Australia's Deadly Volcanic Eruptions Caused the World's First Mass Extinction

About 510 million years ago, volcanic eruptions in Australia spewed ash into the air. These violent eruptions were so large, in fact, that they impacted the Earth's climate. Now, scientists have found that they may have been the cause of the first known mass extinction in the history of complex life.

The Kalkarindji volcanic province in Australia is an area that was volcanically active in the past. In fact, lava once covered an area of more than 2 million square kilometers in the Northern Territory and Western Australia. In order to learn a bit more about the history of this area, the researchers collected samples and used radioactive dating techniques to precisely measure the age of the eruptions that occurred in this region.

Yet what was interesting was that these volcanic eruptions occurred at the same time as the Early-Middle Cambrian extinction, which occurred from 510 to 511 million years ago. This was the first extinction to wipe out complex multicellular life.

"It has been well-documented that this extinction, which eradicated 50 percent of species, was related to climatic changes and depletion of oxygen in the oceans. But the exact mechanism causing these changes was not known, until now," said Fred Jourdan, one of the researchers, in a news release. "Not only were we able to demonstrate that the Kalkarindji volcanic province was emplaced at the exact same time as the Cambrian extinction, but were also able to measure a depletion of sulphur dioxide from the province's volcanic rocks-which indicates sulphur was released into the atmosphere during the eruptions."

The scientists also compared the Kalkarindji volcanic province with other volcanic provinces. This allowed them to learn that the most likely process for all of the mass extinctions was a rapid oscillation of the climate triggered by volcanic eruptions emitting sulphur dioxide, along with greenhouse gases methane and carbon dioxide.

"We calculated a near perfect correlation between large volcanic province eruptions, climate shifts and mass extinctions over the history of life during the last 550 million years, with only one chance over 20 billion that this correlation is just a coincidence," said Jourdan in a news release.

The findings are published in the journal Geology.