Maximum extent and readvance dynamics of the Irish Sea Ice Stream since the Last Glacial Maximum

• Main Authors: Scourse, James, Chiverrell, Richard C., Small, David, Smedley, Rachel, Medialdea, Alicia, Burke, Matt, Saher, Margot, Callard, Louise, van Landeghem, Katrien J.J., Duller, Geoff, Fabel, Derek, Moreton, Steve, Lockhart, Edward, Jenkins, Geraint, Praeg, D, Bateman, Mark, D, Evans, David, M., Roberts, Dave, Mccarron, Stephen, Wilson, Peter, Livingstone, Stephen, Clark, Chris, A
• Other Authors: University of Liverpool, Durham University, University of Sheffield Sheffield, School of Ocean Sciences Menai Bridge, Bangor University, Department of Geography (UNIVERSITé DE DURHAM), Aberystwyth University, University of Glasgow, Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UniCA)-Université Côte d'Azur (UniCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD France-Sud ), Universidade Federal Fluminense Rio de Janeiro (UFF), Department of Geography Sheffield, Department of Geography Maynooth, National University of Ireland Maynooth (Maynooth University), University of Ulster, International Union for Quaternary Research (20th Congress), European Project: 656821,H2020,H2020-MSCA-IF-2014,SEAGAS(2016)
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2019
• Subjects: [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology; [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology; [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy; Ice Sheet; Sea ice
• Online Access: https://hal.science/hal-02363231

International audience The Irish Sea Ice Stream (ISIS) has long had one of the best documented retreat histories of the British-Irish Ice Sheet (BIIS) and was the first ice stream to be constrained by Bayesian analysis of geochronological data. These attributes made it a model system for the BRITICE-CHRONO research project, which aims to produce the best constrained retreat record of any palaeo-ice sheet contributing key observational constraints for ice sheet modelling. The project has generated a suite of new radiocarbon ages from deglacial sequences offshore in the Celtic and Irish seas and terrestrial cosmogenic nuclide and optically-stimulated luminescence ages from ice-marginal sites in the Isles of Scilly, Ireland, Wales and NW England. The ISIS was unusual within the former BIIS, in that it was a compound ice stream with two outlets, one marine terminating that flowed through the Irish Sea Basin into the Celtic Sea, and a terrestrial terminus that flowed southwards through Cheshire-Shropshire lowlands into the English Midlands around 25.5 ka. Here we assess the retreat dynamics across the entirety of the ISIS, integrating the new chronology in a revised Bayesian analysis that constrains the pattern and timing ice marginal fluctuations. The retreat chronology in the Irish Sea is better constrained than in the Celtic Sea, where the ISIS is now recognised to have extended as far as the continental shelf break to the SW of Britain and Ireland between 24 and 27 ka; this advance was synchronous with independently-dated ice-rafted detritus from ISIS in adjacent deep-sea cores. The ISIS then retreated rapidly northwards through the Celtic Sea, with evidence for readvance phases, deglaciating the Isles of Scilly at 25.5 ka, reaching St Georges Channel by 24.3 ka and the Llŷn Peninsula by 23.9 ka. The initiation of retreat from both the eastern (terrestrial) and western (marine) components of ISIS was synchronous. The eastern terrestrial lobe had vacated the Cheshire-Shropshire lowlands by 22-21 ka. The complex ...