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Research Article |
1 Department of Applied Geoscience, German University of Technology Oman GUtech, PO Box 1816, Athaibah PC 130, Muscat, Sultanate of Oman
2 Leibniz Institute of Marine Sciences, Wischhofstr. 1–3, 24148 Kiel, Germany
3 University of Erlangen, Schloßgarten 5, 91054 Erlangen, Germany
4 Department of Earth and Environmental Sciences, University of Portsmouth, Burnaby Road, Portsmouth PO1 3QL, UK
5 81 Crofton Lane, Petts Wood, Orpington BR5 1HB, UK
6 Steinmann Institute for Geology, Mineralogy and Palaeontology, University of Bonn, Poppelsdorfer Schloss, 53115 Bonn, Germany
*Corresponding author (e-mail: svoigt{at}ifm-geomar.de)
A shark-tooth apatite 
18O record of the early Palaeogene North Sea reflects changes in regional hydrography by showing variable temperatures and salinities. A 2–4 Ma period in the early Eocene was particularly influenced by substantial surface-water freshening, indicated by a 3–4
reduction of 18O values. The magnitude of the 18O decrease indicates a depletion in 18O of surface waters by 2–3 relative to Eocene mean ocean water. This value is lower than that of coeval lakes reconstructed from freshwater gastropod 18O values from the Paris Basin, suggesting that large rivers with high-latitude catchment areas drained into the North Sea. The period of surface-water freshening began close to the Palaeocene – Eocene thermal maximum, when relative sea-level fall, tectonic uplift and basaltic volcanism caused a temporary isolation of the North Sea. North Atlantic and North Sea surface waters became reconnected during a series of early Eocene transgressions.
