New research presents the strongest evidence yet that the continents were formed by large meteorite strikes during the first billion years or so of Earth's 4.5 billion year history.
The idea that the continents formed at the sites of massive meteorite impacts, as professed by Dr. Tim Johnson of Curtin University's School of Earth and Planetary Sciences, has been around for decades, but until recently, there has been no concrete 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 sai
“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 impact
“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
Since these landmasses contain the vast majority of Earth's biomass, all people, and practically all of the planet's main mineral reserves, Dr. Johnson emphasised the importance of understanding the genesis and continuing development of the Earth's continent
“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,” Dr Johnson sai
“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 man
“Data 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.”y.d.s..”s.d.
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