Scientists discover more evidence that dinosaurs were killed by a enormous asteroid

Rodiano Bonacci
Settembre 10, 2019

This is an artist's interpretation of the asteroid impact. The buried crater, over 90 miles in diameter, was created when a massive asteroid struck the planet 66 million years ago and brought a calamitous end to the reign of dinosaurs. Nevertheless, the image nicely illuminates the heat generated as the asteroid rapidly compresses upon impact and the vacuum in its wake.

That's the scenario scientists have hypothesized.

The asteroid triggered a tsunami that towered several hundred metres, dumping rock and dirt back in the crater at a tremendous rate - around 130 metres (425 feet) of material was deposited in just a single day, preserving an environmental record of the area in and around the crater in the first minutes and hours after impact.

They discovered layers of charcoal, debris washed in by the tsunami, and a telltale lack of sulfur.

They are all part of a rock record that offers the most detailed look yet into the aftermath of the catastrophe that ended the Age of Dinosaurs, said Sean Gulick, a research professor at the University of Texas Institute for Geophysics (UTIG) at the Jackson School of Geosciences. Here, the researchers drilled into the ground to examine samples of the rock miles below the impact site. "It speaks to the energy of the impact", Katherine Freeman, one of the study's authors and a professor at Penn State, told Gizmodo. Gulick and Morgan co-led the expedition in 2016. Initially, the site of the impact was shallow ocean, less than 30 metres deep. An global team of more than two dozen scientists contributed to this study.

Inside an impact crater off the Gulf of Mexico scientists discovered charcoal and soil, swept inside by the backflow of a tsunami within the first 24 hours of the asteroid impact, research said. Under a thin ring of overlying material is over 400 feet of melt rock that was laid down during the day following the impact.

The impact then generated a tsunami several hundred meters high which reached as far as modern day IL in the US. "Not all the dinosaurs died that day, but many dinosaurs did".

The melted rock indicates that the asteroid hit with the force of 10 billion atomic bombs, setting forests aflame for thousands of kilometres, and triggering a tsunami that reached as far as current IL. This suggests that the charred landscape was pulled into the crater with the receding waters of the tsunami. The team also found an absence of sulfur in the deposits-which is unusual as the area is known for having sulfur-rich rocks.

That sulphur, scientists believe, was the real killer - possibly exacerbated by later volcanic activity thought to have been triggered by the impact.

"It was a momentous day in the history of life, and this is a very clear documentation of what happened at ground zero", said Melosh, who was not involved with this study. But he pointed out that this is just one paper about one core.

This led them to theorize that after the asteroid crashed on Earth, it vaporized the sulfur-containing materials, releasing sulfate aerosols in the atmosphere.

The team estimates that the asteroid released four orders of magnitude more sulfur than that which was expelled during the 1883 eruption of Krakatoa. This destroyed Earth's existing climate, blocking out the sun and causing a global cooling period that caused the "mass extinction" of the dinosaurs. Geologists had detected and studied this effect before, but the new research reinforces the role this atmospheric disruption played in the extinction that followed.

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