The Palaeocene/Eocene boundary section at Zumaia (Basque‐Cantabric Basin) revisited: new insights from high‐resolution magnetic susceptibility and carbon isotope chemostratigraphy on organic matter (δ¹³C_org)

Abstract

Terra Nova, 24, 310–317, 2012 Abstract The Zumaia section, the most complete and representative section of the early Palaeogene (hemi)‐pelagic succession of the Pyrenees, is widely acknowledged as a key reference for the Palaeocene–Eocene boundary. New high‐resolution δ 13 C org of the Zumaia section (−23.8 to −28.8‰) confirms the position of the Carbon Isotope Excursion and enhances the distinction between the different steps of the CIE/PETM event. According to new magnetic susceptibility data and detailed cycle counting, the entire duration of the CIE/PETM in Zumaia is estimated in ∼168 ± 16 ka. Moreover, the investigation of palynofacies and low‐field magnetic susceptibility reveal significant detrital influx during the interval. Several magnetic susceptibility phases and trends are recognised and are interpreted in terms of sea‐level fluctuations before, during and after the PETM. Coupled with results from other sections, our data reveal the presence of an unconformity followed by an eustatic sea‐level rise (TST) in the latest Palaeocene.