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Mineralogy and petrology of chondrules and inclusions in the Mokoia CV3 chondriteThe inclusions and chondrules of the Mokoia CV3 chondrite are studied systematically and compared with those in the Allende meteorite. Five polished thin sections of Mokoia were examined by optical microscopy, backscattered scanning electron microscopy, and electronprobe microanalysis, and objects greater than about 100 microns in apparent diameter were measured and classified petrographically. Three major types of olivine chondrules are distinguished: igneous chondrules, which evidently crystallized from droplets of silicate melt; recrystallized chondrules, apparently metamorphosed at relatively high temperatures; and accretional aggregates, which are probably fragments of igneous chondrules. Refractory inclusions in Mokoia are generally similar to those found in Allende, although Mokoia inclusions include phyllosilicates rather than feldspathoids and melilite-rich Ca, Al-rich inclusions (CAIs) are more abundant in Allende. The small, fine-grained CAIs, which are more abundant than coarse-grained CAIs in both meteorites, are observed to represent aggregates of three distinct constituents: concentric objects, chaotic material and inclusion matrix. It is concluded that most of the CAIs probably formed during metamorphism, partial melting, and incomplete distillation of primitive dust aggregates heated in the solar nebula.
Document ID
19840030934
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Cohen, R. E.
(Smithsonian Astrophysical Observatory Cambridge, MA, United States)
Kornacki, A. S.
(Smithsonian Astrophysical Observatory Cambridge, MA, United States)
Wood, J. A.
(Smithsonian Astrophysical Observatory; Harvard University Cambridge, MA, United States)
Date Acquired
August 12, 2013
Publication Date
October 1, 1983
Publication Information
Publication: Geochimica et Cosmochimica Acta
Volume: 47
ISSN: 0016-7037
Subject Category
Lunar And Planetary Exploration
Accession Number
84A13721
Funding Number(s)
CONTRACT_GRANT: NGL-09-015-150
Distribution Limits
Public
Copyright
Other

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