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

摘要： 长期以来滑坡发育与活动断裂之间的关系备受关注。从活动构造和灾害地质的角度，调查并研究了金沙江断裂带的晚第四纪活动性，并着重分析大型滑坡与金沙江断裂带活动的关系。金沙江断裂带是一条规模宏大而长期活动的缝合线构造，断裂结构复杂，构成宽约50km构造带。它曾是一条具挤压性质的超岩石圈断裂带，上新世以来表现为右旋走滑运动。曾大同、徐龙、尼中、里甫-日雨、郎中和古学断裂沿线断层地貌清晰，表现为平直的断层槽地、线性山脊和断层陡崖等；地质调查和年代学测试结果表明，这些断裂断错了晚更新世~全新世堆积，在晚第四纪具有明显的活动迹象。研究区滑坡具有发生频率高、规模大、破坏性严重之特点。拿荣至绒学长38km的沿江区段内金沙江两岸共发育20余个特大型及大型滑坡，体积一般大于1000×104m3，有的超过10000×104m3，且几乎所有滑坡位于活动断裂上及两侧1km范围内。这些大型滑坡群的发生，与金沙江断裂带的长期活动、演化历史和复杂结构等有密切关系，它不仅使岩体结构变得支离破碎，且持续的活断层作用成为滑坡发生的主要根由。断裂结构组合分析发现，紧密相邻的断裂间、断裂交汇的锐角区、断裂右向转弯部位和主断裂与横向断裂交汇区等特殊构造部位，为构造应力易于集中、有利于特大型滑坡发生的关键部位。活动断裂对滑坡的控制性作用不仅表现在大震过程中，在非地震作用的自然状态下同样能导致大型滑坡的密集发生。此研究对认识金沙江两岸大型滑坡灾害的形成机制和发育规律，以及深刻理解活动断裂与大型滑坡之间的关系具有积极的科学意义。

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