The world’s oldest crater of a meteorite is not an impact crater

A few years after scientists discovered what is considered to be the oldest crater that made a meteorite on the planet, another team found that it was actually the result of normal geological processes.

During fieldwork at the Archean Maniitsoq structure in Greenland, an international scientific team led by the University of Waterloo, Chris Yakymchuk, found that the characteristics of this region did not match an impact crater. In 2012, another team identified it as the remains of a three-billion-year-old meteorite crater.

“Zircon crystals in the rock are like small time capsules,” said Yakymchuk, a professor in Waterloo’s Department of Earth and Environmental Sciences. “They preserve ancient damage caused by shock waves due to a meteorite impact. We did not find such damage in it.”

There are also several places where the rocks melted and recrystallized deep in the earth. This process – called metamorphism – would take place almost immediately if it was produced by an impact. The team led by Waterloo found that this happened 40 million years later than the previous group had suggested.

“We went there to investigate the area for possible mineral exploration, and it was through the careful investigation of the area and data collected since 2012, it was concluded that the features do not correspond to a meteorite impact. , “said Yakymchuk. ‘While we were disappointed that we did not work in a structure that was the result of a meteorite that hit the planet three billion years ago, science is about advancing knowledge through discovery, and our understanding of the ancient history of the Earth continues to evolve. findings provide scientific data to resource companies and Greenlandic prospectors to find new mineral resources. ‘

The study, Stirred not shaken; critical evaluation of a proposed Archean meteorite impact in West Greenland by Yakymchuk and an international team of scientists from Canada, Australia, Denmark, Greenland and the United Kingdom, appears in the journal Earth and Planetary Science Letters.