Redox conditions, glacio-eustasy, and the status of the Cenomanian–Turonian Anoxic Event: new evidence from the Upper Cretaceous Chalk of England

The nature of the Cenomanian–Turonian Oceanic Anoxic Event (CTOAE) and its δ13 C Excursion is considered in light (1) stratigraphical framework which CTOAE developed European shelf seas, (2) conclusions that can be drawn from new detailed investigations Chalk succession at three locations England, Melton Ross Flixton Northern Province where organic-rich ‘black bands’ are present, Dover Southern (part Anglo-Paris Basin) they absent, (3) how these conclusion fit with present understanding CTOAE. application cerium anomaly method (German Elderfield 1990) Dover, has allowed varying palaeoredox conditions Sea sediments to related acid insoluble residues, organic carbon, δ18O (calcite), δ13C (organic matter), Fe 2+ Mn2+ P/TiO2 (acid residue). This provided evidence initial stages England were a drop sea level estimated between 45 85 metres, influxes terrestrial silicate detritus adjacent continental sources reworking exposed marine sediments, presence cold water phases (named Wood , Jefferies Black ) associated appearance cold-water pulse fauna during Plenus Cold Event. Conditions column chalk sediment different two areas. In Province, cerium-enriched waters anoxic widespread; pattern reflects interplay development anoxia preservation matter black bands; here was short-lived (~0.25 Ma) lasting only length Upper Cenomanian Metoicoceras geslinianum Zone. oxic lasted top Lower Turonian Watinoceras devonense Zone, much longer (~1.05 than Province. These differences discussed respect (CTAE) hypothesis when ocean-continent-atmosphere systems linked, limitations chemostratigraphic global correlation, Recovery (CTOAER), term define lengths time it took oceans seas recover once linked system over. possibility glacio-eustasy (the glacial control Jeans et al. 1991) waxing waning polar ice sheets, association degassing large igneous provinces, may have set scene for (CTAE).