东喜马拉雅构造结地貌形态及其构造指示意义

发布时间：2018-09-12 13:28

【摘要】：喜马拉雅构造结位于印度与欧亚板块碰撞的前缘,其内部的南迦巴瓦峰地区隆升速率大于周边区域,被认为是东构造结的核心部位(隆升中心)。近期区域地震观测结果表明,南迦巴瓦峰地区地震活动较弱,而其东南侧区域地震活动频繁。为了研究东构造结地区目前的地球动力学特征,文中利用DEM数据分析了南迦巴瓦峰及其西北、东南两侧和阿萨姆东北部区域的高程频率分布及面积高程积分曲线。结果显示,南迦巴瓦构造结区域属于侵蚀的壮年期,区域构造隆升和剥蚀作用已经达到高度平衡的状态,受到高原气候影响,该地区剥蚀作用相对较弱,表明南迦巴瓦构造结区域目前隆升相对缓慢。西北、东南侧以及阿萨姆东北部区域地貌均表现为年轻的演化阶段,属于侵蚀的幼年期,阿萨姆东北部地区地貌更接近幼年期早期阶段。西北侧的地貌演化阶段反映了区域侵蚀能力较小,仍属于高原气候区;南迦巴瓦峰东南侧至阿萨姆区域受到南亚热带季风的影响,降雨充沛,遭受强烈的侵蚀作用,区域尚属于侵蚀的幼年期,且阿萨姆东北部地貌发育程度更低,表明南迦巴瓦构造结以东地区构造隆升非常强烈,隆升速率最大的地区位于阿萨姆东北部。文中认为,在现今印度板块向N推进的模式下,喜马拉雅东构造结核心部位(隆升中心)向SE发生了偏移,新的核心部位可能位于阿萨姆东北部区域,该地区隆升强烈,构造应力积累发生大地震的可能性较大。
[Abstract]:The Himalayan tectonic junction is located at the front edge of the collision between India and Eurasia plate, and the uplift rate of the Nankabawan region is larger than that of the surrounding area, so it is considered to be the central part of the eastern tectonic junction (uplift center). Recent regional seismological observations show that the seismicity is relatively weak in the Nangarbaawan region and frequent in the southeastern part of the region. In order to study the current geodynamic characteristics of the eastern tectonic junction area, the elevation frequency distribution and area elevation integral curves of the South Ghabawar Peak and its northwest, southeast and northeast Assam regions are analyzed by using DEM data. The results show that the area of Nangabawa tectonic junction belongs to the full age of erosion. The regional tectonic uplift and denudation have reached a highly balanced state, which is affected by the climate of the plateau, and the denudation is relatively weak in this area. It shows that the uplift of the Nanjiabawa tectonic junction is relatively slow at present. The regional geomorphology of northwest, southeast and northeast of Assam shows a young evolutionary stage, which belongs to the early stage of erosion, and the geomorphology of northeast Assam is closer to the early stage of infancy. The geomorphological evolution stage in the northwestern side reflects that the regional erosion capacity is relatively small and still belongs to the plateau climate zone, and the region from southeast to Assam is affected by the South Asian Tropical Monsoon, with abundant rainfall and strong erosion. The area still belongs to the infancy of erosion, and the geomorphology of northeast of Assam is lower, which indicates that the uplift is very strong in the area east of the Nangabawa tectonic junction, and the area with the highest uplift rate is located in the northeast of Assam. In this paper, it is considered that the core of the eastern Himalayan tectonic junction (uplift center) has shifted to SE under the current pattern of the Indian plate moving toward N, and the new core may be located in the northeastern part of Assam, which is a strong uplift. Tectonic stress accumulation is more likely to occur large earthquakes.
【作者单位】：中国地震局地质研究所活动构造与火山重点实验室;
【基金】：中国地震局地震行业科研专项(2015419024)资助
【分类号】：P315.2

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