The use of stable isotope analysis to reconstruct paleoenvironments and paleoclimate in the late Pleistocene (MIS 5) of the North Sea Basin

Abstract

Stable isotope analysis is a widely used method for reconstructing the paleoenvironment and -climate. Isotope composition of foraminiferal tests and mollusc shells are adequate proxies as their isotope uptake for shell carbonate formation is representative for the isotopic composition of ambient water. The oxygen and carbon isotope ratios can provide information about (changes in) paleotemperature and paleosalinity. For paleosalinity, a mixing line framework with freshwater and seawater endmembers can provide insights into the temporal variability of paleosalinity. Here we show that reconstructing paleoenvironment and paleoclimate in MIS5 of the North Sea Basin with stable isotopes is taxon dependent. We found that the isotopic composition of mollusc shells largely reflects temperature of ambient waters. Furthermore, we found that the isotopic composition of foraminifera shells of Ammonia beccarii is largely influenced by salinity. Reconstruction shows a shift during MIS5e in the Amersfoort Basin from polyhaline to euhaline conditions and back with an increasing impact of the Rhine River, and a three-stage temperature evolution during MIS5a in the southern North Sea. This study is anticipated to be a starting point and recommendation for further reconstruction of paleoenvironment and -climate of MIS5 in the North Sea Basin.