Sandra Mclaren1, Chris Carson2, Roger Powell1
1University Of Melbourne, University Of Melbourne, Australia, 2Geoscience Australia, Canberra, AUSTRALIA
Prior to the breakup of Gondwana (beginning around the late Cretaceous) cratonic rocks of southern Australia, including the Gawler and Curnamona cratons, are thought to have been contiguous with similar aged rocks in East Antarctica. In Australia, excellent outcrop exposure means that these rocks are reasonably well understood. One of the key characteristics of these Australian Proterozoic-aged cratonic blocks is unusually high measured surface heat flow, averaging 2-3 times that of similarly-aged cratonic blocks elsewhere globally. This high heat flow arises from anomalously high concentrations of the heat producing elements, U, Th and K, which have been demonstrated to profoundly impact a range of temperature-dependent geological processes, such as metamorphism and magmatism. But the spatial distribution of these rocks is highly variable. Moreover, the vertical distribution of the heat producing elements is also important.
Geochemical analysis of rocks from the George V Land-Terre Adelie and eastern Prydz Bay regions suggest heat flow is highly heterogenous in East Antarctica, with the presence and variable distribution of U, Th and K enriched crustal rocks providing a first-order control on sub-glacial heat flow variations. Our data show that variations in abundance and distribution of heat producing elements within the Antarctic continental crust results in greater and much more variable regional sub-glacial heat flows than currently assumed in ice modelling studies. Such elevated heat flows may have significant effect on ice sheet behavior and highlights the importance of assessing the geological controls on heat flow for predictions of ice mass balance and sea-level change.