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Old 28-05-2020, 05:34 PM
gary
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Asteroid that created Chicxulub crater arrived at the deadliest possible angle

A 26th May 2020 press release by Caroline Brogan at the Imperial
College London discusses results published in Nature Communications
that suggest the asteroid that struck Chicxulub arrived at the deadliest
possible angle and that the geologic composition of the rocks created
a deadly cocktail for life on Earth at the time.

Quote:
Originally Posted by Caroline Brogan, Imperial College London
New simulations from Imperial College London have revealed the asteroid that doomed the dinosaurs struck Earth at the ‘deadliest possible’ angle.

The simulations show that the asteroid hit Earth at an angle of about 60 degrees, which maximised the amount of climate-changing gases thrust into the upper atmosphere.

Such a strike likely unleashed billions of tonnes of sulphur, blocking the sun and triggering the nuclear winter that killed the dinosaurs and 75 per cent of life on Earth 66 million years ago.

Drawn from a combination of 3D numerical impact simulations and geophysical data from the site of the impact, the new models are the first ever fully 3D simulations to reproduce the whole event – from the initial impact to the moment the final crater, now known as Chicxulub, was formed.

Lead researcher Professor Gareth Collins, of Imperial’s Department of Earth Science and Engineering, said: “For the dinosaurs, the worst-case scenario is exactly what happened. The asteroid strike unleashed an incredible amount of climate-changing gases into the atmosphere, triggering a chain of events that led to the extinction of the dinosaurs. This was likely worsened by the fact that it struck at one of the deadliest possible angles.

“Our simulations provide compelling evidence that the asteroid struck at a steep angle, perhaps 60 degrees above the horizon, and approached its target from the north-east. We know that this was among the worst-case scenarios for the lethality on impact, because it put more hazardous debris into the upper atmosphere and scattered it everywhere – the very thing that led to a nuclear winter.”

The results are published in Nature Communications. The simulations, which used a 17-km diameter asteroid with a density of 2630 kgm3 and a speed of 12 km/s, were performed on the Science and Technology Facilities Council (STFC) DiRAC High Performance Computing Facility.

The upper layers of earth around the Chicxulub crater in present-day Mexico contain high amounts of water as well as porous carbonate and evaporite rocks. When heated and disturbed by the impact, these rocks would have decomposed, flinging vast amounts of carbon dioxide, sulphur and water vapour into the atmosphere.

The sulphur would have been particularly hazardous as it rapidly forms aerosols - tiny particles that would have blocked the sun’s rays, halting photosynthesis in plants and rapidly cooling the climate. This eventually contributed to the mass extinction event that killed 75 per cent of life on Earth.
Full press release including graphics here :-
http://www.imperial.ac.uk/news/19769...iest-possible/

Abstract, "Nature Communications", "A steeply-inclined trajectory for the Chicxulub impact" by Collins et. al. :-
https://www.nature.com/articles/s41467-020-15269-x
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