Chicxulub crater: is this the crater from the asteroid that killed the dinosaurs?

March 25, 2024

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What is the Chicxulub crater?

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Artist’s reconstruction of Chicxulub crater soon after impact, 66 million years ago. DETLEV VAN RAVENSWAAY/SCIENCE SOURCE

66 million years ago a massive asteroid, the size of a city hit the Earth. The devastating impact ended the reign of the dinosaurs. It left behind a huge, 150 km crater, at the edge of the Yucatán peninsula in Mexico. The impact was so intense that rocks from deep within the Earth’s crust were thrown high above, reaching 25 km creating a rim of mountains higher than the Himalayas.

Devastation was immediate in the vicinity of the impact sight. Then, there was widespread secondary effect of the asteroid impact, including massive tidal waves to wash over parts of America, and substantial fires, as well as huge amounts of debris thrown into the air, which reduced photosynthesis of plants – reducing the bottom of the food chain and having devastating effects as it went up. These were what resulted in the dinosaur’s sudden mass extinction.

But how do we know that this particular crater, the Chicxulub crater, is the one left from the asteroid that killed the dinosaurs?

Evidence for this crater being the one that killed the dinosaurs?

The theory that this is the impact crater from the asteroid which killed the dinosaurs was published in 1980 by father and son scientists, Luis Alvarez, a Nobel prize winning physicists and his son Walter, a geologist. They stated that the iridium-rich clay found there was left by a large asteroid colliding with the Earth. Iridium, is very rare in the Earth’s crust. However, it is common in some types of asteroids helping them reach this conclusion.

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Iridium is one of the rarest metals found on Earth. It is usually associated with extraterrestrial impacts, as the element occurs more abundantly in meteorites. © Hi-Res Images of Chemical Elements/ Wikimedia Commons (CC BY 3.0)

Scientists have also, discovered traces of this iridium asteroid dust, scattered all around the globe enriching the same geological layer as that of the dinosaurs’ extinction.  The Chicxulub Crater appears to be the same age as this rock layer, leading researchers to be confident that this is creator impact from the asteroid which killed the dinosaurs.

More recent evidence, from rock core samples extracted from the Chicxulub Crater deep beneath the seabed, in 2016, found that these indeed contained the tell-tale sign of asteroid dust. They drilled samples from different regions of the crater. The scientists discovered that the highest concentration of rock peppered with iridium, and mixed with ash from the impact, as well as ocean sediment was in a sample form the peak ring of the crater. The levels of iridium in the Chicxulub impact crater, was found to be four times more concentrated than in the surrounding area. The Iridium levels were found to be in the highest concentrations across the transition into early Paleogene sediments. There was also enhanced levels of other elements common to asteroids, giving a similar chemical fingerprint to the asteroid dust discovered in the 1980’s around the world.

These results confirmed that the Chicxulub Crater was indeed the impact creator from the asteroid which killed the dinosaurs.

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Seen here is the section of rock core from Chicxulub Crater in which researchers found a concentration of iridium, a tracer for asteroid material, mixed with ash from the impact and ocean sediment.
The International Ocean Discovery Program. https://www.astronomy.com/science/asteroid-dust-found-at-chicxulub-crater-confirms-cause-of-dinosaurs-extinction/

Conclusion

Scientists have confirmed that the Chicxulub crater off the cost of Mexico is the result of an asteroid 66 million years ago which wiped out the dinosaurs. The most compelling evidence is that it contains high volumes of iridium, common on asteroid but scare on Earth. This iridium is in the layer of the Earth consistent with the timing of the dinosaur extinction. As well as, evidence of this asteroid dust being found scattered around the world in the same geological layer.

For more detail on asteroids, sign up for one of our courses today. The asteroids features in Mission Astro ‘The Escape from the Blue Marble’ course and our Certificate in Space Science.

This post was written by Dr Heather Campbell for Mission Astro.

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