Ancient volcano landscape found under central Australia
Resources & Energy
An ancient landscape of 100 volcanoes has been discovered underneath Australia’s largest onshore oil and gas region.
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An international team of subsurface explorers from the University of Adelaide in South Australia and the University of Aberdeen in Scotland uncovered the previously undescribed network of volcanoes buried deep within the Cooper-Eromanga Basins of central Australia.
The Cooper-Eromanga Basins in the northeastern corner of South Australia and southwestern corner of Queensland have been the site of about 60 years of petroleum exploration and production. But, until now, this ancient Jurassic volcanic underground landscape has gone largely unnoticed.
The volcanoes developed in the Jurassic period, between 180 and 160 million years ago, and have been subsequently buried beneath hundreds of metres of sedimentary – or layered – rocks.
Published in the journal Gondwana Research, the researchers used advanced subsurface imaging techniques, analogous to medical CT scanning, to identify the plethora of volcanic craters and lava flows, and the deeper magma chambers that fed them.
The Cooper-Eromanga Basins are now a dry and barren landscape.
But the research shows that in Jurassic times it would have been a landscape of craters and fissures, spewing hot ash and lava into the air, and surrounded by networks of river channels, evolving into large lakes and coal-swamps.
Co-author Associate Professor Simon Holford, from the University of Adelaide’s Australian School of Petroleum, said the discovery raised the prospect that more undiscovered volcanic worlds resided beneath the poorly explored surface of Australia.
“While the majority of Earth’s volcanic activity occurs at the boundaries of tectonic plates, or under the Earth’s oceans, this ancient Jurassic world developed deep within the interior of the Australian continent,”
The research was carried out by Jonathon Hardman, then a PhD student at the University of Aberdeen, as part of the Natural Environment Research Council Centre for Doctoral Training in Oil and Gas.
Jurassic-aged sedimentary rocks bearing oil, gas and water have been economically important for Australia, but this latest discovery suggests a lot more volcanic activity in the Jurassic period than previously supposed.
The researchers have called the volcanic region the Warnie Volcanic Province, in recognition of the explosive talent of former Australian cricketer Shane Warne.
“We wrote much of the paper during a visit to Adelaide by the Aberdeen researchers, when a fair chunk was discussed and written at Adelaide Oval during an England vs Cricket Australia XI match in November 2017,” Associate Professor Holford said.
“Inspired by the cricket, we thought Warnie a good name for this once fiery region.”
Co-author Associate Professor Nick Schofield from the University of Aberdeen’s Department of Geology and Petroleum Geology said the Cooper-Eromanga Basins had been substantially explored since the first gas discovery in 1963.
“This has led to a massive amount of available data from underneath the ground but, despite this, the volcanics have never been properly understood in this region until now,” he said.
“It changes how we understand processes that have operated in Earth’s past.”
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