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nitpicker

(7,153 posts)
Thu Mar 23, 2017, 05:34 AM Mar 2017

Dinosaur crater's clue to origin of life

http://www.bbc.com/news/science-environment-39361007

Dinosaur crater's clue to origin of life

By Paul Rincon
Science editor, BBC News website, The Woodlands, Texas

1 hour ago

From the section Science & Environment

The crater made by the asteroid that killed off the dinosaurs is revealing clues to the origins of life on Earth. Scientists have drilled into the 200km-wide Chicxulub crater now buried under the Gulf of Mexico. They say its rocks show evidence of having been home to a large "hydrothermal system", where hot fluids flowed through cracks and fissures. Similar systems, generated by impacts on the early Earth, could have helped kickstart the first lifeforms. The hydrothermal system at Chicxulub may have been active for two million years or more, the scientists say.

Dr David Kring, from the Lunar and Planetary Institute in Houston, is one of the researchers who discovered and reported the crater's location. "The impact generated a very large subsurface hydrothermal system," he told BBC News. "That's exciting because we are using Chicxulub as a proxy for other, large impact events very early in Earth's history when we think these kinds of systems might have been crucibles for pre-biotic chemistry and the habitats for the evolution of the earliest life on our planet."

About 829m of Chicxulub core material was drilled between May and June 2016. Since then, team-members have been hard at work examining rocks from the crater which was punched in the crust by a 15km-wide space object some 66 million years ago. The drilling project targeted an area called the peak ring, which contains the rocks that moved the greatest distance in the impact.
(snip)

The direction of Earth's magnetic field flips every few hundred thousand years. When the Chicxulub extinction event occurred it had the reverse polarity to today. "One thing that was very intriguing was that there were several samples in the breccia melt sequence that had what's now the normal polarity - the same direction as what we have today," the Rutgers University, New Jersey, scientist said. "Three hundred thousand years [after the impact] the Earth's magnetic field crosses over and assumes the 'normal' polarity - it has the opposite direction [to that which existed at the time of the imapct]. These rocks must have acquired their magnetisation during one of these normal polarity times that came later. Since the first of these happened 300,000 years later - that provides a lower bound constraint for the hydrothermal system, telling us how long hot fluids were going through the crater."

The whole system may at first have been too hot for even the most heat-tolerant microorganisms. However, as time went on, the peak ring would have cooled down, allowing tiny lifeforms to exploit the chemicals dissolved in the hot fluids for fuel.
(snip)
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Dinosaur crater's clue to origin of life (Original Post) nitpicker Mar 2017 OP
dr who explained how it happened already. pansypoo53219 Mar 2017 #1
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