A new study from Curtin University has found the strongest evidence yet showing that Earth’s continents were formed by giant meteorite impacts. The paper, ‘Giant impacts and the origin and evolution of continents’, was published in Nature on 10 August.
Dr Tim Johnson from Curtin’s School of Earth and Planetary Sciences, who is one of the authors of the study, said: “Examining small crystals of the mineral zircon in rocks of the Pilbara Craton in Western Australia, which represents the best-preserved remnant of ancient Earth’s crust, we found evidence of these giant meteorite impacts.”
These impacts were frequent during the first billion years or so of the planet’s history.
“Study of the oxygen isotope composition in these zircon crystals revealed a ‘top-down’ process that began with the melting of the rocks near the surface and progressed deeper, according to the “geological effect of giant meteorite impacts. Our research provides the first strong evidence that the processes that eventually formed the continents began with giant meteorite impacts,” added Dr Johson.
He said understanding the formation and ongoing evolution of Earth’s continents was crucial given that these land masses are home to most of Earth’s biomass, all humans and nearly all of the planet’s major mineral deposits.
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Although the hypothesis has been around for decades, until now there was no solid evidence to support it.
The researchers now plan to test the Western Australian findings on other ancient rocks and see if the model is more widely applicable.
SOURCE: CURTIN UNIVERSITY