Abstract: Based mainly on geological and geomorphological data collected from the northern boundary fault belt of Weihe Basin, combined with seismic and geophysic evidences found in recent years, the activity and faulting episode of the northern boundary fault belt,the displacements and slip rates of the main faults, as well as the characteristics of spatial and temporal evolution of the fault belt and its mechanics are discussed in this article. The main conclusions are as follows:1. The northern boundary fault belt has experienced eight episodes of faulting since Eocene. The main fault in the belt have an average slip rate ranging from 0.1 to 1.0mm/yr, with the eastern segment of the belt being more active than the western one since Pleiocene.2. The formation of the fault belt is the result of faulting spreading from the center of the basin to the north, but the spreading direction had a change in Pleiocene. The direction of spreading of the east segment changed from N to NW, while the west segment had only a slight change. This difference as well as the difference in fault activity between the east and west segments has a close relation to the influence of Shan-xi shear zone to the Weihe graben.

Key words: Weihe basin, Active -fault, Structural geomorphology

摘要： 本文从渭河盆地北缘断裂的形成和活动时代,活动特征等资料出发,结合北缘断裂带及整个盆地历史地震活动和新生界地层发育特征的综合分析,对北缘断裂带的活动期次,主要断层的运动幅度和滑动速率及其时空演变规律和机制等问题进行了探讨。文章指出,北缘断裂带的形成是一个由盆地中心向北逐渐扩展的过程,自上新世起,断层活动明显有东强西弱的变化特征,而且扩展方向也发生了偏转。这一转变及活动强度的东西差异与山西剪切带对渭河盆地的影响密切相关。

关键词: 渭河盆地, 活动断裂, 构造地貌