Characteristics and Formation Mechanism of Giant Long‐Runout Landslide: A Case Study of the Gamisi Ancient Landslide in the Upper Minjiang River,China |
| |
| Authors: | GUO Changbao WU Ruian ZHANG Yongshuang REN Sanshao YANG Zhihua and LI Xue |
| |
| Institution: | 1 Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China
2 Key Laboratory of Active Tectonics and Crustal Stability Assessment, Beijing 100081, China,1 Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China,3 Tianjin Center, China Geological Survey, Tianjin 300170, China,1 Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China,1 Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China and 1 Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China |
| |
| Abstract: | The upper reaches of the Minjiang River are in the eastern margin of the Tibetan Plateau, where active faults are well developed and earthquakes frequently occur. Anomalous climate change and the extremely complex geomechanical properties of rock and soil have resulted in a number of geohazards. Based on the analysis of remote sensing interpretations, geological field surveys, geophysical prospecting and geological dating results, this paper discusses the developmental characteristics of the Gamisi ancient landslide in Songpan County, Sichuan Province, and investigates its geological age and formation mechanism. This study finds that the Gamisi ancient landslide is in the periglacial region of the Minshan Mountain and formed approximately 25 ka BP. The landslide initiation zone has a collapse and slide zone of approximately 22.65×106–31.7×106 m3 and shows a maximum sliding distance of approximately 1.42 km, with an elevation difference of approximately 310 m between the back wall of the landslide and the leading edge of the accumulation area. The landslide movement was characterized by a high speed and long runout. During the sliding process, the landslide body eroded and dammed the ancient Minjiang River valley. The ancient river channel was buried 30‐60 m below the surface of the landslide accumulation area. Geophysical prospecting and drilling observations revealed that the ancient riverbed was approximately 80‐100 m thick. After the dam broke, the Minjiang River was migrated to the current channel at the leading edge of the landslide. The Gamisi ancient landslide was greatly affected by the regional crustal uplift, topography, geomorphology and paleoclimatic change. The combined action of periglacial karstification and climate change caused the limestone at the rear edge of the landslide fractured, thus providing a lithological foundation for landslide occurrence. Intense tectonic activity along the Minjiang Fault, which runs through the middle and trailing parts of the Gamisi ancient landslide, may have been the main factor inducing landsliding. Studying the Gamisi ancient landslide is of great significance for investigating the regional response to paleoclimatic change and geomorphologic evolution of the Minjiang Fault since the late Pleistocene and for disaster prevention and mitigation. |
| |
| Keywords: | Tibetan plateau ancient landslide Gamisi long runout formation mechanism |
| 本文献已被 万方数据 等数据库收录！ |
| 点击此处可从《Acta Geologica Sinica》浏览原始摘要信息 |
| 点击此处可从《Acta Geologica Sinica》下载免费的PDF全文 |
|
