Saturday, May 23, 2009

The Mantle Origin of Carbon Dioxide and Sodium



Carbonatite Lava Flows at Oldoinyo Lengai Volcano, Tanzania:
Carbon Dioxide Becomes Solid at Surface of Oldoinyo Lengai
(Hat tip: Quantum Flux)

"We now know the origin of one of the most peculiar magmas on Earth," said William Leeman, program director in the National Science Foundation (NSF)'s Division of Earth Sciences, which funded the research. "These scientists have found that, based on new studies of the chemistry of gas emissions at Oldoinyo Lengai, a very small amount of melting of Earth's mantle, akin to that beneath mid-ocean ridges, can produce carbonatites."

The carbonatites consist of high amounts of carbon dioxide, some 30 percent. Unlike most lavas that are liquid at temperatures above 900 degrees Celsius (1,652 F), carbonatites are much cooler and erupt at only 540 degrees Celsius (1,004 F). However, they're extremely fluid, with a viscosity like that of motor oil.

"We were able to collect pristine samples of the volcanic gases because Oldoinyo Lengai was erupting and under tremendous magma pressure at the time," said Tobias Fischer, a volcanologist at the University of New Mexico and lead author of the paper. "There was minimal air contamination."

"The gases reveal that the carbon dioxide comes directly from the upper mantle, just below the East African Rift," said David Hilton, a geochemist at the Scripps Institution of Oceanography.

"These samples of mantle gases allow us to infer the carbon content of the upper mantle where the carbonatites are produced."

It's about 300 parts per million, a concentration virtually identical to that measured below mid-ocean ridges.

The finding is significant, said geochemist Bernard Marty of the CNRS-CRPG (Centre National de la Recherche Scientifique-Centre de Recherches Pe'trographiques et Ge'ochimiques in France), "because it shows that these extremely bizarre lavas and their parent magmas, called nephelinites, were produced by melting of typical upper mantle minerals--which don't have a high carbon dioxide content."

Previous research, mainly based on laboratory experiments, suggested that a higher carbon dioxide content is needed to produce nephelinites and carbonatites.

"Oldoinyo Lengai magmas also contain an unusually high amount of sodium, up to about 35 percent," said Pete Burnard, a geochemist at CNRS-CRPG.

"It's this sodium content that makes the Lengai carbonatites solid rather than gas at the surface. At all other volcanoes on Earth, carbon dioxide 'degasses' into the atmosphere without forming the sodium-rich carbonatite magmas of Oldoinyo Lengai."

Not all Oldoinyo Lengai's carbon dioxide becomes carbonatite, however. Like other volcanoes, Oldoinyo Lengai does emit carbon dioxide into the atmosphere as a gas.

The scientists conclude that the upper mantle below the continents and the oceans is a uniform and well-mixed reservoir in which the compositions and abundances of carbon dioxide and other gases like nitrogen, argon and helium are essentially the same.

9 comments:

Quantum_Flux said...

Hey, you know, if CO2 is found in the flaming hot magmas from the mantle and everything...

Anaconda said...

Quantum_Flux:

That's right, AGW is complete bullshit. Not to mention this proves there is plently of carbon for hydrocarbons.

And we know there is plenty of hydrogen in various chemicals and minerals in the deep crust and mantle.

QF, as you should know from previous posts and comments there are asphalt volcanoes on the bottom of the Gulf of Mexico.

Oil is abiotic.

Abiotic oil rises up through the cracks, fissures, and faults on tectonic boundaries and even within cratonic settings.

Interestingly, this last week there were a series of earthquakes in Saudi Arabia next to some small volcanoes.

The whole thing has come together.

Oil will be plentiful for a long time.

Excellent post OilIsMastery and great tip Quantum_Flux.

Anaconda said...

@ Quantum_Flux:

I was too quick with my response.

I'm interested in what your initial reaction was when you first read this article and after you thought about it for a while.

Your comment ended, "...and everything..."

What were you suggesting?

Sometimes, I insist on my own ideas too much without inviting other's thoughts.

I really would appreciate your thoughts, as this post raises interesting questions.

Quantum_Flux said...

There is plenty of evidence in support for the existance of abiotic oil, here and in fact on other planets as well, I just don't know why the mainstream doesn't come out and say so.

OilIsMastery said...

QF,

"I just don't know why the mainstream doesn't come out and say so."

Called incentive bias.

Munger, C.T., 24 Standard Causes of Human Misjudgement, 1995

Munger, C.T., The Psychology of Human Misjudgement, Transcript, 1995

Quantum_Flux said...

I don't think this one can be chalked up to "human misjudgement" though, especially when there are chemists studying these lava flows.

OilIsMastery said...

The last time I checked, chemists are humans. And humans make misjudgements. Witness the disagreement among chemists as to the origin of hydrocarbons.

"The capital fact to note is that petroleum was born in the depths of the Earth, and it is only there that we must seek its origin." -- Dmitri Mendeleyev, chemist, 1877

"It may be supposed that naphta was produced by the action of water penetrating through the crevices of the strata during the upheaval of mountain chains because water with iron carbide ought to give iron oxide and hydrocarbons." -- Dmitri Mendeleyev, chemist, 1877

"Whether naphta was formed by organic matter is very doubtful, as it is found in the most ancient Silurian [Ordovician] strata which correspond with the epochs of the earth's existence when there was very little organic matter; it could not penetrate from the higher to the lower (more ancient) strata as it floats on water (and water penetrates through all strata)." -- Dmitri Mendeleyev, chemist, 1877

"Do these fuels result always and necessarily in one way from the decomposition of a pre-existing organic substance? Is it thus with the hydrocarbons so frequently observed in volcanic eruptions and emanations, and to which M. Ch. Sainte-Claire Deville has called attention in recent years? Finally, must one assign a parralel origin to carbonaceous matter and to hydrocarbons contained in certain meteorites, and which appear to have an origin foreign to our planet? These are questions on which the opinion of many distinguished geologists does not as yet appear to be fixed." -- Marcellin Berthelot, chemist, 1866

"One can, then, conceive the production, by purely mineral means, of all natural hydrocarbons. The intervention of heat, of water, and of alkaline metals -- lastly, the tendency of hydrocarbons to unite together to form the more condensed material -- suffice to account for the formation of these curious compounds. Moreover, this formation will be continuous because the reactions which started it are renewed incessantly." -- Marcellin Berthelot, chemist, 1866

Quantum_Flux said...

Perhaps it's possible that J.F. Kenney and all the other Russian chemists made mistakes too then.

Fungus FitzJuggler III said...

Great post, OilIsMastery and clever comment, Anaconda!