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Posted on 04/27/2009 12:33:23 PM PDT by decimon
Impact didn't lead to mass extinction 65 million years ago, geologists find
The enduringly popular theory that the Chicxulub crater holds the clue to the demise of the dinosaurs, along with some 65 percent of all species 65 million years ago, is challenged in a paper to be published in the Journal of the Geological Society on April 27, 2009.
The crater, discovered in 1978 in northern Yucutan and measuring about 180 kilometers (112 miles) in diameter, records a massive extra-terrestrial impact.
When spherules from the impact were found just below the Cretaceous-Tertiary (K-T) boundary, it was quickly identified as the "smoking gun" responsible for the mass extinction event that took place 65 million years ago.
It was this event which saw the demise of dinosaurs, along with countless other plant and animal species.
However, a number of scientists have since disagreed with this interpretation.
The newest research, led by Gerta Keller of Princeton University in New Jersey, and Thierry Adatte of the University of Lausanne, Switzerland, uses evidence from Mexico to suggest that the Chicxulub impact predates the K-T boundary by as much as 300,000 years.
"Keller and colleagues continue to amass detailed stratigraphic information supporting new thinking about the Chicxulub impact, and the mass extinction at the end of the Cretaceous," says H. Richard Lane, program director in the National Science Foundation (NSF)'s Division of Earth Sciences, which funded the research. "The two may not be linked after all."
From El Penon and other localities in Mexico, says Keller, "we know that between four and nine meters of sediments were deposited at about two to three centimeters per thousand years after the impact. The mass extinction level can be seen in the sediments above this interval."
Advocates of the Chicxulub impact theory suggest that the impact crater and the mass extinction event only appear far apart in the sedimentary record because of earthquake or tsunami disturbance that resulted from the impact of the asteroid.
"The problem with the tsunami interpretation," says Keller, "is that this sandstone complex was not deposited over hours or days by a tsunami. Deposition occurred over a very long time period."
The study found that the sediments separating the two events were characteristic of normal sedimentation, with burrows formed by creatures colonizing the ocean floor, erosion and transportation of sediments, and no evidence of structural disturbance.
The scientists also found evidence that the Chicxulub impact didn't have the dramatic impact on species diversity that has been suggested.
At one site at El Penon, the researchers found 52 species present in sediments below the impact spherule layer, and counted all 52 still present in layers above the spherules.
"We found that not a single species went extinct as a result of the Chicxulub impact," says Keller.
This conclusion should not come as too great a surprise, she says. None of the other great mass extinctions are associated with an impact, and no other large craters are known to have caused a significant extinction event.
Keller suggests that the massive volcanic eruptions at the Deccan Traps in India may be responsible for the extinction, releasing huge amounts of dust and gases that could have blocked out sunlight and brought about a significant greenhouse effect.
Well, there's a lot of meat on them critters. If they don't get you first.
No, no, please no!
The story here is, Gerta Kelly has been peddling this for years, has been wrong about it, and tries to push it through with press releases.
Bang goes that theory:
Dinosaur extinction ‘occurred 300,000 years AFTER asteroid impact’
dailymail.co.uk | April 27, 2009 | Daily Mail Reporter
Posted on 04/27/2009 4:35:51 PM PDT by Free ThinkerNY
http://www.freerepublic.com/focus/chat/2239147/posts
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Whoops, thanks decimon. :’)
13th impact crater associated with K/T boundary
From Tom Van Flandern* Received 5.11.03
Last year, a British team of scientists announced the discovery of a multi-ringed crater (named Silverpit) with a central peak beneath the floor of the North Sea, believed to have been caused by an asteroid impact between 60 million and 65 million years ago [1-4]. The crater has 10 concentric rings from 2-20 km in diameter. The rough dating suggests that the asteroid that caused Silverpit might have been a chunk that broke off the larger asteroid that hit the Yucatan Peninsula 65 million years ago. Together with the Chicxulub and other craters, this discovery gives new support to the idea that killer objects from outer space may have sometimes arrived in pairs or even swarms. “It’s so clear,” said Dr. Gerta Keller, a geologist and paleontologist at Princeton, who studies the links between cosmic bombardments and life upheavals. “A tremendous amount of new data has been accumulated over the past few years that points in the direction of multiple impacts.”
