AGU 2005 Fall Meeting - Session B16 Information

AGU 2005 Fall Meeting - Session B16 Organic Compounds in Volcanic Hydrothermal Systems: Field, Experiment, and Theory
Session B16 - Oral Presentation Session B23D - Tuesday, 06 October 2005, 13:40-15:40
Time	Session Code	Location	Title / Presenting Author	Abstract / Coauthors
13:40 PM	B23D-01 Invited	Marriott Salon 13	Molecular Ecology of Carboxylic Acids in Hydrothermal Environments Koichiro Matsuno Nagaoka University of Technology, Japan CXQ02365(at)nifty.com	K Matsuno Hydrothermal environments in the primitive ocean on the Earth must have played an important role for harnessing a molecular ecology processing various carbon through-flows in the pre-RNA world. Even carboxylic acids alone could have maintained a primitive evolutionary ecology near hot vents on the seafloor. We examined whether the citric acid cycle could run in a simulated hydrothermal environment with the aid of neither reducing agents nor enzymes of biological origin under the premise that pyruvate was already available. When the major carboxylic acid molecules constituting the citric acid cycle including pyruvate were prepared in a flow reactor and the reaction fluid was circulated between hot and cold regions in a cyclic manner, the member molecules of the cycle were found to increase with the operation of the reactor. The cycle was found robust enough to synthesize the member molecules from within even in the face of adverse or hostile disturbances from the outside. The cycle was oxidative instead of being reductive, and the effective oxidant was water molecules. Underlying the operation of a molecular ecology running on the oxidative citric acid cycle is the physical pruning principle of the faster temperature drop going with the greater stored latent heat applied to any reactants crossing sharp temperature gradients.
13:55 PM	B23D-02	Marriott Salon 13	A new Optical Technique for Raman Spectroscopy of Hydrocarbon-Water Reaction at Elevated Pressures and Temperatures I-Ming Chou U.S. Geological Survey, USA imchou(at)usgs.gov	I Chou, R Burruss Our understanding of the reaction pathways and decomposition of organic compounds in the presence of water is limited. We constructed a new hydrothermal-reaction optical cell from square, flexible, fused-silica capillary tubing (300 μm x 300 μm with 50 μm x 50 μm cavity and from 3 to 5 cm long) that allows enclosed fluids to react at temperatures (T) up to 300°C with internal pressures up to 100 MPa. The transparent fused silica allows non-destructive Raman spectroscopy of reaction progress. The sample fluids are loaded cryogenically. For example, to load a mixture of methane and water, one end of the capillary tube (about 10 cm long) was sealed by a hydrogen flame, and water was loaded and centrifuged to the enclosed end and then immersed in liquid nitrogen. The open end of the tube was connected to a vacuum line and then pressurized with methane (at about 0.2 MPa pressure) after evacuation. After sufficient solid methane is precipitated, the tube is evacuated and sealed by a hydrogen flame. We have successfully sealed a water-methane mixture, where solid methane hydrate is stable at room T (22.5°C) and 38 MPa. We heated a methane-water mixture with about 10 MPa methane pressure (at room T) at 206°C for 41 hours, and the Raman spectrum (room T) indicates formation of methanol (CH₄ + H₂O = CH₃OH + H₂). However, no methanol was formed when the same sample was initially heated at 160°C for 41 hours. When ethane and water are reacted at 206°C for 41 hours, the Raman spectrum (room T) shows the formation of both ethanol (C₂H₆ + H₂O = C₂H₅OH + H₂) and acetic acid (C₂H₆ + 2 H₂O = CH₃CO₂H + 3 H₂). Our results are in agreement with the reaction pathways proposed by Seewald (2001, Geochim. Cosmochim. Acta, 65, 1641), except our fluid samples were not in contact with any mineral buffers. Hydrogen diffusion out of the capillary tube promotes the oxidation-hydration reactions. This new method has a great potential for studying chemical reactions of organic materials with water at elevated pressures and temperatures, and also for synthesizing fluid inclusions containing organic compounds.
