New research has uncovered the strongest evidence to date that Earth’s continents were formed by giant meteorite impacts, which were especially common during the first billion years or so of the four and a half billion AD ‘history of our planet. Curtin University researchers conducted the study, which was published on August 10, 2022 in the journal Nature.
According to Dr. Tim Johnson, from Curtin’s School of Earth and Planetary Sciences, the idea that the continents were originally formed at sites of giant meteorite impacts has been around for decades. However, until now there was little solid evidence to support the theory.
“Examining tiny crystals of the mineral zircon in rocks of the Pilbara Craton in Western Australia, which represents the best-preserved remnant of Earth’s ancient crust, we found evidence of such giant meteorite impacts,” said Dr. Johnson.
“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, similar to those responsible for the extinction of the dinosaurs, but occurring billions of years earlier.”
Understanding the formation and ongoing evolution of Earth’s continents is crucial, according to Dr. Johnson because these land masses are home to most of Earth’s biomass, all humans, and nearly all of the planet’s major mineral deposits.
“Not least, the continents host critical metals such as lithium, tin and nickel, commodities that are essential for the emerging green technologies needed to meet our obligation to mitigate climate change,” said Dr Johnson.
“These mineral deposits are the end result of a process known as crustal differentiation, which began with the formation of the first land masses, of which the Pilbara craton is just one of many.
“Data related to other areas of ancient continental crust on Earth appear to show similar patterns to those recognized in Western Australia. We would like to test our findings in 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 IH Hartnady, 10 Aug 2022, Nature.
Dr. Johnson is affiliated with The Institute for Geoscience Research (TIGeR), Curtin’s flagship earth science research institute.
#evidence #giant #asteroid #impacts #created #continents