Comparative Petrology & Geochemistry of High Heat-Producing Granites in Australia & Europe

Abstract

To better understand the origin, tectonic setting and generation of high heat-producing granites (HHPG) and provide target criteria for the exploration of granite-hosted Enhanced Geothermal Systems (EGS), Australian examples are being studied and compared with better known European analogues that are being re-examined. Three areas of long-standing interest for EGS in Europe are Cornwall, UK; Soultz-sous-Forêts, France; and the Erzgebirge, Germany. These areas have higher than average heat flow (at surface and depth), and concentrations of the main heat-producing elements Uranium (U), Thorium (Th) and Potassium (K) in granitic rocks. The Big Lake granite suite of the central Australian Cooper Basin (Gatehouse et al., 1995), is a pre-eminent HHPG target for EGS development in Australia. The Big Lake Suite granites are Australia’s hottest with temperatures of >250ºC at ~4km depth (Habanero 1, (Baisch et al., 2006). The Soultz-sous-Forêts and Cooper Basin systems have in common an insulating sediment cover of several kilometres.