A mass extinction event

Ancient impact of a gargantuan asteroid in southern Australia changed the face of the world forever, study reveals

• Six-mile wide rock hit 300million years ago and left 120 mile impact zone
• It is the third largest asteroid impact site on the planet
• Seismic shock and fireball would have 'incinerated large parts of Earth'

Daily Mail,

19 February, 2013

A gargantuan asteroid which struck Australia more than 300million years ago changed the face of the Earth forever, a new study claims.

The six-mile diameter asteroid left an impact zone more than 120 miles wide - the third largest such site on the planet - and likely led to mass extinctions worldwide.

'The dust and greenhouse gases released from the crater, the seismic shock and the initial fireball would have incinerated large parts of the Earth,' said Andrew Glikson, visiting fellow at the Australian National University.

Gargantuan: Researchers have discovered the impact site of a six-mile wide asteroid which struck South Australia some 300million years ago and likely led to mass extinctions across the planet

He added: 'The greenhouse gases would stay in the atmosphere for tens of thousands of years.'

Evidence of the ancient catastrophe was only discovered after another researcher alerted Dr Glikson to unusual mineral deposits in the East Warburton Basin in South Australia.

As the ages have passed, the mammoth impact zone has been buried beneath nearly 2.5 miles of earth.

To identify it Dr Glikson and his colleagues analysed quartz grains drawn from the site and studied underground seismic and magnetic anomalies

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The strike may have been part of an asteroid impact cluster which caused an era of mass extinction, wiping out primitive coral reefs and other species, added Dr Glikson.

However, he added, the impact happened well before the time of the dinosaurs.

Known extent of the Warburton Basin based on the ¿C¿ seismic horizon: The Birdsville Track Ridge divides the eastern Warburton Basin, which underlies the Cooper Basin, from the Western Warburton Basin

'It’s significant because it's so large. It's the third largest impact terrain anywhere on Earth found to date,' he told Australian science news site The Conversation.

'It’s likely to be part of a particular cluster that was linked with a mass extinction event at that time.'

He said there was a chance that the incoming asteroid actually split in two as it made its fiery descent through the Earth's atmosphere.

'We are studying another anomaly in West Warburton that could well be its twin but we don’t know yet,' he said.

Dr Simon O'Toole, research astronomer at the Australian Astronomical Observatory, told The Conversation that the find offered fresh evidence of the links between asteroid impacts and mass extinctions.

'Australia is a fantastic place for impact crater hunters because we have huge open space with nothing in it,' said Dr O'Toole, who was not involved in the research.

'It's huge,' he added. 'Most asteroid impacts are about 100m in diameter.'

Dr Glikson is co-author of a study detailing the findings published in the journal Tectonophysics this month.