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

Abstract

The U k′ 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 U k′ 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 U k′ 37 and coccolithophorid records revealed the absence of significant changes in the U k′ 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 U k′ 37-temperature relationship and that the succession did not primarily depend on climatic change. It also supports the fact that the U k′ 37-derived SST differences observed between glacial stages 2–4, 6 and 8 are not related to the succession of coccolithophorid species.