四川南部及邻区地壳活动性研究

STUDY ON THE CRUSTAL ACTIVITY IN THE SOUTHERN SICHUAN AND THE PARTIAL AREAS OF YUNNAN AND GUIZHOU PROVINCES

摘要:

本文依据表层构造辰布特征、重力、磁力场背景及航磁资料反映的基底构造性质,对四川盆地南部及相邻的滇黔部分地区的地壳结构、构造应力场及潜在的震源区进行了深入探讨。研究表明,该区的构造应力场具有多向性和多期性,在古生代,主压应力方向为近南北向,近代转为近东西向。东西向深断裂活动微弱,仅发生一些微小地震,但东西向深断裂与其他方向断裂交汇区往往是发生地震的场所。另外,不同岩性的基底接壤地带也是地震多发区。

Abstract:

Based on the splaying features of surface structure, the background of gravity field and magnetic field, and the basement structure features from aeromagnetic survey, the crustal structure, tectonic stress field and potential focal region in the southern Sichuan Basin and the adjacent areas of Yunnan and Guizhou provinces are discussed. The results show that the tectonic stress field of these areas is of multidirectivity and multiperiodicity. In Palaeozoic era the direction of principal compression stress was about SN, and now about EW. The deep fault activity in EW is not obvious, only has a few of microearthquakes. But the areas Which EW deep faults intersect other direc tional faults often occur earthquakes. And the areas which the basements, of different rock feature border on are also the seismic prone areas.