Abstract Subglacial topography not only exerts strong controls on contemporary ice sheet dynamics, but also provides an important long-term record of landscape evolution pertaining to past glacial and interglacial conditions. In particular, the bed topography beneath the Greenland Ice Sheet bears the signatures of past processes of landscape evolution that record the development of the ice sheet since its inception. Here we present evidence from airborne radio-echo sounding, gravity, and magnetic data for an enclosed palaeo-lake basin situated beneath the ice sheet in northwest Greenland. Geomorphological analysis and hydrological modelling indicate that the basin once hosted a lake with a surface area of up to ∼7,100 km2 and a volume of up to ∼580 km3. The basin and associated topography control the organisation of a preserved palaeo-fluvial channel network, suggesting that the basin pre-dates widespread glaciation in northwest Greenland. We use flexural modelling to show that the morphology of the basin and surrounding topography is consistent with elastic plate flexure driven by mechanical displacement along a normal fault bounding the basin margin. Analysis of gravity and magnetic anomalies indicates that the basin contains a sedimentary infill up to ∼1.2 km thick, which may contain valuable records of past ice sheet extent and environmental conditions in northwest Greenland. We therefore propose that this newly identified palaeo-lake basin may be a promising target for future acquisition of ground-based active source seismic data and potential recovery of subglacial material by sub-ice drilling programs.

中文翻译：

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保存在格陵兰冰盖下的断层古湖盆地

摘要 冰下地形不仅对当代冰盖动力学施加了强有力的控制，而且还提供了与过去冰川和间冰期条件有关的景观演变的重要长期记录。特别是，格陵兰冰盖下方的床地形带有过去景观演变过程的特征，这些过程记录了冰盖自形成以来的发展。在这里，我们提供了来自位于格陵兰岛西北部冰盖下方的封闭古湖盆地的机载无线电回波探测、重力和磁力数据的证据。地貌分析和水文模型表明，该盆地曾经有一个表面积达 7,100 平方公里、体积达 580 平方公里的湖泊。盆地和相关的地形控制着一个保存完好的古河流域网络的组织，这表明该盆地早于格陵兰岛西北部的广泛冰川作用。我们使用弯曲建模来表明盆地的形态和周围地形与沿盆地边缘正断层的机械位移驱动的弹性板弯曲一致。重力和磁异常分析表明，该盆地包含厚达 1.2 公里的沉积填充物，其中可能包含格陵兰岛西北部过去冰盖范围和环境条件的宝贵记录。