The Yucatan peninsula (Mexico) hidden in its extreme north-west, buried under hundreds of meters of sediments, the costurón left by one of the events most interesting and momentous in the history of the Earth. Is the gigantic crater of Chicxulub , 200 kilometers of width, where some 65 million years ago struck by a meteor of 10 km with a force equivalent to ten thousand billion atomic bombs like the Hiroshima. The violentísimo shock set fire to the forests, triggered a tsunami brutal, and expelled so much sulfur into the atmosphere which blocked the Sunlight, which finally led to the disappearance of 75% of the existing life , including the dinosaurs.
This has been the scenario raised traditionally by scientists to explain one of the five great mass extinctions recorded in the Earth. And that is the hypothesis which supports the new study, which has participated in the Astrobiology Centre of the Higher Council of Scientific Research (CSIC), after analysing the rocks extracted from the central area of the crater in mexico. The material of the "ground zero", recovered by the International Programme on Discovery Ocean (IODP) in 2016 from a platform of offshore drilling, has allowed researchers to describe with unprecedented detail how were the first 24 hours after the impact. The results are published in the latest issue of the journal "Proceedings of the National Academy of Sciences (PNAS)".
Collection of samples from the crater of Chucxulub - International Ocean Discovery ProgramEl impact caused a tsunami that reached up to the interior of north America, 2,000 km from distanciaPrimero scorched, then frozen,
"With this study we know more what happened during and immediately after the impact. We can see how much rock is melted and vaporized, how the presence of sea water affected the craters and we can do calculations on the amount of sulphur that was removed from the rocks", it points to ABC Jens Ormö, a researcher at the Center for Astrobiology and a co-author of the study. The authors estimate that the explosion of the asteroid carbonized all vegetation located thousands of miles around the impact and triggered a tsunami impossible to imagine, that reached the interior of north America, more than 2,000 miles away. Within the crater, they found charcoal and also a biomarker of chemical the presence of fungi from the soil within or just above layers of sand, sign of having been deposited by a reflux of water. These findings suggest that the landscape is charred was brought into the crater by the receding waters of the tsunami.
The greater part of the material that filled the crater in the hours after the impact originated in the same place or was swept away by the ocean water that flowed back to there from the Gulf of Mexico surrounding. In a single day was deposited around 130 metres of material, a rate that is dizzying accumulation that proves that the impact happened a hell of a short duration at the local level, followed by a long period of global cooling. Not in vain Chicxulub means in the mayan language, "well the devil". "It achicharraron and then froze," he says in reference to the dinosaurs, Sean Gulick, a professor at the Institute of Geophysics of the University of Texas and lead author of the study. "Though not all, many dinosaurs died that day ", he concludes.
Örmo indicates that the sediments reveal "enormous amounts of energy transport which are much larger than any other catastrophic flood known on the planet. The water is dense and full of debris moved with speeds that were equivalent to that of the wind of the hurricane ".
"The real killer has to be atmospheric", say the investigadoresAusencia sulphurThe team found molten rock fragments as sandstones, limestones and granites, but none of sulfur in the core. This was puzzling, since the area surrounding the crater is full of rock rich in sulfur. Where was it to stop? The finding supports the theory that the impact of the asteroid vaporized the mineral rich sulphur present at the impact site and released to the atmosphere, that it became opaque to sunlight. This caused profound changes in the climate of the Earth , who suffered a global cooling . The researchers estimate that at least 325.000 million metric tons would have been released to the atmosphere by the impact. That amount is around ten thousand times greater than all the sulfur that was discharged to the atmosphere during the eruption of the volcano Krakatoa (Indonesia) in 1883, which caused an average drop of 2.2 degrees in the global temperature during five years.
it Was precisely this global climate change that caused the mass extinction of not only dinosaurs, but also of most of the creatures that inhabited the planet at that time. "The real killer has to be atmospheric," says Gulick. "The impact was the lethal blow during a time in which the biota was under heavy stress by the large volcanic eruptions in what is now India. Possibly, each process in itself may not have caused an extinction of these proportions, but the impact came in the critical moment", adds Ormö.
A portion of the cores drilled in the rocks that filled the impact crater of the asteroid that wiped out the dinosaurs - International Ocean Discovery ProgramThe sediments deposited in those first moments "let us know how it was the first day of the Cenozoic , the first day of a new era dominated by mammals, and eventually for our own kind", continues the researcher. And he thought: "A species that now, by other causes such as the massive pollution of the oceans and the atmosphere, has initiated the sixth and last of the mass extinctions. Maybe we still have time to learn something of the past."
Date Of Update: 12 September 2019, 19:01
