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Origin and history of chondrite regolith, fragmental and impact-melt breccias from SpainSix ordinary chondrite breccias from the Museo Nacional de Ciencias Naturales, Madrid (Spain), are described and classified as follows: the solar gas-rich regolith breccia Oviedo (H5); the premetamorphic fragmental breccias Cabezo de Mayo (type 6, L-LL), and Sevilla (LL4); the fragmental breccias Canellas (H4) and Gerona (H5); and the impact melt breccia, Madrid (L6). It is confirmed that chondrites with typical light-dark structures and petrographic properties typical of regolith breccias may (Oviedo) or may not (Canellas) be solar gas-rich. Cabezo de Mayo and Sevilla show convincing evidence that they were assembled prior to peak metamorphism and were equilibrated during subsequent reheating. Compositions of olivine and low-Ca pyroxene in host chondrite and breccia clasts in Cabezo de Mayo are transitional between groups L and LL. It is suggested, based on mineralogic and oxygen isotopic compositions of host and clasts, that the rock formed on the L parent body by mixing, prior to peak metamorphism. This was followed by partial equilibrium of two different materials: the indigenous L chondrite host and exotic LL melt rock clasts.
Document ID
19900051944
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Casanova, I.
(New Mexico, University Albuquerque, United States)
Keil, K.
(Hawaii, University Honolulu, United States)
Wieler, R.
(Zuerich, Eidgenoessische Technische Hochschule, Zurich Federal Republic of Germany, United States)
San Miguel, A.
(Barcelona, Universidad Spain)
King, E. A.
(Houston, University TX, United States)
Date Acquired
August 14, 2013
Publication Date
June 1, 1990
Publication Information
Publication: Meteoritics
Volume: 25
ISSN: 0026-1114
Subject Category
Lunar And Planetary Exploration
Accession Number
90A38999
Funding Number(s)
CONTRACT_GRANT: NSF CCB-85-09007
CONTRACT_GRANT: NAG9-30
Distribution Limits
Public
Copyright
Other

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