Deep-water ‘stable’ subglacial lakes likely contain microbial life adapted in isolation to extreme environmental conditions. How water is supplied into a subglacial lake, and how water outflows, is important for understanding these conditions. Isochronal radio-echo layers have been used to infer where melting occurs above Lake Vostok and Lake Concordia in East Antarctica but have not been used more widely. We examine englacial layers above and around Lake Ellsworth, West Antarctica, to establish where the ice sheet is ‘drawn down’ towards the bed and, thus, experiences melting. Layer drawdown is focused over and around the northwest parts of the lake as ice, flowing obliquely to the lake axis becomes afloat. Drawdown can be explained by a combination of basal melting and the Weertman effect, at the transition from grounded to floating ice. We evaluate the importance of these processes on englacial layering over Lake Ellsworth and discuss implications for water circulation and sediment deposition. We report evidence of a second subglacial lake near the head of the hydrological catchment and present a new high-resolution bed DEM and hydropotential model of the lake outlet zone. These observations provide insight into the connectivity between Lake Ellsworth and the wider subglacial hydrological system.

中文翻译：

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冰下埃尔斯沃思湖及其集水区的基底融化：来自冰川分层的见解

深水“稳定”的冰下湖泊可能含有适应极端环境条件的微生物生命。如何将水供应到冰下湖中，以及水如何流出，对于了解这些条件很重要。等时射电回波层已被用于推断在南极洲东部的沃斯托克湖和康科迪亚湖上方发生融化的位置，但尚未得到更广泛的应用。我们检查了南极洲西部埃尔斯沃思湖上方和周围的冰层，以确定冰盖被“拉下”到冰床的位置，从而经历融化。冰层下降集中在湖的西北部和周围，因为冰，倾斜于湖轴流动，变成漂浮的。在从接地冰过渡到浮冰时，可以通过基础融化和 Weertman 效应的组合来解释下降。我们评估了这些过程对埃尔斯沃思湖上冰层的重要性，并讨论了对水循环和沉积物沉积的影响。我们报告了水文集水区头部附近第二个冰下湖的证据，并提出了一个新的高分辨率床 DEM 和湖泊出口区的水势模型。这些观察结果提供了对埃尔斯沃思湖与更广泛的冰下水文系统之间连通性的深入了解。