摘要
青藏高原东缘巴塘断裂带内地震滑坡大量发育,部分保存有堵江证据,是该区历史构造活动的良好地质载体。以川西地区巴塘县黄草坪滑坡为研究对象,通过遥感解译、现场调查、地质时代测年、工程地质分析等方法,对滑坡发育特征和形成演化过程进行研究。结果表明:(1)黄草坪滑坡为巴塘断裂带内全新世大型岩质滑坡,发育于中—下寒武统灰岩和板岩中,体积为142.5×10^(4)~237.5×10^(4)m^(3),历史上曾堰塞巴曲,现今残留滑坡坝、湖相沉积物等滑坡堵江证据;(2)滑坡堰塞湖形成于约7.75 ka B.P.,滑坡坝在约1.07 ka B.P.之后发生溃决,堰塞湖存续时间大于6.68 ka;(3)黄草坪滑坡由降雨、冰川和冻融作用直接诱发形成的可能性较小,巴塘断裂带剧烈活动引起的强烈地震可能是直接诱因,在强震作用下坡脚处断层附近的板岩首先发生剪切破坏,上部灰岩结构面劣化并形成贯通滑面,滑体整体启动并高速下滑堵塞巴曲形成堰塞湖。该研究成果不仅可以为区内类似地震滑坡的形成机制分析提供参考,同时佐证了巴塘断裂带为全新世活动断裂带,对分析巴塘断裂带活动性与完善重建区域构造活动历史具有重要意义。
There are a large number of landslides triggered by the earthquake in the Batang fault zone on the eastern margin of the Qinghai-Tibet Plateau,and some evidence of blocking the river are preserved.It is a good geological case for studying historical tectonic activities in the study area.This paper takes the Huangcaoping landslide in Batang County as a case,to study the development characteristics,formation,and evolution process of the landslide through remote sensing interpretation,ground investigation,geological dating,and engineering geological analysis.The study results are listed as follows:(1)The Huangcaoping landslide is a huge Holocene rock landslide in the Batang fault zone,developing in limestone and slate of the Middle-Lower Cambrian strata,with a volume of 142.5×10^(4)~237.5×10^(4) m^(3).That the Baqu river has been blocked in history is proved by the evidence of the landslide dam and lacustrine sediments.(2)The Huangcaoping landslide was formed in about 7.75 ka B.P.,the landslide dam failure was about in 1.07 ka B.P.from now,and the dammed lake had preserved more than 6.68 ka.(3)The Huangcaoping landslide is unlikely to be directly induced by rainfall,glaciers,and freeze-thaw.A strong earthquake caused by the violent activities of the Batang fault zone could be the direct triggering factor.Under the action of a strong earthquake,the slate near the fault at the toe of the slope is broken first.The upper limestone structural deteriorates and the sliding surface was formed.The sliding mass started as a whole and slid at a high speed to block the Baqu river.The study results can not only provide a reference for the analysis of the formation mechanism of similar landslides triggered by the earthquake in this region but also prove that the Batang fault zone is a Holocene active fault zone,which is of great significance for analyzing the activity of the Batang fault and improving the reconstruction of regional tectonic activity history.
作者
吴瑞安
倪嘉伟
郭长宝
钟宁
张绪教
杨志华
WU Ruian;NI Jiawei;GUO Changbao;ZHONG Ning;ZHANG Xujiao;YANG Zhihua(Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081,China;Key Laboratory of Active Tectonics and Geological Safety,Ministry of Natural Resources,Beijing 100081,China;Research Center of Neotectonism and Crustal Stability,China Geological Survey,Beijing 100081,China;School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China)
出处
《地质通报》
CAS
CSCD
北大核心
2021年第12期1992-2001,共10页
Geological Bulletin of China
基金
国家自然科学基金项目《青藏高原东缘古滑坡复活机理与早期识别研究》(批准号:41731287)
《高原峡谷区内外动力耦合致灾机理研究》(批准号:41941017)
中国地质调查局项目《川西—藏东地区交通廊道活动构造与地质调查》(编号:DD20190319)
中央科研院所基本科研业务费项目《川藏交通廊道水岩作用下大型深层滑坡灾变》(编号:DZLXJK202009)。
关键词
地震滑坡
发育特征
地质年代
形成机制
巴塘断裂带
seismic landslide
development characteristics
geologic age
formation mechanism
Batang fault
