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miércoles, 11 de mayo de 2016

From the Chicxulub crater in the Yucatán. Ancient Asteroid Crater Chicxulub May Show Secrets Of Dinosaur Extinction


  • Chicxulub crater
  • (Photo : Catherine Marshall/plus Google.com) Chicxulub crater 

An ancient asteroid crater that could give an insight into the extinction of dinosaurs about 65 million years ago is being probed by a team of 33 researchers. They are gathering rock samples from the Chicxulub crater in the Yucatán Peninsula, to search for clues to the ancient event.
"The extinction event caused 75 percent of life to go extinct on Earth, including the dinosaurs," said geophysicist Sean Gulick of the University of Texas and co-leader of the expedition. "Thus, determining the potential causes, or kill mechanisms, is a very important step forward in our understanding of the history of life on Earth."
"One aspect that we are studying by driving into the Chicxulub impact crater is the impact event itself - including potential kill mechanisms and the recovery of life after the asteroid struck," he added.
The study began in the 1980s. However, the current $10 million expedition is digging deeper, studying the Chicxulub "peak ring," a geological formation created from large-sized asteroid impacts. They have never been examined earlier.
"It is the best-preserved large impact on Earth, the only one linked to a mass extinction event, and the only one with a confirmed peak ring," Gulick said.
He said they underwent a remarkable amount of the post-impact world. "All the way into the Eocene times - so between 50 and 55 million years ago. We've got all these limestones and rocks that contain the fossils from the world after the impact, all the things that evolved from the few organisms that survived."
"In 1996, and again in 2005, we used seismic data to image beneath the limestone that bury the crater to see its key features, including the ring-shaped faults, crater rim, and peak ring," said geophysicist Joanna Morgan of Imperial College London and co-leader of the expedition. "We decided if we could drill in only one location, drilling into the peak ring was the best target."
As it had been shallow, the drilling took less time and expenses. "It would tell us whether the impact models were correct and it had the best chance for preserving evidence of impacts being used as habits for life that can live off chemical reactions, as opposed to sunlight (chemosynthetic organisms)."
Targeting completion of their collection by June, the team is hoping to send them for analysis so that they can uncover evolutionary patterns after the ancient asteroid impact leading to the extinction of dinosaurs.
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