Radioactive dating techniques allowed a team led by Fred Jourdan of Curtin University in Perth to precisely measure the age of the eruptions of the Kalkarindji volcanic province, which saw lava cover an area of more than two million square kilometres in the Northern Territory and Western Australia. The results, published in a Geology study, placed the eruptions at 510 million years ago, which is when the Early-Middle Cambrian extinction took place. ‘It has been well documented that this extinction, which eradicated 50 per cent of species, was related to climatic changes and depletion of oxygen in the oceans, but the exact mechanism causing these changes wasn’t known, until now,’ Jourdan said.
The scientists also measured a depletion of sulphur dioxide from the province’s volcanic rocks, indicating that significant amounts of sulphur would have been released into the atmosphere during the eruptions. The sulphur dioxide discharged by Mount Pinatubo in the Philippines when it erupted in 1991 lowered the average global temperatures by a few tenths of a degree, suggesting that the effect of the much larger Kalkarindji eruptions on the climate would have been catastrophic.
This story was published in the July 2014 edition of Geographical Magazine