关键词: 巧家古滑坡;地质构造;断裂带;成因分析;金沙江;

Abstract: Qiaojia section of Jinsha River is located in the southeast margin of Qinghai-Tibet Plateau, with active fault zone and frequent earthquakes. According to satellite images, geological conditions and field investigation data of Qiaojia section of Jinsha River, the development characteristics, formation conditions and occurrence time of Qiaojia ancient landslide were analyzed. It was found that Qiaojia slope had landslide features and the Jinsha River at the front edge of the slope toe was curved abnormally, so it was inferred that the Qiaojia slope was an ancient landslide. The lithology of Qiaojia ancient landslide was relatively loose with about 5.5 km length and 9 km width, and an average thickness of 250 m and an estimated volume of 1.2 billion m3, which was a giant landslide. The occurrence of Qiaojia ancient landslide was closely related to slope morphology, lithologic characteristics, fault zone activity and earthquake. The occurrence state of the terrace at the foot of the slope indicated that the landslide occurred (960±100) thousand years ago. Under the coupling action of earthquake, heavy rainfall and reservoir water fluctuation, Qiaojia giant ancient landslide had the possibility of resurrection. Therefore, it is of great significance to study the geological characteristics and formation conditions of Qiaojia ancient landslide for landslide stability analysis and landslide disaster prevention.

Key words: Qiaojia ancient landslide; geological tectonic; fracture zone; cause analysis; Jinsha River