FURTHER EVIDENCE FOR A LINK BETWEEN LATE PLEISTOCENE NORTH-ATLANTIC SURFACE TEMPERATURES AND NORTH-ATLANTIC DEEP-WATER PRODUCTION

Reduced surface temperatures, salinity and North Atlantic Deep-Water (NADW) formation rate may be mechanistically linked. Previous studies have demonstrated the co-occurrence of lowered high-latitude T and NADW during glacial maxima and the brief (t 1000 yr) Younger Dryas cooling event 10,500 years ago. This behavior also appears as a feature of a recent coupled ocean/atmosphere general circulation model. Here, it is shown that rapid fluctuations in North Atlantic surface temperatures (as indicated by variations from 7 to 22% left-cooling N. pachyderma) during oxygen isotope stage 3 also may be linked to fluctuations in deep-water chemistry (as indicated by benthic Cd/Ca variations from 0.080 to 0.120 μmol. mol.-1). Two complete cycles in both properties are observed in 30 cm of sediment; bioturbation modeling suggests that the true extrema are muted and that the reproducibility of replicate analyses is primarily limited by the sampling statistics of bioturbated mixrure. The current evidence raises the question of whether NADW is regulated by a "switch" or by a "valve". © 1990.