A Preliminary Study on the Datong Fault Belt  

作　　者：Li Zhimin Tian Qinjian Yao Shenghai Li Wenqiao Chen Youshun Zou Haining Gao Zhanwu 

机构地区：[1]Earthquake Administration of Qinghai Province, Xining 810001, China [2]Institute of Earthquake Science, CEA, Beijing 100036, China

出　　处：《Earthquake Research in China》2008年第3期348-355,共8页中国地震研究（英文版）

基　　金：the Programof "City Active Fault Experimental Detection"(20042238);National Development and Reform Commission of People's Republic of China and the Earthquake Science Foundation of Qinghai Province (2006A03),China

摘　　要：The Datong fault belt is a NE trending fault in the northern Qinghai-Xizang （Tibet） Plateau and controls the boundary of the Xining Basin and Datong Basin. It consists of the Maziying- Miaogou （F1） fault and the Laoye Mountain-Nanmenxia fault （F2）. There is obvious displacement in vertical direction along the belt. The field investigation results show that this belt has long-term activity. There are several meters long crushed zones and veins along the fault side in the basement rock. On the fault section, the Cambria system thrusts over the red- brick-colored Quaternary Period gravel, and there is a fault gouge of several centimeters thick developed on the fault plane. The fault gouge date （ESR） on the fault plane is 610 ± 61ka. The covering deluvial loess is not dislocated, and the OSL result is 14.6 ± 1.5ka. So it can be concluded that the fault belt was active in the middle Pleistocene, but inactive in the late Pleistocene according to the age data and geomorphologic features. Interior formations of the Datong basin features fold with the major axis orienting northwest. According to the relation of fault and fold deformation, Datong fault is a trausversal tear, which is due to uneven compression of the folds in different parts and NNE trending regional compressive stress. It is common among the NE trending faults in the northeast of Qinghai-Xizang （Tibet） Plateau. These NE trending faults aren＇t large, and most are located in the active plate. They are all nearly vertical to the axis of the folds and compressive basins.The Datong fault belt is a NE trending fault in the northern Qinghai-Xizang (Tibet) Plateau and controls the boundary of the Xining Basin and Datong Basin. It consists of the Maziying-Miaogou (F_1) fault and the Laoye Mountain-Nanmenxia fault (F_2). There is obvious displacement in vertical direction along the belt. The field investigation results show that this belt has long-term activity. There are several meters long crushed zones and veins along the fault side in the basement rock. On the fault section,the Cambria system thrusts over the red-brick-colored Quaternary Period gravel,and there is a fault gouge of several centimeters thick developed on the fault plane. The fault gouge date (ESR) on the fault plane is 610±61ka. The covering deluvial loess is not dislocated,and the OSL result is 14.6±1.5ka. So it can be concluded that the fault belt was active in the middle Pleistocene,but inactive in the late Pleistocene according to the age data and geomorphologic features. Interior formations of the Datong basin features fold with the major axis orienting northwest. According to the relation of fault and fold deformation,Datong fault is a transversal tear,which is due to uneven compression of the folds in different parts and NNE trending regional compressive stress. It is common among the NE trending faults in the northeast of Qinghai-Xizang (Tibet) Plateau. These NE trending faults aren't large,and most are located in the active plate. They are all nearly vertical to the axis of the folds and compressive basins.

关 键 词：Datong fault Xiulng basins Active fault Qinghai-Xizang （Tibet） Plateau Northeastern faults Fold deformation 

分 类 号：P315[天文地球—地震学]