An ancient “Jurassic volcanic underground landscape” that has gone largely unnoticed in Central Australia has been discovered by scientists.
An international team of subsurface explorers from the University of Adelaide and the University of Aberdeen in Scotland have uncovered about 100 ancient volcanoes buried deep within the Cooper-Eromanga Basins.
The Basins, located in the northeastern corner of South Australia and southwestern corner of Queensland, is Australia’s largest onshore oil and gas producing region of Australia.
But despite about 60 years of petroleum exploration and production, the old volcanic world has gone largely undetected.
Researchers used advanced subsurface imaging techniques to identify the plethora of volcanic craters and lava flows, and the deeper magma chambers that fed them.
They say the volcanoes developed in the Jurassic period, between 180 and 160 million years ago, buried beneath hundreds of metres of layered rocks.
While the Basins are now a dry and barren landscape, the researchers say in Jurassic times there would have been craters and fissures, spewing hot ash and lava into the air, surrounded by networks of river channels with large lakes and coal-swamps.
“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,” says co-author Associate Professor Simon Holford, of the University of Adelaide.
“Its discovery raises the prospect that more undiscovered volcanic worlds reside beneath the poorly explored surface of Australia.”
The researchers say that 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 Cooper-Eromanga Basins have been substantially explored since the first gas discovery in 1963,” says co-author Associate Professor Nick Schofield, of the University of Aberdeen.
“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. It changes how we understand processes that have operated in Earth’s past.”
They’ve now named the volcanic region the “Warnie Volcanic Province” after Australian cricket legend 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,” they said.
“Inspired by the cricket, we thought Warnie a good name for this once fiery region.”