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Michael D Lewan - One of the best experts on this subject based on the ideXlab platform.
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understanding and distinguishing reflectance measurements of solid bitumen and vitrinite using Hydrous Pyrolysis implications to petroleum assessment
AAPG Bulletin, 2018Co-Authors: Paul C. Hackley, Michael D LewanAbstract:Solid bitumen is a common organic component of thermally mature shales and typically is identified by embayment against euhedral mineral terminations and by groundmass textures. However, because these textures are not always present, solid bitumen can be easily misidentified as vitrinite. Hydrous Pyrolysis experiments (72 hours, 300-360°C) on shale and coal samples show solid bitumen reflectance (BRo) in shales is less responsive to thermal stress than vitrinite reflectance (VRo) in coal. This effect is most pronounced at lower experimental temperatures (300-320°C) whereas reflectance changes are more similar at higher temperatures (340-360°C). Neither a ‘vitrinite-like’ maceral or ‘suppressed vitrinite’ was identified or measured in our sample set; rather, the experiments show that solid bitumen matures slower than vitrinite. The data may explain some reports of ‘vitrinite reflectance suppression’, particularly at lower thermal maturity (VRo≤1.0%), as a simple case of solid bitumen being mistaken for vitrinite. Further, the experimental results confirm previous empirical observations that VRo and BRo are more similar at higher maturities (VRo>1.0%). It is suggested that ‘vitrinite reflectance suppression’, commonly reported from upper Paleozoic marine shales of early to mid-oil window maturity, is a misnomer. This observation has important implications to petroleum exploration models and resource assessment because it may change interpretations for the timing and spatial locations of kerogen maturation and petroleum generation.
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experimental investigation of changes in methane adsorption of bitumen free woodford shale with thermal maturation induced by Hydrous Pyrolysis
Marine and Petroleum Geology, 2015Co-Authors: Michael D Lewan, Tongwei Zhang, Jaclyn D Wigginscamacho, Geoffrey S Ellis, Xiaolong ZhangAbstract:This study quantifies the effects of organic-matter (OM) thermal maturity on methane (CH4)-sorption, on the basis of five samples that were artificially matured through Hydrous Pyrolysis achieved by heating samples of immature Woodford Shale under five different time temperature conditions. CH4-sorption isotherms at 35 degrees C, 50 degrees C, and 65 degrees C, and pressures up to 14 MPa on dry, solvent-extracted samples of the artificially matured Woodford Shale were measured. The results showed that CH4-sorption capacity, normalized to TOC, varied with thermal maturity, following1 the trend: maximum oil (367 degrees C) > oil cracking (400 degrees C) > maximum bitumen/early oil (333 degrees C) > early bitumen (300 degrees C) > immature stage (130 degrees C). The Langmuir constants for the samples at maximum-oil and oil-cracking stages are larger than the values for the bitumen-forming stages. The total pore volume, determined by N-2 physisorption at 77 K, increases with increased maturation: mesopores, 2-50 nm in width, were created during the thermal conversion of organic-matter and a dramatic increase in porosity appeared when maximum-bitumen and maximum-oil generation stages were reached. A linear relationship between thermal maturity and Brunauer-Emmett-Teller (BET) surface area suggests that the observed increase in CH4-sorption capacity may be the result of mesopores produced during OM conversion. No obvious difference is observed in pore-size distribution and pore volume for samples with pores <2.0 nm with the increase of thermal maturity based on CO2 physisorption at 273 K. The isosteric heat of adsorption and the standard entropy for artificially matured samples ranged from 17.9 kJ mol(-1) to 21.9 kJ mol(-1) and from 85.4 J mol(-1) K-1 to 101.8 J mol(-1) K-1, respectively. These values are similar to the values of immature Woodford kerogen concentrate previously observed, but are larger than naturally matured organic-rich shales. High-temperature Hydrous Pyrolysis might have induced Lewis acid sites on both organic and mineral surfaces, resulting to some extent, in chemical interactions between the adsorption site and the methane C-H bonds. The formation of abundant mesopores (2-50 nm) within organic matter during organic-matter thermal maturation makes a great contribution to the increase in both BET surface area and pore volume, and a significant increase in 2-6 nm pores occurs at maximum-oil-generation and oil-cracking to gas, ultimately controlling the methane-adsorption capacity. Therefore, consideration of pore-size effects and thermal maturity is very important for gas in place (GIP) prediction in organic-rich shales. (C) 2014 Elsevier Ltd. All rights reserved.
