峨眉山玄武岩大规模灾难性崩滑事件的地质构造约束  

The Geological Structure Constraint for Massive and Catastrophic Landslides in Permian Emeishan Basalt

作　　者：徐则民[1,2] 黄润秋[2] 

机构地区：[1]昆明理工大学土木系,昆明650224 [2]地质灾害防治与地质环境保护国家重点实验室,成都610059

出　　处：《地质论评》2010年第2期224-236,共13页Geological Review

基　　金：国家自然科学基金(编号40572159;40772189);教育部高等学校博士点基金(编号20060674009);地质灾害防治与地质环境保护国家重点实验室开放基金(编号GZ2007-1;GZ2009-10)资助项目的成果

摘　　要：滇东台褶带内上二叠统峨眉山玄武岩(P3β)滑坡的规模、失稳方向及其灾难性并不是随机的而是受到了区内地质构造的严格约束。喜马拉雅运动使得包括P3β在内的地台盖层褶皱回返;赋存于单斜断块或褶皱翼部的P3β的倾斜状态为其顺层滑移奠定了基础。滇东台褶带构造线相对稀疏,P3β整体性较好,这对于其发生大规模失稳是重要的;控制P3β岩层产状的断裂和褶皱主要为北东向,这决定了其大规模失稳的主体方向只能为南东向或北西向。北东向构造线控制的不同级别河流下切所形成的同向线状空间为P3β顺层失稳提供了不同序次基准面。北东向干流的支流一般与其垂直或大角度斜交,它们的溯源侵蚀是P3β盖层剥离、P3β斜坡塑造、滑坡物质运移通道与堆积场所形成的直接贡献者。P3β滑坡的灾难性一方面与不同级别北东向干流及其北西向支流构成的网状负地形空间网络有关,同时还与P3β盖层建造特征有关。北东向干流河谷,尤其是其与支流汇合处多具较高的人口密度。北西向支流穿越的P3β盖层为一套易于风化成壤的陆相沉积岩系,不同支流之间的山地具有较高的土地开发程度或植被盖度。土(林)地及水资源的丰富程度及地形条件等因素共同导致北西向支流沟谷也具较高的人口密度。这样,P3β潜在滑坡运移路径及主堆积区内均有密集的人口分布,而滑坡一旦发生,结果很可能就是灾难性的。The size,sliding direction and catastrophe of the Upper Permian Emeishan basalt landslides in eastern Yunnan fold zone of Yangtze paraplatform is not stochastic but being constrained by the geological settings in this area. The Himalayan movement made the paraplatform cover sandwiching Emeishan basalt rise and being folded. The dip state of the Emeishan basalt layers which are interbedded in the monoclinal blocks and fold limbs makes the basis for their slide along the bedding plane. The tectonic lines in eastern Yunnan fold zone are relatively sparse and the higher integrality of the Emeishan basalt is of importance for the basalt massive sliding failure. The strikes of the faults and folds which regulate the attitude of the Emeishan basalt are mainly northeast direction,and thus the direction of the basalt sliding failures is southeast or northwest. Valleys cut by the trunk steams which develop along the faults and folds with northeast strike provide the Emeishan basalt failure with base levels. The branches are in general perpendicular to their trunk streams and their head erosions strip the overlying strata of the dip Emeishan basalt layers and provide the basalt landslides with migration pathways and depositing sites. Tremendous casualties given rise to by the Emeishan basalt landslides have relationship not only with reticulate negative relief cut by the above river system and it＇s northwest tributary,but also with formation character of the overlying strata of the Emeishan basalt. There is a higher population density in the valleys of northeast rivers,especially in the cross positions with their tributaries. The overlying strata of the Emeishan basalt that has being cut by the northwest tributaries is continental sedimentary rock formation and tends to weather into soil. There is a greet extent of land development or vegetation cover in the mountains between different tributaries. The need for land,woodland and water resources make the northwest tributary valleys with a high population density. Thus,the

关 键 词：峨眉山玄武岩 头寨滑坡 烂泥沟滑坡 地质构造约束 

分 类 号：P642.22[天文地球—工程地质学]