Study finds impact craters could have fostered early life

A Curtin University-funded study has revealed that even comparatively small meteorite impact craters might have played a key role in the origin and evolution of early life.

Curtin University researcher Dr Fred Jourdan co-authored the paper, which suggests heat generated by an asteroid impact takes at least several hundred thousand years to cool down, providing an ideal environment for microbial life to thrive.

Together with lead author Dr Martin Schmieder of The University of Western Australia, they analysed impact-molten rock samples from the Lappajärvi crater in Finland at the Western Australian Argon Isotope Facility, based at Curtin.

“We used the argon-argon technique, which is based on the natural radioactive decay of potassium to argon, to measure the age of different minerals formed during the impact,” Dr Jourdan said.

“This meant the longevity of the crater cooling process was, for the first time, directly measured on rocks and minerals from a crater, rather than the initial theoretical simulations that suggest a rather short cool-down period of only 10,000 years.”

Dr Jourdan, a Senior Research Fellow in Curtin’s Department of Applied Geology and John de Laeter Centre, said, “The argon-argon data tells us that the Lappajärvi crater did not cool down as rapidly as expected, but within at least several hundred thousand years, and perhaps more than a million years.

“Cooling impact craters are hot natural laboratories in which hot hydrothermal fluids circulate. We think they provided ideal starting conditions for the origin and evolution of microbial life on early Earth more than three billion years ago.”

Dr Schmieder said craters produced by the impact of incoming asteroids and comets can reach temperatures of several thousand degrees Celsius, capable of melting portions of the target rock.

He said meteorite craters are being continuously discovered worldwide with among 185 so far recognised on Earth, 29 of which were found in Australia.

The research duo is currently undertaking a global-scale, government-funded research project awarded to Dr Jourdan on a number of terrestrial impact craters, some of which are located in Australia. The project investigates other ancient impact craters on all continents and explores geologic age and potential role in the history of life on Earth.

‘The Lappajärvi impact structure (Finland): Age, duration of hydrothermal crater cooling, and implications for life’ has been published in the journal Geochimica et Cosmochimica Acta.