Research out of Curtin University has all but confirmed that Earth’s continents were formed by giant meteorite impacts.
These meteorite impacts, the uni said, were particularly prevalent during the first billion years or so of our planet’s four-and-a-half-billion-year history. The meteorites that formed the continents were similar to those which wiped out the dinosaurs.
The theory that continents originally formed at sites of giant meteorite impacts has been around for years. But the research from Curtin provides some more solid evidence.
“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 Tim Johnson, from Curtin’s School of Earth and Planetary Sciences, said.
The researchers studied the composition of oxygen isotopes in these zircon crystals, which revealed a ‘top-down’ process starting with the melting of rocks near the surface and progressing deeper. This, they said, is 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,” Johnson added.
So why is this important?
Johnson said 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 almost all of the planet’s important mineral deposits.
“Not least, the continents host critical metals such as lithium, tin and nickel, commodities that are essential to the emerging green technologies needed to fulfil our obligation to mitigate climate change,” he said.
These mineral deposits are the end result of a process known as crustal differentiation, which Johnson said began with the formation of the earliest landmasses, of which the Pilbara Craton is just one of many.
You can read more about the research in Nature.