| 岷江上游叠溪古滑坡坝—堰塞湖研究进展 |
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| 引用本文： | 范宣梅,戴岚欣,钟育瑾,李婧娟,王兰生.岷江上游叠溪古滑坡坝—堰塞湖研究进展[J].地学前缘,2021,28(2):71-84. |
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| 作者姓名： | 范宣梅 戴岚欣 钟育瑾 李婧娟 王兰生 |
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| 作者单位： | 成都理工大学地质灾害防治与地质环境保护国家重点实验室,四川成都610059 |
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| 基金项目： | 国家优秀青年科学基金项目(41622206);地质灾害防治与地质环境保护国家重点实验室团队重点课题项目(SKLGP2019Z002) |
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| 摘 要： | 四川岷江上游叠溪发育有一套厚度超过200 m、保存较为完整的湖相沉积,被定名为叠溪古堰塞湖相沉积,其形成于距今30 ka前,存活了约15 ka,因此记录了青藏高原东缘晚更新世—全新世(包括末次冰期)的重大地质与环境事件。现有研究初步揭示了古堰塞的沉积特征,但对叠溪古滑坡及古堰塞湖形成与演化的系统研究还十分不足。本文通过详细的野外调查,结合现代遥感测绘技术(无人机载LiDAR),构建叠溪古滑坡的三维地质模型,研究了其地质与地貌特征。同时,采用高密度电阻率法ERT,在滑坡体上布设2条长870 m和990 m的测线,探明了滑坡体内部结构特征。通过古堰塞湖相沉积露头和钻孔的调查,结合激光粒度测试,重建了古堰塞湖的范围、规模与沉积特征。在此基础上,通过对古湖相沉积坡面上多级阶地的分析,初步探讨了古堰塞湖的消亡及其对下游史前古聚落变迁的影响。研究结果表明,叠溪古滑坡不仅完全堵塞岷江而且还堵塞了对岸支沟,堆积体方量达到(1 400~2 000)×106 m3。古堰塞湖在滑坡坝后向上游延伸26 km,所形成的最大湖面覆盖面积约21.4 km2,库容蓄水量约1 670×106 m3。叠溪古滑坡-堰塞湖在岷江上游形成了陡峭的河道裂点(Knickpoint),对山区河道与地貌演化具有长期影响。
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| 关 键 词： | 地震 古滑坡 古滑坡坝-堰塞湖 溃坝洪水 史前聚落 |
| 收稿时间： | 2020-08-20 |
Recent research on the Diexi paleo-landslide: dam and lacustrine deposits upstream of the Minjiang River,Sichuan, China |
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| FAN Xuanmei,DAI Lanxin,ZHONG Yujin,LI Jingjuan,WANG Lansheng.Recent research on the Diexi paleo-landslide: dam and lacustrine deposits upstream of the Minjiang River,Sichuan, China[J].Earth Science Frontiers,2021,28(2):71-84. |
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| Authors: | FAN Xuanmei DAI Lanxin ZHONG Yujin LI Jingjuan WANG Lansheng |
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| Institution: | State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu 610059, China |
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| Abstract: | 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. |
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| Keywords: | earthquake paleo-landslide paleo-landslide dam and dammed lake dam-breach flood prehistorical settlements |
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