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On Correcting 14C Ages of Gastropod Shell Carbonate for Fractionation

Published online by Cambridge University Press:  18 July 2016

Jeffrey S Pigati
Jeffrey S Pigati*
Affiliation:
Desert Laboratory and Geosciences Department, University of Arizona, Tucson, Arizona 85721, USA. Email: [email protected].
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Abstract

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Correcting the 14C age of a sample for fractionation is straightforward if the measured carbon was derived entirely from the atmosphere, either directly or through chemical and/or biological reactions that originated with atmospheric carbon. This correction is complicated in the case of gastropods that incorporate carbon from limestone or secondary carbonate (e.g. soil carbonate) during shell formation. The carbon isotopic composition of such gastropod shells is determined by fractionation, as well as mixing of carbon from sources with different isotopic values. Only the component of shell carbonate derived from atmospheric carbon should be corrected for fractionation. In this paper, the author derives a new expression for correcting the measured 14C activity of gastropod shells for fractionation, and describe an iterative approach that allows the corrected 14C activity and the fraction of shell carbonate derived from atmospheric carbon to be determined simultaneously.

Type
Articles
Information
Radiocarbon , Volume 44 , Issue 3 , 2002 , pp. 755 - 760
Copyright
Copyright © The Arizona Board of Regents on behalf of the University of Arizona 

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