Science, methane, and experimental petrology



Scary pumpkin: The second law of thermodynamics.
NEWS

This summer (2007) I'm working on calcite solubility measurements at high pressure as a function of oxygen fugacity and CO2 activity. Theoretically, we calculate that at 500C and 10kb, the reducing fluids generated during serpentinization should enhance calcite solubility. An implication of our work is that hydration of the mantle wedge could mobilize a carbon-enriched fluid. In early July, we traveled to Oregon in an attempt to collect josephinite, a rare native nickel-iron alloy formed during serpentinization. We were helped in the field by Robert and Bob Nolan, longtime josephinite fans. We didn't find any large nuggets in the field, but our hosts didn't let us leave empty-handed: they gave us a large helping of placer finds from their claims in the hills. I plan to use them for experimental buffers and catalysts for methanogenesis and solubility projects.

For the past year I've been collaborating with Tom McCollom's lab at the Laboratory for Atmospheric and Space Physics at the University of Colorado. Last summer, Tom showed me how to run experiments using a flexible cell hydrothermal apparatus. We tested the hypothesis that hydration of komatiitic cumulate lava flows by a carbon-bearing fluid could have generated enough methane to influence the atmospheric composition of the early Earth. This work is still in progess, but an unexpected finding suggests that chromite does not catalyze hydrocarbon formation or even methanogenesis as has been previously proposed by Foustoukos and Seyfried (2004).

MY RESEARCH: SIMPLE VERSION

Right now I'm working on a geology Ph.D. at UCLA. Technically, I'm more of a geochemist than geologist. Geologists actually go out in the field and look at live rocks. Geochemists generally make a lot of graphs about rocks, hang out in laboratories, or nerd out in front of a computer. When I first got into this rock racket (Rockit), I imagined my prospecting silhouette perched high upon a remote mountaintop, pick in hand. These days, however, I do most of my geology within a reasonable walking distance from ice cream.

Even more technically speaking, I'm not just a geochemist: I'm a high-pressure aqueous computational and experimental petrologist. Translation: I use large machinery and those persistent laws of thermodynamics to simulate the high pressures and temperatures in the otherwise inaccessible interior of the Earth. I work in the UCLA Experimental Petrology Laboratory where we compress and heat stuff. Yes, we can make diamonds, rubies, sapphires, and other mineralized status symbols of love. Legend has it, a fellow in the Lamont petrology lab--where I did my master's work--once made diamonds from peanut butter. Yet alas, ladies, before you start sneaking out at night to tap on my window, you should know that our lab-grade diamonds are unglamourously powdery and dark, not the sort of hypnotic gems that you might imagine twinkling from your wildly gesticulating fingers in a frenzied pitch to summon the waiter for another order of foie gras on our honeymoon in Provence. Besides, I'm already happily married, so stop pressuring me.

Typical cocktail question: "Hey, so you're a petrologist...does that mean you go hunt for oil?" No. "Petro" is merely a Latin root that means rock. "Petroleum" is roughly translated as "rock oil", or something like that. Ergo, "petrology" just means the study of rocks. For some of you, petrology may thus seem like a punishment for bad behavior at a hard labor camp, but I rather like it, thank you very much. Many petrologists go to every corner of Earth to collect and observe rocks in their natural habitat. Some whack their way through exotic malarial jungles to sample remote lava flows, sustained only by dried monkey meat and tree bark chips. Some go to sea in research submarines to study underwater rocks, active volcanoes, and an occasional hydrothermal vent ecosystem, home to those weird white crabs and tube worms you may have seen on the Discovery Channel between fistfuls of potato chips. So, please promise me that the next time you meet a petrologist at a cocktail party or AA meeting, please don't ask her if she can solve the world's oil crisis. Such an etmylogical misunderstanding would be akin to asking a proctologist if he ever catches cheaters while administering the SAT. The person who looks for oil is called a "petroleum geologist", or depending on your politics, a "baby killer".

