| 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，是研究区内历史构造活动的良好地质载体。本文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、地质测年和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，发育于寒武系中下统灰岩和板岩地层中，体积为142.5× 104~237.5×104 m3，历史上堵塞巴曲，现今残留有滑坡坝和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。 |
| 关键词: 古滑坡 发育特征 地质年代 形成机制 巴塘断裂带 |
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| 基金项目:国家自然科学基金项目（面上项目，重点项目，重大项目） |
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| Formation Mechanism of the Huangcaoping Landslide in the Batang Fault Zone, Western Sichuan |
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WU Ruian1, NI Jiawei2, GUO Changbao1, ZHONG Ning1, ZHANG Xujiao2, YANG Zhihua1
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1.Institute of Geomechanics, Chinese Academy of Geological Sciences;2.School of Earth Sciences and Resources, China University of Geosciences
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| Abstract: |
| There are a large number of landslides triggered by earthquake in the Batang fault zone on the eastern margin of the Qinghai-Tibet Plateau, and some evidences of blocking the river are preserved. It is a good geological carrier for tectonic historical activities in the study area. This paper takes Huangcaoping landslide in Batang County, western Sichuan as the study object. Study the development characteristics, formation and evolution process of the landslide through remote sensing interpretation, ground investigation, geological dating, and engineering geological analysis. The results are listed as follows. (1) The Huangcaoping landslide is a large-scale Holocene rock landslide in the Batang fault zone, developed in the Middle-Lower Cambrian strata, with a volume of 142.6×104~237.5×104 m3. Baqu has been blocked in history, and there are evidences of the landslide blocking the river such as landslide dam and lake sediment. (2) Huangcaoping paleo-landslide dammed lake was formed about 7.75 ka B.P., the dam failure time was about 1.07 ka B.P. from now, and the dammed lake preserved more than 6.68 ka. (3) The Huangcaoping landslide is unlikely to be directly induced by rainfall, glaciers and freeze-thaw. The strong earthquake caused by the violent activities of the Batang fault zone could be the direct cause. Under the action of strong earthquakes, the slate near the fault at the toe of the slope sheared failure first. The upper limestone structural deteriorates and the sliding surface was penetrated. The sliding mass started as a whole and slid at a high speed to block the Baqu and form a dammed lake. The study results can not only provide a reference for the analysis of the formation mechanism of similar landslides triggered by earthquake in the 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 activitiy history. |
| Key words: paleo-landslide developmental characteristics geologic age formation mechanism Batang fault zone |