Ocean ventilation during the last 12,000 years: Hypothesis of counterpoint deep water production

Abstract

Available radiocarbon data on selected planktonic foraminifera species suggest that differential dissolution reduces the 14 C C ratio in planktonic tests, removing 14C-rich specimens from assemblages of surface-dwelling species. The effect is analogous to that observed for stable isotope composition in planktonic foraminifera. Other disturbing factors apparently affect benthic radiocarbon data, as well. Thus, radiocarbon stratigraphies are difficult to interpret in terms of history of deep-water ages, that is, deep-ocean mixing. The best data at hand (South China Sea ∗ ∗ See Andree et al., 1986. ), after corrections for differential dissolution and benthic (vital?) deviations, suggest a high variability of deep-water mass ages in the late glacial period, which is explained in terms of vertical motion of deep-water mass boundaries across the recording sites. The fluctuations are ascribed to sporadic increases in deep-water production in the North Pacific during cold periods and to the presence of a glacial bottom-water mass which resisted mixing during deglaciation.