Actually, that brings the list of impact craters sometimes associated with the K/T boundary (65Ma) to 13. These are: Beyenchime-Salaatin (Siberia), Eagle Butte (Oregon), Upheaval Dome (Utah), Manson (Iowa), Kara (Western Siberia), Kamensk (Siberia), Gusev (W. Russia near Ukraine), Unnamed (Pacific Ocean), Chicxulub (Yucatan), Belize (south of Yucatan), Haiti (Caribbean), Alvaro Obregón (N. Mexico), Silverpit (North Sea) [5-10]. However, the global distribution of these impacts argues strongly against chunks off a parent asteroid, which would be expected to have much less than a hemispheric distribution, assuming Earth’s atmosphere is the agent responsible for the break up. Capture and tidal break up by Earth, similar to Jupiter’s capture of Comet Shoemaker-Levy 9, is extremely unlikely (by a factor of over 10 million) because Earth has a much smaller mass and is closer to the Sun. The clear implication of this global terrestrial cratering cluster is the explosion of a planet-sized parent body in the main asteroid belt, a hypothesis for which considerable astronomical evidence already exists [11-22].
http://www.geolsoc.org.uk/gsl/site/GSL/lang/en/page5055.html
More and more Epicycles!!!
Maybe the 14th will be the one that proves it!
Thanks! I’m a little surprised that a British team was involved, since there’s a pronounced antipathy toward the impact extinction models among the teadrinkers.
Lawyers?
There was a much, much bigger one a billion years or so ago.
Google SUDBURY METEOR
Dinosaurs died out from global cooling. It happened like this: meat eaters gradually overtook the plant eaters which had kept the ‘flatulence’ gases at a heat sustaining level; when the flatulence curve plummeted, the temperatures did too, and the planet fell into a massive ice age, until the plant sea creatures’ methane production from fecal build up on the sea floors was able to once again raise the flatulence quotient via methane releases from the ocean beds with an asteroid/meteoroid impact. Lawyers and lying liberals are functioning much the way plant eaters did ... but the Sun is fighting back, stopping its spots which counters the lawyer and liberal flatulence quotient. Moral of the story: Al goreghoul needs hundreds-of-millions more vegetarians so he can earn his nobel prize.
The newest research....suggest that the Chicxulub impact predates the K-T boundary by as much as 300,000 years.
So let me get this straight. The dinosaurs didn't die out 65 million years ago. They died out 64.7 million years ago.
Or, are they really trying to tell us they can tell the differnce between 64.7 and 65 million years ago?
I think it all started when they found one of their own:
An oblique view from southeast showing the central crater, with its 300m-high inner peak, and the surrounding rings. The Silverpit structure, cut into chalk, is now covered by about 1km of rock, mostly shales. (Image: GSAB/Stewart/Allen)
Last Updated: Friday, 18 March, 2005, 12:05 GMT
North Sea crater shows its scars By Jonathan Amos BBC News science reporter
What is thought to be the UK's only space impact crater has been mapped in detail in 3D for the first time.
The so-called Silverpit structure lies several hundred metres under the floor of the North Sea, about 130km (80 miles) east of the Yorkshire coast.
The new pictures show a spectacular set of rings sweeping out around a 3km-wide (1.8 miles) central hole.
Researchers report their description and interpretation of the images in the Geological Society of America Bulletin.
Dr Simon Stewart and Phil Allen detail how the crater's features would have developed from the cataclysmic fall of an asteroid or comet about 60-65 million years ago.
"I'm 99% certain - as certain as you can be - that this is an impact structure," Phil Allen told the BBC News website.
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