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re os geochronology and os isotope fingerprinting of petroleum sourced from a type i lacustrine kerogen insights from the natural green river petroleum system in the uinta basin and Hydrous Pyrolysis experiments
Geochimica et Cosmochimica Acta, 2014Co-Authors: David Selby, Vivien M Cumming, Paul G Lillis, Michael D LewanAbstract:Abstract Rhenium–osmium (Re–Os) geochronology of marine petroleum systems has allowed the determination of the depositional age of source rocks as well as the timing of petroleum generation. In addition, Os isotopes have been applied as a fingerprinting tool to correlate oil to its source unit. To date, only classic marine petroleum systems have been studied. Here we present Re–Os geochronology and Os isotope fingerprinting of different petroleum phases (oils, tar sands and gilsonite) derived from the lacustrine Green River petroleum system in the Uinta Basin, USA. In addition we use an experimental approach, Hydrous Pyrolysis experiments, to compare to the Re–Os data of naturally generated petroleum in order to further understand the mechanisms of Re and Os transfer to petroleum. The Re–Os geochronology of petroleum from the lacustrine Green River petroleum system (19 ± 14 Ma – all petroleum phases) broadly agrees with previous petroleum generation basin models (∼25 Ma) suggesting that Re–Os geochronology of variable petroleum phases derived from lacustrine Type I kerogen has similar systematics to Type II kerogen (e.g., Selby and Creaser, 2005a , Selby and Creaser, 2005b , Finlay et al., 2010 ). However, the large uncertainties (over 100% in some cases) produced for the petroleum Re–Os geochronology are a result of multiple generation events occurring through a ∼3000-m thick source unit that creates a mixture of initial Os isotope compositions in the produced petroleum phases. The 187Os/188Os values for the petroleum and source rocks at the time of oil generation vary from 1.4 to 1.9, with the mode at ∼1.6. Oil-to-source correlation using Os isotopes is consistent with previous correlation studies in the Green River petroleum system, and illustrates the potential utility of Os isotopes to characterize the spatial variations within a petroleum system. Hydrous Pyrolysis experiments on the Green River Formation source rocks show that Re and Os transfer are mimicking the natural system. This transfer from source to bitumen to oil does not affect source rock Re–Os systematics or Os isotopic compositions. This confirms that Os isotope compositions are transferred intact from source to petroleum during petroleum generation and can be used as a powerful correlation tool. These experiments further confirm that Re–Os systematics in source rocks are not adversely affected by petroleum maturation. Overall this study illustrates that the Re–Os petroleum geochronometer and Os isotope fingerprinting tools can be used on a wide range of petroleum types sourced from variable kerogen types.
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Generation of unusual branched long chain alkanes from Hydrous Pyrolysis of anammox bacterial biomass
Organic Geochemistry, 2014Co-Authors: Michael D Lewan, Jaap S. Sinninghe Damsté, Darci Rush, Andrea Jaeschke, Jan A. J. Geenevasen, Erik Tegelaar, Jos Pureveen, Stefan SchoutenAbstract:Abstract Anammox, the microbial anaerobic oxidation of NH 4 + by NO 2 − to produce N 2 , is recognised as a key process in the marine, freshwater and soil N cycles, and has been found to be a major sink for fixed inorganic N in the ocean. Ladderane lipids are unique anammox bacterial membrane lipids used as biomarkers for such bacteria in recent and past environmental settings. However, their fate during diagenesis and early catagenesis is not well constrained. In this study, Hydrous Pyrolysis experiments were performed on anammox bacterial biomass and the generated aliphatic hydrocarbons, present in oil generated at 220–365 °C, were analysed. A unique class of hydrocarbons was detected, and a representative component was isolated and rigorously identified using 2D nuclear magnetic resonance (NMR) spectroscopy. It consisted of C 24 to C 31 branched long chain alkanes with two internal ethyl and/or propyl substituents. The alkanes were generated above 260 °C, with maximum generation at 320 and 335 °C. Their stable carbon isotopic values were depleted in 13 C, similar to carbon isotope values of the original anammox lipids, indicating that they were thermal products generated from lipids of anammox bacterial biomass. A range of sediments from different geological periods where anammox may have been an important process was screened for the presence of these compounds as possible catagenetic products. They were not detected, either because the concentration was too low, or the sediments screened were too immature for them to have been generated, or because the artificially produced products of anammox lipids may not reflect the natural diagenetic and catagenetic products of ladderane lipids.
