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It's hard to imagine how billions of tons of rock can suddenly behave like a liquid, but that's exactly what happened when an asteroid hit the Earth 66 million years ago.
The samples obtained from the crater formed after the collision made it possible to conclude that the rocks had undergone a process of "fluidification".
In other words, the pulverized material began to behave like a water-like substance
200 km crater
Computer models allowed us to determine what would happen if a rocky object, 12 km in diameter in space, collided with the surface of the Earth. almost instantly a concave space of about 30 km deep and 100 km in diameter.
The instability of the ground would collapse later on the crater's banks. And this collapse would in turn generate a rebound reaction from the bottom of the crater to heights greater than the Himalayas.
This crater is precisely what is now buried under a layer of sediment in the Gulf of Mexico, near the port of Chicxulub
As on the Moon [19659006] The model calls it a "model of cracking "by the crater" and the impact it describes is only possible if the rocks lose for a time their strength and flow without friction.
A new study, published in the journal Nature, presents evidence of this process, based on rock drilling materials from a peak ring in the center of the Chicxulub Depression. "What we discovered when looking at the rocks, is that they were fragmented," BBC researcher Ulrich Riller, a researcher at the University of California at Berkeley, told BBC. "clbad =" img img-responsive image-wide "/>
" The rock was crushed and broken into tiny fragments at first millimeters. This gave rise to a fluid behavior which explains the flat base of the crater, "
Fluidisation is not a process of melting rocks but a fragmentation of them by enormous vibratory forces, explains Sean Gulick of the University of Texas in Austin, United States, and one of the leaders of the drilling team
"It is a pressure effect, a mechanical damage. The rock is equivalent to earthquakes of magnitude 10 or 11. It is estimated that the total impact had an energy equivalent to 10 billion bombs of Hiroshima. "
After their fragmentation and fluidification, the rocks have regained their solidity to form the crater ring, resulting in discontinuities showing how the rocks slide relative to other rocks. These flat structures testify to the strength of the rock at the end of the year. "The 1962-kilometer asteroid made a hole 100 kilometers in diameter and 30 kilometers deep in the Earth's crust," said Riller
Chicxulub crater – The collision that changed life on Earth
– The crater center collapsed again, producing an inner ring.
– Today Much of the crater is in the sea, under 600 m of sediment.
– On the mainland, the crater is covered with limestone, but its edges can be identified along one arc of cenotes – natural cavities in the rocks dissolved by the ssage.
"Not only in our solar system"
Research sheds new light on some of the most catastrophic days in the Earth's history and on the mbadive extinction produced by the impact . "" image = large img-responsive image "
