Study Finds Evidence That Giant Meteorite Impacts Created the Continents

hubie writes:

New Curtin research has provided the strongest evidence yet that Earth's continents were formed by giant meteorite impacts:

Dr Tim Johnson, from Curtin's School of Earth and Planetary Sciences, said the idea that the continents originally formed at sites of giant meteorite impacts had been around for decades, but until now there was little solid evidence to support the theory.

"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," Dr Johnson said.

"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, similar to those responsible for the extinction of the dinosaurs, but which occurred billions of years earlier."

[...] "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.

Journal Reference:
Johnson, T.E., Kirkland, C.L., Lu, Y. et al. Giant impacts and the origin and evolution of continents. Nature 608, 330-335 (2022). 10.1038/s41586-022-04956-y

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