In Siberia, at the mouth of the Popigai River, there is a crater of the same name, which ranks fourth among the largest craters on Earth. Its diameter is 100 kilometers, that is, such an impressive dent was formed as a result of the fall of a very large celestial body.
Researchers from the University of California at Los Angeles established the exact age of the rocks inside the crater and determined that at the same time when they formed, that is, 33.7 million years ago, there was a mass extinction of animals. This event, known as the Eocene-Oligocene extinction, led to the extinction of many species of snails, sea urchins and toothed whales.
Previously, scientists blamed climate change for the incident. However, if the main catalyst of the process was the fall of a meteorite, then the animals could die due to nuclear winter: during a collision, large bodies lift a mass of particles into the Earth's atmosphere that reflect sunlight, as a result of which a sharp cooling is observed.
“We still have a lot of work to do before we make a revolutionary discovery. But we have again proven that the history of Popigai crater formation can be inextricably linked to the Eocene-Oligocene extinction,”said study lead author Matt Wielicki, a graduate student at the University of California.
Popigai Crater is not the only one who can be blamed for the Earth's climate change during the Eocene. There are at least three more craters, the formation of which 35-36 million years ago, could affect the development of the fauna of the Earth. The Chesapeake Impact Crater, Toms Canyon and Mistatin craters may also have been implicated in mass extinctions.
Previously, the blame for all four meteorites was ruled out due to inaccurate dating. Previous analyzes have shown that Popigai is at least 35.7 million years old, which means that by the time of the mass extinction, about two million years have passed, and the events cannot be connected. Wheeeliki's team pushed scientists to pay attention to this geographic feature again by providing new, accurate data on the age of the crater.
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In one thing, the researchers are sure for sure - global cooling is behind the Eocene-Oligocene mass extinction. Both Wilicki and his predecessors analyzed the isotopes of oxygen, carbon, and other elements in rocks of the same age as the Eocene, and reported that at that time there was a sharp climate change from warm and humid to dry and cold.
“The age of the Popigai crater fits perfectly into the concept of global cooling. I'm pretty sure the climate change was caused by a meteorite impact and nuclear winter,”Wheelyki says in a press release.
The researcher and his colleagues believe that the result of the cosmic collision was a sharp release of the smallest particles of sulfur, which filled the Earth's atmosphere and reflected sunlight and heat. This is how the climate change came, which became fatal for many representatives of the fauna.
Wheelycki and his team presented their hypothesis at the annual Goldschmidt Conference on Geochemistry.
Asya Gorina
