Implications of 36Cl exposure ages from Skye, northwest Scotland for the timing of ice stream deglaciation and deglacial ice dynamics

• Published in: Quaternary Science Reviews
• Main Authors: Small, David, Rinterknecht, Vincent, Austin, William E. N., Bates, C. Richard, Benn, Douglas I., Scourse, James D., Bourlès, Didier L., Hibbert, Fiona Danielle, ASTER Team
• Other Authors: University of St Andrews. School of Geography and Geosciences, University of St Andrews. Earth and Environmental Sciences, University of St Andrews. Marine Alliance for Science & Technology Scotland, University of St Andrews. Scottish Oceans Institute, University of St Andrews. Geography & Sustainable Development, University of St Andrews. St Andrews Sustainability Institute, University of St Andrews. Centre for Ancient Environmental Studies, University of St Andrews. Bell-Edwards Geographic Data Institute
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2017
• Subjects: Deglaciation; Scotland; Cosmogenic exposure ages; Chlorine-36; GE Environmental Sciences; NDAS; SDG 13 - Climate Action; SDG 14 - Life Below Water; GE; Ice Sheet
• Online Access: https://hdl.handle.net/10023/11550; https://doi.org/10.1016/j.quascirev.2016.08.028; http://www.sciencedirect.com/science/article/pii/S0277379116303183#appd001

The French national AMS facility ASTER (CEREGE, Aix en Provence) is supported by the INSU/CNRS, the ANR through the "Projets thématiques d’excellence" program for the "Equipements d’excellence" ASTER-CEREGE action, IRD and CEA. The authors would like to thank Shasta Marrero for helpful and informative discussion on the CRONUScalc online calculator. DS was supported by a SAGES studentship and fieldwork by funds from the QRA and BSG. Geochronological constraints on the deglaciation of former marine based ice streams provide information on the rates and modes by which marine based ice sheets have responded to external forcing factors such as climate change. This paper presents new 36Cl cosmic ray exposure dating from boulders located on two moraines (Glen Brittle and Loch Scavaig) in southern Skye, northwest Scotland. Ages from the Glen Brittle moraines constrain deglaciation of a major marine terminating ice stream, the Barra-Donegal Ice Stream that drained the former British-Irish Ice Sheet, depending on choice of production method and scaling model this occurred 19.9 ± 1.5–17.6 ± 1.3 ka ago. We compare this timing of deglaciation to existing geochronological data and changes in a variety of potential forcing factors constrained through proxy records and numerical models to determine what deglaciation age is most consistent with existing evidence. Another small section of moraine, the Scavaig moraine, is traced offshore through multibeam swath-bathymetry and interpreted as delimiting a later stillstand/readvance stage following ice stream deglaciation. Additional cosmic ray exposure dating from the onshore portion of this moraine indicate that it was deposited 16.3 ± 1.3–15.2 ± 0.9 ka ago. When calculated using the most up-to-date scaling scheme this time of deposition is, within uncertainty, the same as the timing of a widely identified readvance, the Wester Ross Readvance, observed elsewhere in northwest Scotland. This extends the area over which this readvance has potentially occurred, reinforcing the view ...