-speed anomaly zone.2) The velocity structure in the eastern part of the study area is obviously inhomogeneous compared with the Ordos block, and the upper mantle high-speed anomaly has the north-south unevenness It shows that the lithosphere in the eastern and western China may have undergone different tectonic deformation processes during the destruction of the North China Craton, large-scale destruction of the eastern lithosphere, the disintegrated upper mantle material is unevenly distributed from north to south, and the Ordos block lithosphere Maintain a relatively stable cratonic characteristics, there is no evidence of large-scale damage .3) North China craton lithosphere thickness by The whole area of the Ordos block gradually increases in the east, with large-scale low-velocity anomalies in the east at a depth of 100 km, indicating that the lithosphere thickness of the Ordos block in the western part of the Ordos block was about 250 km.4) To the east of the Lishi fracture zone.