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Chicxulub event
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New Suspects in a 65 Million-Year-Old Mystery

Calculations show that the Chicxulub meteorite was certainly big enough to have triggered eruptions at its antipode. But it seems the Deccan Traps probably lay at least 1,000 miles away from Chicxulub's antipode at the time, though it would take just a little error in our assumptions about the speed and direction of Mexico's and India's motion to put India over the antipode.
Another possibility is that Chicxulub was one of a swarm of large meteorites to strike at the same time, all from a fragmented asteroid or comet. There are roughly contemporary craters in the North Sea and Ukraine and a disputed one off the west coast of India. Against this, recent analysis suggests only a single iridium layer, implying a single big impact.

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Impact study: Princeton model shows fallout of a giant meteorite strike

Seeking to better understand the level of death and destruction that would result from a large meteorite striking the Earth, Princeton University researchers have developed a new model that can not only more accurately simulate the seismic fallout of such an impact, but also help reveal new information about the surface and interior of planets based on past collisions.
Princeton researchers created the first model to take into account Earth's elliptical shape, surface features and ocean depths in simulations of how seismic waves generated by a meteorite collision would spread across and within the planet. Current projections rely on models of a featureless spherical world with nothing to disrupt the meteorite's impact, the researchers report in the October issue of Geophysical Journal International.

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Paleontologist Kenneth Lacovara is looking deep in a New Jersey silt mine for the exact moment, 65 million years ago, when all dinosaurs perished.
That secret could be harder to uncover if the fossils here can no longer be unearthed after a housing and retail development is built on this open pit.
Lacovara, an associate professor of biology at Drexel University in Philadelphia, looks at this 40-foot deep hole at the end of a dirt road and sees a line in the sand where the Cretaceous period begins and ends. Below that line are dinosaurs, above it, not a single one.

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Cretaceous–Tertiary extinction event
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La célèbre limite Crétacé-Tertiaire plus ancienne qu'estimée jusqu'à présent

En analysant par la méthode de la cyclostratigraphie des séries sédimentaires marines prélevées dans les océans Indien et Atlantiques lors d'anciennes campagnes océanographiques des programmes internationaux « ODP » et « DSDP », une équipe de chercheurs français et américains a pu démontrer la corrélation des cycles sédimentaires avec les variations des paramètres orbitaux de la Terre et dater la limite Crétacé-Paléogène, soit à 65.59±0.07 Ma, soit à 66±0.07 Ma. Cette deuxième proposition est plus en accord avec les dernières données radiométriques, ce qui recule dans le temps cette limite de 405 000 ans par rapport à ce qui est actuellement admis.
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Chicxulub crater
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Dino crater focus for ocean drilling plans

A plan to study the Chicxulub crater by boring 1.5km into the sea bed is among the highlights of ocean drilling projects proposed for the next decade.
The Integrated Ocean Drilling Program (IODP) also plans expeditions to study earthquakes and ancient climate, and says the need is greater than ever.

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RE: Chicxulub event
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Bone suggests dinosaurs survived meteorite strike

A fossilised sauropod bone, dated by a team of Canadian and U.S. scientists to 64.8 million years ago, appears likely to force a serious rethinking of the demise of dinosaurs, which were supposed to have been wiped out in a catastrophic meteorite strike no later than 65.5 million years ago.
But that meteorite hit 700,000 years before the death of the giant, vegetarian beast that left its femur behind in present-day New Mexico.

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Dinosaur extinction link to crater confirmed

An international panel of experts has strongly endorsed evidence that a space impact was behind the mass extinction event that killed off the dinosaurs.
They reached the consensus after conducting the most wide-ranging analysis yet of the evidence.
Writing in Science journal, they rule out alternative theories such as large-scale volcanism.

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The extraterrestrial body that slammed into Earth 65 million years ago is best known for killing off the dinosaurs. But it also snuffed out more than 90% of the tiny plankton species that made up the base of the food web in the oceans. By sifting through geological records of ancient sediments from around the globe, palaeoceanographers have culled clues about how the impact caused so much havoc.
The researchers report in Nature Geoscience1 today that the most severe extinctions of nannoplankton happened in the northern oceans and that the ecosystems there took 300,000 years to recover, much longer than in the south.
Geological evidence suggests that the body that hit Earth was travelling from the southeast to the northwest.

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Image1-11.jpg
Credit: NASA/JPL/NGA

The topography of Mexico's Yucatan Peninsula reveals a subtle, but unmistakable, indication of the Chicxulub asteroid impact crater, believed by many scientists to be the cause of a mass extinction event 65 million years ago. In this computer-enhanced image, the crater's outer boundary is visible as the semi-circular, darker green line in the peninsula's upper left corner: a trough only 3 to 5 metres deep and 5 kilometres wide.

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Why did mammals survive the 'K/T extinction'?

Picture a dinosaur. Huge, menacing creatures, they ruled the Earth for nearly 200 million years, striking fear with every ground-shaking stride. Yet these great beasts were no match for a 6-mile wide meteor that struck near modern-day Mexico 65 million years ago, incinerating everything in its path. This catastrophic impact -- called the Cretaceous-Tertiary or K/T extinction event -- spelled doom for the dinosaurs and many other species. Some animals, however, including many small mammals, managed to survive.
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