摘要
多拉寺滑坡是位于怒江构造混杂岩带的特大型古滑坡,具有典型的地质构造与特殊岩性联合控制的特点.采用现场调查和地球物理勘查、无人机测绘、岩土力学和年代学测试等技术手段,揭示了多拉寺滑坡的易滑地质结构、多期次发育特征及高位启滑机制.结果表明:(1)厚层大理岩与蛇纹岩交互堆叠及黏土化蚀变带是多拉寺滑坡重要的易滑地质结构,蚀变黏土是影响滑坡高速远程运移的重要因素.(2)多拉寺滑坡具有多期活动特征,可划分出主滑体区、次级滑体区和现代崩积区,主滑体的形成时代为距今19.4±2.8 ka,次级滑体为距今4.24±0.35 ka.(3)主滑坡体的高位启滑过程与陡峻的斜坡地貌、岩溶多重渗透结构、蚀变黏土的软弱基座效应、地震动力促发作用等因素密切相关.(4)主滑坡体呈现上部粗大块石与下部细粒物质分层堆积的伪地层模式,说明滑坡整体以剪切运动为主,滑坡上部物质比下部物质运动得更快.上述认识可为青藏高原东缘构造混杂岩带大型滑坡形成机制研究和风险防控提供参考依据.
The Duolasi landslide is a super-large scale ancient landslide located in the Nu River tectonic mélange belt,which is characterized by the combination control of typical geological structure and special lithology.In this paper,several technical means,such as field investigation,geophysical exploration,unmanned aerial vehicle mapping,geo-mechanics and chronological testing,were applied to reveal the prone sliding geological structure,multi-stage development characteristics and high-position initiating mechanism of the Duolasi landslide.The results show follows:(1)The thick-bedded marble and ophiolite are stacked alternately and the corresponding clay-altered zone is an important prone-sliding geological structure of the Duolasi landslide.The altered clay is an important factor to the high-speed and long run-out of the landslide.(2)The Duolasi landslide has the characteristics of multi-stage activity,and can be divided into the main sliding body area,the secondary sliding body area and the modern colluvial area.The formation age of the main sliding body is 19.4±2.8 ka,and that of the secondary sliding bodies is 4.24±0.35 ka.(3)The high-position initiating process of the main landslide is closely related to factors such as steep slope landform,multi-permeable karst structure,weak base effect of altered clay,and seismic dynamic triggering.(4)The main landslide presents a pseudo-stratigraphic pattern of layered accumulation,i.e.,coarse boulders in the upper part and fine-grained materials in the lower part,indicating that the overall landslide is mainly shear motion,and the material in the upper part of the landslide moves faster than the material in the lower part.The above understanding can provide a reference for the formation mechanism research and risk control of large scale landslides in the tectonic mélange belt on the east Tibetan plateau.
作者
张永双
任三绍
李金秋
廖国忠
Zhang Yongshuang;Ren Sanshao;Li Jinqiu;Liao Guozhong(School of Engineering and Technology,China University of Geosciences,Beijing 100083,China;Institute of Hydrogeology and Environmental Geology,Chinese Academy of Geological Sciences,Shijiazhuang 050061,China;Chengdu Center,China Geological Survey,Chengdu,610081,China)
出处
《地球科学》
EI
CAS
CSCD
北大核心
2023年第12期4668-4679,共12页
Earth Science
基金
国家自然科学基金项目(No.41941017)
科技部重点研发项目(No.2021YFB2301305)
中央院所基本科研业务费项目(No.SK202109)。
关键词
易滑地质结构
黏土化蚀变岩
构造混杂岩带
高位滑坡
伪地层模式
工程地质
prone sliding geo-structure
clayey altered rock
tectonic mélange belt
high-position landslide
pseudo-stratigraphic model
engineering geology