14:10 PM	B23D-03 Invited	Marriott Salon 13	Organics in volcanic gases: a review on their distribution and applications to volcanic surveillance Bruno Capaccioni University of Urbino, Italy b.capaccioni(at)uniurb.it	B Capaccioni, F Tassi, M Maione, F Mangani, O Vaselli Over the past fifteen years, a large amount of quantitative analytical data has been accumulated on light hydrocarbons in fumarolic and geothermal gas discharges from several volcanic and geothermal systems around the world. These data, which include new and published data on approximately 500 low-temperature, geothermal, and volcanic gas discharges from different geodynamical settings, have enabled a systematic understanding of the behavior and mechanisms of formation of C1-C6 hydrocarbons and heterocompounds. These processes and their possible thermodynamic controls have been a matter of debate over the past decade. The three main classes of hydrocarbons (alkanes, alkenes and aromatics) in these discharges display recurring distributions among different volcanic and geothermal systems. This finding suggests a similar compositional evolution of light hydrocarbons through common genetic processes. Additionally, the possible role of partial equilibrium in the system can be investigated by the direct comparison of predicted versus experimental data. If we consider the chemical reactions involving C1-C4 alkanes via a free-radical mechanism, even partial chemical equilibrium seems to be only rarely attained. This may be due to the high activation energies required for the breaking of C-C bonds. In contrast, interactions between alkenes and their saturated equivalents (e.g., ethene-ethane, propene-propane and isobutene-isobutane pairs) through dehydrogenation processes seem to be at least partially thermodynamically controlled. The improved understanding of the processes controlling the generation, modification and fate of hydrocarbons in these systems leads to the recognition of certain types of systems and possible predictive applications for volcanic monitoring. For example, temporal monitoring of hydrocarbon species carried out off-shore at Panarea Island after a gas blast occurred in November 2002, as well as monitoring at the Phlegrean Fields (southern Italy) have contributed to the identification of a shift in the feeding systems towards more reducing conditions, possibly due to declining inputs of deep magmatic fluids. For heterocompounds, data have indicated that thiophenes and dimethylsulphide are widely produced and at similar levels, whereas furans have only been recognized in high temperature volcanic gases in agreement with their relative thermodynamic stabilities. Lastly, significant amounts of halocarbons and hydrogenated halocarbons have been measured in volcanic gases, and their relative distribution at Vulcano Island (southern Italy) seems to suggest a non-atmospheric origin. Estimation of total CFC emission rates were provided based on measurements of the whole-gas flux from the active crater of Vulcano Island. The processes controlling the formation of C1-C6 hydrocarbons and heterocompounds and their possible thermodynamic controls, as well as potential applications, will be discussed and reviewed in detail.
14:25 PM	B31B-0985 formerly B23D-04	Marriott Salon 13	-- CHANGE IN PRESENTER -- Possible Evidences for Abiogenic Hydrocarbons in Hydrothermal Fluids of Everman Volcano, Socorro Island, Mexico Yuri Taran UNAM, Ciudad Universitaria, Mexico taran(a)geofisica.unam.mx	Taran Y Geochemists believe that the Fischer-Tropsch reaction may be responsible for the abiogenic production of hydrocarbons (HC) in nature. Among environments where this is possible, terrestrial and submarine hydrothermal systems are main candidates. Among geochemical criteria for a natural FT process there are two most popular: Shultz-Flory distribution of alkanes and the decrease of ¹³C of alkanes with increasing carbon number: the heavier alkanes should be isotopically ligher. The application of the first criterion is often wrong, because for the FT synthesis it makes sense only for n>4. The light HC products of a real FT synthesis have a maximum at C₃-C₄. The second rule is also not absolute, because after a heating of organic matter at >700°C the set of light alkanes formed as the result of such high-temperature thermo-degradation shows the same inverse, "synthetic", ¹³C distribution. In the fumarolic steam of Everman volcano at Socorro island both criteria were fulfilled. Vapors from Socorro have 96° C, very high hydrogen and methane concentrations and a local minimum at ethane in the HC concentration distribution. Methane of Socorro is isotopically heavy (-9 > ¹³C1 > -15 PDB) and ¹³C2 > ¹³C3 > ¹³C4 (-21, -24, -25 , respectively). The source of high H₂ and CH₄ in Socorro gases is thought to be the serpentinization of Mg-rich gabbroid intrusive bodies inside and beneath the volcano edifice by infiltrated seawater in presence of magmatic CO₂. The methane can be a mixture of isotopically heavier abiogenic CH₄ and isotopically lighter thermogenic CH₄. In that case, the inverse isotopic distribution could be an artifact, if most of C₂+ are of thermogenic origin.
14:40 PM	B23D-05 Invited	Marriott Salon 13	Experimental Studies of Abiotic Organic Synthesis Under Hydrothermal Conditions Tom McCollom University of Colorado, USA mccollom(at)lasp.colorado.edu	TM McCollom It has become widely accepted among geochemists that methane and other organic compounds are readily synthesized in hydrothermal systems, and that the products of this synthesis make a significant contribution to the hydrocarbons observed in vapors and fluids from hydrothermal environments. The mechanism most frequently invoked for this synthesis is the Fischer-Tropsch (FT) process, which involves the surface-catalyzed reduction of CO (or CO₂) to methylene followed by polymerization of methylene into more complex hydrocarbons. Owing to the significance of the Fischer-Tropsch process to industrial applications, it has been extensively studied and there are numerous publications on the process in the chemical engineering literature. However, the vast majority of these studies are performed under conditions with little relevance to natural systems, and the behavior of FT synthesis under geologic conditions remains largely unclear. While there is substantial geochemcial evidence for the occurrence of abiotic organic compounds in hydrothermal systems and elsewhere, experimental studies have thus far generally failed to produce significant organic compounds under analogous conditions. For instance, because of the strongly reducing environments created during serpentinization, serpentinites are frequently cited as a particularly favorable environment for abiotic organic synthesis. Yet, experimental studies of this process have thus far failed to yield any significant organic compounds other than methane. On the other hand, experiments performed with native iron present generate abundant hydrocarbons, but it remains uncertain whether the reaction conditions are suitable analogs to geologic environments. The reasons for this gap between the experimental results and environmental observations remain uncertain. One issue remaining unresolved is whether or not significant amounts of organic compounds can be synthesized under purely aqueous conditions. This issue is particularly relevant to submarine hydrothermal systems, since pressures there restrict occurrences of a separate vapor phase. To date, experimental attempts to synthesize organic compounds under purely aqueous conditions have not produced significant amounts of organic compounds except for methane, suggesting that a vapor phase may be required for synthesis of complex organic compounds in hydrothermal environments. Another unresolved issue is the isotopic fractionation resulting from abiotic synthesis. Recent analyses of natural samples by Sherwood-Lollar et al. (Nature 416:522, 2002) and other researchers have suggested that light hydrocarbon gases produced by abiotic synthesis may have a unique isotopic signature that can be used to distinguish them from hydrocarbons generated by thermal degradation of biogenic organic matter. Although experimental studies might confirm these trends, there have been very few isotopic studies of Fischer-Tropsch products. Initial results, however, have not confirmed the same isotopic trends among FT products, suggesting that alternative catalysts or other processes such as methane polymerization may be involved. Interestingly, the carbon isotopic signature of higher molecular weight hydrocarbons produced by FT synthesis appear to fall within the range of typical biological processes, suggesting it may be difficult to discriminate between biologic and non-biologic sources on the basis of carbon isotopes. Additional experimental study is required to resolve all of these issues in order to clarify the contribution of abiotic synthesis to the organic matter found in hydrothermal environments.
