Two-Dimensional Thermo-Mechanical Modelling of Flow and Depth-Age Profiles Near the Ice Divide in Central Greenland

Abstract

The ice divide on an ice sheet is a special place on the ice sheet, where the velocity and stress distributions are different from those found just two ice thicknesses from the ice divide. A two-dimensional thermo-mechanical model has been used to model the flow near the ice divide in central Greenland. The results show that the surface strain-rates are increased by 50% of the values found 15 km down-stream and that the basal temperatures rise by 3°C. Estimates of a depth–age distribution in the vicinity of Crête show that the isochrones rise at the dome. The model calculations predict 1600 m of Holocene ice, 1000 m of Wisconsin ice, and 400 m of ice older than 115kyear. 15 km down-stream from the dome, the thickness of ice older than 115 kyear will be reduced by 50%. In these calculations it has been assumed that the ice thickness at the dome is time-invariant. The existence of the old ice depends on the basal temperature. The estimates of the basal temperature depend strongly on past accumulation rates and on the geothermal heat flux but the ice has most likely been below the pressure-melting point throughout the last glacial period.