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Illustration of a meteor heading towards Earth. Some scientists think such a meteor impact may have led to the formation of the continents as they exist today.
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Nationalgeographic.co.id—To date, Earth is the only one planet what we know that has continent. How exactly they formed and evolved remains unclear. However, we do know that because the edges of the continents are thousands of miles apart, we agree that at some point in the past, Earth’s landmass was concentrated in one large supercontinent.
Since the planet doesn’t look the way it does today, something must have caused the supercontinent to break up. Now, we have new evidence to show that the effects of meteorite giants play an important role in that.
A new study by Curtin University has provided the strongest evidence yet that Earth’s continents were formed by the impact of a giant meteorite. This happened during about the first billion years of our planet’s four and a half billion year history.
The results of this study have been published in the journal Nature on August 10 yesterday with the title Giant impacts and the origin and evolution of continents.
Dr Tim Johnson, from Curtin’s School of Earth and Planetary Sciences, said the idea. According to him, the continent was originally formed at the site of a giant meteorite impact. This has been around for decades. But until now there has been little solid evidence to support the theory.
“By examining the small crystals of minerals zircon in rocks from the Pilbara Craton in Western Australia, which represent the best-preserved remnants of ancient crust on Earth. There we found evidence of this giant meteorite impact,” Johnson said.
“Studying the composition of the oxygen isotopes in these zircon crystals can reveal the processes ‘top-down‘ begins with the melting of rocks near the surface and progresses deeper, consistent with the geological effects of giant meteorite impacts.” he explained.
Dr Johnson said understanding the formation and continuous evolution of Earth’s continents was critical. Given that this land holds most of the Earth’s biomass. All humans and almost all important mineral deposits exist on this planet.
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A gorge in Karijini National Park showcases the Pilbara Craton rocks.
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“Our research provides the first strong evidence that the process that eventually formed the continents began with the impact of a giant meteorite. This is similar to the one responsible for the extinction of the dinosaurs, but which occurred billions of years earlier,” Johnson said, as reported Science Alert. “At the very least, the continent plays host to important metals such as lithium, lead and nickel. Which are essential commodities for emerging green technologies and necessary to meet our obligations to mitigate climate change.”
These mineral deposits are the end result of a process known as crustal differentiation. Starting with the formation of the earliest landmasses, Pilbara Craton is just one of many.
The work was carried out on 26 rock samples containing zircon fragments, aged between 3.6 and 2.9 billion years. The research team carefully analyzed the oxygen isotopes; specifically, the ratios of oxygen-18 and oxygen-16, which have 10 and 8 neutrons, respectively. This ratio is used in paleogeology to determine the temperature of the rock formation at which the isotope was found.
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