| Abstract |
Understanding the distribution of subsurface temperatures is an important early step in a geothermal exploration process. With the exception of a few areas of hot springs, there are no surface manifestations of anomalous temperature at depth in Australia. The Australian continent has no active magmatism, the deep heat flow regime is conductive, and thick layers of insulating sediments are necessary to obtain elevated temperatures at depth suitable for electricity generation or industrial use. The distribution of direct temperature measurements and surface heat flow determinations is described in Gerner and Holgate (2010). The majority of these measurements were made by the petroleum industry and, while there are over 5000 wells, they are heterogeneously distributed, resulting in unconstrained temperature uncertainties over many parts of the continent. An alternative approach is needed to provide indications of temperature at depth in uncharacterised areas, so that the whole of Australia can be evaluated for geothermal prospectivity. A new approach for developing a 3D temperature map of the Australian continent is being developed that combines available proxy data using high-performance computing and large continental-scale datasets. The Thermal Map from Assessed Proxies (TherMAP) is a 3D new modelling approach that brings together up-to-date national-scale datasets collected by Geoscience Australia and others, including OZTemp, OZ SEEBASETM, OZCHEM, surface temperature, Australian Geological Provinces, Moho depth, thermal conductivity of sedimentary basins and the National Gravity Map of Australia. Bringing together such a range of datasets provides a geoscientific basis by which to estimate temperature in regions where direct observations are not available. Furthermore, the performance of computing facilities, such as the Australian National University’s (ANU) National Computational Infrastructure (NCI), is enabling insights into the nature of Australia’s geothermal resources that had not been previously available. This includes developing an understanding of the errors involved in such a mapping study through the quantification of uncertainties. At this stage the reported uncertainties around thermal anomalies remain high, but still provide a basis by which to assess temperature estimates at different locations. Encouragingly, TherMAP has been able to reproduce many observed temperature features without using direct bore-hole temperature observations as an input into the modelling process. Furthermore, a number of areas have been identified, due to the difference in estimated temperature distributions from previous methods, which may warrant further study. |