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sources of natural gases in middle cambrian reservoirs in polish and lithuanian baltic basin as determined by stable isotopes and Hydrous Pyrolysis of lower palaeozoic source rocks
Chemical Geology, 2013Co-Authors: Maciej J Kotarba, Michael D LewanAbstract:Abstract Origin of natural gases associated with oil and condensate accumulations within the Middle Cambrian sandstone reservoir of the Polish and Lithuanian Baltic Basin was characterised by means of molecular composition, stable carbon isotopes of methane, ethane, propane, butanes, pentanes and carbon dioxide, stable hydrogen isotopes of methane and stable nitrogen isotopes of gaseous nitrogen. Generated gas from potential Upper Cambrian, Tremadocian, and Llandovery source rocks by Hydrous Pyrolysis at 330 °C and 355 °C for 72 h was used to characterise thermogenic gas to evaluate correlation parameters based on molecular composition and stable isotopes. The Pyrolysis conditions represent gas generation during oil generation, which appears to be the conditions represented by the natural gas accumulations and their low GORs (gas:oil ratios). The dryness of the Pyrolysis and natural hydrocarbon compositions compare well, but do not provide a means of distinguishing the contributions of each source rock to the natural gas accumulations. The average δ 13 C value of the natural methane is 6.9‰ depleted in 13 C compared to methane generated in the Hydrous Pyrolysis experiments. This difference is less for ethane and essentially nonexistent for propane, butanes, and pentanes. Tentatively, this diminishing difference with increasing carbon number is attributed to kinetic effects resulting from higher experimental temperatures. Although the δ 13 C values of methane and ethane from the Hydrous Pyrolysis experiments are not useful in direct correlations with natural gas accumulations, δ 13 C of propane, butanes, and pentanes is useful, and indicates that the Upper Cambrian and Tremadocian source rocks are the main contributors and that the Llandovery source rocks are not significant contributors to the Polish and Lithuanian Baltic natural gases. Polish natural gases with relatively higher methane and ethane are attributed to the mixing of drier, more mature gases from deeper parts of the basin to the west. Carbon dioxide of natural gases was generated during thermogenic processes and gaseous nitrogen was generated from NH 4 -rich illites of the clayey facies and from thermal transformation of organic matter of the Lower Palaeozoic strata. Hydrous Pyrolysis gases have higher concentrations of CO 2 , H 2 S and H 2 than the natural gases. This difference is attributed to reduction or loss of these highly reactive and soluble gases during migration and entrapment of the natural gases. Although CO 2 concentrations between Pyrolysis and natural gases are different, the δ 13 C values of the former fall within the range of the latter.
Vivien M Cumming - One of the best experts on this subject based on the ideXlab platform.
