Elevation lines of modelled ice sheet extension during last glacial maximum

A numerical ice-sheet model was used to reconstruct the Late Weichselian glaciation of the Eurasian High Arctic, between Franz Josef Land and Severnaya Zemlya. An ice sheet was developed over the entire Eurasian High Arctic so that ice flow from the central Barents and Kara seas toward the northern Russian Arctic could be accounted for. An inverse approach to modeling was utilized, where ice-sheet results were forced to be compatible with geological information indicating ice-free conditions over the Taymyr Peninsula during the Late Weichselian. The model indicates complete glaciation of the Barents and Kara seas and predicts a “maximum-sized” ice sheet for the Late Weichselian Russian High Arctic. In this scenario, full-glacial conditions are characterized by a 1500-m-thick ice mass over the Barents Sea, from which ice flowed to the north and west within several bathymetric troughs as large ice streams. In contrast to this reconstruction, a “minimum” model of glaciation involves restricted glaciation in the Kara Sea, where the ice thickness is only 300 m in the south and which is free of ice in the north across Severnaya Zemlya. Our maximum reconstruction is compatible with geological information that indicates complete glaciation of the Barents Sea. However, geological data from Severnaya Zemlya suggest our minimum model is more relevant further east. This, in turn, implies a strong paleoclimatic gradient to colder and drier conditions eastward across the Eurasian Arctic during the Late Weichselian.

本研究采用冰盖模型（ice-sheet model）重建了法兰士约瑟夫地群岛（Franz Josef Land）与北地群岛（Severnaya Zemlya）之间的欧亚高北极地区（Eurasian High Arctic）晚魏克塞尔冰期（Late Weichselian glaciation）的冰川演化过程。研究区域内整个欧亚高北极区域均发育冰盖，由此可合理解释巴伦支海（Barents Sea）与喀拉海（Kara Sea）中部向俄罗斯北极北部的冰流现象。本研究采用反演建模方法，使冰盖模拟结果与地质资料相匹配——后者表明泰梅尔半岛（Taymyr Peninsula）在晚魏克塞尔冰期处于无冰状态。模拟结果显示巴伦支海与喀拉海全域被冰川覆盖，并预测晚魏克塞尔冰期俄罗斯高北极地区存在“最大规模”冰盖。在此情景下，冰盛期（full-glacial conditions）的巴伦支海区域冰厚达1500米，冰体沿数个大型水深槽谷（bathymetric troughs）向北及向西流动，形成巨型冰流（ice streams）。与上述重建结果不同，“最小规模”冰川模型仅在喀拉海有限区域发育冰川：南部冰厚仅300米，北地群岛以北区域则完全无冰。本研究的最大规模重建结果与巴伦支海全域被冰川覆盖的地质资料相符，但北地群岛的地质数据则支持最小规模模型在更东区域的适用性。这一结果进一步表明，晚魏克塞尔冰期欧亚北极地区自西向东存在显著的古气候梯度（paleoclimatic gradient），呈现出向东逐渐变冷、变干的特征。