ИСТИНА

Ice temperature, viscosity, and water content, as well as basal melting, are strongly influenced by geothermal heat flux, which in turn determines the deformation response of ice under stresses applied by the overlying ice column. Therefore, high quality maps of geothermal heat flux are crucial when monitoring ice shape, mass balance and dynamic behavior of the Antarctic Ice Sheet. Direct measurements are sparse because of the large ice thickness, hence other solid earth models are necessary to estimate the heat flux. We determine the geothermal heat flux over the Antarctic continent based on a 3D thermal model of the lithosphere, obtained from seismic tomography using a mineral physics approach. Compositional changes were compensated through a joint inversion with gravity data in an iterative scheme. Since this model provides reliable relative temperature variations but shows bias in the absolute values, we calibrate it using standard geotherms for well-studied cratons for each depth layer while considering the non-linear relationship between velocity and temperature. The resulting model provides accurate temperature variations as well as consistent absolute temperatures within each layer. The lower boundary of the thermal lithosphere, defined here as the 1300°C isotherm, is found to lie around 100km in West Antarctica while extending down to almost 300km in East Antarctica. Heat flux is subsequently calculated using the heat conduction equation in 1D independently for every grid point and in full 3D. The resulting surface heat flux shows a clear distinction between East and West Antarctica with locally elevated fluxes, e.g. in the Antarctic Peninsula and in Marie Byrd Land, coinciding well with known locations of subglacial volcanos.