Upper Ordovician δ13Corg chemostratigraphy, K-bentonite stratigraphy, and biostratigraphy in southern Scandinavia: A reappraisal

Abstract

A pioneer δ 13 Corg study through the upper Sandbian and Katian (Upper Ordovician) succession in the Röstånga 1 drill 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 δ 13 C excursions, the Guttenberg (GICE,) Waynesville (Saunja), Whitewater (Moe), Paroveja, and Hirnantian (HICE) isotopic carbon excursions are recognized but the Kope (Rakvere) δ 13 C 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 δ 13 Corg curve from the upper Sularp Shale shows a striking similarity to that of the Katian GSSP in Oklahoma, suggesting the potential of transAtlantic 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.

RNames, a stratigraphical database designed for the statistical analysis of fossil occurrences – the Ordovician diversification as a case study

“…The relative position of these beds to the stage boundary is not fully resolved and as a consequence during the last several years the boundary interval has been intensively discussed (e.g., Young et al, 2005;Ainsaar et al, 2010;Bergström et al, 2010;Bergström et al, 2011;Chen et al, 2013;Pouille et al, 2013;Carlucci et al, 2015;Sell et al, 2015;Taylor and Loch, 2015;Bergström et al, 2016;Kröger et al, 2016;Quinton et al, 2016).…”

Upper Katian (Upper Ordovician) trans‐Atlantic δ13C chemostratigraphy: the geochronological equivalence of the ELKHORN and PAROVEJA excursions and its implications

“…It should be noted that a minor excursion just below the PAROVEJA interval in the Röstånga 1 drill core, which was identified as the ELKHORN Excursion by Bergström et al . (, fig. 3), is now interpreted as rather representing a still unnamed minor excursion between the WHITEWATER/MOE and the PAROVEJA excursions.…”

“…Among the successions currently investigated in southern Sweden, the PAROVEJA excursion has been recognized in the Röstånga-1 drill core (Bergström et al 2016) in which there is a modest excursion in the middle portion of the Lindegård Mudstone between the WHITEWATER/MOE and HICE perturbations ( Fig. 5).…”

Darriwilian (Middle Ordovician) chemostratigraphy linked to graptolite, conodont and trilobite biostratigraphy in the Fågelsång-3 drill core, Scania, Sweden

“…Whereas, there is a considerable number of Darriwilian δ 13 C carb curves published, very few reports of chemostratigraphic investigations of the Darriwilian-Sandbian interval using δ 13 C org are currently available (e.g., Young et al 2008). Because δ 13 C org and δ 13 C carb often, but not always, exhibit close similarity (e.g., Bergström et al 2016), it is of interest to examine how the Fågelsång-3 δ 13 C org curve compares with δ 13 C carb curves from stratigraphically continuous Darriwilian successions with excellent biostratigraphic control. The latter is very important because, as noted by Schmitz et al (2010), in several well-known carbonate successions around the world, such as the classical one at Hällekis in south-central Sweden, there is a very significant stratigraphic gap in the middle Darriwilian corresponding to several conodont subzones that cuts out most of the MDICE and severely complicates chemostratigraphic correlation.…”