Lest you think I spend long winter nights in candlelit sub-museum basements cataloging grey chips of dusty stone, painstakingly labeling each specimen with a feather quill and occasionally removing my green visor to properly flip down my monocle ("Ah, yes, these lithostriations remind me of an Appalachian apatite-bearing aplitic haplogranitoid!"), I actually do real scientific research. Among other things, I'm interested in how a process called serpentinization produces methane. Serpentinization is a common geological process wherein nature adds water to a special type of rock called peridotite, which is unstable when it gets wet. In a manner less delicious but otherwise not to dissimilar to the soggification of a crouton in French onion soup, peridotite expands in the presence of water and transforms into a softer, greasier rock called serpentinite. During the bloating, most of the iron in the rock oxidizes (rusts) and gives its electrons up for adoption. Water, being such a gracious host to so many chemical guests, takes in the estranged electrons and, in a classy act of self-administered chemical plastic surgery, transforms itself to hydrogen gas. If there happens to be any carbon dioxide around, the hydrogen reacts with it to form methane.

Most methane in modern times is produced in your digestive system or in hydrocarbon deposits. Both of these environments are essentially biological. The methane made during serpentinization is, however, "abiogenic" or "abiotic", meaning it's formed during a process that had nothing to do with living (or dead) organisms. The whole process is called something like serpentinization-induced abiotic methanogenesis, and may be responsible for supplying not only enough syllables to impress your next date, but also enough methane to influence the bulk composition of a planetary atmosphere. That the process is common on Earth--and likely throughout the solar system--should inspire images of flatulent, methane-oozing planets. This, of course, appeals to the 12 year old in me: I study Rock Farts.

One of the more compelling aspects of serpentinite-hosted abiotic methanogenesis is that this process may have played host to the beginning of life. It's well-established by the geeks who study this stuff that if you take a bunch of methane and put it under the right conditions, it can react to form more complex molecules such as hydrocarbons. If you add nitrogen under the right conditions, you can even make amino acids: the building blocks of life. How life began is one of the nagging mysteries in all of science. I think serpentinization may be the key; either that we're an alien experiment after all.

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MY RESEARCH: GEEK VERSION

(1) Experimental synthesis of hydrocarbons during awaruite-stabilized serpentinization
(2) Experimental methanogenesis during komatiitic alteration: implications for methane in the Hadean and Archean atmosphere
(3) Experimental fractionation of chlorine stable isotopes in ultramafic phyllosilicates and brucite
(4) The effect of silica on oxygen fugacity in hydrothermal systems
(5) Methanogenesis and chlorine systematics in ultrabasic serpentinite-hosted terrestrial springs
(6) Ion probe analyses of surficially-hosted hydrocarbons on Fischer-Tropsch-type catalysts
(7) The effect of oxygen fugacity and CO2 activity on calcite solubility at high pressure


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TEACHING

Here's some images from my two years as an earth science teacher in NYC public high school.

TA assignments:
Metamorphic Petrology, Spring 2007
Intro to Earth Science, Fall 2006
Igneous Petrology, Spring 2006

Other:
Interpretive Guide, Idaho, National Park Service, 1997
Assistant instructor, Univ of FL Brazilian Music Ensemble, 1995
Music counselor, Timber Ridge Camps, 1994

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PUBLICATIONS

Experimental study of the role of komatiite alteration on methane in Earth's early atmosphere. Lazar, C., McCollom, T.M., and Manning, C.E. (2006) AGU Fall meeting poster session.
Poster pdf (27.3MB)
Abstract pdf (20KB)

Thermodynamic modeling of methane production by metamorphic serpentinization at 0.25-5 kb and 300-600 °C: Implications for Archean atmospheric evolution and subduction fluid composition. Lazar, C., and Manning, C.E. (2005) NASA Astrobiology Science Conference poster session.
Poster pdf (224KB)
Abstract pdf (56KB)

Thermodynamic modeling of methane production in Early Archean crust by serpentinization: implications for atmospheric methane. Lazar, C., and Manning, C.E. (2005) AGU Fall meeting poster sesion.
Abstract pdf (100KB)

Experimental partitioning of Tc, Mo, Ru, and Re between solid and liquid during crystallization in Fe-Ni-S. Lazar, C., Walker, D., and Walker, R.J. Geochimica et cosmochimica acta (2004) 68, 3, 643-651.
Full pdf (260KB)

Experimental partitioning of Tc, Mo, Ru, and Re in Fe-Ni-S. Lazar, C., and Walker, D. (2002) Lunar and Planetary Science Conference XXXIII abstracts Full pdf (28KB)


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IMAGES

Here's a photo gallery of the UCLA PTX lab.

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