Posted on 10/30/2007 1:31:46 PM PDT by crazyshrink
Dinosaur Deaths Outsourced to India? Boulder, CO, USA - 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.
Hmm. This article refers to that as a myth, however, it sez that increased CO2 levels could make a small difference (ordinarily, plant cells get overloaded with sugars during peak hours, shut their pores, and run on respiration):
http://environment.newscientist.com/channel/earth/climate-change/dn11655
[snip] However, it is extremely difficult to generalise about the overall impact of the fertilisation effect on plant growth. Numerous groups around the world have been conducting experiments in which plots of land are supplied with enhanced CO2, while comparable nearby plots remain at normal levels... These experiments suggest that higher O2 levels could boost the yields of non-C4 crops by around 13 per cent... However, while experiments on natural ecosystems have also found initial elevations in the rate of plant growth, these have tended to level off within a few years. In most cases this has been found to be the result of some other limiting factor, such as the availability of nitrogen or water. [end snip]
I personally think that the Iridium is ET in origin but, Sunk, we don’t know that as a fact. We merely postulate it as we cannot prove it.
No one was around to see the event and take samples immediately thereafter; however, the ET origin is no longer in dispute (other than by some diehards).
http://palaeo.gly.bris.ac.uk/Communication/Lee/page1.html
[snip]Ir found in sediments is from cosmogenic fallout and constitutes around 0.03 ppb. The levels found at Gubbio are in the order of 500ppb. Higher concentrations can be attributed to longer periods of deposition, in this case the death of many calcium carbonate producers stopping the production of limestone which surrounds the clay layer, thus slow clay deposition could result in higher Ir. But this amount of Ir would require a depositional time of around 500,000 years. The high resolution records at the K-T in Caravaca, Spain ( Smit, 1981 ) however indicate a period of no more than 50 years ( other sites resolve the length of time to roughly 1,000 years ). Combined with this is that the ratio of Ir to platinum, osmium, ruthenium, rhodium and gold are the same ( within 5% ) in the boundary layer as they are in type one carbonaceous chondrite meteorites ( Asaro,1990 ). From this evidence it was clear that at least some form of extraterrestrial influence had taken part in the extinction. [unsnip]
http://www.scn.org/~bh162/iridium.html
[snip] To give you an idea of how rare the element is in sedimentary rocks, in a randomly-selected rock weighing one gram, the amount of iridium contained within it would be less than 1 to 2 BILLIONTHS of a gram (1-2 nanograms). In fact, the amount of iridium is often so small that it sometimes cannot be measured at all using today’s scientific equipment (it is estimated to be as low as 0.05 nanograms/gram of sediment). In the clay layer at the Cretaceous-Paleogene boundary, the concentration of iridium is still unbelievably diluted, but it is abundant enough to be easily measured by instruments... In meteorites (iron meteorites + the stoney meteorites), platinum-group metals are significantly more abundant than they are in rocks in the Earth’s crust, often hundreds to thousands of times more concentrated (averaging about 500 nanograms/gram of meteorite in a type of stoney meteorite called a chondrite) (Alvarez et al., 1980). Iron meteorites contain much higher concentrations of these elements. Platinum-group metals are also found in cometary nuclei, but in a somewhat lesser concentration than in chondrites. [unsnip]
Impacts do not cause volcanic eruptions
Dr. H. Jay Melosh
http://www.lpl.arizona.edu/~jmelosh/ImpactVolcanism.pdf
Not to be argumentative but inquisitive. It is my understanding that the high CO2 levels were accompanied by higher (than current) temperatures. As far as asphyxia, would the location of a dinosaurs brain (deep in a very large head), and being about the size of a walnut, counter this in any way?
Pretty much yes, The impact hypothesis is falsified by the fact that it can't explain how Alligators & Crocodiles, Turtles, 100% of the Amphibians, diatoms, Dinoflagellates, birds, honeybees, 97% of freshwater fish and many others who would have been the 1st to go under an impact scenario with it's resulting nuclear winter all survived unscathed.
I'll go with Geologist Norman Macleod who said it best
"The impact theory says in effect that a rock fell out of the sky and killed everything, except for the things that it didn't kill. I don't think that's much of an explanation."
Not to mention That "Thin" layer of iridium as it is described represents 10,000-100,000 years of sediment. How on Earth could iridium (a heavy metal no less) stay up in the atmosphere that long? It would at most wash out within months if not weeks or days.
are we always teaching our kids false info?
Yep, this is actually similar to global warming, if you remember during the Reagan years the Dinosaurs were killed by an Asteroid hypothesis because of it's "nuclear winter" aspect was embraced by Liberals as an anti-nuclear weapons argument.
For an example see Carl Sagan's The Atmospheric and Climatic Consequences of Nuclear War written in 1983
The higher CO2-higher temperature argument is just part of the global warming politics, as well as the gradualist response to dinosaurs in the Arctic and Antarctic (note that drifting continents doesn’t account for dinos in those places; the fossils are however, there).
No, it’s not wrong. The asteroid impact happened and killed the dinosaurs 65 million years ago.
I never got the nuclear winter argument. Were they libs around when it happened? because they seemed hell bent on making that theory so.
you’re wrong. it was global warming that killed the dinosaurs.
Is there some proof that the Iridium is ET in origin? Volcanoes also emit Iridium. The earth isn’t devoid of Iridium, it is just relatively rare in the crust (like most denser metals).
See Toutain, J., and Meyer, G., 1989, Iridium-bearing sublimates at the hot-spot volcano
What ever happened the the talk about a Shiva Crater [caused by impact off Bombay] as being the cause of the Deccan phenomenon. Also, I tried to respond to another post regarding the antipodal possibility of the Yucatan meteor causing the Deccan events. It did not come up on my computer, but said there should have been two antipodal events. My question: wouldn’t the location of the antipodal reaction depend on the angle of entry of the original boloid?
See the link to the H. Jay Melosh response regarding whether impacts cause volcano outbreaks. :’)
Sea floor records ancient Earth
BBC | Friday, 23 March 2007, 09:09 GMT
Jonathan Fildes Science and technology reporter, BBC News
Posted on 03/24/2007 2:06:03 AM EDT by Ernest_at_the_Beach
http://www.freerepublic.com/focus/f-news/1805973/posts
The quantity of iridium found in the tiny layer at the K-T boundary precludes terrestrial sources.
Fred Flintstone was involved.
Or Sankar Chatterjee's Shiva impact?
Are any other FReepers here at the GSA meeting? Please FReepmail me before you head out of town...maybe we can get together for adult beverages?!
Just had a similar discussion over lunch yesterday (Shoemaker-Levy style impact chain, and impact-triggered volcanism). That didn’t happen to be you at the table, did it? The discussion that followed had to do with basins and mare.
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