Thursday, September 29, 2022

Scientists find evidence that continents were formed by giant meteor impacts

Scientists have discovered what they believe is the strongest evidence yet that continents were formed by giant meteor impacts during Earth’s early history.

According to researchers at Curtin University, meteorite impacts were “particularly prevalent during the first billion years of our planet’s four-and-a-half billion year history”.

The theory that continents originally formed at the sites of these impacts has been around for decades, but there is little solid evidence to support it – until now, says Dr. Tim Johnson.

“By examining tiny crystals of the mineral zircon in rocks from the Pilbara Craton in Western Australia, which represent Earth’s best-preserved remnant of ancient crust, we found evidence of the impacts of these giant meteorites,” Dr Johnson said.

The mineral deposits around the Pilbara, which are rich in iron, are some of the oldest on Earth, and have previously been the site of the search for evidence of the earliest known life on land.

A road leads to an open mine in the area known as the Pilbara region, in the north-west of Western Australia
image:
A road leads to an open mine in the area known as the Pilbara region, in the north-west of Western Australia

Johnson explained, “Studying the composition of the oxygen isotopes in these zircon crystals revealed a ‘top-down’ process triggered by the melting of rocks near the surface and progressed in depth, which is similar to the geologic impact of giant meteorite impacts. conforms.”

“Our research provides the first concrete evidence that the processes that eventually formed continents were initiated by giant meteorite impacts, which were responsible for the extinction of the dinosaurs, but which occurred billions of years ago.”

Understanding how Earth’s continents formed and continued to develop is important, the scientists explained, because we are so dependent on their mineral deposits – as well as the fact that land hosts most of our planet’s biomass.

“The continents host important metals such as lithium, tin and nickel, which are essential commodities for the emerging green technologies needed to meet our obligation to mitigate climate change,” Dr Johnson said.

“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 one of several.

“Data related to other areas of ancient continental crust on Earth show patterns similar to those recognized in Western Australia. We want to test our findings on these ancient rocks to see if we suspect that our model is more widely applicable.”

Nation World News Desk
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