阿尔金断裂系及其邻区中——新生代构造演化

Tectonic Evolution of the Altun Fault System and Its Adjacent Areas in the Meso-Cenozoic

对阿尔金断裂系及邻区的重磁电、遥感及地面地质研究表明,该断裂系展布经敦煌、金塔进入银根—额济纳旗盆地沿鼎新、务桃亥向恩格日乌苏东北向延伸,该断裂系的中—新生代构造演化可划分为6个阶段:印支期、燕山早期、燕山中期、燕山晚期、早喜马拉雅期、晚喜马拉雅—新构造期。每个阶段有不同的构造应力场、不同性质的断裂活动以及不同的盆地类型和沉积特征。走滑活动基本贯穿了整个中—新生代,但不同时期的走滑方向、走滑强度大小及走滑性质有所差异。侏罗纪—白垩纪是沉积盆地主要走滑拉分裂陷时期,在造山带和隆起带前缘形成走滑拉分裂陷盆地。第三纪、第四纪转为前陆盆地发育时期。

According to research results of gravity, magnetic exploration, electrical prospecting, remote sensing and surface geology, this paper points out that the Altun fault system stretches along Dunhuang and Jinta into the Yinggen—Ejin Basin and then extends northeastwards along Dingxin and Wutaohai to Engger Us,and proposes that the Meso-Cenozoic tectonic evolution of the system is divided into six stages:Indosinian, Early Yanshanian, Middle Yanshanian, Late Yanshanian, Early Himalayan and Himalayan—Neotectonic stages. Each stage has a special tectonic stress field, faulting behaviour, basin type and depositional characteristics. In the whole Meso-Cenozoic Era, there occurred strike-slip activity withdifferent directions, intensities and natures in different stages. The Jurassic—Cretaceous period is a major stage in which a series of strike-slip rift basins were formed in the frontal regions of the orogens and uplift zones, and the Tertiary—Quaternary period became another major stage in which foreland basins were well developed.