Nadir Crater: Scientists Discover 5-Mile-Wide Undersea Crater Created When Dinosaurs Extinct

No, it wasn’t that asteroid that wiped out the dinosaurs, but a previously unknown crater that formed around the same time 248 miles off the coast of West Africa. Further study of the nadir crater, as it’s called, could shake up what we know about that cataclysmic moment in natural history.

Uistien Nicholson, an assistant professor at Heriot-Watt University in Edinburgh, happened upon the crater by chance — he was analyzing seismic survey data for another project on the tectonic rift between South America and Africa. Seabed sedimentation.

“While interpreting the data, I (came) across a very unusual crater-like feature that I had never seen before,” he said.

To confirm that the crater was caused by an asteroid impact, he said, it would be necessary to drill into the crater and test the minerals from the crater floor. But it has all the hallmarks scientists expect: the perfect width-to-depth ratio of the crater, the height of the rims and the height of the central uplift — a ridge in the center formed by rock and sediment forced by shock pressure. .

“The discovery of a terrestrial impact crater is always significant because they are so rare in the geologic record. There are less than 200 confirmed impact structures on Earth and there are still a few candidates that have not been unequivocally confirmed,” Mark said. Boslow is a research professor of Earth and planetary sciences at the University of New Mexico. He was not involved in this research, but agreed that it could be due to an asteroid.

The most important aspect of the find is that it is an example of a submarine impact crater, Bozlow said, of which there are only a few known examples.

“The opportunity to study an underwater impact crater of this scale will help us understand the process of ocean impacts, which are very common but poorly preserved or understood.”

cascading effects

The crater is 8 kilometers (5 mi) wide, and Nicholson believes it may have been caused by an asteroid 400 meters (1,300 ft) wide that penetrated the Earth’s crust.

The 100-mile-wide Chicxulub crater that hit the coast is much smaller than the city-sized asteroid that left it. Mexico This led to the mass extinction of most life on the planet, which is still a pretty substantial space rock.

“The (nadir) impact would have had severe consequences locally and regionally — at least across the Atlantic Ocean,” Nicholson explained by email.

“A major earthquake (magnitude 6.5 – 7) would have occurred, and therefore significant seismicity locally. The wind blast would have been heard around the world, and would have caused severe localized damage across the region.

The asteroid that killed the dinosaurs hit in the spring

This would have generated an “exceptionally large” tsunami wave around the crater 3,200 feet (1 kilometer) high, which would have dissipated to a height of about five meters upon reaching South America.

By comparison, a much smaller 50-meter-wide asteroid exploded in Russia in 1908. The Tunguska Incident 1,000 square kilometers of forest leveled.

“At 400 meters or so, the wind blast (which caused the crater in West Africa) would have been orders of magnitude larger.”

Microfossil data from nearby exploratory wells show that the crater formed at the end of the Cretaceous period — 66 million years ago. However, there is still uncertainty — a margin or error of about 1 million years — as to its exact age.

The Chixula impact could be connected to an asteroid strike, or it could be a coincidence — an asteroid of this size hits Earth about every 700,000 years, Nicholson said.

If attached, the asteroid could be the result of the breakup of a near-Earth parent asteroid — separate fragments scattered during Earth’s previous orbit, or it could be part of a long-lasting shower. Asteroids that hit Earth every million years.

A meteorite exploded above Antarctica 430,000 years ago

“Determining the precise age to test this is critical—again, only possible through drilling.”

Even if connected, it would have been dwarfed by the Chicxulub impact, but it would still add to the overall cascading effect, he said.

“Understanding the exact nature of the relationship with Chicxulub (if any) is important to understanding what was going on in the inner Solar System at the time, and raises some interesting new questions,” Nicholson said.

“If there were two impacts at the same time, there could be other craters, and what is the cascading effect of multiple collisions?”

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