| 小江断裂带巧家段巨型古滑坡及其工程地质特征 |
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| 引用本文：冯振,吴中海,曹佳文,胡萌萌,哈广浩,康怀信.2019.小江断裂带巧家段巨型古滑坡及其工程地质特征[J].地球学报,40(4):629-636. |
| DOI：10.3975/cagsb.2019.012401 |
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| 基金项目:中国地质调查局地质调查项目(编号: DD20160268);国家自然科学基金项目(编号: 41571013) |
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| 中文摘要:巧家地处小江断裂带与则木河断裂、五莲峰断裂相交地带, 地质构造复杂, 断裂与地震活动频繁, 崩滑流地质灾害极为发育。通过遥感解译与工程地质分析, 在小江断裂带巧家段东侧识别出一处巨型古滑坡。巧家古滑坡平面形态为筲箕形, 堆积体长5.5 km, 宽9 km, 平均厚度约250 m, 预测体积达到约 10亿m3。古滑坡后缘为典型的圈椅状地貌, 两侧边界多沿基岩地层中的次级断层发育, 并在地表呈阶梯式的台阶状地形。堆积体的岩性主要由二叠系阳新组灰岩组成, 局部存在二叠系峨眉山组玄武岩, 多具碎裂-松散结构。整体上看, 该滑坡体风化强烈, 中前部发育大型纵向冲沟, 暗示形成时代较老。综合分析认为, 巧家古滑坡成因极可能是由于小江断裂带强烈左旋走滑作用下, 导致巧家东侧山地发生持续性的构造抬升, 并在巨大地震活动触发下形成。关于小江断裂带巧家段在未来的大地震活动背景下, 是否可能导致古巨型滑坡复活, 或该区是否还存在发生类似巨型地震滑坡的风险等问题, 显然值得进一步深入研究。 |
| 中文关键词:小江断裂带 金沙江 巨型古滑坡 地震地质灾害 工程地质 |
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| Engineering Geological Characteristics of Gigantic Pre-historic Landslide along Qiaojia Section of the Xiaojiang Fault |
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| Abstract:Qiaojia County is located at the intersection area of Xiaojiang fault, Zemuhe fault and Wulianfeng fault. This area is characterized by complicated geological structures, frequent fault and earthquake activities, and high susceptibility to geological hazards. To the east of the Qiaojia section of Xiaojiang fault, a gigantic pre-historic landslide was identified through remote sensing interpretation and engineering geology analysis. Displaced material of the Qiaojia landslide is 5.5 km long and 9 km wide. Estimation shows that the average depth is 250 m and the volume is 1×109 m3. The Qiaojia landslide has a shape of round-backed armchair. The lateral boundaries are developed along small-scale secondary faults. Terrace of displaced material consists of multiple flat to moderate benches connected with steep slopes. The Qiaojia landslide deposit is mainly composed of Permian limestone of Yangxin Formation and basalt of Emei Formation. The rock mass is heavily broken and cut into angular rocks by many intersecting discontinuity sets. The deposit has been intensively weathered with the preservation of several large-scale longitudinal gullies. It is believed that the Qiaojia landslide probably resulted from differential tectonic lift or strong earthquake due to intensive activity of Xiaojiang fault. Further research should be carried out to assess the risk of landslide reactivity or the possible generation of similar gigantic landslides under the condition of possible strong earthquake along the Qiaojia section of Xiaojiang fault. |
| keywords:Xiaojiang fault Jinsha River gigantic pre-historic landslide earthquake engineering geological characteristics |
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