High-resolution heat-flow measurements in the Southern Carnarvon Basin, Western Australia

Abstract

In June 1999, I undertook a series of heat-flow measurements in the Gascoyne Region of Western Australia. The measurements involved precision temperature logging of stratigraphic boreholes, and thermal conductivity measurements on core samples. Results indicate that the surface heat flow in the onshore Southern Carnarvon Basin is about 55 mW/m2. This is 3.5 mW/m2 less than the average heat flow in the Dampier Sub-basin, suggesting that the lithosphere beneath the Dampier Sub-basin may still retain heat from the Mid-Jurassic rifting event. The precision temperature logs suggest that the ground surface temperature across the Gascoyne Region is about 6°C warmer than the average air temperature, implying a relatively high absorption of solar radiation or relatively low surface albedo. The logs also suggest that the thermal diffusivity of the surface alluvium is about 1.4 ´ 10-6 m2/s. Observations near the eastern margin of the Southern Carnarvon Basin support the prediction of elevated heat flow resulting from heat refraction and extra heat input from an underlying, heat-generating body of granite.