δ ¹³C chemostratigraphy in the Lower–Middle Ordovician succession of Öland (Sweden) and the global significance of the MDICE

Abstract

Based on the Tingskullen drillcore, we present the first continuous carbon isotope stratigraphy from the Lower–Middle Ordovician “orthoceratite limestone” of Öland, 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 δ ¹³C 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 (46 m 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.

Keywords::

• Ordovician
• Sweden
• CRE
• Evae transgression
• MDICE

Acknowledgements

We thank reviewers Svend Stouge (Copenhagen) and Christian Rasmussen (Lund) for valuable comments to our manuscript. We also acknowledge Anders Lindskog (Lund) for general discussions about the Ordovician succession of Sweden and the Tingskullen drillcore at several occassions. MC acknowledges the support by the Swedish Research Council and thanks the Crafoord Foundation for funding the drilling of the Tingskullen core. OL is very grateful for the support by the Deutsche Forschungsgemeinschaft (DFG project LE 867/8-1 and 8-2). This paper is a contribution to the IGCP 591 project “The Early to Middle Paleozoic Revolution”.