When an asteroid collided with what is now the Gulf of Mexico 66 million years ago, wiping out the dinosaurs, did he have a companion?
Was Earth bombarded on that terrible day by more than one space rock?
The discovery of what appears to be a second impact crater across the Atlantic, of very similar age, is raising these questions.
It’s not as big as the one we know in Chicxulub, Mexico, but it still speaks of a catastrophic event.
Dubbed the Nadir Crater, the new feature sits more than 300 meters below the sea floor, about 400 km off the coast of Guinea in West Africa.
With a diameter of 8.5 km, it is likely that the asteroid that created it was just under half a kilometer in diameter.
Hidden depression was identified by Dr. Uisdean Nicholson of Heriot-Watt University, Edinburgh, UK.
He was analyzing seismic survey data, looking for a place to drill, to better understand past climate change on Earth.
Such surveys, often obtained by oil and gas prospectors, record the different layers of rocks and sediments underground, often several kilometers deep.
“These surveys are like an ultrasound of the Earth. I’ve probably spent the last 20 years interpreting them, but I’ve never seen anything like this,” he told BBC News.
“The Nadir shape is diagnostic of an asteroid impact. It has a raised edge around a central area of elevation and then layers of debris that extend outward.”
The asteroid that created the Chicxulub crater in the Gulf of Mexico is estimated to be about 12 km in diameter. It uprooted a depression 200 km wide and, in the process, unleashed powerful earthquakes, tsunamis and a global storm. So much dusty material was thrown into the sky that the Earth plunged into a deep freeze. Dinosaurs did not survive the climate shock.
By comparison, the effects of an impactor the size of Nadir would have been much, much smaller.
“Our simulations suggest that this crater was caused by the collision of a 400m wide asteroid in 500-800m of water,” explained Dr. Veronica Bray, University of Arizona, USA.
“This would have generated a tsunami more than a kilometer high, as well as an earthquake of magnitude 6.5 or more.
“The energy released would have been about 1,000 times greater than that of the January 2022 Tonga eruption and tsunami.”
Chicxulub would have been 10 million times bigger.
A 12 km wide object has dug a hole about 100 km in diameter and 30 km deep
This basin then collapsed, leaving a crater 200 km in diameter and a few km deep.
Today, much of the crater is buried in the sea, under 600m of sediment.
On land, it is covered by limestone, but its edge is traced by sinkholes.
Scientists recently drilled into the crater to learn about its formation
The team of Dr. Nicholson needs to be cautious when linking the two impacts.
Nadir was given a very similar date to Chicxulub based on an analysis of fossils of known age that were drilled from a nearby well. But to make a definitive statement, the rocks in the crater itself would need to be pulled out and examined. This would also confirm that Nadir is indeed an asteroid impact structure and not some other unrelated feature caused, for example, by ancient volcanism.
The idea that Earth may have been hit by a cluster of large space rocks in the past is not new.
And people have already speculated that the impactor that created the Boltysh Crater in Ukraine could also be related in some way to the Chicxulub event. Your age is not much different.
Professor Sean Gulick, who co-led the recent Chicxulub crater drilling project, said that Nadir may have fallen to Earth on the same day. Or it may have hit the planet a million or two years on either side of the Mexican cataclysm. Scientists won’t know for sure until the West African crater rocks are inspected in the lab.
“A much smaller cousin, or sister, doesn’t necessarily add to what we know about the dinosaur extinction, but it does contribute to our understanding of the astronomical event that was Chicxulub,” the University of Texas at Austin researcher told BBC News. .
“Was this a breakup of a parent body that had multiple fragments that hit Earth over time? Was Chicxulub a double asteroid where a smaller object orbited a larger one?
“These are interesting questions to investigate, because knowing that Chicxulub can have that extra thrill of a second crater at the same time changes the story a little bit about how Chicxulub came to be.”
The Nadir Crater feature is reported in the journal Science Advances.