Wed. Feb 19th, 2020

The impact of the first asteroid ended the “Snowball Land”



The oldest impact of an asteroid on Earth occurred in western Australia 2,229 million years ago, according to a study published Tuesday by the magazine “Nature”.

The research, led by Curtin University, in Australia, confirmed that this new date exceeds 200 million years to what was so far the most primitive.

This is suggested by the evidence found in the Yarrabubba crater, 70 kilometers in diameter and caused by the impact of an asteroid at the end of the period of global glaciation known as “Snowball Land” (“Snowball Earth”)

The scientists applied isotopic analyzes of minerals to calculate the precise age of that crater, which allowed them to set the figure of 2,229 million years, explains the main author of the study, Timmons Erickson, from the Curtin School of Planetary and Terrestrial Sciences and the NASA Johnson Space Center.

End of the glaciers?

His team found samples of zirconia and monacite “recrystallized by the shock” of the impact at the eroded base of the crater, suggesting that it occurred in an ice-covered landscape.

Also, this study raises the possibility that the impact of the oldest known asteroid could help end the aforementioned period of “superglaciation”.

“We now know that the Yarrabubba crater was made just at the end of what we commonly call ‘Snowball Land’ early, a period in which the atmosphere and oceans were evolving and became more oxygenated and the rocks deposited on many continents they recorded glacial conditions, “Chris Kirkland of Curtin University said in a statement.

His colleague Nicholas Timms adds that they have also observed that there is a Temporary “precise coincidence” between the impact of Yarrabubba and the disappearance of glacial deposits.

“The age of the impact of Yarrabubba coincides with the disappearance of a series of ancient glaciations. After the impact, glacial deposits are absent in the rock record for 400 million years. This turn of fate suggests that the great impact of the meteorite may having influenced the global climate, says Timms.

Another team member, Aaron Cavosie, highlights the importance of accurately determining the age of “known craters” such as Yarrabubba, which “was in sight for almost two decades before we realized its importance.”

“Yarrabubba is about half the age of Earth and raises the question of whether all the older impact craters have eroded or are still there waiting to be discovered,” concludes Cavosie. EFE

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