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re os geochronology and os isotope fingerprinting of petroleum sourced from a type i lacustrine kerogen insights from the natural green river petroleum system in the uinta basin and Hydrous Pyrolysis experiments
Geochimica et Cosmochimica Acta, 2014Co-Authors: David Selby, Vivien M Cumming, Paul G Lillis, Michael D LewanAbstract:Abstract Rhenium–osmium (Re–Os) geochronology of marine petroleum systems has allowed the determination of the depositional age of source rocks as well as the timing of petroleum generation. In addition, Os isotopes have been applied as a fingerprinting tool to correlate oil to its source unit. To date, only classic marine petroleum systems have been studied. Here we present Re–Os geochronology and Os isotope fingerprinting of different petroleum phases (oils, tar sands and gilsonite) derived from the lacustrine Green River petroleum system in the Uinta Basin, USA. In addition we use an experimental approach, Hydrous Pyrolysis experiments, to compare to the Re–Os data of naturally generated petroleum in order to further understand the mechanisms of Re and Os transfer to petroleum. The Re–Os geochronology of petroleum from the lacustrine Green River petroleum system (19 ± 14 Ma – all petroleum phases) broadly agrees with previous petroleum generation basin models (∼25 Ma) suggesting that Re–Os geochronology of variable petroleum phases derived from lacustrine Type I kerogen has similar systematics to Type II kerogen (e.g., Selby and Creaser, 2005a , Selby and Creaser, 2005b , Finlay et al., 2010 ). However, the large uncertainties (over 100% in some cases) produced for the petroleum Re–Os geochronology are a result of multiple generation events occurring through a ∼3000-m thick source unit that creates a mixture of initial Os isotope compositions in the produced petroleum phases. The 187Os/188Os values for the petroleum and source rocks at the time of oil generation vary from 1.4 to 1.9, with the mode at ∼1.6. Oil-to-source correlation using Os isotopes is consistent with previous correlation studies in the Green River petroleum system, and illustrates the potential utility of Os isotopes to characterize the spatial variations within a petroleum system. Hydrous Pyrolysis experiments on the Green River Formation source rocks show that Re and Os transfer are mimicking the natural system. This transfer from source to bitumen to oil does not affect source rock Re–Os systematics or Os isotopic compositions. This confirms that Os isotope compositions are transferred intact from source to petroleum during petroleum generation and can be used as a powerful correlation tool. These experiments further confirm that Re–Os systematics in source rocks are not adversely affected by petroleum maturation. Overall this study illustrates that the Re–Os petroleum geochronometer and Os isotope fingerprinting tools can be used on a wide range of petroleum types sourced from variable kerogen types.
Arndt Schimmelmann - One of the best experts on this subject based on the ideXlab platform.
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nitrogen isotopic exchange during maturation of organic matter
Organic Geochemistry, 2010Co-Authors: Arndt Schimmelmann, Grzegorz P LisAbstract:Abstract The definition of kerogen as the insoluble fraction of sedimentary organic matter leads to the assumption that all of its chemical constituents are autochthonous. Evidence is presented that some of the organic N in kerogen derives from allochthonous mobile and chemically reactive N species (e.g., ammonium, HCN and low molecular weight organic N containing compounds) that are delivered by migrating fluids to stationary kerogen. Reactions of humic compounds (e.g., protokerogen) with ammonium in soil and sediment are facilitated biologically. At higher temperatures, reactions between kerogen in rocks and N containing compounds in mobile fluids are driven geochemically. N isotopic exchange between kerogen and NH 4 + or NH3 is evident from experiments where 15N enriched ammonium chloride solutions and source rocks containing kerogen types I, II, IIS and III were heated over 5 years at temperatures of 100, 144 and 196 °C. The resulting data corroborate earlier results from Hydrous Pyrolysis experiments (330 °C for up to 144 h) and prove that ammonium is readily converted abiogenically to organic N in kerogen at temperatures that approach those in naturally maturing sediments. The propensity of different types of kerogen to react with NH 4 + or NH3 increases in the order II
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ftir absorption indices for thermal maturity in comparison with vitrinite reflectance r0 in type ii kerogens from devonian black shales
Organic Geochemistry, 2005Co-Authors: Arndt Schimmelmann, Michael D Lewan, Artur B. StankiewiczAbstract:Abstract FTIR absorbance signals in kerogens and macerals were evaluated as indices for thermal maturity. Two sets of naturally matured type-II kerogens from the New Albany Shale (Illinois Basin) and the Exshaw Formation (Western Canada Sedimentary Basin) and kerogens from Hydrous Pyrolysis artificial maturation of the New Albany Shale were characterized by FTIR. Good correlation was observed between the aromatic/aliphatic absorption ratio and vitrinite reflectance R 0 . FTIR parameters are especially valuable for determining the degree of maturity of marine source rocks lacking vitrinite. With increasing maturity, FTIR spectra express four trends: (i) an increase in the absorption of aromatic bands, (ii) a decrease in the absorption of aliphatic bands, (iii) a loss of oxygenated groups (carbonyl and carboxyl), and (iv) an initial decrease in the CH 2 /CH 3 ratio that is not apparent at higher maturity in naturally matured samples, but is observed throughout increasing R 0 in artificially matured samples. The difference in the CH 2 /CH 3 ratio in samples from natural and artificial maturation at higher maturity indicates that short-term artificial maturation at high temperatures is not fully equivalent to slow geologic maturation at lower temperatures. With increasing R 0 , the (carboxyl + carbonyl)/aromatic carbon ratio generally decreases, except that kerogens from the Exshaw Formation and from Hydrous Pyrolysis experiments express an intermittent slight increase at medium maturity. FTIR-derived aromaticities correlate well with R 0 , although some uncertainty is due to the dependence of FTIR parameters on the maceral composition of kerogen whereas R 0 is solely dependent on vitrinite.
