Evidence that Earth’s continents were formed by giant meteorite impacts has been discovered in new research.
New research has revealed the strongest evidence yet that Earth’s continents were formed by giant meteorite impacts, which were especially common during the first billion or so years of our planet’s four-and-a-half billion-year history. Curtin University researchers conducted the study, which was published in the journal Aug. 10, 2022 Nature.
According to Dr. Tim Johnson, from Curtin’s School of Earth and Planetary Sciences, the idea that the continents originally formed at sites of giant meteorite impacts has been around for decades. Until now, however, there has been little solid evidence to support the theory.
“By examining tiny crystals of the mineral zircon in rocks of the Pilbara Craton in Western Australia, which represents the best-preserved remnant of an ancient crust on Earth, we found evidence of these giant meteorite impacts,” said Dr. Johnson.
“Studying the composition of oxygen isotopes in these zircon crystals revealed a ‘top-down’ process that begins with the melting of rocks near the surface and progresses deeper, consistent with the geological effect of giant meteorite impacts.
“Our research provides the first solid 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.”
According to Dr. Johnson, it is critical to understanding the formation and ongoing evolution of Earth’s continents, as these land masses harbor most of the Earth’s biomass, all humans, and nearly all of the planet’s major mineral deposits.
Last but not least, the continents are home to critical metals such as lithium, tin and nickel, raw materials essential to the emerging green technologies needed to meet our commitment 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 earliest landmasses, of which the Pilbara Craton is just one of many.
“Data related to other areas of ancient continental crust on Earth appear to show patterns similar to those in Western Australia. We want 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 IH Hartnady, Aug 10, 2022, Nature.
dr. Johnson is affiliated with The Institute for Geoscience Research (TIGeR), Curtin’s flagship earth science research institute.