Complementary Use of Amino-Acid Epimerization and Radiocarbon Analysis for Dating of Mixed-Age Fossil Assemblages
AuthorGoodfriend, Glenn A.
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CitationGoodfriend, G. A. (1989). Complementary use of amino-acid epimerization and radiocarbon analysis for dating of mixed-age fossil assemblages. Radiocarbon, 31(3), 1041-1047.
DescriptionFrom the 13th International Radiocarbon Conference held in Dubrovnik, Yugoslavia, June 20-25, 1988.
AbstractSeveral approaches to dealing with the problem of mixed-age fossil assemblages are presented. These involve the use of amino-acid epimerization analysis (D-alloisoleucine/L-isoleucine ratio, or A/I) and are illustrated by deposits of land snail shells. This method requires only very small samples, so shells can be analyzed individually. Mixed-age deposits are indicated when variation in A/I among individual shells within the deposit exceeds the analytical error. Methods are presented for 1) estimating the true time of deposition of slightly-mixed-age assemblages based on bulk 14C dates and epimer analyses, 2) selection (for 14C analysis) of a set of individual shells that are uniform in age and represent the true time of deposition, and 3) estimating ages of individual shells within a mixed-age deposit based on their A/I ratios.