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Experimental controls on D/H and 13C/12C ratios of kerogen, bitumen and oil during Hydrous Pyrolysis
Organic Geochemistry, 2003Co-Authors: Arndt Schimmelmann, Michael D Lewan, Jean-paul Boudou, Robert P. WintschAbstract:Large isotopic transfers between water-derived hydrogen and organic hydrogen occurred during Hydrous Pyrolysis experiments of immature source rocks, in spite of only small changes in organic 13C/12C. Experiments at 330'C over 72 h using chips or powder containing kerogen types I and III identify the rock/water ratio as a main factor affecting ASD for water and organic hydrogen. Our data suggest that larger rock permeability and smaller rock grain size increase the H-isotopic transfer between water-derived hydrogen and thermally maturing organic matter. Increasing hydrostatic pressure may have a similar effect, but the evidence remains inconclusive
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d h isotope ratios of kerogen bitumen oil and water in Hydrous Pyrolysis of source rocks containing kerogen types i ii iis and iii
Geochimica et Cosmochimica Acta, 1999Co-Authors: Arndt Schimmelmann, Michael D Lewan, Robert P WintschAbstract:Abstract Immature source rock chips containing different types of kerogen (I, II, IIS, III) were artificially matured in isotopically distinct waters by Hydrous Pyrolysis and by Pyrolysis in supercritical water. Converging isotopic trends of inorganic (water) and organic (kerogen, bitumen, oil) hydrogen with increasing time and temperature document that water-derived hydrogen is added to or exchanged with organic hydrogen, or both, during chemical reactions that take place during thermal maturation. Isotopic mass-balance calculations show that, depending on temperature (310–381°C), time (12–144 h), and source rock type, between ca. 45 and 79% of carbon-bound hydrogen in kerogen is derived from water. Estimates for bitumen and oil range slightly lower, with oil–hydrogen being least affected by water-derived hydrogen. Comparative Hydrous pyrolyses of immature source rocks at 330°C for 72 h show that hydrogen in kerogen, bitumen, and expelled oil/wax ranks from most to least isotopically influenced by water-derived hydrogen in the order IIS > II ≈ III > I. Pyrolysis of source rock containing type II kerogen in supercritical water at 381°C for 12 h yields isotopic results that are similar to those from Hydrous Pyrolysis at 350°C for 72 h, or 330°C for 144 h. Bulk hydrogen in kerogen contains several percent of isotopically labile hydrogen that exchanges fast and reversibly with hydrogen in water vapor at 115°C. The isotopic equilibration of labile hydrogen in kerogen with isotopic standard water vapors significantly reduces the analytical uncertainty of D/H ratios when compared with simple D/H determination of bulk hydrogen in kerogen. If extrapolation of our results from Hydrous Pyrolysis is permitted to natural thermal maturation at lower temperatures, we suggest that organic D/H ratios of fossil fuels in contact with formation waters are typically altered during chemical reactions, but that D/H ratios of generated hydrocarbons are subsequently little or not affected by exchange with water hydrogen at typical reservoir conditions over geologic time. It will be difficult to utilize D/H ratios of thermally mature bulk or fractions of organic matter to quantitatively reconstruct isotopic aspects of paleoclimate and paleoenvironment. Hope resides in compound-specific D/H ratios of thermally stable, extractable biomarkers (“molecular fossils”) that are less susceptible to hydrogen exchange with water-derived hydrogen.