14:55 PM	B23D-06	Marriott Salon 13	Abiotic Methane Synthesis: Caveats and New Results Anurag Sharma Rensselaer Polytechnic Institute, USA anurag_sharma(at)rpi.edu	R Zou A Sharma The role of mineral interaction with geochemical fluids under hydrothermal conditions has invoked models of geochemical synthesis of organic molecules at deep crustal conditions. Since Thomas Gold's (1992) hypothesis of the possibility of an abiotic organic synthesis, there have been several reports of hydrocarbon formation under high pressure and temperature conditions. Several previous experimental studies have recognized that small amounts of methane (and other light HC compounds) can be synthesized via catalysis by transition metals: Fe, Ni (Horita and Berndt, 1999 Science) and Cr (Foustavous and Seyfried, 2004 Science). In light of these pioneering experiments, an investigation of the feasibility of abiotic methane synthesis at higher pressure conditions in deep geological setting and the possible role of catalysis warrants a closer look. We conducted three sets of experiments in hydrothermal diamond anvil cell using FeO nanopowder, CaCO₃ and water at 300° - 600° C and 0.5 – 5 GPa : (a) with stainless steel gasket, (b) gold-lined gasket, and (c) gold-lined gasket with added Fe and Ni nanopowder. The reactions were monitored in-situ using micro-Raman spectroscopy with 532nm and 632nm lasers. The solids phases were characterized in-situ using synchrotron X-ray diffraction at CHESS-Cornell and quenched products with an electron microprobe. Interestingly, a variable amount of hydrocarbon was observed only in runs with stainless steel gasket and with Fe, Ni nanoparticles. Experiments with gold-lined reactors did not show any hydrocarbon formation. Added high resolution microscopy of the products and their textural relationship within the diamond cell with Raman spectroscopy data show that the hydrocarbon (methane and other light fractions) synthesis is a direct result of transition metal catalysis, rather than wustite – calcium carbonate reaction as recently reported by Scott et al (2004, PNAS). The author will further present new results highlighting abiotic methane synthesis using a various metal oxides and sulfides without transition metal catalysis under conditions simulating deep crust that show syngenetic methane formation with carbonates.
15:10 PM	B23D-07 Invited	Marriott Salon 13	Thermodynamics of Organic Compound Alteration in Hydrothermal Systems Prof. Everett Shock Arizona State University, USA eshock(at)asu.edu	EL Shock Organic compounds enter hydrothermal systems through infiltrating surface waters, zones of microbial productivity in the subsurface, extracts of organic matter in surrounding host rocks, and abiotic synthesis. Owing to variations in pH, oxidation state, composition, temperature, and pressure throughout the changing pathways of fluid migration over the duration of the system, organic compounds from all of these sources are introduced to conditions where their relative stabilities and reactivities can be dramatically transformed. If those transformations were predictable, then the extent to which organic alteration reactions have occurred could be used to reveal flowpaths and histories of hydrothermal systems. Speciation and mass transfer calculations permit some insight into the underlying thermodynamic driving forces that result in organic compound alteration. As an example, the speciation of many geochemist's canonical organic matter: CH₂O depends strongly on oxidation state, temperature, and total concentration of dissolved organic matter. Calculations show that at oxidation states buffered by iron-bearing mineral assemblages, organic acids dominate the speciation of CH₂O throughout hydrothermal systems, with acetic acid (itself equivalent to 2 CH₂O by bulk composition) and propanoic acid generally the most abundant compounds. However, at more reduced conditions, which may prevail in organic-rich iron-poor sediments, the drive is to form ketones and especially alcohols at the expense of organic acids. The distribution of organic carbon among the various members of these compound classes is strongly dependent on the total concentration of dissolved organic matter. As an example, at a bulk concentration equivalent to average dissolved organic matter in seawater (45μm), the dominant alcohols at 100°C are small compounds like ethanol and 1-propanol. In contrast, at a higher bulk concentration of 500μm, there is a drive to shift large percentages of dissolved organic carbon into 1-pentanol and 1-hexanol. As the fugacity of H₂ increases so does the complexity of the mixture of organic compounds that would result in the lowest energy state. However, the number of dominant compounds in the mixture decreases with increasing temperature for similar extents of reduction referenced to mineral buffered conditions.
