Comparison of uranium-series, radiocarbon, and amino acid data from marine molluscs, Baffin Island, Arctic Canada

Uranium-series and 14C dates and the extent of amino acid racemization are reported for 24 marine shell samples from three areas of Baffin Island, Arctic Canada. When the radiometric dates are plotted against the ratio of D-alloisoleucene:L-isoleucene in the shells, five broad age groups are recognized. The uranium-series data indicate that 231Pa is incompletely retained in most fossil shells and that 230Th is lost from some of the samples. Therefore, their apparent ages are minimum. However, a few dated samples in each group have yielded useful age results, and the minimum ages of the five groups of samples are estimated as 7,000 to 11,000, greater than or equal to70,000, greater than or equal to136,000, greater than or equal to190,000 and >300,000 yr. Calculated integrated thermal histories based on the epimerization reaction in the mollusc Hiatella arctica Linne give paleotemperature estimates of around -5/sup o/C, compared to the present mean annual air temperature of about -11/sup o/C