The peaks and patterns of Antarctic crustal heat production

The geothermal heat flux to the base of the Antarctic ice sheet is inherently difficult to measure, yet accurate estimates are necessary to better understand cryosphere dynamics. Radiogenic heating within the crust from decay of naturally occurring radioactive heat producing elements (HPEs) is a significant component of the total surface heat flux budget. The distribution of HPEs is heterogeneous at a range of scales, and fundamentally tied to the geological evolution of the lithosphere in space and time. Despite this, current Antarctic geothermal heat flux models use laterally homogeneous heat production. Furthermore, regional ice sheet models have shown that localised regions of high HPE-enriched crust can impact the organisation of ice flow in slow-flowing regions, underscoring the need for improved knowledge of both the magnitude and spatial variability of heat production in the Antarctic crust.

We have assembled the first database of Antarctic-wide geochemical data, with over 14,000 entries, >8,000 of which can be utilised for heat production calculations. Preliminary analysis suggests that the mean heat production rates for Antarctic Archean, Proterozoic and Phanerozoic rocks exceed global averages and are higher and more variable than those currently used in Antarctic geothermal heat flux models. Felsic igneous rocks that intruded during/after the Ediacaran-Cambrian assembly of Gondwana are particularly HPE-enriched (mean >3.5 μW/m³ compared to global upper crust ~1.6 μW/m³), and require further identification/mapping across East Antarctica. Our ultimate aim is to work towards more accurate predictions of Antarctic geothermal heat flux for use by (for example) the ice sheet modelling community.