曲靖-昭通断裂带北段晚第四纪活动特征

Characteristics of the Late Quaternary Activities of the Northern Section of the Qujing-Zhaotong Active Fault Zone,Yunnan Province

曲靖-昭通断裂带(图1)北段南起昭通盆地,止于四川马边凹陷以北,全长180km。主要由大关口断裂、中坝断裂、高桥断裂、大毛滩断裂、玛瑙断裂和利店断裂以及与之平行的团山断裂、中(关)村断裂等组成。该断裂带总体走向南北,多数断裂为西倾的高角度逆冲断裂。该断裂带控制了部分中生代地层、古生代地层,可能还有震旦纪地层的沉积。因而认为此断裂带形成于晋宁运动之后。上新世以来,尤其是晚更新世以来有明显的活动,表现为以左旋走滑为主,兼有逆倾滑的运动特征。本文在前人资料的基础上,结合本课题的野外调查和航片解译,拟对该活动断裂带北段的几何展布,活动性状,运动学特征以及古地震等进行探讨。

The northern section of the Qujing-Zhaotong fault zone has been further divided into six segments in this paper,according to their geometry,geological and geomorphic features and slip rates.Obviously the fault zone has been active since the late Pleistocene;but the segments differed with one another in their activities.It can be seen from their slip rates that the northern and,secondly,southern segments are relatively strong,while the middle ones relatively weak.