Patrick Landais - One of the best experts on this subject based on the ideXlab platform.
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artificial coalification comparison of confined Pyrolysis and Hydrous Pyrolysis
Fuel, 1994Co-Authors: Raymond Michels, Patrick LandaisAbstract:Abstract Two artificial coalification series were obtained by pyrolysing an immature coal in Hydrous and confined systems. The solid residues as well as extractable liquid hydrocarbons were analysed. Both Pyrolysis systems yield similar results that are generally consistent with data from natural coalification series. However, the amounts of total soluble organic matter are greater in artificial maturation than in natural maturation. This is attributed to the ability of natural coals to retain significant quantities of hydrocarbons. Emphasis is also placed on the amount of expelled hydrocarbons obtained by Hydrous Pyrolysis, which exceeds that observed in confined Pyrolysis and suspected in the natural system. Detailed inspection of the analytical results indicates slight differences between Hydrous and confined Pyrolysis that are tentatively attributed to pressure effects.
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artificial coalification comparison of confined Pyrolysis and Hydrous Pyrolysis
Fuel, 1994Co-Authors: Raymond Michels, Patrick LandaisAbstract:Abstract Two artificial coalification series were obtained by pyrolysing an immature coal in Hydrous and confined systems. The solid residues as well as extractable liquid hydrocarbons were analysed. Both Pyrolysis systems yield similar results that are generally consistent with data from natural coalification series. However, the amounts of total soluble organic matter are greater in artificial maturation than in natural maturation. This is attributed to the ability of natural coals to retain significant quantities of hydrocarbons. Emphasis is also placed on the amount of expelled hydrocarbons obtained by Hydrous Pyrolysis, which exceeds that observed in confined Pyrolysis and suspected in the natural system. Detailed inspection of the analytical results indicates slight differences between Hydrous and confined Pyrolysis that are tentatively attributed to pressure effects.
Hiroshi Naraoka - One of the best experts on this subject based on the ideXlab platform.
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carbon isotopic composition of acetic acid generated by Hydrous Pyrolysis of macromolecular organic matter from the murchison meteorite
Meteoritics & Planetary Science, 2006Co-Authors: Yasuhiro Oba, Hiroshi NaraokaAbstract:Low molecular weight monocarboxylic acids, including acetic acid, are some of the most abundant organic compounds in carbonaceous chondrites. So far, the 13C- and D-enriched signature of water-extractable carboxylic acids has implied an interstellar contribution to their origin. However, it also has been proposed that monocarboxylic acids could be formed by aqueous reaction on the meteorite parent body. In this study, we conducted Hydrous Pyrolysis of macromolecular organic matter purified from the Murchison meteorite (CM2) to examine the generation of monocarboxylic acids with their stable carbon isotope measurement. During Hydrous Pyrolysis of macromolecular organic matter at 270-330 °C, monocarboxylic acids with carbon numbers ranging from 2 (C2) to 5 (C5) were detected, acetic acid (CH3COOH; C2) being the most abundant. The concentration of the generated acetic acid increased with increasing reaction temperature; up to 0.48 mmol acetic acid/g macromolecular organic matter at 330 °C. This result indicates that the Murchison macromolecule has a potential to generate at least ~0.4 mg acetic acid/g meteorite, which is about four times higher than the amount of water-extractable acetic acid reported from Murchison. The carbon isotopic composition of acetic acid generated by Hydrous Pyrolysis of macromolecular organic matter is ~-27‰ (versus PDB), which is much more depleted in 13C than the water-extractable acetic acid reported from Murchison. Intramolecular carbon isotope distribution shows that methyl (CH3-)-C is more enriched in 13C relative to carboxyl (-COOH)-C, indicating a kinetic process for this formation. Although the experimental condition of this study (i.e., 270-330 °C for 72 h) may not simulate a reaction condition on parent bodies of carbonaceous chondrite, it may be possible to generate monocarboxylic acids at lower temperatures for a longer period of time.
