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The Blue Angel: I. The mineralogy and petrogenesis of a hibonite inclusion from the Murchison meteorite

Armstrong, John T. and Meeker, G. P. and Huneke, J. C. and Wasserburg, G. J. (1982) The Blue Angel: I. The mineralogy and petrogenesis of a hibonite inclusion from the Murchison meteorite. Geochimica et Cosmochimica Acta, 46 (4). pp. 575-595. ISSN 0016-7037. https://resolver.caltech.edu/CaltechAUTHORS:20130924-090528876

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Abstract

A detailed mineralogie, chemical, and petrologic study of the Blue Angel, a relatively large (~1.5 mm) hibonite-containing inclusion from the Murchison meteorite, was performed in an attempt to understand the mechanisms of formation and modification of hibonite-rich inclusions. The Blue Angel inclusion is composed of roughly equal amounts of hibonite and calcite, with minor amounts of spinel, perovskite, diopside, and an Fe-rich silicate. The inclusion can be divided into three roughly concentric zones—a hibonite-rich core, a calcite-rich mantle, and a spinel-rich layered rim. The mineral chemistry and petrography of the Blue Angel are consistent with a three-stage formation history: (1) an early stage of nebular condensation which produced the hibonite, perovskite, and spinel; (2) a moderate temperature stage of aqueous alteration and metamorphism occurring on a small planetary body containing CO_2 and H_2O during which calcite was formed in the inclusion; and (3) the final emplacement of the Blue Angel into its present position in Murchison. The study of the Blue Angel indicates that extensive alteration of Ca-Al-rich inclusions (CAI) may have occurred by aqueous alteration and thermal metamorphism followed by explosive mixing processes on a parent body. Such metamorphic reactions may involve formation and destruction of phases, such as melilite and diopside, which have been previously thought to be primary condensates. The mechanisms proposed for the formation and modification of the Blue Angel help to explain the secondary phases and oxygen isotope anomalies found in many CAI and eliminate the need for invoking kinetically-complicated back-reactions at very low pressures with a cool part of the solar nebula. The contribution of planetary metamorphism in the formation and alteration of CAI must be considered along with nebular processes in order to understand the formation of carbonaceous chondrites.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1016/0016-7037(82)90160-0 DOIArticle
http://www.sciencedirect.com/science/article/pii/0016703782901600PublisherArticle
ORCID:
AuthorORCID
Wasserburg, G. J.0000-0002-7957-8029
Additional Information:© 1981 Pergamon Press Ltd. Received June 19, 1981; accepted in revised form November 26, 1981. This work is dedicated to Fritz and Melitta Laves who (van Kopf bis Fuss) have shared the beauties and temptations of another Blue Angel with one of us in an earlier era. We gratefully acknowledge J. W. Larimer, W. V. Boynton, H. Y. McSween, Jr., and R. Brett for their helpful reviews and comments. We are indebted to Richard Becker for his color vision and generous nature. This work was supported by funds from the National Aeronautics and Space Administration through grant NGL 05-002-188 and the National Science Foundation through grant PHY 79-2368A2.
Funders:
Funding AgencyGrant Number
NASANGL 05-002-188
NSFPHY 79-2368A2
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Caltech Division of Geological and Planetary Sciences3522
Lunatic Asylum Lab370
Issue or Number:4
Record Number:CaltechAUTHORS:20130924-090528876
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20130924-090528876
Official Citation:John T Armstrong, G.P Meeker, J.C Huneke, G.J Wasserburg, The Blue Angel: I. The mineralogy and petrogenesis of a hibonite inclusion from the Murchison meteorite, Geochimica et Cosmochimica Acta, Volume 46, Issue 4, April 1982, Pages 575-595, ISSN 0016-7037, http://dx.doi.org/10.1016/0016-7037(82)90160-0. (http://www.sciencedirect.com/science/article/pii/0016703782901600)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:41491
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:24 Sep 2013 16:19
Last Modified:09 Mar 2020 13:19

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