Summary
Geothermal heat flow (GHF) is a key basal boundary condition for Antarctic ice-sheet flow. Large-scale variations are resolved by several recent models but knowledge of the smaller-scale variations, crucial for ice sheet dynamics, is limited by unresolved variations in crustal radiogenic heat production. To define this at continent-scale we use 3D gravity inversion constrained by seismic Moho estimates to identify variations in crustal composition and geometry beneath thick ice. Geochemically-defined empirical relationships between density and heat production capture the global average trend and its variability, and allow to estimate from upper-crust density spatial variations in radiogenic heat production. Significant variations are observed typically 1.2–1.6 ?W/m3, and as high as 2 ?W/m3 in West Antarctica. The contribution to GHF from these heat-production variations is similarly variable, typically 16–24 mW/m2 and up to 60 mW/m2. The mapped variations are significant for correctly representing GHF in Antarctica.