The ancient volcanic chain reportedly runs from Cape Hillsborough on the central Queensland coast, south-west through central New South Wales to Cosgrove in Victoria.
“This volcanic chain was created over the past 33 million years, as Australia moved north-northeast over a mantle plume hotspot which we believe is now located in Bass Strait,” the study’s lead author Rhodri Davies of Australian National University, said.
“This track, which we’ve named the Cosgrove hotspot track, is nearly three times as long as the famous Yellowstone hotspot tracks on the North American continent,” he said, adding this kind of volcanic activity is surprising because it occurs away from tectonic plate boundaries where most volcanoes are found.
The authors examined 15 extinct volcanoes in eastern Australia that had been known about for quite some time and appeared to follow a generally similar track.
“The volcanoes in central Queensland showed an age progression, so they got younger towards the south, and so too did those in New South Wales and Victoria,” Mr. Davies said.
The researchers looked at the movement of the Australian tectonic plate.
“Australia is actually the fastest moving continent on Earth, moving towards Indonesia at around seven centimeters per year,” Mr. Davies said.
“It is always nice to discover something like this. We are getting much better at understanding volcanism in Australia. People don’t realize we have the most extensive volcanoes on Earth but there are still some individual provinces yet to explore,” he said.
“We showed that these volcanoes are surface manifestations of the same mantle plume. However, the two groups of volcanoes were geochemically very distinct from each other and were separated by a gap of 700 kilometers, so no-one ever put these two volcanic chains together,” Mr. Davies said.