Radiocarbon data from North Atlantic marine sediments directly linked to millennial-scale climate variability through the last glacial period

Planktonic foraminifera from well-constrained marine event-stratigraphies, provide the only practical means of achieving a record of past surface ocean 14C that spans the entire range of the radiocarbon method 0-50ka. Such data are included in the most recent radiocarbon calibration IntCal09 because they significantly extend the currently limited range of dendrochronologically dated records, despite the fact that they are not strictly bona fide calibration archives and that the surface ocean experiences large reservoir age changes over time. The international working group on radiocarbon calibration warns about the limitations of the assumption of constant reservoir effect in the current calibration and recognises that suitable data sets with which to quantify temporal variations in reservoir ages are urgently needed so that the accuracy and precision of the many radiocarbon based marine chronologies and models can be improved. The temporal shifts in radiocarbon reservoir ages have furthermore provided quantitative information about ocean circulation patterns. The aim of this proposal is to establish a 14C stratigraphy for high-resolution marine cores MD04-2822 and MD95-2006 from the mid-latitude NE Atlantic, in order to constrain the 14C age-differences between cold (stadial) and warm (interstadial) D-O oscillations which characterised the last glacial period. We will undertake detailed 14C analysis in the interval 25-50 ka, providing the first replicated mid-latitude marine 14C data for radiocarbon calibration and a quantified reconstruction of marine radiocarbon reservoir age effect, constrained by event-based stratigraphies and tephrochronology.