As an intern at COSMOS Online:
A large chunk of the Australian continental crust that broke off and sank millions of years ago has just been discovered, providing new clues to the slow geological ballet that formed Australia.
Marine geoscientist Neville Exon working with a team from Geoscience Australia dragged what he calls a "bucket with a big chain bag" along the Ken Plateau – a 140,000 square kilometre area located about 450 kilometres off the northeast Australian coast. The material they collected from 3.5 kilometres down was analysed and found to be remnant of the mainland continental crust.
The plateau broke off from the mainland about 60 million years ago, following plate tectonic changes that started in Victoria 35 million years earlier. The Ken Plateau, which was next to the Bundaberg region in Queensland at the time, moved about 300 kilometres to the northeast, pirouetting 30 degrees anti-clockwise over the next nine million years.
The same tectonic shift formed the Lord Howe Rise to the southeast of the plateau.
Exon's exploration of the Ken Plateau mapped the final region of terra incognita (unknown territory) in offshore Australia, revealing the nature and long-term resource potential of the area.
Efforts to map Australia's vast offshore territory began shortly after the Second World War. However, high-quality, detailed mapping was only made possible in the last 15 years, after the development of multibeam sonar systems.
It will take another 50 years to collate a detailed map of our entire offshore area.
"A comprehensive map of the ocean floor will be a starting point for full assessment of tectonic movement," Exon said, explaining that this would add to our understanding of the offshore and onshore history of Australia.
"There's also a biological interest and mineral interest," he added. "The questions are: what are these blocks made of; where do they come from; and is there petroleum potential."
There is no evidence of petroleum in rock samples from the Ken Plateau, he said.
