藏东南典型第四纪堆积阶地成因研究-以雪瓦卡平台为例

藏东南地区是研究海洋型冰川的天然宝库，帕隆藏布流域作为冰川活跃区，因其独特的地形地貌、气候条件，沿岸不仅堆积形态各异的第四纪冰碛垄、泥石流扇，而且发育断续分布的平台地形。利用无人机技术、高精度遥感影像、钻探、物探，结合实测剖面对藏东南典型第四纪堆积阶地成因进行详细的分析，为研究区域性堆积阶地成因提供依据，并得出以下结论：（1）雪瓦卡平台为第四纪堆积体，所在区域曾经发育了一个堰塞湖；（2）雪瓦卡平台第二级阶地下部为巨厚湖相砂层，上部为河床沉积卵砾石，这种下细上粗的物质接触关系可能为沉积区由堰塞湖转变为河道沉积，堰塞坝逐步疏通的过程；（3）上、下游支沟不仅为平台形成提供物质来源，而且为其形成提供地形地貌条件；（4）帕隆藏布沿岸断续分布的平台地形在形成过程中普遍受到上下游支沟冰川运动、泥石流发育的影响。

The typical Quaternary platform in the South-Eastern margin of the Qinghai-Tibet plateau-A case study of Xuewaka platform

The southeastern part of Tibet is a natural treasure trove of the study of marine glaciers. The Parlung Zangbo watershed as a glacier active area, due to its unique terrain, climatic conditions, there are not only the Quaternary moraine ridge, debris flow fan, but also the platform topography along the coast. Based on the analysis of Technology of UAV, High Precision Romote Sensing, investigation from field, borehole core, and geophysical exploration of the typical Quaternary accumulation terrain in the South-Eastern margin of the Qinghai-Tibet plateau, this paper provides a basis for studying the causes of the regional accumulation of terraces the following conclusions are drawn: (1) The Xuewaka platform is Quaternary accumulation , the region has developed a barrier lake; (2) The second stage terrace of The Xuewaka platform are composed of two layers, the lower one consists of thick lakes sand, the upper part consists of the sediment of the riverbed gravel. This phenomenon which shows the possibility of the process that depositional area transformed from lacustrine environment to fluvial environment; (3) The upper and lower branch channels not only provide material source for the formation of Quaternary accumulation terrace platform, but also provide topographic and geomorphic conditions for the formation of Quaternary accumulation terrace. (4) The platform topography of the intermittent distribution along the coast of the Parlung Zangbo is generally affected by Glacier movement and debris flow development branch gullys which are located beside these platform.