Late Weichselian fluvial evolution on the southern Kara Sea Shelf, North Siberia
Late Weichselian fluvial evolution on the southern Kara Sea Shelf, North Siberia
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DOI：
10.1016/j.gloplacha.2006.12.006
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发表时间：
2008-02
影响因子：
3.9
通讯作者：
K. Dittmers;F. Niessen;R. Stein
中科院分区：
文献类型：
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作者：
K. Dittmers;F. Niessen;R. Stein
冰川对全球海平面，特别是北极环境产生了深远的影响。与此相关的关键问题之一是，西伯利亚鄂毕河和叶尼塞河的流量如何与近端冰盖相互作用？为了回答这个问题，在喀拉海大陆架被动大陆边缘收集了高分辨率（1-12千赫）浅穿透地震剖面，以研究鄂毕河和叶尼塞河的古水系格局。这两条河流都切入到最近的大陆架，留下充满和未充满的河道和河流峡谷/山谷连接到一个复杂的古排水网络。这些通道是在末次冰盛期全球海平面下降阶段形成的。超过最近的货架深度120米的颗粒运输表现在海底通道堤坝复合体作为河流衍生的罚款输送机。在东北地区，观察到均匀披覆沉积物。主要的形态决定因素是（1）海平面波动和（2）末次冰期冰盖的影响。大多数个别渠道显示典型的蜿蜒河流的几何形状，似乎是一个数量级大于最近的渠道配置文件的测量站在陆地上。叶尼塞古通道比Ob的例子有更大的尺寸，并可能起源于LGM Putoran冰块融化过程中额外的水释放。不对称的海底通道-堤坝复合体，通道深度为60米或更发达，在某些地方与冰川主导的形态接壤，这意味着LGM冰块的偏转。总共超过12，000公里的声学剖面没有显示出几位工作人员假设的更大面积的冰坝湖的证据。此外，河道-堤坝复合体的存在表明泥沙向北流动畅通无阻。位于120米水深以上的陆架上的渠道在海平面低水位期间没有出现积水和/或填充的阶段。这些发现表明，喀拉海大陆架的大片地区不存在冰盖。
Glaciations had a profound impact on the global sea-level and particularly on the Arctic environments. One of the key questions related to this topic is, how did the discharge of the Siberian Ob and Yenisei rivers interact with a proximal ice sheet? In order to answer this question high-resolution (1–12 kHz), shallow-penetration seismic profiles were collected on the passive continental margin of the Kara Sea Shelf to study the paleo-drainage pattern of the Ob and Yenisei rivers. Both rivers incised into the recent shelf, leaving filled and unfilled river channels and river canyons/valleys connecting to a complex paleo-drainage network. These channels have been subaerially formed during a regressive phase of the global sea-level during the Last Glacial Maximum. Beyond recent shelf depths of 120 m particle transport is manifested in submarine channel–levee complexes acting as conveyor for fluvial-derived fines. In the NE area, uniform draping sediments are observed. Major morphology determining factors are (1) sea-level fluctuations and (2) LGM ice sheet influence. Most individual channels show geometries typical for meandering rivers and appear to be an order of magnitude larger than recent channel profiles of gauge stations on land. The Yenisei paleo-channels have larger dimensions than the Ob examples and could be originated by additional water release during the melt of LGM Putoran ice masses. Asymmetrical submarine channel–levee complexes with channel depths of 60 m and more developed, in some places bordered by glacially dominated morphology, implying deflection by the LGM ice masses. A total of more than 12,000 km of acoustic profiles reveal no evidence for an ice-dammed lake of greater areal extent postulated by several workers. Furthermore, the existence of the channel–levee complexes is indicative of unhindered sediment flow to the north. Channels situated on the shelf above 120-m water depth exhibit no phases of ponding and or infill during sea-level lowstand. These findings denote the non-existence of an ice sheet on large areas of the Kara Sea shelf.