15:25 PM	B23D-08	Marriott Salon 13	Organics in hydrothermal fluids from ultramafics on the Mid-Atlantic Ridge (MAR) - Abiogenic and/or biogenic origin? JL Charlou Dept.Géosciences Marines Ifremer, France charlou(at)ifremer.fr	J Charlou, J Donval, Y Fouquet, P Jean-Baptiste, F Dehairs, N Holm, A Godfroy Between 12°N and the Azores Triple Junction along the MAR, CH₄ anomalies over axial ultramafic sites are common and point to the association of high or low temperature hydrothermal activity and mantle degassing indicative of ongoing serpentinization process. The general occurrence of isotopically-heavy methane shows the possible abiogenic synthesis of hydrocarbons in hydrothermal systems. The abiogenic formation of CH4 and more complex organic compounds is related to the process of serpentinization of mantellic rocks. Three sites (Logachev, 14°45’N; Rainbow, 36°14’N; Lost City Field, 30°N) are known on the MAR. New fresh fluids were recently sampled at Rainbow and Lost City by the French ROV-Victor during EXOMAR cruise (July 24 to August 28, 2005). The Rainbow and Lost City fluids issued from contrasted ultramafic environments are both enriched in H₂, CH₄ and hydrocarbons. Hydrogen gas represents more than 40 per cent total gas volume extracted from fluids. SPME (Solid Phase Micro-Extraction) and SBSE (Stir-Bar Sorptive Extraction) extraction techniques were used on board for organic recovery and the analysis was performed on shore by direct GC/MS or by Thermo-Desorption/GC/MS. The hydration of olivine and pyroxen minerals with conversion of Fe(II) to Fe(III) in magnetite during serpentinization leads to production of H₂ and conversion of dissolved CO₂ to reduced-C species including methane, ethane, propane. In addition heavier straight chain hydrocarbons as alcohols, aldehydes, ketones, aromatics, and cyclic compounds are identified at Rainbow. These compounds may be generated in ultramafic rocks through catalytic reactions (Fischer-Tropsch type reactions), but a biogenic contribution cannot be excluded. Abiogenic organic compounds may be produced from crystalline basement, from volcanic structures, from riftogenic zones and probably from sedimented margins.
Session B16 II - Poster Presentation Session B31B - Wednesday, 07 October 2005, 8:00-12:20
Time	Session Code	Location	Title / Presenting Author	Abstract / Coauthors
8:00 AM	B31B-0986	MCC Level 2	Multidimensional Field Mapping of Gaseous C-H-O-S Species in Hydrothermal Systems: Distinguishing Potential Sites for Hydrocarbon Generation Florian Schwandner Arizona State University, USA fschwand(at)asu.edu http://geopig.asu.edu	Schwandner FM, Dunn EE, Shock EL AB: Organic compounds in hydrothermal gas emissions have been documented since the mid-1800's, yet their origin is still a matter of some debate. Thermal alteration such as maturation and cracking can produce thermogenic hydrocarbons from pre-existing organic matter in hydrothermal systems. Gas-phase radical reactions and catalytic hydrogenation reactions of CO₂ and CO to methane and higher hydrocarbons have also been suggested as being responsible for observations of organic compounds in hydrothermal emissions. Recently published data indicated that some organic signatures in volcanic-hydrothermal systems cannot be explained by pre-existing organic matter alone, and more representative analyses are now required to shed light on this question. Choosing a representative site within a hydrothermal field for sampling is in itself a complicated task, and heterogeneities can be easily missed. Spatial analysis of the distribution of C-O-H-S species in the gas phase can potentially indicate possible sites of increased hydrocarbon generation potentials via the catalytic hydrogenation pathway. This approach offers the advantage of providing information in the field that can be used to judge appropriate sampling locations prior to the more complex and costly standard organic analyses of gaseous emissions. A portable multi-sensor system with electrochemical and infrared sensors can in a short time provide large spatial data sets that yield potential target areas for selectively sampling organic compounds. Statistical methods, including probability tests and spatial correlation of concentrations and fluxes of selected species, can be applied later to yield information on the number of populations as well as genetic relationships between different populations. This approach was tested at three acid-sulfate sites in Yellowstone National Park, USA. The chosen sites were the Greater Obsidian Pool area (GOPA, Mud Volcanoes hot spring group), the Sylvan Springs area, and the Washburn Springs area. The test sites represent different structural regimes of the Yellowstone Caldera complex: (a) inner caldera radial faults related to the Sour Creek resurgent dome at GOPA, (b) an extra-caldera regional fault systems in a region where local seismicity appears to be focused to in recent decades (Sylvan), and (c) the caldera rim ring fracture system (Washburn). Flux data on CO₂, H₂, CO, and H₂S were acquired, as well as temperature/depth profiles which yielded soil temperatures, geothermal gradient and heat flux data. The results indicate that at least two populations are present in all four species at all sites, and that the dominant populations of H₂ and CO₂ appear to be structurally controlled. In contrast, CO and H₂S appear to form high-flux clusters around hot pools. The former are explained by a strong influence of deeper processes such as magmatic degassing, while the latter may be explained by more shallow chemical or biological processes. A magmatic signature (high CO₂/H₂S ratios) is not evident along lineaments but appears localized. High reduced gas fluxes are observed at ground wetted by adjacent thermal pools, and similarly, the ground's thermal budget appears to be strongly controlled by localized conductive heating by thermal waters rather than advective heat transport. These findings provide the context for the organic compounds found in these and other hydrothermal and volcanic gas emissions.
