Radiocarbon dating of alkenones from marine sediments: III. Influence of solvent extraction procedures on C-14 measurements of foraminifera

As a result of the growing use of multiple geochemical proxies to reconstruct ocean and climate changes in the past, there is an increasing need to establish temporal relationships between proxies derived from the same marine sediment record and ideally from the same core sections. Coupled proxy records of surface ocean properties, such as those based on lipid biomarkers (e.g. alkenone-derived sea surface temperature) and planktonic foraminiferal carbonate (oxygen isotopes), are a key example. Here, we assess whether 2 different solvent extraction procedures used for isolation of molecular biomarkers influence the radiocarbon contents of planktonic foraminiferal carbonate recovered from the corresponding residues of Bermuda Rise and Cariaco Basin sediments. Although minor Delta C-14 differences were observed between solvent-extracted and unextracted samples, no substantial or systematic offsets were evident. Overall, these data suggest that, in a practical sense, foraminiferal shells from a solvent-extracted residue can be reliably used for C-14 dating to determine the age of sediment deposition and to examine age relationships with other sedimentary constituents (e.g. alkenones).