Matthew Gard1, Derrick Hasterok1
1University Of Adelaide, Adelaide, Australia
In this study, we develop a new model for heat flux and crustal temperatures for the Antarctic continent utilising new geophysical and geochemical constraints. Crustal heat flux directly influences ice sheet stability, glacial dynamics and basal melting. However, the geothermal input into the base of the ice sheets is poorly constrained due to the logistical difficulty and high expense of obtaining direct measurements through the ice sheets. Thus we require robust indirect estimates by utilising proxies. Past studies focus on seismic velocity estimates of temperature, but this method is limited to mantle temperatures, which constrain mantle contributions to crustal heat loss. However, seismic models have poor sensitivity to the crustal radiogenic contribution to the crustal heat loss. Radiogenic heat generation can contribute anywhere from 30-80% of the total crustal heat loss, and therefore must be considered as part of any geothermal model. In this study, we improve estimates of crustal heat generation by employing empirical estimators applied to geophysical datasets. The empirical estimators are calibrated to geochemical estimates of heat production made on Antarctic rock samples and from formerly adjacent continental terranes determined by tectonic reconstructions. We combine this radiogenic model with crustal temperatures constrained though Curie depth analysis. Curie depth estimates computed from the equivalent dipole method are achieved by utilising a new lithospheric magnetic model derived from SWARM and CHAMP satellites. This improved lithospheric magnetic model is much higher resolution than previous Curie depth studies. Our estimates of temperature and crustal heat flux into the base of the Antarctic ice sheet represent an improvement over previous models, allowing for more realistic models of ice sheet dynamics.