Science

Giant meteorite impacts in Earth’s distant history may have contributed to the formation of continents

New evidence supports the idea that Earth’s continents were created in the distant past when massive meteorites fell on the planet.

A team of researchers from Curtin University in Australia has found that Earth’s continents could have formed at the sites of meteorite impacts, which were much more common in the early history of the solar system. Earth is currently the only planet we know to have continents, and until now, researchers haven’t been completely sure why that is. These new finds represent the first hard evidence to support the long-held hypothesis that meteorites are behind this unique geological feature.

“By examining tiny crystals of the mineral zircon in the rocks of the Pilbara craton in Western Australia, which are the best-preserved remains of ancient crust on Earth, we found evidence of these giant meteorite impacts,” said Tim Johnson, a geologist at Curtin University and lead researcher. the author of the new study, the statement said. (will open in a new tab) “Studying the composition of oxygen isotopes in these zircon crystals revealed a ‘downward’ process starting with the melting of rocks near the surface and developing deeper, which is consistent with the geological effect of giant meteorite impacts.”

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A meteorite is a space rock that survived its journey through the Earth’s atmosphere and hit the planet’s surface. Many meteorites broke off from larger asteroids that formed about 4.6 billion years ago, when the planets of the solar system were also born.

The most famous example of an asteroid impact in Earth’s history is the Chicxulub impact 66 million years ago. This collision wiped out the dinosaurs and left a 10-kilometer-wide crater off the Yucatan Peninsula in Mexico. Johnson and colleagues’ findings suggest that similar impacts shaped the Earth’s geology billions of years before this infamous event, they argue.

A better understanding of the formation and development of continents may have ramifications for our understanding of how life forms and valuable minerals are dispersed across the planet.

“Continents are home to critical metals such as lithium, tin and nickel, commodities that are essential for the new green technologies needed to meet our commitment to climate change mitigation,” Johnson said. “These mineral deposits are the end result of a process known as crustal differentiation that began with the formation of the earliest land masses, one of many of which is the Pilbara Craton.”

He added that the team intends to continue studying ancient rocks in areas like the Pilbara Craton to see if these findings are reflected globally.

The researchers say the early signs are encouraging for the theory that the continents were created by ancient meteorite impacts.

“Data related to other areas of ancient continental crust on Earth appear to show patterns similar to those found in Western Australia,” Johnson concluded.

The team’s research is presented in an article published in August. 10 in Nature (will open in a new tab).

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