Upper Ordovician δ¹³C_org chemostratigraphy, K-bentonite stratigraphy, and biostratigraphy in southern Scandinavia : A reappraisal

Summary, in English

A pioneer δ¹³C_org study through the upper Sandbian and Katian (Upper Ordovician) succession in the Röstånga 1 drill core in the classical geological outcrop area at Röstånga in southernmost Sweden produced a wealth of new carbon isotope data which are useful for local and regional correlations. Among the Upper Ordovician positive δ¹³C excursions, the Guttenberg (GICE), Waynesville (Saunja), Whitewater (Moe), Paroveja, and Hirnantian (HICE) isotopic carbon excursions are recognized but the Kope (Rakvere) δ¹³C excursion is missing, suggesting a stratigraphic gap. All these isotopic excursions are tied closely to biostratigraphy, especially graptolite biostratigraphy, and in the case of the Waynesville (Saunja) and Whitewater (Moe) excursions, for the first time anywhere in the world. The Röstånga GICE δ¹³C_org curve from the upper Sularp Shale shows a striking similarity to that of the Katian GSSP in Oklahoma, suggesting the potential of trans-Atlantic correlation. Based on a projection from the Katian GSSP, the previously poorly constrained position of the base of the Katian in southern Sweden appears to be in the uppermost Sularp Shale in strata of the upper Diplograptus foliaceus Zone. Previous interpretations of the relations between K-bentonite successions in southern Scandinavia are somewhat revised and the Kinnekulle K-bentonite is recognized for the first time in Scania. Based on new radiometric dates, this very prominent and widespread ash bed appears to be slightly older than the Deicke and Millbrig K-bentonites in eastern North America.