8:00 AM	B31B-0987	MCC Level 2	Origin of methane expelled from the "Macalube di Aragona" mud volcanoes area (Central Sicily, Italy): thermogenic or bacterial? Salvatore Inguaggiato Istituto Nazonale di geofisica e Vulcanologia, Italy s.inguaggiato(a)pa.ingv.it	Grassa F, Inguaggiato S, Favara R The "Macalube di Aragona" area is located in Central Sicily (Italy) within a thick accretionary wedge (up to 6 km), developing along the frontal part (Southern margin) of the Sicilian thrust belt. Mud volcanoes are among the most important natural emissions of waters, oil and gaseous hydrocarbons from buried sediments. We have periodically collected gases from one mud volcano and one pool with the aim to investigate the origin of the hydrocarbons from the "Macalube di Aragona". Gas released from mud volcano and mud pool from the "Macalube di Aragona" show very similar chemical and isotopic composition. They consist of mostly CH₄ (90 to 92.5 Vol.%) with δDCH₄ and δ¹³CCH₄ around -190 and -48 respectively. N₂, O₂ and CO₂ are only minor components with N₂/O₂ ratios very close to same ratio of Air. The carbon isotope composition of methane straddles the fields relative to thermogenic and microbial gas, thus giving ambiguous indication on the origin of gases. However, coupling the molecular and the isotopic composition of hydrocarbons, the hypothesis of a mixing process seems to be not realistic. Then, the occurrence of secondary post-genetic processes which masks the original molecular composition and/or the isotope signature should be invoked. Three post-genetic processes have been considered and evaluated. The first process suggests that gas are thermogenic in origin and they are selectively enriched in CH₄ with respect to heavier molecular gas during migration. The remaining processes include that gas are preferentially originated by bacterial reduction and the change in the composition are due (1) to the depletion of substrate, which cause a progressive enrichment in ¹³C in the residual reservoir and consequently in the produced gases or (2) to the preferential loss of CH₄ as a consequence of oxidation processes. In fact, being methane oxidized much more easily than heavier hydrocarbons such a process causes an enrichment of heavier isotope in the residual methane. According to the first hypotheses, the Bernard parameter (C₁/(C₂+C₃) ratio) can be modified during gas migration from reservoir towards surface. Because of CH4 rises more quickly that heavier hydrocarbons, an increasing of the C₁/(C₂+C₃) ratio is then expected. Hydrocarbon can be also selectively adsorbed on clays and/or organic matter causing a shift of the Bernard parameter. In the case of a microbial origin of gas, the methanogenic pathways can be identified considering the carbon isotope signature of CH₄ and the coexisting CO₂ and/or the hydrogen isotope ratios of methane and of formation water. Both these isotope pairs indicate that hydrocarbon have been generated by carbonate reduction. Late stage of hydrocarbon generation are compatible with intermediate values for methane between and the unusual positive isotope values for the isotopic composition of Carbon dioxide.
8:00 AM	B31B-0988	MCC Level 2	Volcanic Source for Abiotic Organics and Inorganics on Early Earth and Mars Delphine Nna Mvondo Centro de Astrobiolog¡a (CSIC/INTA), Spain nnamvondod(at)inta.es	NNA MVONDO D, MARTINEZ-FRIAS J Volcanic activity has been theoretically proposed as a potential source of organic compounds on Early Earth. Volcanoes could also potentially constituted an important source of fixed nitrogen in the early Earth, producing as much as ~1011 mol yr-1 during major episodes of volcanism (Mather et al., 2004). Volcanic source can produce water-soluble polyphosphates through partial hydrolysis of P₄O₁₀, which seems to be the only viable mechanism identified so far for the production of these species on the primitive Earth (Yamagata et al., 1991). Moreover, the predominance of high-temperature mafic (e.g. picrites) and ultra-mafic (like komatiites) lava on early Earth would have favor effusive eruptions with high H₂ and CO contents in volcanic gases owing to CO-CO₂ and H₂O-H₂ equilibria in magmatic gases. In addition, the amount of CO and H₂ (and NH3) increases if magmas were more reduced (f_O₂ down to C0 -, Fe0 -bearing buffers) than on the present Earth. These buffers provide significant thermodynamic drive to form hydrocarbons below ~400°C. The best conditions for organic synthesis on early Earth is achieved in submarine Hawaiian-type eruptions of high temperature and/or reduced magmas. The hydrocarbons might be formed by Fisher-Tropsh type synthesis catalyzed by magnetite and/or Fe0 present in solid volcanic products (Anderson, 1984). Fisher-Tropsch-type reactions may have produced hydrophobic compounds. Such hydrophobic material would have formed a hydrophobic layer on the surface of the sea, which would have provided an environment thermodynamically more suitable than water for the concentration and polymerization of organic molecules fundamental to life, particularly amino acids and pyridine bases. In the purpose of studying the significance of volcanic activity for producing compounds important for life and its evolution, we have decided to develop laboratory simulations of the volcanic source performing high-temperature experiments under early Earth and Mars conditions, with the presence of komatiite. We are introducing and explaining such experimental study.
