Basal Conditions in Marie Byrd Land in the Presence of a Deep Mantle Plume

Abstract:

Conditions at the base of ice sheets are critical to understand ice motion and the future evolution of the ice sheets but remain largely unknown due to the lack of direct measurements. These conditions are influenced by the underlying crust and mantle, including the presence of mantle plumes, which translate into high geothermal heat flux at the interface between ice and the underlying bedrock. Recent seismic measurements in West Antarctica reveal the presence of a deep late-Cenozoic mantle plume in Marie Byrd Land but the spatial extent of the associated enhanced heat-flux remains poorly understood. We perform here a series of numerical experiments based on parameterization of the plume and ice sheet numerical modeling using the Ice Sheet System Model (ISSM) to better characterize the conditions at the base of Marie Byrd Land as well as provide more robust constraints to the heat supplied by the solid Earth and the characteristics of a deep mantle plume. Our results show that the presence of such a plume is compatible with the presence of ice in the West Antarctic Ice Sheet. While our simulations suggest that the geothermal heat flux cannot be as high as some recent studies suggest in West Antarctica, the presence of the plume has a strong influence on the thermal state of the ice in this area, including basal melt rate and ice hardness. Well-studied plumes beneath continental crust provide bounds on the spatial extent of heat supplied to the base of the crust and ice sheet from the deep mantle.