Scientists found that they still underestimated the diameter of the celestial bodies, and during the fall, Fredburg, the largest impact crater on our planet, formed. A new estimate of its size also explains why the rock ejected by this impact was found in Karelia .
Vredefort Remains of impact structure: from space
Today, 190 impact craters were found on on the surface of the earth. The largest of these is the South African crater Vrederfort, with an estimated diameter of 250-280 kilometers. It was formed by the fall of the celestial body about 2 billion years ago, which also makes it one of the oldest celestial bodies on Earth.
Previous calculations show that it may be an asteroid with a diameter of 10-15 kilometers, moving at a speed of 15 kilometers per second. However, new work by scientists at the University of Rochester in the United States shows that we greatly underestimate its size. Judging from these data, celestial bodies have increased by 20-25 kilometers and hit the Earth's surface at a speed of 20 kilometers per second. An article by Miki Nakajima and colleagues was published in Journal of Geophysical Research .
erosion and other geological processes have almost wiped out the outline of Fredburg over the past billions of years. Most likely, it became smaller during this period, but initially it could reach nearly 300 km in diameter. Furthermore, today most of its area is occupied by farmland, which makes it even more difficult to estimate the true size of the crater and to leave its body.
This is what the epicenter of ancient disasters looks like today. The dome of the Vredefort crater is listed as a UNESCO World Heritage Site
In their work, American scientists rely on new data on their outlines and also use the iSALE model, which makes it possible to simulate shock (shock) events. Calculations show that a 15-km celestial body can form a crater with a diameter of no more than 172 km. In order to create a large crater at a speed of 15 kilometers per second, the asteroid must reach 25 kilometers in diameter or move faster.
Scientists also used this data to study how the mass thrown by celestial body impact is subsequently distributed. Today, its deposits are found even in Karelia, Russia. Based on the characteristics of this layer, and their model, the authors of the work show that when the asteroid fell, the region was only 2000-2500 kilometers away from it—much closer than today.
New estimates make this object even more important than the famous asteroid, whose falls are related to Chicthulub crater and Cretaceous-Paleogene extinction events, which resulted in all flightless dinosaurs extinction. "Unlike Chicxulub, the Vredefort impact did not leave any traces of mass extinction because there were only single-celled organisms and no trees at the time. However, its impact on the global climate may have a greater impact than Chicthulub," explained Miki Nakajima.
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