安宁河断裂带新构造运动的初步研究

安宁河断裂带位于四川省西南部,是我国西南地区一条规模较大的、具有长期发育历史的深大断裂带。新第三纪以来,该断裂带新构造运动强烈。我们根据在西南地区进行地震地质考察取得的有关资料,并结合前人研究成果,对安宁河断裂带新构造运动的迹象、类型及特征作了初步综合分析,得出几点粗浅的看法,草成此文提出来与大家共同讨论。

A PRELIMINARY STUDY OF NEOTECTONIC MOVEMENT ALONG THE ANNINGHE FAULTING BELT

The Anninghe faulting belt is accepted as a large-scale deep faulting belt with a long history of development running in the southwestern part of China. The neo-tectonic characteristics of the faulting belt are that "they are divided into strips longitudinaly, and the stripes are cut into blocks further". The nature of tectonic activities of this belt can be proved not only by its left-lateral compressive shearing movement, which may be roughly correspond to the Sichuan movement (at the end of Cretaceous), but also by the intermittently northwards body upwarping and complex differential block movement. During its development in the different periods of geological history, the intensity of neotectonic movements had been decline northward and the width of such neotectonic belts being narrowing successively.Since the end of Early Pleistocene the intensive active belt concerned falls mainly along the eastern bank of River Anninghe, between Mianning county and Huanglianguan. Tectonically and geomorphologically this belt is characterized by the strong compressive deformation of younger beds (as Xigeda bed N2-Q1, Huanglianguan conglomerate-bed Q2), by the development of a system of graben and horst in transversal direction, and the longitudinal distribution of block uplift and depression in alternation. Therefore this faulting belt is referred to as "the youngest belt of neotectonic movement" according to its tectonic and geomorphological features and the relationship to the seismic activity. The belt under investigation is regarded just to be strong earthquake-generating belt.