金沙江主断裂带中段构造特征与活动性研究

金沙江断裂带是一条具有多期活动的缝合线构造,由金沙江主断裂及其西界断裂、东界断裂等3条主要断裂和西支断裂、巴塘断裂以及其它一些近南北向的次级断裂组成,宽约50～60 km,总体走向近南北向,控制不同构造层的边界。大致以北侧巴塘断裂和南侧德钦-中甸-大具断裂为界,断裂带可分为北、中、南3段。通过地质调查、地震活动性研究及断裂带物质测年分析等,认为金沙江主断裂带中段各条次级断裂最新活动时代为早-中更新世至全新世,活动方式以右旋水平走滑兼逆冲运动为主。据断裂活动时代、滑动速率及历史地震活动情况等综合分析,认为金沙江主断裂带的里甫-日雨断裂、曾大同断裂等具有发生6.5级地震的构造条件。

Study on tectonic characteristics and activity of middle section of Jinshajiang Main Fault Zone

The Jinshajiang Fault Zone is a multi-stage active?stylolite, which is composed of three main faults including the Jinshajiang main fault, the West Boundary fault and the East Boundary fault, and other secondary faults such as the West Branch fault, the Batang fault and other north-south trending faults. The Jinshajiang fault zone is about 50-60 km wide, with a total north-south strike, controlling the boundary of different geological structures. The Jinshajiang fault zone can be divided into three sections(north, middle and south) by the north Batang fault and the south Deqin-Zhongdian-Daju fault. Through geological survey, seismicity study and fault zone material dating analysis, it is concluded that the latest active age of each secondary fault in the middle section of Jinshajiang main fault zone is from early Middle Pleistocene to Holocene, and the main active mode is dextral horizontal strike-slip and thrusting. According to the comprehensive analysis of faults active age, faults sliding rate and historical earthquake activity, it is considered that the Lifu-Riyu fault and the Zengdatong fault in the Jinshajiang main fault zone have tectonic conditions for the occurrence of 6.5 magnitude earthquake.