马边-雷波峨边-金阳大断裂构造特征及活动性

Characteristics and Activity of the Mabian-Leibo-Ebian-Jinyang Major Fault

地质调查中,利用断层泥石英颗粒形貌扫描分析及石英电子自旋共振(ESR)测年等方法对四川马边-雷波地区峨边-金阳大断裂的构造特征及活动性进行分析,认为该大断裂形成于燕山期后,总体呈南北走向,西倾,主体为由西向东脆性逆冲运动,是在区域隔挡式褶皱基础上进一步构造变形形成的走向断裂,由多条近于平行的逆冲断层呈叠瓦状组成。该断裂可划分出三个构造期次:第一期为由西向东逆冲运动,主断裂形成,第二期为右行剪切运动,第三期为左行拉张运动。该断裂中更新世以来活动性明显。

Study of the texture of fault gouge quartz grain surface under scanning electronic microscope and quartz electron spin resonance dating indicate that the Mabian-Leibo-Ebian-Jinyang major fault is a longitudinal fault consisting of multiple parallel imbricate thrusts formed based on regional wide-spread fold in the post-Yanshanian epoch.It may be divided into tectonically active phases:eastward thrust movement responsible for main fracture,right-lateral shear slide and left-lateral extensional faulting.It has been strong active since the Pleistocene.