The fear that a meteorite or comet could collide with Earth, like that celestial object that exterminated dinosaurs 66 million years ago, has always inhabited popular imagination, and also a problem in several scientific studies.
For this reason, impact craters, a type of geological impression that occurs when a smaller object in space collides with a larger one, in this case Earth, have been studied by scientists around the world. Accordingly, in 2012, a study published in the journal Earth and Planetary Science Letters located the oldest impact crater on Earth in the Maniitsoq region of Greenland.
However, a study published in the same journal earlier this month (1st) disputes this research, even stating that a 100 km depression in Greenland is not even a crater, and that a geological formation of about 3 billion years would be the result of natural forces.
Two versions of the Maniitsoq crater
When geologist Adam Garde of the Geological Survey of Denmark and Greenland and his team explored a giant crater 55km southeast of Maniitsoq in Greenland in 2012, he concluded it was formed by a meteor strike, and said it was the first case of its kind on Earth. .
The author of the new study, Chris Yakymchuk, a geologist at the University of Waterloo in Canada, told Live Science that extensive research conducted in the region did not reveal any microscopic traces of impact deformation, a characteristic “found in almost all other impact craters.”
Therefore, current research has concluded that field relationships are inconsistent with the circular impact crater and suggests “that the structure in the region is the product of movement, deformation, and warming of ancient tectonic plates over hundreds of millions of years. “. But Adam Garde disagrees
Why is Maniitsoq not an Impact crater?
The main argument of Garde and his colleagues to ensure that Maniitsoq was an impact crater was the structure of the central rocks. In a 2012 study, they wrote that the depth of these solid aggregates and the way they were pushed into the ground could only be justified by the impact of meteorites.
Yakymchuk admitted in an interview with Live Science that, “with the data they had at the time,” that explanation was acceptable. But by gathering more data, using newer technology, the team arrived “open-minded” to discover and present new evidence against the theory of impact.
The main one came from the analysis of zirconium crystals, small structures of this metal, extremely durable in the form of silicates. After carefully examining the structures of about 5,000 of these small grains, the team found no signs, such as possible internal fractures, that indicate any type of impact.
Replica of the defense theory defender
After presenting elements of the new research, Adam Garde continues to defend his 2012 position, acknowledging that he “would be happy to change my interpretation” if new subject matter experts provided a compelling alternative physical explanation for the central part of the format. structures, whose observations have not been discussed in the current study.
As for zirconium crystals, he understands that they cannot be taken as a reliable source, given the antiquity of the crater, which may have erased the evidence of impact through long-standing geological processes.
Regardless of the outcome of the discussion, the Earth Impact Database considers Yarrabubba’s structure in Western Australia to be the oldest crater in the world today.