(CNN)66 million years ago, an asteroid from outer space crashed into the Earth's surface, leaving a huge crater under the ocean. and caused havoc. Star.
No, it wasn't the asteroid that drove the dinosaurs to extinction, but an unknown crater 248 miles off the coast of West Africa that was created around the same time. Further study of the crater, called the nadir crater, could shake up what we know about that cataclysmic moment in natural history.
His Uisdean Nicholson, an assistant professor at Heriot-Watt University in Edinburgh, came across the crater by chance. He was reviewing seismic survey data for another project on crustal splitting between South America and Africa and found evidence of it. A crater beneath 400 meters of marine sediment.
"When I was interpreting the data, I came across a very unusual crater-like feature that I had never seen before," he said.
"had all the characteristics of an impact crater."
To be absolutely sure the crater was caused by an asteroid impact, a He said it would be necessary to drill a hole in the crater and test for minerals from the bottom of the crater. But it has all the features scientists would expect: a good ratio of crater width and depth, a high rim, and a high central ridge. Central Uplift - A central mound created by rock and sediment pushed up by impact pressure.
"Discoveries of impact craters on Earth are always important because they are extremely rare in the geological record. Fewer than 200 impact structures have been identified on Earth, and more have yet to be identified." "There are quite a few possible candidates that are not yet clearly confirmed," said Mark Boslow, professor of Earth and Planetary Sciences research at the University of New Mexico. Although he wasn't involved in the study, he agreed that an asteroid was probably to blame.
According to Boslow, the most important aspect of the discovery is that it is an example of an ocean floor impact crater, of which there are only a few known examples.
"The opportunity to study underwater impact craters of this size will help us understand the processes of ocean impacts, which are the most common but poorly preserved and poorly understood."
Causal consequences
The crater is 8 km (5 miles) wide and Nicholson was caused by an asteroid over 400 meters (1,300 feet) I think it is highly possible. It makes a big lunge into the earth's crust.
A 100-mile-wide Chicxulub off the coast of Mexico He is an asteroid of considerable size, though much smaller than the city-sized asteroid that cratered and mass-extinctioned much of Earth's life. . Pretty space rock.
"A (nadir) collision would have had serious consequences both locally and regionally, at least across the Atlantic," Nicholson explained by email.
"A large earthquake (magnitude 6.5 - 7) would have occurred, causing significant local ground shaking.
A "very large" tsunami with a height of 3,200 feet (1 km) around the crater dissipated to a height of about 5 meters as it reached South America.
"Had it been 400 meters or so, the blast wave (which caused the crater off West Africa) would have been orders of magnitude larger." , indicating that the crater formed about 66 million years ago -- at the end of the Cretaceous.
Nicholson said the asteroid impact could be related to the Chicxulub impact, or it could just be a coincidence.
If linked, the asteroid could be the result of the breakup of a parent asteroid near the Earth - separate fragments dispersed during the Earth's early orbit. It could have been part of an asteroid shower that hit Earth over a million years or so.
"Finding the exact age is very important in testing this. Again, only by excavation."
Even if linked, It would have been dwarfed by Chicxulub's influence, but would still have added to the overall cascading set of results, he said. It was important to understand what was going on inside the solar system at that time, and raised some interesting new questions. craters may exist.What was the cascading effect of multiple collisions?"
