Volcano, Asteroid or Both, What Killed the Dinosaurs? Extinction Mystery Solved? (NFL) Did a giant volcanic eruption in India help a meteorite kill off the dinosaurs? Recent study suggests that It wasnt just an asteroid, they caused extinction together. Editor : Marika Colins Category : SCIENCE 13 Aralık 2014 Cumartesi - 17:04 Scientists have started to argue that a giant volcanic eruption in India may have led to the end of the dinosaurs, after a recently published study. They suggest that It wasnt just an asteroid, a massive volcanic eruption and an asteroid caused extinction together, ending the reign of the dinosaurs. The study which is published in Science Magazine online recently, focuses on an area in India called the Deccan Traps. The Deccan Traps is a large area of mountain-sized basalt lava deposits that were created, by what scientists consider, by one of the largest volcanic eruptions that Earth has even seen. The lead author of the paper, Blair Schoene, a professor of geosciences at Princeton, said the results indicate that both the catastrophic impact and the more gradual, but extraordinary, volcanic eruption could have been factors in the end-Cretaceous mass extinction. The new evidence has Blair Schoene favoring both catastrophes as the cause for the mass extinction. The new study suggests that it was not a massive asteroid that caused the dinosaurs to go extinct, but rather one of the world’s largest volcanic eruptions. The new evidence comes from within the Deccan Traps, a geological formation that covers 200,000 square miles around Mumbai. Scientists were able to date the crystal samples from the site, which contain trace amounts of uranium that have since decayed into lead. Because its well-known how long uranium takes to decay, scientists were able to pinpoint when the volcano began its devastating eruption 250,000 years—before the extinction event. But it ended around 500,000 years after, adding an interesting twist. Schoene and his co-authors don’t claim volcanoes alone wiped out the dinosaurs; only that they changed the climate enough to put ecosystems under stress, setting them up for the final blow. “We don’t know the exact mechanism,” he admits. Co-author of the Science paper, Sam Bowring of M.I.T., said whats important is that everyone now knows more accurately when the Deccan Traps eruptions began and ended. Until 1980, scientists struggled to understand why so many life forms abruptly went extinct. Not only did the dinosaurs disappear, so did many species in the seas, including most of the species of tiny marine organisms called foraminifera. At the start of the 1980s, the question of what forced dinosaurs and huge numbers of other creatures to become extinct 65 million years ago was still a mystery. By the decade’s end, that mystery was solved: a comet or asteroid had slammed into Earth, throwing so much sun-blocking dust into the air that the planet plunged into a deep-freeze. The discovery of a massive impact crater off the coast of Mexico, of just the right age, pretty much sealed the deal in most scientists’ minds. But there has long been an alternate theory, espoused by a rump caucus of researchers who think they’ve never been given a fair hearing. They believe the extinction was caused, at least in part, by an extraordinary volcanic eruption in India. The reason for their extinction has divided the scientific community into two main camps: by asteroid or by volcanic eruption. But Gerta Keller, another co-author of the study, has a more one-sided view of the event, maintaining the theory that the Deccan Traps eruption caused the mass-extinction. She views that the asteroid impact happened too early to cause the die-off and sees the findings in India as strength in the case that a volcanic eruption was the extinction event. Sam Bowring, the Robert R Shrock Professor of Earth and Planetary Sciences at MIT, added: “I don’t think the debate will ever go away. “The [asteroid] impact may have caused the extinction. But perhaps its effect was enhanced because things were softened up a bit by the eruption of these volcanoes.”
Posted on: Mon, 15 Dec 2014 07:44:36 +0000
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