Late Weichselian Ice Sheet of Northern Eurasia
Late Weichselian Ice Sheet of Northern Eurasia
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欧亚大陆北部晚威克塞尔冰盖
DOI：
10.1016/0033-5894(80)90080-0
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发表时间：
1980
影响因子：
2.3
通讯作者：
M. Grosswald
中科院分区：
文献类型：
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作者：
M. Grosswald
在魏切尔时代晚期，欧亚大陆北部的相当大一部分地区，特别是大陆架，被内陆冰川冰化。这首先是从冰川条纹、海底海槽、海底直径、邻近陆地上的巨石列和冰川均衡地壳运动的模式等证据中推断出来的。随后，关于魏氏末期冰雹和前冰期湖泊沉积的产状和地理位置的数据证实了这一推断。俄罗斯平原东北部、西西伯利亚北部和泰米尔半岛的南向外冰雹被含有木材和泥炭的沉积物所覆盖，放射性碳测年得出的年龄为2.2万到4.5万年B.P.。最年轻的晚冰期冰雹是全新世时代：佩科拉河下游的Double Markhida Moraine，推测与Barents冰穹的退化潮有关被沉积在9000至9900年B.P.的木材和泥炭所覆盖：这表明欧亚大陆北极大陆架的消融直到9000年B.P.之后才完成。重建的冰前线导致了这样的结论：北欧亚大陆的魏克斯勒晚期冰盖(拟议名称：欧亚冰盖)从爱尔兰西南部不间断地从爱尔兰西南部延伸到泰米尔半岛东北端，距离6000公里：它覆盖了8，37万平方公里的面积，其中一半位于今天的大陆架上，四分之一位于均衡低于海平面的低地上。因此，冰盖主要是以海洋为基础的。根据冰穹的高度与其半径的关系以及关于基岩地形对冰川起伏的影响的事实数据，绘制了冰盖的等高线图。冰盖的主要特征是英国、斯堪的纳维亚、巴伦支省和卡拉的冰穹，它们的高度在1.9到3.3公里之间，彼此之间被大约1.5公里高的冰鞍所隔开。在魏克斯勒冰期末期，所有主要的冰扩散中心都在大陆架和沿海低地，而山脉中心，如极地乌拉尔山脉和伯兰加山脉，只起到了当地的作用。部分冰盖固定在海平面以下约700至900米的大陆架上，天生不稳定，只能与覆盖北冰洋、格陵兰和挪威海的受限和固定的浮动冰架结合在一起。欧亚冰盖滞留了Severnaya Dvina、Mezen、Pechora、Ob、Irtysh和Yneisei河，导致俄罗斯北部平原和西伯利亚形成了冰损湖。在大约13,500年前，冰川湖泊和溢洪道系统呈放射状，包括西西伯利亚大湖、里海和黑海，最后到达地中海。后来，这个系统变得边缘，主要将冰川水排放到挪威海。
A considerable portion of Northern Eurasia, and particularly its continental shelf, was glaciated by inland ice during late Weichsel time. This was first inferred from such evidence as glacial striae, submarine troughs, sea-bed diamictons, boulder trains on adjacent land, and patterns of glacioisostatic crustal movements. Subsequently, the inference was confirmed by data on the occurrence and geographic position of late Weichselian end moraines and proglacial lacustrine deposits.The south-facing outer moraines in the northeastern Russian Plain, northern West Siberia, and on Taimyr Peninsula are underlain by sediments containing wood and peat, the radiocarbon dating of which yielded ages of 22,000 to 45,000 yr B.P. The youngest late-glacial moraines are of Holocene age: the double Markhida moraine in the lower Pechora River basin, presumably associated with “degradational” surges of the Barents Ice Dome, is underlain by sediments with wood and peat dated at 9000 to 9900 yr B.P.: this suggests that deglaciation of the Arctic continental shelf of Eurasia was not completed until after 9000 yr B.P.The reconstructed ice-front lines lead to the conclusion that the late Weichselian ice sheet of Northern Eurasia (proposed name: the Eurasian Ice Sheet) extended without interruptions from southwestern Ireland to the northeastern end of Taimyr Peninsula, a distance of 6000 km: it covered an area of 8,370,000 km2, half of which lay on the present-day continental shelves and a quarter on lowlands that were depressed isostatically below sea level. Hence, the ice sheet was predominantly marine-based.A contour map of the ice sheet based both on the dependence of the heights of ice domes upon their radii and on factual data concerning the impact of bedrock topography upon ice relief has been constructed. The major features of the ice sheet were the British, Scandinavian, Barents, and Kara Ice Domes that had altitudes of 1.9 to 3.3 km and were separated from one another by ice saddles about 1.5 km high. At the late Weichselian glacial maximum, all the main ice-dispersion centers were on continental shelves and coastal lowlands, whereas mountain centers, such as the Polar Urals and Byrranga Range, played only a local role.The portions of the ice sheet that were grounded on continental shelves some 700 to 900 m below sea level were inherently unstable and could exist only in conjunction with confined and pinned floating ice shelves that covered the Arctic Ocean and the Greenland and Norwegian Seas.The Eurasian Ice Sheet impounded the Severnaya Dvina, Mezen, Pechora, Ob, Irtysh, and Yneisei Rivers, and caused the formation of ice-dammed lakes on the northern Russian Plain and in West Siberia. Until about 13,500 yr B.P. the proglacial system of lakes and spillways had a radial pattern; it included large West Siberian lakes, the Caspian and Black Seas, and ended in the Mediterranian Sea. Later, the system became marginal and discharged proglacial water mainly into the Norwegian Sea.