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C/O atomic ratios in micrometer-size crushed grains from Antarctic micrometeorites and two carbonaceous meteoritesAntarctic micrometeorites (AMM's) have similarities (but also differences) with primitive meteorites, such as unequilibrated mineral assemblages. To further assess such similarities, we have measured the carbon content of micrometeorites and meteorites (Orgueil and Murchison), as determined in a random selection of micrometer-size crushed grain, with an analytical transmission electron microscope. Such analyses yield the C/O atomic ratio, the major and minor elements contents, and the textural features of the grains on a scale of approx. equal to 100 nanometers. An important proportion of micrometeorites from both the 100-400 micron and the 50-100 micron size fractions contains much more carbon than CI chondrite Orgueil. The average C-content of all micrometeorites in these two size fractions amount to approximately 1.8 x CI, and approximately 0.8 x CI, respectively (CI refers to the bulk C-content of Orgueil, of about 3.5 percent by weight). Carbon is usually not homogeneously distributed in the micrometeorite but is concentrated in C-rich grains. So far, most of these grains are amorphous, and seem to be associated with an oxidized Fe-rich phase (possibly a variety of 'dirty' magnetite). About 5 percent of them have the composition of 'COPS', a phase additionally enriched in O, P, and S.
Document ID
19940016205
Document Type
Conference Paper
Authors
Perreau, M. (Office National d'Etudes et de Recherches Aeronautiques Paris, France)
Engrand, C. (Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse Orsay, France)
Maurette, Michel (Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse Orsay, France)
Kurat, G. (Naturhistorisches Museum Vienna, Austria)
Presper, TH. (Naturhistorisches Museum Vienna, Austria)
Date Acquired
September 6, 2013
Publication Date
January 1, 1993
Publication Information
Publication: Lunar and Planetary Inst., Twenty-Fourth Lunar and Planetary Science Conference. Part 3: N-Z
Subject Category
ASTROPHYSICS
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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