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Accretionary rims on inclusions in the Allende meteoriteThe origin and composition of the rim sequence on the refractory inclusion in the Allende meteorite are studied. The different textures, mineralogy, and mineral-chemistry of the four layers of the rim are described. The layers are composed of: pyroxene, needles, olivine, hedenbergite, and andradite. Tables of the element and chemical compositions of the layers are presented. The data reveals that: (1) the layers are highly porous masses of euhedral crystals with no intergrowth; (2) layers contain highly disequilibrium mineral assemblages; and (3) the thickness of the layers varies with the underlying topography. These results support the theory that rim structures are accretionary aggregates formed from accretion of independently grown particles onto the surface of inclusions. The formation of the grains in the layers and matrix from nebular condensates is studied.
Document ID
19860034389
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Macpherson, G. J.
(Chicago Univ. Chicago, IL, United States)
Hashimoto, A.
(Chicago Univ. Chicago, IL, United States)
Grossman, L.
(Chicago, University IL, United States)
Date Acquired
August 12, 2013
Publication Date
November 1, 1985
Publication Information
Publication: Geochimica et Cosmochimica Acta
Volume: 49
ISSN: 0016-7037
Subject Category
Lunar And Planetary Exploration
Accession Number
86A19127
Funding Number(s)
CONTRACT_GRANT: NAG9-54
CONTRACT_GRANT: NSF EAR-82-18154
CONTRACT_GRANT: NGR-14-001-249
Distribution Limits
Public
Copyright
Other

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