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Mystery crater potentially due to relative of dinosaur-killing asteroid

Mystery crater potentially caused by relative of dinosaur-killing asteroid
The way the crater could have formed. Credit: Author provided

The ocean floor is famously less explored compared to the surface of Mars. So when we of scientists recently mapped the seabed, and ancient sediments beneath, we discovered what appears like an asteroid impact crater.

Intriguingly, the crater, named “Nadir” following the nearby volcano Nadir Seamount, is of exactly the same age because the Chicxulub impact the effect of a huge asteroid by the end of the Cretaceous period, around 66 million years back, which destroyed the dinosaurs and several other species.

The finding, published in Science Advances, raises the question of if the crater may be linked to Chicxulub for some reason. If confirmed, it could also be of huge general scientific interest since it would be among a very few known marine asteroid impacts therefore give unique new insights into what goes on during this type of collision.

The crater was identified using “seismic reflection” within a wider project to reconstruct the tectonic separation of SOUTH USA from Africa back the Cretaceous period. Seismic reflection works in the same way to ultrasound data, sending through the ocean and its own floor and detecting the power that’s reflected back. This data allows geophysicists and geologists to reconstruct the architecture of the rocks and sediments.

Scrolling through this data by the end of 2020, we found an extremely unusual feature. On the list of flat, layered sediments of the Guinea Plateau, west of Africa, was what were a big crater, just a little under 10km wide and many hundred meters deep, buried below several hundred meters of sediment.

A lot of its features are in keeping with a direct effect origin, like the scale of the crater, the ratio of height to width and the height of the crater rim. The current presence of chaotic deposits outside the crater floor also appear to be “ejecta”material expelled from the crater rigtht after a collision.

We did consider other possible processes which could have formed this type of crater, like the collapse of a submarine volcano or perhaps a pillar (or diapir) of salt below the seabed. An explosive release of gas from below the top may be an underlying cause. But none of the possibilities are in keeping with the neighborhood geology or the geometry of the crater.

Earthquakes, airblast, fireball and tsunamis

After identifying and characterizing the crater, we built computer types of a direct effect event to see if we’re able to replicate the crater and characterize the asteroid and its own impact.

The simulation that best fits the crater shape is for an asteroid 400 meters in diameter hitting an ocean that has been 800 meters deep. The results of a direct effect in the ocean at such water depths are dramatic. It could bring about an 800-meter thick water column, along with the asteroid and a considerable level of sediment being instantly vaporizedwith a big fireball visible a huge selection of kilometers away.

Shock waves from the impact will be equal to a magnitude 6.5 or 7 earthquake, which may likely trigger underwater landslides round the region. A train of tsunami waves would form.

The air blast from the explosion will be bigger than anything heard on the planet in recorded history. The power released will be approximately one thousand times bigger than that from the recent Tonga eruption. Additionally it is possible that the pressure waves in the atmosphere would further amplify the tsunami waves a long way away from the crater.

Mystery crater potentially caused by relative of dinosaur-killing asteroid
Nadir crater. Credit: Author provided

Chicxulub relative?

Probably the most intriguing areas of this crater is that it’s exactly the same age because the giant Chicxulub event, give or take one million years, at the boundary between your Cretaceous and Paleogene periods 66 million years back. Again, if this can be an , might there be some relationship between them?

We’ve three ideas concerning their possible relationship. The foremost is that they may have formed from the break-up of a parent asteroid, with the bigger fragment leading to the Chicxulub event and an inferior fragment (the “little sister”) forming the Nadir crater. If that’s the case, the damaging ramifications of the Chicxulub impact might have been put into by the Nadir impact, exacerbating the severe nature of the mass extinction event.

The break-up event may have formed by a youthful near-collision, once the asteroid or comet passed close enough to Earth to see gravitational forces strong enough to pull it apart. The specific collision could then have occurred on a subsequent orbit.

Although, that is not as likely for a rocky asteroid, this pull-apart is strictly what happened to the Shoemaker-Levy 9 comet that collided with Jupiter back 1994, where multiple comet fragments collided with the earth during the period of several days.

Another possibility is that Nadir was section of an extended lived “impact cluster”, formed by way of a collision in the asteroid belt earlier in solar system history. That is referred to as the “little cousin” hypothesis.

This collision could have sent a shower of asteroids in to the inner solar system, which might have collided with the planet earth along with other inner planets over a far more extended time frame, perhaps a million years or even more. We’ve a precedent for this event back the Ordovician periodover 400 million years agowhen there have been numerous impact events in a brief period of time.

Finally, needless to say, this may you need to be a coincidence. We do expect a collision of a Nadir-sized asteroid every 700,000 years roughly. For the present time, however, we can not definitively declare that the Nadir crater was formed by an asteroid impact until we physically recover samples from the , and identify minerals that may only be formed by extreme shock pressures. Compared to that end, we’ve recently submitted a proposal to drill the crater through the International Ocean Discovery Program.

Much like the primary impact crater hypothesis, we are able to only test the tiny sister and little cousin hypotheses by accurately dating the using these samples, and also by searching for other candidate craters of an identical age.

Perhaps moreover, could this event happen soon? It really is unlikely, however the size of the asteroid that people model is quite like the Bennu asteroid currently in near-Earth orbit. This asteroid is known as to be among the two most hazardous objects in the solar system, with a one-in-1,750 potential for collision with Earth within the next handful of centuries.



More info: Uisdean Nicholson et al, The Nadir Crater offshore West Africa: An applicant Cretaceous-Paleogene impact structure, Science Advances (2022). DOI: 10.1126/sciadv.abn3096

This short article is republished from The Conversation under an innovative Commons license. Browse the initial article.The Conversation

Citation: Mystery crater potentially due to relative of dinosaur-killing asteroid (2022, August 20) retrieved 20 August 2022 from https://phys.org/news/2022-08-mystery-crater-potentially-relative-dinosaur-killing.html

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