青藏高原东北部东西向构造及其地震活动和构造力学模式研究

STUDY ON GEOPHYSICAL FEATURES OF THE EW DIRECTIONAL TECTONICS, EARTHQUAKE ACTIVITIES AND TECTONIC MECHANICAL MODELS IN THE NORTHEASTERN QINGHAI-TIBET PLATEAU

摘要:

本文通过对重力和航磁资料解译,研究了青藏高原东北部东西向构造特征。在该区域存在6条大型东西向构造带,它们的共同特点是:(1)东西向延伸超过1000km,南北宽约60km;(2)越向深部东西向构造越明显;(3)两条相邻构造带的间距为1°20',显示等间距分布特征;(4)在大型东西向的构造带之外还有次级东西向构造带存在。青藏高原东北部强震活动与东西向构造有密切的关系,这是由于在北东向主压应力作用下东西向构造左旋剪切运动的结果。

Abstract:

According to the gravitational and aeromagnetic interpretation, there exist six larger-scale tectonic belts of EW direction in the crust in the northeastern Qinghai-Tibet Plateau, which have common features as follows:1) they all extend more than 1000 km from east to west and about 60 km from north to south. 2) the deeper it is, the more outstanding the EW directional tectonics is. 3) the central distance between the adjacent tectonic belts is 1°20' and has a equidistant feature. 4) there are also secondary tectonic, belts in EW strike beyond,the large-scale belts. The stong earthquake activities in the northeastern Plateau are closely related to the EW trending tectonic belts. The close relationship results from the left-lateral shear motion of EW structures under acting of the, principal compressive stress in the NE direction.