CAGE - Centre for Arctic Gas Hydrate, Environment, and Climate, Department of Geosciences, UiT The Arctic University of Norway, Tromsø, Norway.
Geography Research Unit, University of Oulu, Oulu, Finland.
Nat Commun. 2022 Nov 30;13(1):7377. doi: 10.1038/s41467-022-35072-0.
Ice can sculpt extraordinary landscapes, yet the efficacy of, and controls governing, glacial erosion on geological timescales remain poorly understood and contended, particularly across Polar continental shields. Here, we assimilate geophysical data with modelling of the Eurasian Ice Sheet - the third largest Quaternary ice mass that spanned 49°N to 82°N - to decipher its erosional footprint during the entire last ~100 ka glacial cycle. Our results demonstrate extreme spatial and temporal heterogeneity in subglacial erosion, with rates ranging from 0 to 5 mm a and a net volume equating to ~130,000 km of bedrock excavated to depths of ~190 m. A hierarchy of environmental controls ostensibly underpins this complex signature: lithology, topography and climate, though it is basal thermodynamics that ultimately regulates erosion, which can be variously protective, pervasive, or, highly selective. Our analysis highlights the remarkable yet fickle nature of glacial erosion - critically modulated by transient ice-sheet dynamics - with its capacity to impart a profound but piecemeal geological legacy across mid- and high latitudes.
冰可以雕刻出非凡的景观，但在地质时间尺度上，冰川侵蚀的效果及其控制因素仍未得到很好的理解和争论，特别是在极地大陆盾上。在这里，我们综合地球物理数据和欧亚大陆冰盖的建模——这是第三大第四纪冰体，跨越 49°N 至 82°N——来解读其在整个最近的100 万年冰期循环中的侵蚀足迹。我们的结果表明，亚冰下侵蚀具有极端的空间和时间异质性，速率范围从 0 到 5 毫米/年，净体积相当于130000 公里的基岩被挖掘到~190 米的深度。显然，环境控制因素的层次结构构成了这种复杂的特征：岩性、地形和气候，但最终控制侵蚀的是基底热力学，它可以起到各种保护、普遍或高度选择性的作用。我们的分析强调了冰川侵蚀的显著但易变的性质——由冰盖动力的瞬态变化强烈调节——其在中高纬度地区留下深刻但零碎的地质遗产的能力。