8:00 AM	B31B-0989	MCC Level 2	Formation of Intermediate Carbon Phases in Hydrothermal Abiotic Organic Synthesis Qi Fu University of Minnesota, USA fuxx0033(at)umn.edu	Fu Q, Foustoukos DI, Seyfried WE With high dissolved concentrations of methane and other hydrocarbon species revealed at the Rainbow and Logatchev vent systems on the Mid-Atlantic Ridge, it is essential to better understand reaction pathways of abiotic organic synthesis in hydrothermal systems. Thus, we performed a hydrothermal carbon reduction experiment with ¹³C labeled carbon source at temperature and pressure conditions that approximate those inferred for ultramafic-hosted hydrothermal systems. Pentlandite, a common alteration mineral phase in subseafloor reaction zones, acted as a potential catalyst. Surface analysis techniques (XPS and ToF-SIMS) were used to characterize intermediate carbon species within this process. Time series dissolved H₂ and H₂S concentrations indicated thermodynamic equilibrium. Dissolved H₂ and H₂S concentrations of 13 and 2 mmol/kg, respectively, are approximately equivalent to measured values in Rainbow and Logatchev hydrothermal systems. Isotopically pure ¹³C methane and other alkane species (C₂H₆ and C₃H₈) were observed throughout the experiment, and attained steady state conditions. XPS analysis on mineral product surface indicated carbon enrichment on mineral surface following reaction. The majority of surface carbon involves species containing C-C or C-H bonds, such as alkyl or methylene groups. Alcohol and carboxyl groups in fewer amounts were also observed. ToF-SIMS analysis, which can offer isotope identification with high mass resolution, showed that most of these carbon species were ¹³C-labeled. Unlike gas phase Fischer-Tropsch synthesis, no carbide was observed on mineral product surface during the experiment. Therefore, a reaction pathway is proposed for formation of dissolved linear alkane species in hydrothermal abiotic organic synthesis, where oxygen-bearing organic compounds are expected to form in aqueous products by way of alcohol and carboxyl groups on mineral catalyst surface.
8:00 AM	B31B-0990	MCC Level 2	Alkaline fluid circulation in ultramafic rocks and formation of nucleotide constituents Nils G Holm Stockholm University, Sweden nils.holm(at)geo.su.se	Holm NG, Dumont M, Ivarsson M, Konn C Seawater is constantly circulating through oceanic basement, often at temperatures up to 150°C. In cases when ultramafic rocks are exposed to the fluids, for instance during the initial phase of subduction, ferromagnesium minerals are weathered, leading to high pH and formation of secondary magnesium hydroxide - brucite - that scavenges borate and phosphate from seawater. The high pH may promote abiotic formation of pentoses, particularly ribose. Borate is known to stabilize ribose, since cyclic ribose forms a stable, less reactive complex with borate. NMR analysis have shown that borate occupies the 2' and 3' positions of ribose, thus leaving the 5' position available for reactions like phosphorylation. The purine coding elements (adenine, in particular) of RNA as well as amino acids may be formed in the same general hydrothermal environments of the seafloor.
8:00 AM	B31B-0991	MCC Level 2	Possible Reaction Pathways for the Formation of Organic Compounds in Volcanic Hydrothermal Systems Marion Dumont Stockholm University, Sweden marion.dumont(at)geo.su.se	Dumont M, Holm NG Conditions in volcanic hydrothermal systems (high temperature, high pressure and availability of metals for catalysis and redox control) make them perfect reactors for a broad range of organic synthesis reactions. In this study, the organic signatures of high temperature (240°C to 290°C) hydrothermal fluids from two very different environments are presented. The first group of samples is from the Rainbow vent field (36°14AŸA›A›ƒ_sAªA›ƒ_zA›N) on the Mid-Atlantic-Ridge, with low pH and organic-rich fluids resulting from the circulation of seawater through ultramafic rocks. The second group of samples is from Iceland, a basaltic ridge-hotspot system, where the original fluid percolating through the rocks ranges from seawater in the Reykjanes Peninsula to meteoric water in the Nesjavellir area. Tentative reaction pathways, based on organic synthesis literature are suggested to account for the presence of some of the organic compounds commonly found in those fluids.
