Abstract:

Based on the geological and geomorphological research of geometric distribution,segmentation and segment boundaries of the northern piedmont fault of Liuleng Mountain,we suggest thatthis active fault can be divided into four segments.The eastern segment is considered to be theearly Pleistocene active fault and the other three segments to the late Pleistocene-Holocene activefaults. The length of the segments is 10～39 km. This fault was a thrust fault in the late Mesozoic,but in the Cenozoic it turned into normal fault due to the change of regional stress field.The vertical displacement on each segment is characterized by enveloping curve,with its unequalaverage vertical slip rate. The rate is high in the west and gradually decreases from west to east,suggesting a difference of the activity along the fault.

Key words: Fen-Wei seismotectonic zone, Active fault, Fault displacement rate, Fault segmentatlon

摘要：

通过对六棱山北麓活动断裂的几何结构、分段活动特征及段落边界等方面的地质地貌调查与研究,认为该活动断裂可分为4段,除东段在早更新世有过活动外,其他3段均为晚更新世晚期～全新世活动段,段落长度10～39km.该断裂在晚中生代表现为逆冲性质,至新生代随区域构造应力场的变化而转变为倾滑正断层。各段落上垂直位移量分布呈包络线状,而且各段平均滑动速率不同,西大东小,显示断裂新活动强度自西向东变弱。

关键词: 汾渭地震构造带, 活动断裂, 断层位移速率, 断层分段