d(13)C chemostratigraphy in the Lower-Middle Ordovician succession of Oland (Sweden) and the global significance of the MDICE

Based on the Tingskullen drillcore, we present the first continuous carbon isotope stratigraphy from the Lower-Middle Ordovician orthoceratite limestone of oland, Sweden. The extremely condensed Tremadocian and Floian stages include large gaps as well as the Ceratopyge Regressive Event and the widespread Evae transgression accompanied by prominent shifts in the C-13 record. The Dapingian and Darriwilian stages are characterised by low sedimentation rates and a relatively complete sedimentary record. A total of 99 whole-rock samples were analysed for carbon isotope geochemistry from the Ordovician part of the succession (46m thick). The most striking anomaly detected is the middle Darriwilian isotope carbon excursion (MDICE) that appears unusually well developed and complete for the region, and thus forms an important proxy for intercontinental correlation of the succession.