南极长城湾滨岸砾石堤特征及动力环境

本文着重讨论了长城湾现代滨岸砾石沉积的形态、规模、粒度和组构特征及滨岸带沉积动力环境。认为砾石堆积体系中高纬滨岸风暴沉积的产物。堆积体规模较小，形似堤坝，走向与海岸线大体平行。砾石主要由玄武质火山熔岩的岩屑组成，颗粒表面新鲜，多为扁度差的多角体，保留着冰碛砾石的粒态特征。粒度组成和粒级分配上具有冰川－海洋作用双重性质。砾石堤中砾石排列杂乱，层序不清，层理构造不发育，形态分带不显著，仅在堤的向海侧稍显粒度分带现象，由堤的顶部到上中部至基部，分别为砾石带、粗细砾带和砂砾带。滨岸带不同地貌部位，沉积动力环境存在一些差异。从风暴高潮位至大潮低潮位，水动力的簸选作用具有好→差→较好→较差的规律性变化，沉积物随之出现：较粗较匀→粗细混杂→较细较匀→粗细颗粒较混杂的韵律式波动。并指出这些特征与极区独特的自然地理条件有关。

The gravel characteristics and dynamic environments of the Great Wall Bay coast, Antarctica

This paper mainly discusses the form, range, grain size and fabric of the gravel sediment and depositional dynamic environments of the modern coast of the Great Wall Bay. The gravel sediments are thought to be products of high latitude coast storm deposition, and the range is small, just like a dyke, with trend paralleling to the coastline. The sediment mostly consists of the rock fragments of the basalt volcanic lavas and has a low maturity of composition. Most of the gravels are flat and polyangular in shape, retaining the form characters of the tills. The component and distribution of the grain size of the sediment have the characteristics of glacial marine sediments. The gravels in the sediment are jumbled up and neither sequences nor bedding structures. The shape zoning of the gravels is not clear. Only the belts can be seen of grain size, gravels, coarse fine gravels and sand gravels on the seaward side of the gravel dyke from top to bottom.The environments of depositional dynamic changed with different geomorphic parts,from he storm high tide level to the subtidal zone of the coast. That is: the watar sorting andthe deposition and erosion had changed regularly, individually from good to bad, and from weak to strong. Also the sediment has rhythmic variation from coarse and even to coarse and fine. These characteristics result from the special conditions of physical geography in the Antarctica.