The study of palaeo-glacial landforms and sediments can give insights into the nature and dynamics of ice sheets. This is particularly the case with regards to the subglacial record, which is challenging to observe in contemporary glaciated settings and hence remains only partially understood. The subglacial hydrological system is an essential component of ice dynamics, where increased water pressure enhances ice motion and sediment deformation, thus reducing ice-bed contact. Tunnel valleys are large, sinuous, steep-sided incisions that, together with smaller scale meltwater channels, indicate subglacial meltwater discharge beneath large ice sheets. Through the use of high-resolution marine geophysical data, a system of buried and exposed tunnel valleys, possible subglacial or proglacial meltwater channels and palaeo-fluvial valleys have been identified across the shelf of the Celtic Sea between Ireland and Britain. The presence of steep-sided and overdeepened tunnel valleys is indicative of a large channelized meltwater drainage system beneath the former Irish Sea Ice Stream, the most extensive ice stream to drain the last British–Irish Ice Sheet. After the rapid ice expansion across the Celtic Sea shelf around 28–26 ka, the tunnel valleys were carved into both bedrock and glacigenic sediments and are associated with rapid ice stream retreat northwards into the Irish Sea Basin between 25.6 and 24.3 ka. The presence of a major subglacial meltwater system on the relatively shallow shelf suggests that significant erosive meltwater discharge occurred during the last deglaciation and highlights the important contribution of meltwater to the retreat of the British–Irish Ice Sheet on the continental shelf.

中文翻译：

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爱尔兰南部大西洋大陆架晚更新世冰下融水系统

对古冰川地貌和沉积物的研究可以深入了解冰盖的性质和动力学。对于冰下记录而言尤其如此，在当代冰川环境中很难观察到，因此只能部分了解。冰下水文系统是冰动力学的重要组成部分，其中增加的水压会增强冰运动和沉积物变形，从而减少冰床接触。隧道谷是大的、弯曲的、陡峭的切口，连同较小规模的融水通道，表明大冰盖下的冰下融水排放。通过使用高分辨率海洋地球物理数据、地下和暴露隧道谷系统，在爱尔兰和英国之间的凯尔特海大陆架上发现了可能的冰下或前冰河融水通道和古河流山谷。陡峭和过深的隧道谷的存在表明了前爱尔兰海冰流下方的大型渠道化融水排水系统，这是排出最后一个英国 - 爱尔兰冰盖的最广泛的冰流。在 28-26 ka 左右跨过凯尔特海陆架的冰快速膨胀后，隧道谷被雕刻成基岩和冰川沉积物，并与 25.6 至 24.3 ka 之间的快速冰流向北退缩到爱尔兰海盆地有关。