青藏高原东缘区域地壳稳定性评价

摘要

青藏高原东缘新构造运动复杂而强烈，地震与地质灾害多发，区域地壳稳定性评价工作意义重大。基于地质力学和大陆动力学相互补充的区域地壳稳定性评价理论，选择深部地球物理场、区域构造变形、地震活动、区域构造应力场作为内动力因素，地形地貌、降雨量、河流冲蚀组合计算所产生的地质灾害条件作为外动力因素，地层岩性和活动断裂影响带作为介质因素，进行了区域地壳稳定性评价。结果表明，采用地质要素梯度来反映内动力作用和通过地质环境要素综合分析表现外动力作用是提高评价准确性的有效手段；青藏高原东缘可分为8个构造特征差异显著的一级分区，75个综合因素差别较大的二级分区，653个外动力条件有一定差别的三级分区；总体而言，龙门山断裂、鲜水河断裂和安宁河断裂带构成的Y字型构造格架断裂带附近的地壳稳定性最差，西部次之，东部最好，北部区块较完整，南部复杂破碎。%Eastern margin of the Tibetan Plateau is a sharpen change zone of geomorphology and geology, with complex and strong Neotectonic movement, breeding environment of numerous earthquakes and geo-hazards occurred largely. It is of great significance to carry out Regional Crustal Stability Assessment (RCSA). Using RCSA combined geo-mechanics and continental dynamics theo⁃ry, this paper selected four types data, deep geophysical fields, regional tectonic deformation, regional tectonic stress fields and seismic activity, as internal dynamic factors, geo-hazard combining with topography, rainfall and river erosion as the external factors, litholo⁃gy and affecting strip of active fault as the medium factors, then to carry out the RCSA. The results show that: ( 1) it is an effective means to improve the assessment accuracy that using geological elements gradient reflects the internal dynamic action and using com⁃prehensive analysis of geological environment reflects external dynamic action;(2)evaluation results show that the study area can be divided into eight one-class zonations by tectonic characteristics significantly different, 75 secondary zonations by comprehensive fac⁃tors differences vary greatly, and 653 three-class zonations by outside dynamic conditions;(3)in brief, fault belts near and/or in the tectonic skeleton, composed mainly with Longmenshan fault, Xianshuihe fault, Anninghe fault, are the worst, followed by the west, the east is best, the north relatively complete, and the southern breaking and complex.