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Ibitira: A basaltic achondrite from a distinct parent asteroidI have done detailed petrologic study of Ibitira, nominally classified as a basaltic eucrite. The Fe/Mn ratio of Ibitira pyroxenes with <10 mole % wollastonite component is 36.4 0.4, and is well-resolved from those of five basaltic eucrites studied for comparison; 31.2-32.2. Data for the latter completely overlap. Ibitira pyroxenes have lower Fe/Mg than the basaltic eucrite pyroxenes. Thus, the higher Fe/Mn ratio does not reflect a simple difference in oxidation state. Ibitira also has an oxygen isotopic composition, alkali element contents and a Ti/Hf ratio that distinguish it from basaltic eucrites. These differences support derivation from a distinct parent asteroid. Ibitira is the first recognized representative of the fifth known asteroidal basaltic crust.
Document ID
20060009026
Acquisition Source
Johnson Space Center
Document Type
Preprint (Draft being sent to journal)
Authors
Mittlefehldt, David W.
(NASA Johnson Space Center Houston, TX, United States)
Date Acquired
September 7, 2013
Publication Date
January 1, 2004
Subject Category
Geophysics
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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