Credit: NASA
Several years after scientists discovered what was believed to be the oldest crater a meteorite made on the planet, another team discovered that it is actually the result of normal geological processes.
During fieldwork on the Archean Maniitsoq structure in Greenland, an international team of scientists led by Chris Yakymchuk from the University of Waterloo found that the features of this region are inconsistent with 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 little time capsules,” said Yakymchuk, a professor in Waterloo’s Department of Earth and Environmental Sciences. “They keep old damage caused by shock waves you get from a meteorite impact. We have not found such damage in them. ‘
In addition, there are several places where the rocks melted and were recrystallized deep within the earth. This process – called metamorphism – would occur almost instantly if caused by an impact. The Waterloo-led team found that it happened 40 million years later than the earlier group had suggested.
“We went there to explore the area for possible mineral exploration, and it was through close examination of the area and data collected since 2012 that we concluded that the features are not consistent with a meteorite impact,” said Yakymchuk. “While we were disappointed to not work in a structure resulting from a meteorite hitting the planet three billion years ago, science is about advancing knowledge through discovery, and our understanding of Earth’s ancient history remains are evolving. Findings provide scientific data for resource companies and Greenland prospectors to find new mineral resources. “
The study was 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
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Chris Yakymchuk et al. Stirred, not shaken; critical evaluation of a proposed Archaeological meteorite impact in West Greenland, Earth and Planetary Science Letters (2021). DOI: 10.1016 / j.epsl.2020.116730
Provided by University of Waterloo
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