渭河断裂西段活动差异性分析

渭河断裂是一条纵贯渭河盆地中部的大断裂，对渭河盆地的形成和发展乃至盆地内的地震活动都具有控制作用。本文将宝鸡峡口以东，西安市草滩镇以西的渭河断裂西段作为研究区。从渭河断裂北侧黄土台源地貌存在的分级现象、自西向东渭河断裂新近系错距大小非均匀变化、渭河断裂西段断坎地貌差异等方面的分析，讨论了渭河断裂西段存在的活动差异性，认为以千河断裂、岐山-马召断裂和泾河推测断裂为分界点，渭河断裂西段可分为三个亚段，各个亚段在断裂活动时间、活动强度等方面均有明显的差异。通过对渭河断裂西段所处新构造环境的分析，认为第四纪以来渭河盆地西部地壳的向东掀斜拾升运动是造成渭河断裂西段出现差异性活动的根本原因。

Analysis of Activity Difference of the West Section of the Weihe Fault

The Weihe fault is a large fault which traverses the central section of the Weihe basin. It controls the formation and growth of the Weihe basin, as well as the seismic activity in the basin. Taking the west section of the Weihe fault stretching from the Baoji Gorge to Caotan Village of Xi'an city as a study area, this paper analyzes and discusses the activity difference of the west section of the Weihe fault based on the grading phenomenon of the loess platform geomorphology on the north side of the Weihe fault, uneven changes of fault displacement of the Tertiary system from west to east, and geographic difference of the steep faulting slope along the west section of the Weihe fault. It is considered that the west section of the Weihe fault can be divided into three sub-sections : the eastern, middle and western ones, and they are different distinctly in fault active period and active strength. Through the analysis of the Neotectonic environment of the west section of the Weihe fault, this paper also considers that the crust tilting movement characterized by eastward upwarping in the west part of the Weihe basin since Quaternary is the main cause of the activity difference of the west section of the Weihe fault.