Late Cretaceous carbon isotope stratigraphy in Europe: Correlation and relations with sea level and sediment stability

Abstract

Abstract Upper Cretaceous (Upper Cenomanian to Lower Coniacian) stable carbon isotope stratigraphy of German hemipelagic marls (borehole Dresden-Blasewitz), pelagic carbonates (quarries Salzgitter-Salder and Sohlde), and of two Turonian to Santonian pelagic sections in the northern Alpine Helvetic Zone, supplemented by published carbon isotope data (Kent, southern England; Gubbio, Italy), are used for correlations of northern temperate (boreal) and Tethyan sections. General carbon isotopic trends are different in pelagic and hemipelagic carbonates, probably in response to the input of terrestrial organic carbon to the inner shelf carbon reservoir (including sediments). The global component in the carbon isotope stratigraphy is best recorded in pelagic carbonates. Sufficient biostratigraphic control is present to correlate all sections across facies boundaries and between the two biogeographic provinces. Hiatuses produce breaks in the gradual carbon isotopic trends and their duration can be estimated relative to complete sections. A broad δ13C minimum straddles the Turonian-Coniacian boundary at the proposed boundary stratotype Salzgitter-Salder, with its center about 0.5–1 m below the biostratigraphic reference level (first occurrence of C. rotundatus Fiege sensu Troger non Fiege). Increases and maxima of pelagic δ13C values occur during phases of sediment accumulation. Decreasing pelagic °13C values and minima characterise phases of sediment erosion. The amplitudes of these stratigraphic fluctuations may indicate the intensity of sediment reworking. Changes in the sediment accumulation/erosion ratio and accompanied carbon isotopic variation may be related to short-term sea-level fluctuations and their effect on fine-grained sediment stability.