Earth Science Frontiers ›› 2021, Vol. 28 ›› Issue (2): 71-84.DOI: 10.13745/j.esf.sf.2020.9.2

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Recent research on the Diexi paleo-landslide: dam and lacustrine deposits upstream of the Minjiang River, Sichuan, China

FAN Xuanmei(), DAI Lanxin, ZHONG Yujin, LI Jingjuan, WANG Lansheng   

  1. State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu 610059, China
  • Received:2020-08-20 Revised:2020-09-10 Online:2021-03-25 Published:2021-04-03


A paleo-lacustrine deposit, more than 200 m thick, named the “Diexi paleo-landslide-dammed lake deposit” was found upstream of the Minjiang River in Sichuan Province. The paleo-lake was formed around 30 ka BP and the dam started to fail around 15 ka BP. Therefore, the paleo-lacustrine deposit could have recorded important geological and geoenvironmental events (earthquakes, paleo-climate changes, etc.) during the period from the late Pleistocene to Holocene. The formation and evolution of the Diexi paleo-landslide and the landslide-dammed lake are poorly understood. Through detailed field investigation and LiDAR measurements, we constructed a 3D geological model and found the geomorphological and geological evidence to determine the boundary and volume of the paleo-landslide that formed the Diexi paleo-lake deposit. Using geophysical measurements (ERT) and laser grain size analysis, we determined the internal structure of the landslide deposit. We then reconstructed and analyzed the extent, volume, and sedimentological features of the paleo-lake based on a survey of outcrops and boreholes, and discussed the possible failure processes of the paleo-dam and its implications for the migration of prehistoric settlements. The results indicate that the Diexi paleo-landslide not only completely blocked the Minjiang River but also blocked its upstream branches, with the deposit volume reaching 1400×10 6-2000×106 m3. The paleo-lake extended upstream to about 26 km behind the dam; the maximum surface area and volume of the lake was approximately 21.4 km2 and 1670 × 10 6 m3, respectively. The paleo-landslide caused a knickpoint that may have a long-term impact on the mountain landscape evolution in the region.

Key words: earthquake, paleo-landslide, paleo-landslide dam and dammed lake, dam-breach flood, prehistorical settlements

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