New RSL Constraints for the Minch Ice Stream from Optically Stimulated Luminescence Dated Marine Deposits: Implications for Improving GIA Models for NW Scotland

• Main Authors: Huffman, Emily, Simms, Alexander R, DeWitt, Regina, Best, Louise, Lloyd, Jeremy, Bradwell, Tom
• Format: Conference Object
• Language: unknown
• Published: 2023
• Subjects: G Geography (General); GB Physical geography; GE Environmental Sciences; Misi; Ice Sheet
• Online Access: https://eprints.glos.ac.uk/14355/; https://agu.confex.com/agu/fm23/meetingapp.cgi/Paper/1364250

Marine-ice sheet instability (MISI) provides the potential to significantly increase rates of global sea level rise, as ice sheets extending seaward over landward sloping beds can collapse. Some estimates suggest it could increase future rates of sea-level rise to over 15 mm/yr by the end of the century. However, other sea-level feedbacks (SLFs) may act as stabilizing mechanisms by hindering MISI through ice sheet retreat-induced uplift of the seafloor, resulting in shallower water depths. Our overall aim is to explore whether SLFs stabilized a former rapidly retreating marine ice stream located in Northwestern Scotland during the last deglacial (~15-20 ka). In this study, we provide new constraints on the late Pleistocene relative sea level (RSL) history along the flanks of the Minch Ice Stream (MnIS). Optically stimulated luminescence dating of raised marine deposits was used to determine the age of the oldest preserved RSL indicators immediately after ice-sheet retreat. Our preliminary ages confirm the early deglacial age of ~21-18 ka for the earliest post-LGM (Last Glacial Maximum) shorelines of NW Scotland. We also identify potential pre-LGM shorelines across NW Scotland. The new constraints on RSL will be used to refine Glacial Isostatic Adjustment (GIA) models for NW Scotland and investigate both SLFs and shed light on mantle rheology and ice-stream behavior of the former MnIS.