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All sediment samples were freeze-dried, disaggregated in a buffered Calgon (sodium hexametaphosphate) solution, shaken for 2 hr in deionized water, and washed through a 63-µm sieve. Between 1 and 15 benthic foraminiferal specimens were picked from the >150-µm fraction of each sample. We selected Nuttalides umbonifera and species of Cibicidoides for measurement. Stable isotope ratios were measured at the University of Cambridge on a Micromass Multicarb sample preparation system attached to a PRISM mass spectrometer and are reported relative to the Vienna Peedee belemnite standard. Analytical precision was better than 0.08.
