NOAA/WDS Paleoclimatology - Tropical Pacific changes in deep circulation

Eastern tropical Atlantic benthic foraminiferal Ba/Ca and Cd/Ca data from core V30–49 (3093 m) reveal large inferred changes in nutrient concentrations of deep Atlantic waters during the last 250 kyr. Relative changes in North Atlantic Deep Water contribution to this site are estimated by scaling the V30–49 Cd/Ca record to values of modern end-member water masses; these estimates agree well with the relative structure and timing of circulation changes in the eastern tropical Atlantic reconstructed from a δ13C record-based mixing model [Raymo et al., 1997]. Temporal differences between V30–49 Cd/Ca and Ba/Ca records suggest that the Ba/Ca record reflects changes in circulation with an additional increase in the Ba composition of deep Atlantic water masses during glacial episodes, possibly resulting from increased productivity. Similarity between the δ13C and Ba/Ca records suggests that carbon isotopes in the deep glacial Atlantic also reflect productivity increases.