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We present new, detailed carbon-isotope records for bulk carbonate, total organic carbon (TOC) and phytane from three key sections spanning the Cenomanian--Turonian boundary, interval (Eastbourne, England; Gubbio, Italy; Tarfaya, Morocco), with the purpose of establishing a common chemostratigraphic framework for Oceanic Anoxic Event (OAE) 2. Isotope curves from all localities are characterized by a positive carbon-isotope excursion of c. 4[per thousand] for TOC and phytane and c. 2.5[per thousand] for carbonate, although diagenetic overprinting appears to have obliterated the primary carbonate carbon-isotope signal in at least part of the Tarfaya section. Stratigraphically, peak [[delta].sup.13]C values for all components are followed by intervals of high, near-constant [[delta].sup.13]C in the form of an isotopic plateau. Recognition of an unambiguous return to background [[delta].sup.13]C values above the plateau is, however, contentious in all sections, hence no firm chemostratigraphic marker for the end-point of the positive isotopic excursion can be established. The stratigraphically consistent first appearance of the calcarcous nannofossil Quadrum gartneri at or near the Cenomanian--Turonian boundary as established by ammonite stratigraphy, in conjunction with the end of the [[delta].sup.13]C maximum characteristic of the isotopic plateau, provides a potentially powerful tool for delimiting the stratigraphic extent and duration of OAE 2. This Oceanic Anoxic Event is demonstrated to be largely, if not wholly, confined to the latest part of the Cenomanian stage. Keywords: Oceanic Anoxic Event 2, Eastbourne, England, Gubbio, Italy, Tarfaya, Morocco, [sup.13]C.

Micropalaeontological and chemostratigraphic results from the mid-Cretaceous 'upper siliceous zone' of the Ionian zone, studied in two localities of NW Greece (Paliambela and Panaya), provide new insights into the palaeoceanographic evolution of Tethys and better correlation with well-studied Italian successions. [[delta].sup.13]C carbonate and organic-carbon isotope stratigraphy allows an improved correlation of the early Aptian Fourcade Level with Oceanic Anoxic Event 1a. Calcareous nannofossils point to intervals of reduced sedimentation within the late Aptian part of the limestones overlying the Fourcade Level. Combined calcareous nannofossil, radiolarian and planktonic foraminiferal biostratigraphy suggests that the overlying radiolarites (named herein the 'Dercourt Member') are essentially mid-Albian in age. Radiolarites of this age and thickness have not been identified in the well-explored Italian sections of in southern Albania. It is therefore likely that the Dercourt radiolarites reflect a high-productivity event localized in the Greek area of the Ionian zone, possibly caused by a bathymetrically induced upwelling of intermediate to deep waters that entered the Ionian trough following the opening of new oceanic gateways in the Eastern Mediterranean Tethys. Keywords: Ionian zone, Cretaceous, palaeoceanography, chemostratigraphy, micropalaeontology.