New advances in the stratigraphy of Aptian oceanic anoxic events (Castro Urdiales, Basque-Cantabrian Basin, Spain)

The Aptian sedimentary deposits of the Castro Urdiales area in north Spain record an episode disoxia/anoxia which postdates Oceanic Anoxic Event 1a (OAE 1a). Carbonate platform and overlying facies are analysed for stratigraphy, sedimentology, total organic carbon isotopes. Lower shallow-water limestones covered by deeper-water marlstones organic-carbon-rich black lutites lower to upper Aptian, ranging from Dufrenoyia furcata Zone Cheloniceras (Epicheloniceras) martinioides Zone. Biostratigraphy chemostratigraphic calibration based on ammonites, isotopes analyses, revealing consistency with global reference framework. black-shale levels transition together their encasing series correlated other sections Basque-Cantabrian Basin (northern Spain) southeastern France. shales Aparein Level eastern Basin. Prior this oxygen deficient episode, glauconite-and-ostreid were also deposited under oxic conditions during Gutiolo volcanic event This volcanism correlates part Cretaceous superplume eruptions Ontong Java, Manihiki Plateaus North Atlantic opening as a result increasing seafloor spreading rates.