Carbon isotopic compositions of Antarctic carbonaceous chondrites with relevance to the alteration and existence of organic matter.

Naraoka, Hiroshi; Shimoyama, Akira; Matsubaya, Osamu; Harada, Kaoru

doi:10.2343/geochemj.31.155

Cited by 10 publications

(11 citation statements)

References 38 publications

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“…The bulk carbon concentrations range from 0.67 to 2.5 wt% with an average value of ~1.7 wt% (Kerridge 1985;Naraoka et al 1997;Yoneda et al 2001). Powdered samples (0.5-1 g) were extracted with water and organic solvents to analyze solventextractable organic compounds such as amino acids, carboxylic acids, and polycyclic aromatic hydrocarbons (PAHs).…”

Section: Samples and Analytical Proceduresmentioning

confidence: 99%

“…The isolated macromolecule was dried and subjected to CHN elemental analysis (Perkin Elmer 240 or Carlo Erba EA-1180) in duplicate to determine the C-H-N concentrations. The carbon isotopic composition of the isolated macromolecule was determined as in Naraoka et al (1997). The five purified macromolecules were subjected to a differential thermal analysis-thermogravimetry (DTA-TG, Shimadzu DTG-40) from room temperature to 800°C at 10 °C/min in a He gas flow (Komiya et al 1993).…”

Section: Samples and Analytical Proceduresmentioning

confidence: 99%

“…c Naraoka et al (1997); Kerridge (1985); Yoneda et al (2001). d Kerridge et al (1987); Naraoka et al (1997). e Yanai and Kojima (1995).…”

Section: Samples and Analytical Proceduresmentioning

confidence: 99%

“…Murchison, Y-74662, Y-791198, and A-881458 yielded appropriate amounts of solvent-extractable organic compounds, while B-7904, Y-793321, Y-86720, and A-881280 are extremely depleted in spite of comparable concentration of carbon (~1-2.5 wt%). The depletion is unlikely to be due to leaching by Antarctic water (Naraoka et al 1997). …”

Section: H/c-n/c Sequence As An Indicator For Thermal Alteration Of Mmentioning

confidence: 99%

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A chemical sequence of macromolecular organic matter in the CM chondrites

Naraoka

Mita

Komiya

et al. 2004

Meteorit & Planetary Scien

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Abstract-A new organic parameter is proposed to show a chemical sequence of organic matter in carbonaceous chondrites, using carbon, hydrogen, and nitrogen concentrations of solvent-insoluble and high-molecular weight organic matter (macromolecules) and the molecular abundance of solvent-extractable organic compounds. The H/C atomic ratio of the macromolecule purified from nine CM chondrites including the Murchison, Sayama, and seven Antarctic meteorites varies widely from 0.11 to 0.72. During the H/C change of ~0.7 to ~0.3, the N/C atomic ratio remains at ~0.04, followed by a sharp decline from ~0.040 to ~0.017 between H/C ratios from ~0.3 to ~0

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Section: Samples and Analytical Proceduresmentioning

confidence: 99%

Section: Samples and Analytical Proceduresmentioning

confidence: 99%

“…c Naraoka et al (1997); Kerridge (1985); Yoneda et al (2001). d Kerridge et al (1987); Naraoka et al (1997). e Yanai and Kojima (1995).…”

Section: Samples and Analytical Proceduresmentioning

confidence: 99%

Section: H/c-n/c Sequence As An Indicator For Thermal Alteration Of Mmentioning

confidence: 99%

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A chemical sequence of macromolecular organic matter in the CM chondrites

Naraoka

Mita

Komiya

et al. 2004

Meteorit & Planetary Scien

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“…The free carboxylic acids in carbonaceous chondrite show 13 C-and D-enriched signature (Yuen et al 1984;Epstein et al 1987;Krishnamurthy et al 1992;Huang et al 2005). On the other hand, bulk macromolecular organic matter is depleted in 13 C relative to free organic matter (Robert and Epstein 1982;Kerridge et al 1987;Krishnamurthy et al 1992;Naraoka et al 1997).…”

Section: Introductionmentioning

confidence: 99%

Carbon isotopic composition of acetic acid generated by hydrous pyrolysis of macromolecular organic matter from the Murchison meteorite

Oba

Naraoka

2006

Meteoritics &Amp; Planetary Science

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Abstract-Low molecular weight monocarboxylic acids, including acetic acid, are some of the most abundant organic compounds in carbonaceous chondrites. So far, the 13 C-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 (C 2 ) to 5 (C 5 ) were detected, acetic acid (CH 3 COOH; C 2 ) 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 13 C than the water-extractable acetic acid reported from Murchison. Intramolecular carbon isotope distribution shows that methyl (CH 3 -)-C is more enriched in 13 C 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.

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