关键词: 金沙江断裂带, 晚第四纪活动, 大型滑坡, 特殊构造部位, 关系

Abstract: The relationship between large-scale landslides and active faults has attracted much attention. From the point of view of active tectonic and disaster geology, the late Quaternary activity of the Jinsha River fault zone is investigated and studied, and the relationship between large-scale landslides and the activity of the Jinsha River fault zone is emphatically analyzed. The Jinsha River fault zone is a large-scale, long-term active suture structure, with many branches, forming a 50 km wide structural fracture zone. It was a strongly active super lithosphere fault zone with obvious compressional property，characterized by dextral shear since Pliocene influenced by the eastward extrusion of the Tibet Plateau. In the study area, the fault landforms along Zeng Datong, Xu Long , Ni Zhong , Lifu-Riyu, Lang Zhong and Guxue faults are clear, which are mainly manifested as straight fault trough, linear ridge, fault scarp, fault triangle and fault passes; results of field geological and geomorphological investigation and chronology show that the late Pleistocene and Holocene deposits are faulted, and indicated the faults are active during the late Quaternary. The landslide in the area has the characteristics of high frequency, large scale and serious damage. There are 23 large-scale and super large-scale landslides in the main stream and its tributaries of Jinsha River within 38 km from Narong to Rongxue. Most of them are super large-scale landslides with a volume of more than 10 million cubic meters, even have a volume of more than 100 million cubic meters. Most of the landslides are located within 1km on both sides of faults, and many of them are developed on the fault zone. The occurrence of these large-scale landslides is closely related to the long-term activity, movement and evolution history and complex structure of Jinsha River fault zone along the river. It not only makes the rock mass structure become fragmented, but also makes the continuous tectonic stress become the main cause of landslides. Further analysis of the fault structure shows that，being related to the movement evolution history of Jinsha River fault zone，the special structural combination parts (mechanical mechanism) such as the close adjacent faults, the acute angle area where faults intersect, the right turning part of the faults and the intersection area between the main faults and the transverse faults are the key sites where the structural stress is easy to concentrate and conducive to the occurrence of large-scale landslides. The controlling effect of active faults on landslides is not only during large earthquakes, but also in the natural state, promoting the intensive occurrence of giant landslides. This research has positive scientific significance for understanding the formation mechanism and development law of landslides on both sides of Jinsha River, and for understanding the relationship between fault activities and large landslides.

Key words: Jinsha river fault zone, late Quaternary activity, large-scale landslides, special structural position, relationship