Formation and reactivationmechanisms of large-scale ancient landslides in the Longwu River basin in the northeast Tibetan Plateau, China Formation and reactivationmechanisms of large-scale ancient landslides in the Longwu River basin in the northeast Tibetan Plateau, China

最小化 最大化

Vol19 No.6: 1558-1575 

Title】Formation and reactivationmechanisms of large-scale ancient landslides in the Longwu River basin in the northeast Tibetan Plateau, China

Author】TIAN Jing-jing1; LI Tian-tao1*; PEI Xiang-jun1; DING Feng2; SUN Hao1; XIE Xian-gang3; GUO Jian4

Addresses】1 State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu 610059, China; 2 College of Earth Sciences, Chengdu University of Technology, Chengdu 610059, China; 3 School of Earth System Science, Tianjin University, Tianjin 300072, China; 4 Department of Civil Engineering, Panzhihua University, Panzhihua 617000, China

Corresponding author】LI Tian-tao

Citation:Tian JJ, Li TT, Pei XJ, et al. (2022) Formation and reactivation mechanisms of large-scale ancient landslides in the Longwu River basin in the northeast Tibetan Plateau, China. Journal of Mountain Science 19(6).https://doi.org/10.1007/s11629-021-7261-x

DOI】https://doi.org/10.1007/s11629-021-7261-x

Abstract】The northeastern Tibetan Plateau exhibits steep topography and strong internal or external dynamic geological effect and is frequently subjected to strong earthquakes and heavy rainfall. The geological evolution has resulted in a wide distribution of ancient landslides, which has become a hotspot for studying ancient landslide formation and reactivation. In recent decades, several ancient landslides on both banks of the Longwu River,Qinghai Province, Chinawere reactivated, causing serious economic losses and casualties. This study conducted remote sensing interpretation and ground surveys on these ancient landslides.Totally 59 ancient landslides were identified, and the formation mechanism, evolution process, and resurrection mechanism of the Longwu Xishan No.2 ancient landslide were analyzed by means of a detailed field geological survey, drilling, and series of experimental tests such as the particle size distribution test, the X-ray diffraction test and the mechanical properties test. The results show that the formation of these ancient landslides is closely associated with the uplift of the Tibetan Plateau and the erosion of the Longwu River. Firstly, the intermittent uplift of the Tibetan Plateau lead to the diversion and downcutting of the Longwu River basin, which forms the alternate slope topography with steep and slow slopes, thereby providing favourable topography and slope structure conditions for the formation of landslides. Secondly, 34.5% clay-mineral content in the Neoproterozoic mudstone with 32.7% particle size less than 0.005 mm, and the corrosion and softening effects of the Neogene mudstone with high clay mineral content under the erosion of water provides favourable material conditions for the formation of landslides.Thirdly, rainfall and human activities are the primary triggering factors for the revival of this ancient landslide group. It is revealed that the evolution process of the ancient landslides on both banks of the Longwu River can be divided into five stages namely tectonic rapid uplift slope formation, river erosion creep-sliding deformation, slope instability critical status, landslide failure-movement-accumulation, and slope reactivation under rainfall erosion and engineering excavation.

Keywords】Remote sensing interpretation; Tectonic movement; Ancient landslide; Reactivation mechanism; Formation process; Tibetan Plateau.