Oops! The “World’s Oldest Meteorite Impact Crater” Isn’t an Impact Crater After All
Several years after scientists discovered what was considered the oldest crater a meteorite made on the planet, another team found it’s actually the result of normal geological processes.
During fieldwork at the Archean Maniitsoq structure in Greenland, an international team of scientists led by the University of Waterloo’s Chris Yakymchuk found the features of this region are inconsistent with an impact crater. In 2012, a different team identified it as the remnant 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 preserve ancient damage caused by shockwaves you get from a meteorite impact. We found no such damage in them.”
Additionally, there are multiple places where the rocks melted and recrystallized deep in the Earth. This process—called metamorphism—would occur almost instantaneously if produced from an impact. The Waterloo-led team found it happened 40 million years later than the earlier group proposed.