8:00 AM	B31B-0992	MCC Level 2	The Influence of Surfaces on the Reaction Kinetics of Biomolecules Under Hydrothermal Conditions Jenny S Cox Arizona State University, USA jenny.cox(at)asu.edu	Cox JS, Seward TM Surface catalysis and other interferences by reactor vessel walls are an accepted fact in many systems related to chemical engineering or food processing, yet there has been little exploration of this aspect in the geochemical literature with regard to experimental studies of hydrothermal organic reactions. There is an increasing body of evidence that many previous observations may have been influenced to varying degrees by the inside surfaces of the reactor vessels in which they were performed. This influence can take many different forms, such as changes in the observed rates or mechanisms of the reaction, the facilitation of one reaction pathway over another, the presence of unanticipated metal complexing of the reactants or products, and the introduction of new compounds and side reactions. The hydrothermal reaction kinetics of amino acids, oligopeptides, carboxylic acids, and smaller molecular weight molecules in general, appear to all be susceptible to the effects of the surfaces in contact with the solution. This may also provide an approach towards reconciling conflicting published data. A general discussion of these issues will be presented, together with several specific examples from our own experimental studies on the hydrothermal reaction kinetics of aspartic acid and alanine. Experimental data were acquired up to 185°C under hydrothermal conditions using a custom-built gold-lined spectrophotometric reaction cell which permits in situ observation, as well as under lower temperature conditions using different apparatus. Results at similar temperatures, but with different surfaces contacting the solution, will be presented for comparison. Our results indicate that the reaction kinetics of amino acid solutions are significantly different depending on the presence or absence of catalytic surfaces in the reactor such as standard metal alloys. These results will also be discussed in the broader context of understanding complex, natural hydrothermal systems.
8:00 AM	B31B-0995	MCC Level 2	Hydrogen-Isotopic Ratios of Lipids From Hydrogen-Consuming Bacteria Brian Campbell University of California, USA bjcampbell(at)umail.ucsb.edu	Campbell BJ, Fox DN, Sessions AL, Valentine DL Molecular hydrogen (H₂) plays several key roles in aquatic sediments. Metabolized by a wide variety of prokaryotes, it both serves a vehicle for interspecies electron transfer and exerts thermodynamic control over microbial metabolic processes. H₂ is typically depleted in deuterium (D) by up to 600‰ relative to water, providing a potential isotopic marker for H₂-consuming organisms. Preservation of that isotopic signal in sediments requires that molecular H₂ can be an indirect source of carbon-bound hydrogen in microbial lipids, a question that is the target of our ongoing laboratory-based investigations. Here we report compound-specific H-isotopic analyses of lipids extracted from H₂-consuming bacteria grown under defined isotopic conditions (δD-H₂ and δD-H₂O). Cupriavidus necator, an aerobe, is a facultatively lithoautotrophic "knallgas" bacterium. C. necator was grown on H₂ + O₂ + CO₂ in liquid media with differing δD-H₂O values. The results of compound-specific isotopic analysis show a strong correlation between the H-isotopic ratio of lipids and that of H₂O in the growth medium. Cultures grown in media of δD-H₂O = -24‰ produced lipids in which δD values were from -258‰ to -197‰. In media of δD-H₂O = +527‰, δD-lipid values were from +117‰ to +228‰. In media of δD-H₂O = +1115‰, δD-lipid values were from +514‰ to +675‰. Linear regression was performed on the data from each lipid compound (R² > 0.9994 in all cases). Regression lines intercepted the δD-lipid axis between -966‰ ([D]/[H] = 5.23×10^-6) and -827‰ ([D]/[H] = 1.60×10^-5); slopes were between and 0.670 and 0.764. These results indicate that the isotopic composition of lipids is entirely controlled by that of water, i.e. that the isotopic depletion of H2 is not recorded in the lipids - in sharp contrast to previous results from another hydrogenotroph, Sporomusa sp., where part of lipid H is derived indirectly from H2. The results are consistent with two possibilities: 1) no hydrogen from H2 is incorporated, even indirectly, into lipid molecules in C. necator, or 2) isotopic equilibration of H2 with an internal H pool occurs prior to any incorporation in lipids. Without varying δD-H₂ in the experiment, it is not possible to distinguish between these explanations. Finally, three strains were grown in this experiment: the wild type and two different hydrogenase mutants. Systematic variation in the slopes of regression lines suggested that H from water was fractionated more strongly by the cytoplasmic hydrogenase of C. necator than by the membrane-bound hydrogenase. Desulfobacterium autotrophicum, an anaerobe, is a facultatively lithoautotrophic sulfate-reducing bacterium. D. autotrophicum was cultivated on H₂ + CO₂ in liquid media with differing δD-H₂O values. In order to characterize fully the H isotopic systematics, D. autotrophicum was also grown on formate + CO₂ under otherwise identical conditions. Isotopic analyses of this organism are ongoing and will be presented.
8:00 AM	B31B-0996	MCC Level 2	Polymerization Experiment Of Amino Acids Under High Pressure And Temperature Conditions Simulating The Deep Lithosphere Shohei Ohara Tohoku University, Japan ohara(at)ganko.tohoku.ac.jp	Ohara S, Kakegawa T, Nakazawa H Chemical evolution in deep sea or deep lithosphere is one of the popular hypotheses for the origin of life on the early Earth. In such hypothesis, effects of pressure and temperature on polymerization (and/or stability) of amino acids needed to be evaluated. In this study, high temperature and pressure experiments were performed using of a test-tube-type autoclave for polymerization of amino acids. Approximately 100 mg of Glycine powder were placed into sterilized gold capsule. Multiple experiments were done at 150 degrees for 1 to 8 days at variable pressures (25MPa, 50MPa, 75MPa and 100MPa). Glycine peptides were identified and quantified by high performance liquid chromatography (HPLC). Each capsule was opened carefully and 1 ml of mobile phase was added to release the amino acids and oligopeptide from the solid phase. Liquid phases were separated by the cetrifugal method. Peptides were identified by retention times of authentic reference substances. The reaction yields were determined as percentage of the reactant converted to the reaction product. Pligopeptides more than hexamer were additionally identified by the detection of the molecular ion by liquid chromatography mass spectrometry (LC / MS). A HPLC chromatogram of the products indicated at least seven oligomers: diketopiperazine (cyc(Gly)2), di-glycine (Gly2), tri-glycine (Gly3), tetra-glycine (Gly4), penta-glycine (Gly5) and hexa-glycine (Gly6). We also identified hepta-glycine (Gly7), octa-glycine (Gly8) and nona-glycine (Gly9) with LC/MS. This is the first report that up to nona-glycine was synthesized under high temperature and pressure conditions. In addition, our experiments indicate that polymerization occurs wide range of pressure from 25 to 100 MPa. On the other hand, yields of total amounts of peptide did not change with pressure, suggesting that an unknown process in the autoclave is limiting the yield. We speculate the activity of water vapor, generated by peptide formation reaction, controlled the yield in the autoclave. The results from this study support the theory that chemical evolution could happen in deep Earth environments, such as inside of lithosphere.
