A detailed comparison of the Uk′37 and coccolith records over the past 290 kyears: implications to the alkenone paleotemperature method

The Uk′37 record and the coccolithophorid remains in a sediment core from the North Atlantic Ocean have been compared to assess the possible influence of changes in alkenone-producing coccolithophorids on the Uk′37-sea surface temperature relationship. We have determined three major reversals in the populations of Noelaerhabdaceae (Gephyrocapsa and Emiliania species) in the Central North Atlantic over the last 290 kyears: 245–260, 170, and 40–50 kyears BP. A detailed comparison of the Uk′37 and coccolithophorid records revealed the absence of significant changes in the Uk′37 values despite major changes in coccolithophorid assemblages. The data indicate that changes in alkenone-producing organisms in the past do not involve significant changes in the Uk′37-temperature relationship and that the succession did not primarily depend on climatic change. It also supports the fact that the Uk′37-derived SST differences observed between glacial stages 2–4, 6 and 8 are not related to the succession of coccolithophorid species.