(Table 1) Age determination of surface sediment samples from the North Atlantic

• Main Authors: Keigwin, Lloyd D, Guilderson, Thomas P
• Format: Dataset
• Language: English
• Published: PANGAEA 2009
• Subjects: Age; 14C AMS; dated; dated material; dated standard deviation; BC; Box corer; DEPTH; sediment/rock; Elevation of event; Event label; Fraction modern carbon; error; Knorr; KNR178; KNR178-1-1-1; Laboratory code/label; Latitude of event; Longitude of event; MUC; MultiCorer; North Atlantic Ocean; OCE326-BC9; OCE326-MC13; OCE326-MC25; Reference/source; Δ14C; Antarc*; Antarctic; North Atlantic; Planktonic foraminifera
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.831644; https://doi.org/10.1594/PANGAEA.831644

Most seafloor sediments are dated with radiocarbon, and the sediment is assumed to be zero-age (modern) when the signal of atmospheric testing of nuclear weapons is present (Fraction modern (Fm) > 1). Using a simple mass balance, we show that even with Fm > 1, half of the planktonic foraminifera at the seafloor can be centuries old, because of bioturbation. This calculation, and data from four core sites in the western North Atlantic indicate that, first, during some part of the Little Ice Age (LIA) there may have been more Antarctic Bottom Water than today in the deep western North Atlantic. Alternatively, bioturbation may have introduced much older benthic foraminifera into surface sediments. Second, paleo-based warming of Sargasso Sea surface waters since the LIA must lag the actual warming because of bioturbation of older and colder foraminifera.