Heat flow in southern Australia and connections with East Antarctica

Abstract

Viscosity and melt generation at the base of ice sheets are critically dependent upon heat flow. Yet subglacial heat flow is poorly constrained due to the logistical challenges of obtaining boreholes that intersect the bedrock beneath thick ice cover. Currently, continental estimates of Antarctic heat flow are derived from geophysical methods that provide ambiguous constraints of crustal heat sources, despite their demonstrated importance for accurate predictions of future ice sheet behavior. This study pursues an alternative approach by using heat flow measurements from rock units in the Coompana Province of southern Australia, which represent the geological counterparts of those beneath Wilkes Land in East Antarctica. We present nine new surface heat flow estimates from this previously uncharacterized region, ranging from 40 to 70 mW/m² with an average of 57 ± 3 mW/m². These values compare favorably to recent geophysically derived estimates of 50–75 mW/m² for the Totten Glacier catchment of East Antarctica, and to the single in situ measurement of 75 mW/m² from the Law Dome deep ice borehole. However, they are appreciably lower than the range of 56–120 mW/m² (83 ± 13 mW/m² average) for the abnormally enriched Proterozoic terranes of the Central Australian Heat Flow Province. This study provides the first regional heat flow map of geological provinces formerly contiguous with East Antarctica through the application of continent‐scale heat flow data sets tied to a Jurassic plate tectonic reconstruction for Gondwana. Our approach reveals several discrepancies with current heat flow models derived from geophysical methods and provides a more robust analysis of subglacial heat flow using this plate tectonic synthesis as a proxy for East Antarctica.