A Late Pleistocene channelized subglacial meltwater system on the Atlantic continental shelf south of Ireland
A Late Pleistocene channelized subglacial meltwater system on the Atlantic continental shelf south of Ireland
复制标题
DOI：
10.1111/bor.12536
复制
发表时间：
2021-06
期刊：
影响因子：
2.2
通讯作者：
C. Giglio;S. Benetti;F. Sacchetti;Edward Lockhart-;J. H. Hughes Clarke;R. Plets;K. V. van Landeghem;C. Ó Cofaigh;J. Scourse;P. Dunlop
中科院分区：
文献类型：
--
作者：
C. Giglio;S. Benetti;F. Sacchetti;Edward Lockhart-;J. H. Hughes Clarke;R. Plets;K. V. van Landeghem;C. Ó Cofaigh;J. Scourse;P. Dunlop
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。冰下记录的情况尤其如此，在当代冰川环境中观察冰下记录具有挑战性，因此仍然只有部分了解。冰下水文系统是冰动力学的重要组成部分，其中增加的水压增强了冰的运动和沉积物变形，从而减少了冰床接触。隧道谷是大型、弯曲、陡峭的切口，与较小规模的融水通道一起，表明冰下融水在大冰盖下排放。通过使用高分辨率海洋地球物理数据，在爱尔兰和英国之间的凯尔特海大陆架上发现了一个埋藏和暴露的隧道谷系统，可能是冰下或冰前融水通道和古河流谷。陡峭和过度加深的隧道山谷的存在表明，在前爱尔兰海冰流下方存在一个大型的渠道化融水排水系统，这是最广泛的冰流，可以排出最后的英国-爱尔兰冰盖。在大约28-26 ka的凯尔特海陆架的快速冰扩张后，隧道谷被雕刻成基岩和冰川沉积物，并与25.6和24.3 ka之间的快速冰流向北撤退到爱尔兰海盆地。一个主要的冰下融水系统的存在相对较浅的货架上表明，显着的侵蚀性融水排放发生在最后一次冰消期，并突出了融水的重要贡献，撤退的英国-爱尔兰冰盖的大陆架。
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.