8:00 AM	B31B-0997	MCC Level 2	Middle Archean island arc volcano-hydrothermal sequence: 3.2-Ga Dixon Island Formation, coastal Pilbara terrane, Australia Shoichi Kiyokawa Kyushu University, Japan kiyokawa(at)geo.kyushu-u.ac.jp	Kiyokawa S, Katagami A, Ito T, Ikehara M, Kitajima F The 3.2-Ga Dixon Island Formation in the Cleaverville Group of the coastal Pilbara terrane, Australia, is one of the most complete and best-preserved examples of middle Archean oceanic stratigraphy. Field observations and geochemical evidence suggest that this formation contains a low-temperature hydrothermal-vent system with a biogenic microbial colony from the Archean ocean. The Dixon Island Formation is approximately 350 m thick and consists of the Rhyolite Tuff, Black Chert and Varicolored Chert members, in ascending order. The Rhyolite Tuff Member contains many vein swarms, such as fine quartz vein and two black-chert veins with in highly altered rhyolite tuff layers. This vein rich and highly altered vein zones are identified as an underground bypass zone for circulating hydrothermal fluid. The Black Chert Member, which is 10 - 15 m thick, is composed of massive black chert, laminated black chert, dark greenish siliceous shale, stromatolite-like biomat bed and tuffaceous laminated chert. The absence of detrital sediment of continental origin and the many vein injections imply that this sedimentary facies represents a pelagic hydrothermal environment at about 500 - 2000 m in paleodepth, and may have been on the slope of an immature island arc. More then 500 samples of detail chemical anarysis from black chert veins and black chert bed suggest that the total organic carbon (TOC) value of massive black chert in the lower part of the Black Chert Member is higher (TOC=0.15-0.45%) than that of the overlying laminated chert section (TOC=0.02-0.15%) and the black chert vein (TOC=0.1-0.13). The carbon isotope (delta13C) values of this lithology (-33 - -27 per mil) are also lighter than for the black-chert veins (-29--26 per mill) and the laminated black chert in the upper part of the Black Chert Member and the Vari-colored Chert Member (-27 - -13‰). Especially, -40 per mill carbon isotope identified near the biomat beds. These evidences suggest that the carbonaceous grains bearing massive black chert in the lower part of the Black Chert Member is identified as directory from the black chert vein. On the other hand, biogenic materials, biomat bed and very low carbon isotope suggest the biogenic activity formed above a low-temperature hydrothermal vent. The microbial colony may have been rapidly fossilized by silicification related to hydrothermal activity. Laminated black chert in the upper part of the Black Chert and the Varicolored Chert members may have formed by cyanobacterial sedimentation from the ocean surface.
8:00 AM	B31B-0998	MCC Level 2	Fluorescent signatures of 2 Ma old travertine deposits in Death Valley, CA Tomoko Adachi NASA-GSFC, Solar System Exploration - Astrochemistry, USA tomoko.adachi(at)gsfc.nasa.gov	Adachi, T Kletetschka, G Epifluorescence petrography clearly images information that cannot be seen in a standard petrographic microscope with regular transmitted polarized light. Epifluorescence examination reveals hidden structures located in less transparent areas of the thin section from Pliocene-Pleistocene spring travertine deposits in Funeral Formation in Death Valley, CA. Thin section material absorbs and reradiates light (autofluorescence). This can be caused by an extremely small number of fluorescent molecules (50 molecules per cubic micron). Fluorescent material in our thin section can be both of organic and inorganic nature. We cannot rule out micropore space filled with organic matters (aminoacids with ring structures autofluoresce). Fabric-specific isotope and textural analysis on the spring travertine deposits indicate that these deposits closely resemble modern hot-spring travertine in Yellowstone National Park. Modern deposits are known to contain abundant microbial life forms. These microbial communities live in the hot-spring and entrapped by rapidly precipitating calcite or aragonite. Epifluorescence examination of thin sections of the spring travertine calcite revealed presence of autofluorescence material in less transparent areas of thin section where the hidden distinctive structure was not otherwise seen by regular transmitting polarized light. These structures may be organic signatures trapped in between the inorganic precipitates and may be the hall mark for future approach of biosignature detection in ancient hydrothermal deposits on terrestrial and extraterrestrial environment.

updated post-conference.