Abstract:

Ground surface deformations due to some kinds of active structures have been modeled by the boundary element method. In terms of the theoretical results and the related geological data for the Xianshuihe fault zone, the formation mechanisms of the Dandu upheaval along the northwestern segment of the fault zone and the Huiyuansi pullapart basin in the middle have been discussed. It is concluded that the Dandu upheaval is caused by the local horizontal stress concentration due to the barrier of the fault bend to the left lateral strike slip on it; and the Huiyuansi basin reflects the effect of horizontal extension in the crust which is created by the non-equal left lateral strike slips on the two left stepping faults. Such structures may show the segmentation of the Xianshuihe fault zone and could control to some extent the start and end of some seismic ruptures.

Key words: Xianshuihe fault zone, Geomorphological feature, Boundary element model, Formation mechanism

摘要：

应用边界单元法数值模拟了几种活动构造的地面形变效应。在此基础上,结合有关地质资料讨论了鲜水河断裂带西北段旦都隆起和中段惠远寺拉分盆地的形成机制。结果表明,前者是断层拐点对左旋走滑运动的障碍导致的水平应力集中所引起,后者则反映了左行羽列断层不等规模反扭造成的水平拉伸效应。这些特征地貌在某种程度上显示了该断裂带的分段性,并对地震破裂的起止具有某种控制作用。

关键词: 鲜水河断裂带, 地貌特征, 边界单元模型, 成因机制