Evaluating the difference between geothermal flux and basal heat flux in the context of ice divide stability, Little Dome C, East Antarctica

Lucas H. Beem1, Jason L. Roberts2, Catherine Ritz3, Duncan A. Young1, Thomas G. Richter1, Donald D. Blankenship1

1University Of Texas – Institute For Geophysics, Austin, United States, 2Australian Antarctic Division, Kingston, Australia, 3University of Grenoble Alpes, Grenoble, France

Basal heat flux is the thermal energy that crosses the ice/bed interface and is geothermal flux modified by processes such as vertical advection of groundwater and local variability in geology. The basal conditions of Little Dome C are of particular interest due to the potential for the existence of 1.5 Myr old ice that is interpretable as a paleoclimate proxy. The stability of Dome C is a function of the basal interface character including basal heat flux and water distribution and each can be modified by groundwater, water flow in the subglacial sediment and bedrock.  Here we test the rate of heat flux from groundwater flow and its sensitivity to assumed subglacial geology and associated hydrological parameters. Multiple probable geological models are constructed for the Dome C region from radar derived geometry and interpretation of co-located gravity and magnetic field observations. The impact of groundwater on basal heat flux is sensitive to the chosen background geothermal gradient, but more so to the degree of assumed hydrological permeability. In certain configurations groundwater flow can modify local basal heat flux but a factor greater than 2.  Our interpretation is that the position of Dome C is above a region of lower hydrological permeability that decreases exposure of basal ice to heat and may play a stabilizing role, and therefore increase the likelihood of 1.5 Myr old ice survival. These result suggest the hypothesis that ice divide stability and old ice survivability are, in part, a function of the underlaying geology.


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