The continents of Earth were formed by massive meteorite impacts, which occurred often over the first billion years of our planet’s four and a half billion year history and are now supported by the greatest evidence yet. The study was carried out by researchers from Curtin University, and it was released on August 10th, 2022, in the magazine Nature.
The notion that the continents initially formed at locations of massive meteorite impacts has been around for decades, according to Dr. Tim Johnson from Curtin’s School of Earth and Planetary Sciences. There wasn’t much reliable evidence to back up the theory, though, until recently.
“We found evidence of these massive meteorite impacts by analysing microscopic crystals of the mineral zircon in rocks from the Pilbara Craton in Western Australia, which represents Earth’s best-preserved relic of ancient crust,” Dr. Johnson stated.
Studying the oxygen isotope composition in these zircon crystals indicated a “top-down” process that began with the melting of rocks close to the surface and moved deeper, in line with the geological impact caused by massive meteorites.
Our research offers the first convincing evidence that the mechanisms that eventually gave rise to the continents started with enormous meteorite hits that happened billions of years earlier than those that killed off the dinosaurs.
Dr. Johnson argues that it is imperative to comprehend the origins and ongoing evolution of the Earth’s continents since they are home to the vast majority of the planet’s biomass, all humans, and practically all of the planet’s significant mineral reserves.
Not least, Dr. Johnson noted, “the continents are home to vital metals like lithium, tin, and nickel, commodities that are crucial to the emerging green technology required to fulfil our duty to mitigate climate change.”
“The creation of the oldest landmasses, of which the Pilbara Craton is only one, led to a process known as crustal differentiation that produced these mineral deposits.
“Data related to other areas of ancient continental crust on Earth appears to show patterns similar to those recognized in Western Australia. We would like to test our findings on these ancient rocks to see if, as we suspect, our model is more widely applicable.”
Reference: “Giant impacts and the origin and evolution of continents” by Tim E. Johnson, Christopher L. Kirkland, Yongjun Lu, R. Hugh Smithies, Michael Brown and Michael I. H. Hartnady, 10 August 2022, Nature. DOI: 10.1038/s41586-022-04956-y
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