Using stable oxygen isotope stratigraphy to construct an age model for the Pliocene section of the ‘Hank’ North Sea sediment core

Abstract

The Pliocene period is a good analogue for future climate. Firstly, CO2 concentration in the atmosphere was similar to modern day values. Furthermore, temperatures were slightly higher (ΔT = 2-3 °C), something which is expected to happen in the future due to an enhanced greenhouse effect. The North Atlantic Ocean is crucial in controlling global climate, because North Atlantic ocean circulation has a major impact on Northern hemisphere glaciation. During the Pliocene, large parts of the Netherlands were submerged in a shallow sea. Previous studies of the southern North Sea Basin (Hank core) that have reconstructed sea surface temperature reconstructions, among other proxies, have yielded mixed results. An independently calibrated age model will aid in understanding trends in terrestrial and marine proxies, and will crucially provide a framework for the timing of trends observed in the proxy records. To this aim, oxygen and carbon isotope ratios of foraminifera in the Hank succession were analyzed. The species Cassidulina Laevigata and Bulimina Aculeata, both endobenthic, were studied. The resulting age model presented in this study is subject to a number of uncertainties, mostly caused by the core’s proximal location to the coast. Nevertheless, with support of other terrestrial and marine proxies, as well as a seismic section, a representative age model could be created that agrees with previous proxies and age estimations.