Evidence for subglacial ponding across Taylor Glacier, Dry Valleys, Antarctica

Ice-penetrating radar and modelling data are presented suggesting the presence of a zone of temperate ice, water ponding or saturated sediment beneath the tongue of Taylor Glacier, Dry Valleys, Antarctica. The proposed subglacial zone lies 3-6 km up-glacier of the terminus and is 400-1000 m across. The zone coincides with an extensive topographic overdeepening to 80 m below sea level. High values of residual bed reflective power across this zone compared to other regions and the margins of the glacier require a high dielectric contrast between the ice and the bed and are strongly indicative of the presence of basal water or saturated sediment. Analysis of the hydraulic equipotential surface also indicates strong convergence into this zone of subglacial water flow paths. However, thermodynamic modelling reveals that basal temperatures in this region could not exceed -7 degrees C relative to the pressure-melting point. Such a result is at odds with the radar observations unless the subglacial water is a hypersaline brine.