Relative sea-level change and carbon isotopes: Data from the Upper Jurassic (Oxfordian) of central and Southern Europe

Studies on Cretaceous pelagic Limestones have shown a close correspondence between putative sea-level curves and the carbon-isotope profile, suggesting a possible relationship between the two phenomena. Such a relationship could relate to shelf-sea area governing the global burial rate of organic carbon which, in turn, controls the C-13/C-12 ratio of dissolved inorganic carbon in the oceanic reservoir. In order to see whether or not this relationship might be of more general applicability, the major mid-Oxfordian (Jurassic) transgression is documented to zonal level and appropriate carbon-isotope data are presented. Although the applicability of ammonite zonation to the mid Oxfordian is problematic on a regional scale, a clear delta(13)C excursion is present in the transversarium Zone, which is coincident with regional overstep and/or evidence of shoreline retreat and/or evidence of bathymetric deepening in Europe and elsewhere. The use of the carbon-isotope curve as a proxy for shelf-sea area or relative sea level is worthy of further exploration.