The effects of sedimentary basins on the dynamics of the East Antarctic Ice Sheet from enhanced groundwater and geothermal heat flow

Abstract

It is well known that ice sheets heavily influence groundwater systems, however, the impact of groundwater on ice sheet dynamics is not. This poorly understood aspect of ice-sheet hydrology is relevant to the subglacial hydrology of ice sheets lacking surface or englacial meltwater such as the East Antarctic Ice Sheet (EAIS). How groundwater systems redistribute geothermal heat at the base of an ice sheet is also largely unknown. Geothermal heat and subglacial hydrology are important basal processes controlling ice flow. Large sedimentary basins underlie the EAIS, which likely play host to many groundwater systems. I hypothesized that groundwater systems in these sedimentary basins may be the main water transport mechanism over water sheets (or films) at large scales in the interior of the ice sheet where basal melt rates are very low. I also hypothesized that these groundwater systems are likely important to the basal processes (specifically heat flux) and dynamics of the EAIS (particularly in rheological and sliding behavior). To test these, I created various one- and two-dimensional numerical models incorporating relevant datasets and conservative assumptions about the subsurface. The models ranged from simple groundwater and thermal simulations to a complex subsurface fluid and thermal model coupled to a fully dynamic ice sheet simulator. The models suggest that groundwater most likely has measurable effects on the dynamics of ice sheets like the EAIS. I have shown that probable groundwater systems underneath the interior of the EAIS can likely transport most of the meltwater produced and that groundwater can strongly affect the heat flux (positively, as well as, negatively) at the ice base under kilometers of relatively slow-moving ice. I have also not only shown that groundwater systems under the EAIS are strongly controlled by the ice sheet’s dynamics but that groundwater systems have a feedback to the ice dynamics, mostly through enhanced basal sliding and changes to the ice rheology. These results provide the justification to include groundwater in future simulations of the EAIS as well as a call to collect more data to better delineate its subsurface sedimentary basins – a critical input for groundwater and heat transport modeling.