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Ancient Asteroid Impact Revealed

By Stephen Luntz

Australia's second-largest impact linked to geothermal energy.

Research into the geothermal energy potential of the Cooper Basin has led to the discovery of an ancient asteroid impact, possibly Australia’s second-largest. Intriguingly, the impact may be the reason that the Basin holds so much potential to supply Australia with clean energy.

Dr Tonguc Uysal of the Queensland Geothermal Energy Centre of Excellence was exploring the area on behalf of the Queensland Government, searching for clues as to why the granites under the Basin are so hot. “I noticed that the quartz grains in the rock had unusual planar deformation features that indicated either they had been exposed to extreme tectonic pressure or a large asteroid impact,” Uysal says.

He had the grains tested, and an asteroid impact was confirmed. Dating of the granite rocks into which the asteroid slammed, and sedimentary rocks laid down after the impact, suggest an age of around 300 million years. The crater has been eroded, but distribution of the shocked quartz suggests it was once 80 km wide, making it our second-largest impact crater after the 120 km giant at Woodleigh, east of Shark Bay.

The location of the impact in possibly the world’s largest geothermal resource may not be a coincidence. “It is a well-known fact that the kinetic energy released from an impact event can cause hydrothermal circulation, enriching rocks with heat-producing elements,” Uysal says.

“The impact also causes fracture zones, providing permeability for hot water to circulate.” While these are both necessary for the extraction of energy from locations such as the Cooper Basin, Uysal stresses that attributing the Basin’s suitability to the impact is at this stage “just speculation”.

Uysal will continue investigating the impact and any links it may have to the Basin’s geothermal resource.