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Integrated Cambrian biostratigraphy and carbon isotope chemostratigraphy of the Grönhögen-2015 drill core, Öland, Sweden

Published online by Cambridge University Press:  28 May 2018

PER AHLBERG ,
FRANS LUNDBERG ,
MIKAEL ERLSTRÖM ,
MIKAEL CALNER ,
ANDERS LINDSKOG ,
PETER DAHLQVIST  and
MICHAEL M. JOACHIMSKI
PER AHLBERG*
Affiliation:
Department of Geology, Lund University, Sölvegatan 12, SE-223 62 Lund, Sweden
FRANS LUNDBERG
Affiliation:
Department of Geology, Lund University, Sölvegatan 12, SE-223 62 Lund, Sweden
MIKAEL ERLSTRÖM
Affiliation:
Geological Survey of Sweden, Kiliansgatan 10, SE-223 50 Lund, Sweden
MIKAEL CALNER
Affiliation:
Department of Geology, Lund University, Sölvegatan 12, SE-223 62 Lund, Sweden
ANDERS LINDSKOG
Affiliation:
Department of Geology, Lund University, Sölvegatan 12, SE-223 62 Lund, Sweden
PETER DAHLQVIST
Affiliation:
Geological Survey of Sweden, Kiliansgatan 10, SE-223 50 Lund, Sweden
MICHAEL M. JOACHIMSKI
Affiliation:
GeoZentrum Nordbayern, Friedrich-Alexander University of Erlangen-Nürnberg, Schloßgarten 5, D-91054 Erlangen, Germany
*
†Author for correspondence: [email protected]
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Abstract

The Grönhögen-2015 core drilling on southern Öland, Sweden, penetrated 50.15 m of Cambrian Series 3, Furongian and Lower–Middle Ordovician strata. The Cambrian succession includes the Äleklinta Member (upper Stage 5) of the Borgholm Formation and the Alum Shale Formation (Guzhangian–Tremadocian). Agnostoids and trilobites allowed subdivision of the succession into eight biozones, in ascending order: the uppermost Cambrian Series 3 (Guzhangian) Agnostus pisiformis Zone and the Furongian Olenus gibbosus, O. truncatus, Parabolina spinulosa, Sphaerophthalmus? flagellifer, Ctenopyge tumida, C. linnarssoni and Parabolina lobata zones. Conspicuous lithologic unconformities and the biostratigraphy show that the succession is incomplete and that there are several substantial gaps of variable magnitudes. Carbon isotope analyses (δ13Corg) through the Alum Shale Formation revealed two globally significant excursions: the Steptoean Positive Carbon Isotope Excursion (SPICE) in the lower–middle Paibian Stage, and the negative Top of Cambrian Excursion (TOCE), previously referred to as the HERB Event, in Stage 10. The δ13Corg chemostratigraphy is tied directly to the biostratigraphy and used for an improved integration of these excursions with the standard agnostoid and trilobite zonation of Scandinavia. Their relations to that of coeval successions in Baltoscandia and elsewhere are discussed. The maximum amplitudes of the SPICE and TOCE in the Grönhögen succession are comparable to those recorded in drill cores retrieved from Scania, southern Sweden. The results of this study will be useful for assessing biostratigraphic relations between shale successions and carbonate facies on a global scale.

Keywords

carbon isotope excursiontrilobitesagnostoidsBorgholm FormationAlum Shale FormationScandinavia
Type
Original Article
Information
Geological Magazine , Volume 156 , Issue 6 , June 2019 , pp. 935 - 949
Copyright
Copyright © Cambridge University Press 2018 

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