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New Curtin research has provided the strongest evidence yet that Earth鈥檚 continents were formed by giant meteorite impacts that were particularly prevalent during the first billion years or so of our planet鈥檚 four-and-a-half-billion year history.

Dr Tim Johnson, from Curtin鈥檚聽,聽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.

鈥淏y examining tiny crystals of the mineral zircon in rocks from the Pilbara Craton in Western Australia, which represents Earth鈥檚 best-preserved remnant of ancient crust, we found evidence of these giant meteorite impacts,鈥� Dr Johnson said.

鈥淪tudying the composition of oxygen isotopes in these zircon crystals revealed a 鈥榯op-down鈥� process starting with the melting of rocks near the surface and progressing deeper, consistent with the geological effect of giant meteorite impacts.

鈥淥ur 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.鈥�

Dr Johnson said understanding the formation and ongoing evolution of the Earth鈥檚 continents was crucial given that these landmasses host the majority of Earth鈥檚 biomass, all humans and almost all of the planet鈥檚 important mineral deposits.

鈥淣ot 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,鈥� Dr Johnson said.

鈥淭hese 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.

鈥淒ata related to other areas of ancient continental crust on Earth appears to show patterns similar to those recognised 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.鈥�

Dr Johnson is affiliated with The Institute for Geoscience Research (TIGeR), Curtin鈥檚 flagship earth sciences research institute.

The paper, 鈥�Giant impacts and the origin and evolution of continents鈥�, was published in Nature and is available online .