Comparisons between Antarctic and non-Antarctic meteorites based on carbon isotope geochemistry

Journal Article · Tue Jan 01 04:00:00 EST 1991 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(91)90398-O· OSTI ID:5949921

Grady, M M; Wright, I P; Pillinger, C T ^[1]

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1. The Open Univ., Milton Keynes (England)

The whole-rock C isotopic composition of a suite of ordinary chondrites indicates that there is a difference between Antarctic and non-Antarctic meteorites. However, this apparent distinction is not due to an inherent difference in the meteorite source populations, but is rather a result of the presence of Antarctic weathering products, mainly bicarbonates, which affect the overall {delta}{sup 13}C of these meteorites. When these weathering products are removed, either by acid-washing or combustion to 500{degree}C, the perceived division also disappears, leading to the conclusion that ordinary chondrites (both Antarctic and non-Antarctic) have similar {delta}{sup 13}C values. The C chemistry of CI, CM, and CR chondrites is also subject to problematic interpretation. Whilst the indigenous C abundance is too high to be compromised by the addition of terrestrial weathering products, the inhomogeneous distribution of an array of components with widely varying isotopic signatures leads to a random distribution of {delta}{sup 13}C values. Analyses of individual components (insoluble macromolecular material, carbonates, and silicon carbide) reveal that there are no gross differences in C chemistry between Antarctic and non-Antarctic chondrites. The few distinctions that do exist might readily be explained by weathering or isotopic exchange in Antarctic. Whilst not forming a separate population, Antarctic carbonaceous chondrites may extend the range of properties of non-Antarctic chondrites beyond the currently known limits.

• OSTI ID: 5949921
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 55:1; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
ANTARCTIC REGIONS
ANTARCTICA
CARBON 13
CARBON ISOTOPES
CHEMICAL COMPOSITION
CHEMICAL REACTIONS
CHEMISTRY
CHONDRITES
COMPARATIVE EVALUATIONS
EVEN-ODD NUCLEI
GEOCHEMISTRY
GEOLOGIC HISTORY
ISOTOPE RATIO
ISOTOPES
ISOTOPIC EXCHANGE
LIGHT NUCLEI
METEORITES
NUCLEI
POLAR REGIONS
STABLE ISOTOPES
STONE METEORITES
WEATHERING