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Al-Mg systematics of hibonite-bearing Ca,Al-rich inclusions from Ningqiang

Hsu, Weibiao and Guan, Yunbin and Wang, Ying (2011) Al-Mg systematics of hibonite-bearing Ca,Al-rich inclusions from Ningqiang. Meteoritics and Planetary Science, 46 (5). pp. 719-728. ISSN 1086-9379. https://resolver.caltech.edu/CaltechAUTHORS:20110526-133716941

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Abstract

Hibonite-bearing Ca,Al-rich inclusions (CAIs) usually occur in CM and CH chondrites and possess petrographic and isotopic characteristics distinctive from other typical CAIs. Despite their highly refractory nature, most hibonite-bearing CAIs have little or no ^(26)Mg excess (the decay product of ^(26)Al), but do show wide variations of Ca and Ti isotopic anomalies. A few spinel-hibonite spherules preserve evidence of live ^(26)Al with an inferred ^(26)Al/^(27)Al close to the canonical value. The bimodal distribution of ^(26)Al abundances in hibonite-bearing CAIs has inspired several interpretations regarding the origin of short-lived nuclides and the evolution of the solar nebula. Herein we show that hibonite-bearing CAIs from Ningqiang, an ungrouped carbonaceous chondrite, also provide evidence for a bimodal distribution of ^(26)Al. Two hibonite aggregates and two hibonite-pyroxene spherules show no ^(26)Mg excesses, corresponding to inferred ^(26)Al/^(27)Al < 8 × 10^(−6). Two hibonite-melilite spherules are indistinguishable from each other in terms of chemistry and mineralogy but have different Mg isotopic compositions. Hibonite and melilite in one of them display positive ^(26)Mg excesses (up to 25‰) that are correlated with Al/Mg with an inferred ^(26)Al/^(27)Al of (5.5 ± 0.6) × 10^(−5). The other one contains normal Mg isotopes with an inferred ^(26)Al/^(27)Al < 3.4 × 10^(−6). Hibonite in a hibonite-spinel fragment displays large ^(26)Mg excesses (up to 38‰) that correlate with Al/Mg, with an inferred ^(26)Al/^(27)Al of (4.5 ± 0.8) × 10^(−5). Prolonged formation duration and thermal alteration of hibonite-bearing CAIs seem to be inconsistent with petrological and isotopic observations of Ningqiang. Our results support the theory of formation of ^(26)Al-free/poor hibonite-bearing CAIs prior to the injection of ^(26)Al into the solar nebula from a nearby stellar source.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1111/j.1945-5100.2011.01185.xDOIArticle
http://onlinelibrary.wiley.com/doi/10.1111/j.1945-5100.2011.01185.x/abstractPublisherArticle
ORCID:
AuthorORCID
Guan, Yunbin0000-0002-7636-3735
Additional Information:© 2011 The Meteoritical Society. Received 12 September 2010; revision accepted 07 January 2011. Article first published online: 25 Apr 2011. The authors thank Steve Simon, Julie Paque, Christine Floss, and one anonymous reviewer for their constructive reviews. This work was supported by Chinese National Natural Science Foundation (grant nos. 40773046, 41003026, 10621303) and by the Minor Planet Foundation of China. Editorial Handling-Dr. Christine Floss.
Funders:
Funding AgencyGrant Number
National Natural Science Foundation of China40773046
National Natural Science Foundation of China41003026
National Natural Science Foundation of China10621303
Minor Planet Foundation of ChinaUNSPECIFIED
Issue or Number:5
Record Number:CaltechAUTHORS:20110526-133716941
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20110526-133716941
Official Citation:Al-Mg systematics of hibonite-bearing Ca,Al-rich inclusions from Ningqiang (pages 719–728) Weibiao HSU, Yunbin GUAN and Ying WANG Article first published online: 25 APR 2011 | DOI: 10.1111/j.1945-5100.2011.01185.x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:23811
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:26 May 2011 21:24
Last Modified:27 Nov 2019 18:27

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