Geothermal Potential in Queensland

Abstract

Hot rocks occur at depth over significant areas of Queensland offering a number of targets for geothermal energy extraction. On the published maps showing temperatures at 5 kilometre depths, the area beneath the Cooper and Eromanga Basins in southwest Queensland shows as the largest area of hot rocks. Much of this area is underlain by low grade meta-sedimentary rocks. The meta-sedimentary rocks are intruded by granites of different ages. In the central Eromanga Basin, the granites are of Middle Ordovician age. They are s-type granites and are not high heat producing. In the southwest, the granites are of mid Silurian age. They are also s-types and not high heat producing. None the less, they have high residual heat. The Late Carboniferous, high heat producing granite at Habernero in South Australia does cross the border into Queensland, but has no known equivalents in Queensland. High heat producing granites are common in the Mount Isa area and extend under the Eromanga Basin. High heat producing granites are present beneath the Carpentaria Basin. Several heat anomalies of unknown cause occur in western central Queensland. There are limited heat flow measurements in north Queensland. Although there are many high heat producing granites, there are no apparent insulating blanket rocks. The youngest basalt flows in north Queensland are 10,000 years old and new flows could yet occur- there may be heat associated with magma chambers. There are hot springs and warm springs in the area, but they are poorly understood. Exploration for geothermal energy will begin in Queensland in 2006 with the grant of exploration permits.