Role of sediments in controlling the dynamics of paleo-ice sheets

• Main Authors: Gowan, Evan J., Niu, Lu, Knorr, Gregor, Lohmann, Gerrit
• Format: Conference Object
• Language: unknown
• Published: 2017
• Subjects: Hudson; Hudson Bay; Ice Sheet
• Online Access: https://epic.awi.de/id/eprint/45093/; https://epic.awi.de/id/eprint/45093/1/PAGES-Evan_Gowan.pdf; http://www.pages-osm.org/osm/program-osm; https://hdl.handle.net/10013/epic.51300; https://hdl.handle.net/10013/epic.51300.d001

The motion of glacial ice is predominantly controlled by basal conditions, which include a variety of parameters such as ice rheology, temperature, water content, the presence of sediments, and topography. Soft sediment deformation has long been hypothesized to be a dominant control on the size and dynamics of temperate ice sheets such as the Laurentide Ice Sheet. The transition from hard-bedded regions (areas that lack significant sediment cover) to soft sediment areas put a limit on the maximum volume of these ice sheets. When the ice sheet margin reached soft sediment cover, it may have caused the ice sheet to surge, with global-scale climatic impacts. Current generation ice sheet models only have limited control on how sediments modify the behavior of an ice sheet. We present a model of sediment deformation that can take into account the thickness, lithology and hydrology at the base of the ice sheet using the Parallel Ice Sheet Model (PISM). We assess how changes in sediment properties affect the advance and retreat of the ice sheet, including standstills in the margin when the ice sheet becomes restricted to the hard-bedded interior areas. We apply this model to the Wisconsin Glaciation (~85-11 kyrs ago) of the Laurentide ice sheet. We show how the distribution of sediments affect its growth and retreat. We specifically focus on how the soft bedded Hudson Bay impeded the growth of the ice sheet, up to the lead up to the Last Glacial Maximum. We also investigate the relationship between Dansgaard–Oeschger and Heinrich events and the basal dynamics of the ice sheets.