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Actinide abundances in ordinary chondrites

Hagee, B. and Bernatowicz, T. J. and Podosek, F. A. and Johnson, M. L. and Burnett, D. S. and Tatsumoto, M. (1990) Actinide abundances in ordinary chondrites. Geochimica et Cosmochimica Acta, 54 (10). pp. 2847-2858. ISSN 0016-7037. https://resolver.caltech.edu/CaltechAUTHORS:20150427-095816014

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Abstract

Measurements of ^(244)Pu fission Xe, U, Th, and light REE (LREE) abundances, along with modal petrographic determinations of phosphate abundances, were carried out on equilibrated ordinary chondrites in order to define better the solar system Pu abundance and to determine the degree of variation of actinide and LREE abundances. Our data permit comparison of the directly measured Pu/U ratio with that determined indirectly as (Pu/Nd) × (Nd/U) assuming that Pu behaves chemically as a LREE. Except for Guareña, and perhaps H chondrites in general, Pu concentrations are similar to that determined previously for St. Séverin, although less precise because of higher trapped Xe contents. Trapped ^(130Xe)/_(136Xe) ratios appear to vary from meteorite to meteorite, but, relative to AVCC, all are similar in the sense of having less of the interstellar heavy Xe found in carbonaceous chondrite acid residues. The Pu/U and Pu/Nd ratios are consistent with previous data for St. Séverin, but both tend to be slightly higher than those inferred from previous data on Angra dos Reis. Although significant variations exist, the distribution of our Th/U ratios, along with other precise isotope dilution data for ordinary chondrites, is rather symmetric about the CI chondrite value; however, actinide/(LREE) ratios are systematically lower than the CI value. Variations in actinide or LREE absolute and relative abundances are interpreted as reflecting differences in the proportions and/or compositions of more primitive components (chondrules and CAI materials?) incorporated into different regions of the ordinary chondrite parent bodies. The observed variations of Th/U, Nd/U, or Ce/U suggest that measurements of Pu/U on any single equilibrated ordinary chondrite specimen, such as St. Séverin, should statistically be within ±20–30% of the average solar system value, although it is also clear that anomalous samples exist.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1016/0016-7037(90)90019-HDOIArticle
http://www.sciencedirect.com/science/article/pii/001670379090019HPublisherArticle
Additional Information:© 1990 Pergamon Press. Received 14 August 1989, Accepted 17 July 1990. We thank E. Olsen, G. J. Wasserburg, C. Moore, R. Hutchison, and P. Pellas for meteorite samples. The manuscript was improved by thorough reviews from G. Crozaz, U. Ott, P. Pellas, and an anonymous reviewer. This research was supported by NASA grants T-783-H (USGS), NAG 9-94 (Caltech), and NSF grant EAR-8709445 (Washington U.). Editor handling: H. Palme.
Funders:
Funding AgencyGrant Number
NASAT-783-H
NASANAG 9-94
NSFEAR-8709445
Issue or Number:10
Record Number:CaltechAUTHORS:20150427-095816014
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20150427-095816014
Official Citation:B. Hagee, T.J. Bernatowicz, F.A. Podosek, M.L. Johnson, D.S. Burnett, M. Tatsumoto, Actinide abundances in ordinary chondrites, Geochimica et Cosmochimica Acta, Volume 54, Issue 10, October 1990, Pages 2847-2858, ISSN 0016-7037, http://dx.doi.org/10.1016/0016-7037(90)90019-H. (http://www.sciencedirect.com/science/article/pii/001670379090019H)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:56996
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:27 Apr 2015 19:30
Last Modified:03 Oct 2019 08:19

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