- Jonathan Amos
- BBC Science Correspondent
image source,Getty Images
66 million years ago, a meteorite from outer space crashed into Earth and hit what is now the Gulf of Mexico, killing the dinosaurs. Were there other meteorites with the meteorite that hit Earth?
Did multiple meteorites hit Earth on the same day as a large meteorite?
These suspicions stem from the discovery of a second large impact crater on the other side of the Atlantic Ocean, which also appeared at the same age.
The meteorite that caused the impact that caused the Chicxulub crater in Mexico was not as large as we already know, but it was still large enough to cause a large impact.
Called the Nadir Crater, it is located 400 km off the coast of Guinea in West Africa at a depth of 300 meters.
The 8.5 km diameter crater was probably formed by the impact of a small meteorite less than 500 meters in diameter.
image source,Getty Images
Mexico’s famous cenotes were formed when the limestone in the crater crumbled
Dr. Heriot-Watt University, Edinburgh, UK. Uisdean Nicholson discovered latent depression.
He is analyzing Geological Survey data to better understand Earth’s past climate changes.
These surveys, usually obtained during oil and gas exploration campaigns, document different layers of underground rocks and sediments, often several kilometers below the surface.
“This survey is like an ultrasound of the Earth,” he told the BBC. “I’ve been trying to interpret the data for the last 20 years, but I’ve never seen anything like it.”
image source,Max Alexander/B612/Asteroid Day
Impact Rocks: Rocks from Chicxulub Crater provide many clues
“The shape of the nadir crater shows the effect of the meteorite impact. The rim bulges in the center, and the fractosphere extends outward.”
The meteorite that formed the Chicxulub crater is estimated to be 12 km in diameter. The meteorite impacted the Earth to create a 200 km wide shock pressure zone, a process that was accompanied by massive earthquakes, tsunamis and global fires. A large amount of dust was scattered into the air and the ground was deeply frozen. Dinosaurs could not withstand this climate change.
In contrast, the impact of the meteorite that caused the Nadir Crater was much smaller.
Dr. Veronica Bray of the University of Arizona explained, “This impact would cause a tsunami of up to a kilometer and a magnitude 6.5 earthquake.”
“The impact unleashed was a thousand times more powerful than the January 2022 volcanic eruption and tsunami in Tonga.”
image source,NASA
Outer rim of Chicxulub crater (white arc) beneath Mexico’s Yucatan Peninsula
The Chicxulub crater in Mexico is over 10 million times stronger.
- A 12 km wide object crashed into a 100 km wide and 30 km deep crater.
- The impact crater then collapsed, leaving a crater 200 kilometers wide and several kilometers deep.
- Now, the crater is mostly underwater and contains 600 meters of sediment
- On land, the crater is covered with limestone, but there is a low level on the rim of the crater.
- Researchers recently drilled geological samples into the crater to study its structure
image source,Getty Images
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In terms of connecting the two craters, Dr. Nicholson’s team was cautious.
Based on analysis of fossils of known age extracted from nearby holes, the nadir is believed to be close to the age of Chicxulub. But to come to a conclusion, the crater rocks need to be exhumed and analyzed. This confirms that Nadir is a geological structure formed by a meteorite impact rather than other unrelated structures such as ancient volcanic eruptions.
The idea that a group of giant interstellar meteorites may have hit Earth in the past is not new today.
It has been speculated that the Boltish Crater in Ukraine was also caused by an extraterrestrial impact and may be somehow related to Chiksulub. The age difference between the formations of the two craters is not large.
image source,Tim Peake/NASA/ESA
View of Mexico’s Yucatan Peninsula from the International Space Station
Sean Gulick, a professor at the University of Texas at Austin who recently played a key role in the drill-to-prototype project at Chicxulub, said the formation of the nadir crater could have been an impact from an extraterrestrial object on the same day. Or maybe the shock occurred a million or two million years after the impact on the Mexican side. The company’s conclusions can only be reached after researchers analyze West Africa’s crater rocks in the laboratory.
Professor Gulick told the BBC: “As a much smaller sibling meteorite, it won’t help us much with what we know about the extinction of the dinosaurs, but it will improve our understanding of what happened at Chicxulub. Astronomical events.”
“Was it part of a fragmented parent body, meaning multiple fragmented meteorites hit Earth over a period of time? Was Chicxulub a cluster of meteorites, meaning it was surrounded by a smaller meteorite?”
“There are a lot of interesting questions to study, because knowing that Chicxulub may have formed at the same time as another crater is even more exciting because it changes the understanding of Chicxulub a little bit.”
The Nadir Crater article was published in the journal Science Advances.
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