Asteroids craters played key role in evolution

Asteroids hitting the Earth cause immense destruction, but some of them may have played a key role via their craters in the origin and evolution of early life, a new study has found.

Geologist Martin Schmieder, a research associate in The University of Western Australia UWA's School of Earth and Environment, said study results suggested that heat generated by an asteroid impact took at least several hundred thousand years to dissipate.

Schmieder, the lead author of the study published in the journal Geochimica et Cosmochimica Acta, said as impact craters cooled, they provided an ideal environment for microbial life to thrive.

"As a case study, we analysed impact-molten rock samples from the 23km-diameter and 76-million-year-old Lappajarvi crater in Finland, and were quite surprised by the results," Schmieder said in a statement.

"Our new argon-argon data tell us that the Lappajarvi crater did not cool down as rapidly as expected but within at least several 100,000 years, and perhaps more than a million years," said Dr Fred Jourdan, Director of the Western Australian Argon Isotope Facility at Curtin University.

"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 two billion years ago," he said.

"Although usually associated with massive havoc and destruction, asteroid impacts also acted as extraterrestrial boosters of life in the past.

"A prime example is the giant Chicxulub impact that helped wipe out the dinosaurs 66 million years ago and eventually paved the way for mammals and mankind," Jourdan said.

The researchers believe the large Acraman impact in South Australia more than 500 million years earlier probably had a major influence on the evolutionary radiation of the first multicellular life forms during the Ediacaran period.

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