【摘要】 雅鲁藏布江大拐弯地区的构造活动与河流侵蚀作用都十分强烈。利用数值地貌参数对构造抬升的敏感响应,本文对雅鲁藏布江中、下游流域的DEM数据进行了地貌参数的提取。通过对雅鲁藏布江及其支流的面积-高程积分和河流陡峭系数的分析,结合区域降雨量及岩性分布特征,探讨了不同区段地貌参数变化所蕴含的构造活动信息。研究发现雅鲁藏布江大拐弯地区的隆升活动具有明显的差异性,南迦巴瓦峰东部和北部的隆升活动强度高于西部,喜马拉雅构造结东端的隆升中心存在向北扩展、向东迁移的趋势,尤其以加拉至墨脱河段的岩石隆升最为强烈。加查裂点与南迦巴瓦裂点均位于隆升块体的西边界,横向构造隆升可能控制了裂点的形成和稳定。更多还原

【Abstract】 The strong surface erosion in the middle and lower reaches of the Tsangpo River due to the river development,heavy rainfall and glacier movement is coupled with the intense tectonic activities in the Eastern Himalayan Syntaxes, which makes the Tsangpo River Gorge one of the strongest tectonic active areas. Some geomorphology parameters in the Tsangpo River could reflect the geomorphic evolution under the influence of tectonics because of their sensitivity to Cenozoic tectonic movements. The study area starts from Toxia（ 29°20′N, 90°E） in Renbu County to Bashika（28°06′N, 95°32′E）. The watershed area is about 13. 36×10⁴ km², which is account for about52% of the Brahmaputra in China’s drainage area. The strata can be divided into three stratigraphic zones by the Tsangpo suture zone under the control of regional structure. The north strata of the study area is the GangdiseTengchong formation, the middle is the Tsangpo formation and the south is the Himalaya formation.By using digital geomorphology, precipitation and lithology, this article analyzes 30 m SRTM DEM data to extract the geomorphology parameters along the middle and downstream of Tsangpo River. Based on the erosion cycle and the stream-power river incision model, we extract 2698 subdivision of watershed in the study area to calculate the Hypsometric Integral values（ HI）, channel steepness index( k_sn) and other geomorphic parameters in order to discuss the spatial distribution of tectonic differential uplifting. The results show that the values of HI and k_sn in the northeast of the Namche Barwa massif are very high, which indicate that there is a differential tectonic uplift in the Eastern Himalayan Syntaxes controlled by collision of the Indian plate with the Eurasian plate. The tectonic activities of the north and eastern blocks are more intense than the western Namche Barwa syntaxis. In addition, the spatial distribution characteristics of geomorphology parameters show that the center of uplift block in Eastern Himalayan Syntaxes is intend to expand northward and move eastward, especially for Gala to Medog, where the tectonic activities are extremely ’obvious and intense. The Namche Barwa and Gala knickpoints extracted by DEM data are just located in the western boundary of uplift block, which can conclude that the conformation and stability of these knickpoints is the result of transverse tectonic uplift.更多还原