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.本研究采用数值冰盖模型（numerical ice-sheet model），重建了法兰士约瑟夫地群岛与北地群岛（Severnaya Zemlya）之间的欧亚北极高纬地区晚魏克塞尔冰期（Late Weichselian）的冰川作用历史。整个欧亚北极高纬区域均发育冰盖，以此合理解释巴伦支海与喀拉海中部向俄罗斯北极北部的冰流运动机制。建模过程采用反演方法，使冰盖模拟结果与地质资料相匹配——后者显示晚魏克塞尔冰期期间泰梅尔半岛处于无冰状态。该模型表明巴伦支海与喀拉海曾完全被冰川覆盖，并预测晚魏克塞尔冰期俄罗斯北极高纬区域存在"最大规模"冰盖。在此情景中，冰盛期的典型特征为巴伦支海上方发育1500米厚的冰体，冰体沿数个海底谷（bathymetric troughs）向北、西侧流动，形成大型冰流（ice streams）。与上述重建结果不同，冰川作用的"最小规模"模型显示喀拉海的冰川发育受限：其南部冰厚仅300米，北部北地群岛区域则完全无冰。我们的最大规模重建结果与巴伦支海曾完全被冰川覆盖的地质资料相符；但北地群岛的地质数据表明，向东延伸区域更适配我们的最小规模模型。这进而表明，晚魏克塞尔冰期期间，欧亚北极地区自西向东存在显著的古气候梯度，气候逐渐向寒冷干燥方向演变。