Earth's continents likely created by giant meteorite impacts

A study on the continents titled "Giant impacts and the origin and evolution of continents" has been published in the journal Nature.

Researchers from Curtin University have shown that giant meteorite impacts during the first billion years of Earth's 4.5 billion year lifetime are the likely cause of the planet's continents. Evidence to support the theory was previously thin, but scientists have found strong evidence now by studying the Pilbara Craton in Western Australia, one of the two pristine Earth crusts from the Archaean period 3.6 to 2.7 billion years ago.

"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. 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," said Dr. Tim Johnson, from Curtin's School of Earth and Planetary Sciences.

The findings show that the processes that ultimately resulted in the continents forming began with these giant meteorite impacts. The meteorites that landed on Earth would have been similar to those that wiped out the dinosaurs much later. Dr. Johnson highlighted that it is critical to understand how the continents formed to understand how they will continue to evolve, as they support most of Earth's biomass, including human life, and contain important mineral deposits.

"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 appears to show patterns similar to those recognized 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," Johnson continued.

You can read more from the study here.