Late Cretaceous to Palaeogene carbon isotope, calcareous nannofossil and foraminifera stratigraphy of the Chalk Group, Central North Sea

Abstract A highly resolved record of stable carbon isotope values (δ13C) of the Late Cretaceous to Palaeogene (Cenomanian – Danian) was generated from ditch-cuttings material recovered from the Shearwater A9 hydrocarbon production well, Shearwater Field, Central North Sea. The profile of δ13C values was integrated with calcareous nannofossil and foraminifera biostratigraphy to provide an integrated stratigraphy for the Late Cretaceous Chalk Group. Detailed correlation between Shearwater A9 carbon isotope stratigraphy and associated biostratigraphic events with other similar records from both the Boreal and Tethyan Realms, including several proposed and/or ratified Global Boundary Stratotype Sections and Points had enabled the identification of major Stage and sub-Stage boundaries. This study provides a long-term and near-continuous stratigraphic record of the Late Cretaceous and earliest Palaeogene from more basinal facies of the Central North Sea. The record is punctuated with several short duration hiatal intervals, and a longer hiatus is identified whereby most of the Cenomanian is missing at this location.