A new Curtin University study has found the most robust 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 August 10. Dr Tim Johnson from Curtin’s School of Earth and Planetary Sciences, who is one of the study's authors, said: “By examining tiny crystals of the mineral zircon in rocks from the Pilbara Craton in Western Australia, which represents Earth’s best-preserved remnant of ancient crust, we found evidence of these giant meteorite impacts.” These impacts were prevalent during the first billion years or so of the planet's history. “Studying the composition of oxygen isotopes in these zircon crystals revealed a ‘top-down’ process starting with the melting of rocks near the surface and progressing deeper, consistent with the geological effect of giant meteorite impacts. Our research provides the first solid evidence that the processes that ultimately formed the continents began with giant meteorite impacts,” Dr Johson added. He said that understanding the formation and ongoing evolution of the Earth’s continents was crucial given that these landmasses host the majority of Earth’s biomass, all humans and nearly all of the planet’s important mineral deposits. Newsletter | Click to get the day's best explainers in your inbox While the hypothesis has been there for decades, so far there was no solid evidence to back it. The researchers now plan to test the findings from Western Australia on other ancient rocks and see if the model is more widely applicable. SOURCE: CURTIN UNIVERSITY
