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U and Th zonation in Fish Canyon Tuff zircons: Implications for a zircon (U–Th)/He standard

Dobson, K.J.; Stuart, F.M.; Dempster, T.J.; EIMF

U and Th zonation in Fish Canyon Tuff zircons: Implications for a zircon (U–Th)/He standard Thumbnail


Authors

K.J. Dobson

F.M. Stuart

T.J. Dempster

EIMF



Abstract

The inability to accurately determine the distribution of U and Th in zircon crystals analysed using (U–Th)/He is a major source of error, and limits the confidence in subsequent data interpretation. The Fish Canyon Tuff (FCT) zircon standard shows (U–Th)/He age reproducibility in excess of ±10%. We have tested the extent to which this is due to U and Th zonation using a combination of cathodoluminescence and ion probe analysis of a population of FCT zircons. Primarily we find that FCT zircons exhibit extreme U and Th zonation, and the population has large inter-crystalline variability. Furthermore, the net cathodoluminescence intensity from the FCT zircons is negatively correlated with U and Th concentration, allowing cathodoluminescence emission to be used as a proxy for U and Th zonation. This correlation was exploited to constrain the U and Th zonation within the crystal population, and to show that the poor age reproducibility of the FCT zircons is consistent with the observed zonation.

Citation

Dobson, K., Stuart, F., Dempster, T., & EIMF. (2008). U and Th zonation in Fish Canyon Tuff zircons: Implications for a zircon (U–Th)/He standard. Geochimica et Cosmochimica Acta, 72(19), 4745-4755. https://doi.org/10.1016/j.gca.2008.07.015

Journal Article Type Article
Acceptance Date Jul 24, 2008
Online Publication Date Aug 3, 2008
Publication Date Oct 1, 2008
Deposit Date May 5, 2016
Publicly Available Date May 31, 2016
Journal Geochimica et Cosmochimica Acta
Print ISSN 0016-7037
Publisher Meteoritical Society
Peer Reviewed Peer Reviewed
Volume 72
Issue 19
Pages 4745-4755
DOI https://doi.org/10.1016/j.gca.2008.07.015

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Copyright Statement
NOTICE: this is the author’s version of a work that was accepted for publication in Geochimica et Cosmochimica Acta. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Geochimica et Cosmochimica Acta, 72, 1 October 2008, 10.1016/j.gca.2008.07.015




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