Dinosaur Deaths Outsourced to India?
October 29, 2007
A vertical mile of Deccan lavas visible from Arthur's Seat at Mahabaleshwar. Photo courtesy Mike Widdowson
A series of monumental volcanic eruptions in India may have killed the dinosaurs 65 million years ago, not a meteor impact in the Gulf of Mexico. The eruptions, which created the gigantic Deccan Traps lava beds of India, are now the prime suspect in the most famous and persistent paleontological murder mystery, say scientists who have conducted a slew of new investigations honing down eruption timing.
"It's the first time we can directly link the main phase of the Deccan Traps to the mass extinction," said Princeton University paleontologist Gerta Keller. The main phase of the Deccan eruptions spewed 80 percent of the lava which spread out for hundreds of miles.
It is calculated to have released ten times more climate altering gases into the atmosphere than the nearly concurrent Chicxulub meteor impact, according to volcanologist Vincent Courtillot from the Physique du Globe de Paris.
Keller's crucial link between the eruption and the mass extinction comes in the form of microscopic marine fossils that are known to have evolved immediately after the mysterious mass extinction event. The same telltale fossilized planktonic foraminifera were found at Rajahmundry near the Bay of Bengal, about 1000 kilometers from the center of the Deccan Traps near Mumbai. At Rajahmundry there are two lava "traps" containing four layers of lava each. Between the traps are about nine meters of marine sediments. Those sediments just above the lower trap, which was the mammoth main phase, contain the incriminating microfossils.
Keller and her collaborator Thierry Adatte from the University of Neuchatel, Switzerland, are scheduled to present the new findings on Tuesday, 30 October, at the annual meeting of the Geological Society of America in Denver. They will also display a poster on the matter at the meeting on Wednesday, 31 October.
Previous work had first narrowed the Deccan eruption timing to within 800,000 years of the extinction event using paleomagnetic signatures of Earth's changing magnetic field frozen in minerals that crystallized from the cooling lava. Then radiometric dating of argon and potassium isotopes in minerals narrowed the age to within 300,000 years of the 65-million-year-old Cretaceous-Tertiary (a.k.a. Cretaceous-Paleogene) boundary, sometimes called the K-T boundary.
The microfossils are far more specific, however, because they demonstrate directly that the biggest phase of the eruption ended right when the aftermath of the mass extinction event began. That sort of clear-cut timing has been a lot tougher to pin down with Chicxulub-related sediments, which predate the mass extinction.
"Our results are consistent and mutually supportive with a number of new studies, including Chenet, Courtillot and others (in press) and Jay and Widdowson (in press), that reveal a very short time for the main Deccan eruptions at or near the K-T boundary and the massive carbon dioxide and sulfur dioxide output of each major eruption that dwarfs the output of Chicxulub," explained Keller. "Our K-T age control combined with these results strongly points to Deccan volcanism as the likely leading contender in the K-T mass extinction." Keller's study was funded by the National Science Foundation.
The Deccan Traps also provide an answer to a question on which Chicxulub was silent: Why did it take about 300,000 years for marine species to recover from the extinction event? The solution is in the upper, later Deccan Traps eruptions.
"It's been an enigma," Keller said. "The very last one was Early Danian, 280,000 years after the mass extinction, which coincides with the delayed recovery."
Keller and her colleagues are planning to explore the onset of the main phase of Deccan volcanism, that is, the rocks directly beneath the main phase lavas at Rajahmundry. That will require drilling into the Rajahmundry Traps, a project now slated for December-January 2007/2008.
Source: Geological Society of America
May 04, 2009 |
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Unfortunately paleontologists like Gerta Keller just will not listen to non-paleontologists. Psychologists (like me) couldn't possibly draw a straight line or look up a K-T map.
However, volcanologists who I have spoken with about this idea rather like it.
What do you say Dr. Keller?
The one, two punch resolves all the issues. Well, there is an issue of how the forces are transmitted - surface waves, forces transmitted through the mantel, the interior, arrival time, compression then tension, etc. I wish I had a physical model I could shoot with an air gun or something!
If I was 60 years younger I might go for a Ph.D. in one of the earth sciences. But it needs more energy than I have left. I just whine.
Thanks for the comments!
Those aren't small issues; and I'm always sceptical when someone claims their hypothesis 'resolves all the issues' (just haven't been looking hard enough, even the best theories have issues). For example, does it explain why the dinosaurs died, but not the frogs?
its unlikely that these events happened at the same time, "nearly concurrent" means somewhere within a hundred thousand years to a couple million. In fact, this article reminded me of one of Keller's articles ealier this year:
http://geoweb.pri...r_et_al_ EPSL_2007.pdf
How would a meteor impact cause volcanism on the other side of the world which may have occured around the same time, or maybe a couple hundred thousand to a million years later? And what about other major meteor impacts, it would add a lot of weight to your hypothesis if you could find major volcanic eruptions on the opposite sides of the Earth for the following big impacts: http://en.wikiped...on_Earth
either that or search for "Chicxulub impact predates the K-T boundary mass extinction"
BTW, shocked quartz can be created either way.
Can anyone confirm or deny that? The book which treats the matter of the Sibrian Traps, 'When Life Nearly Died", is on loan to one of my children.
I've always felt the impact begot the eruptions.