Dapingian to lower Darriwilian (Middle Ordovician) graptolite biostratigraphy and correlation of the Krapperup drill core, Scania, Sweden

ABSTRACT

The Dapingian and lower Darriwilian graptolite succession of the Krapperup drill core from Scania, southern Sweden, provides a detailed insight into the axonophoran (biserial) graptolites and their early Palaeozoic evolutionary changes on the Scandinavian platform. Even though earliest Darriwilian axonophorans are not represented, the succession includes faunal elements of the basal Darriwilian Arienigraptus zhejiangensis Subzone of the Levisograptus austrodentatus Biozone, followed by Levisograptus mui and Levisograptus sinicus specimens higher up in the successsion. The highest interval is referred to the Eoglyptograptus cumbrensis Biozone and bears a number of axonophoran elements, including Oelandograptus oelandicus and Undulograptus camptochilus, previously known exclusively from chemically isolated material from the island of Öland. The top of the interval investigated is below the base of a carbonate-rich interval correlated with the Komstad Limestone of Scania, indicating that the investigated interval entirely belongs to the upper part of the Tøyen Shale Formation. Pseudisograptus manubriatus and Pseudisograptus koi are not restricted to the upper Dapingian, but range into the basal Darriwilian. Arienigraptus robustus n. sp. from the uppermost Dapingian, and Arienigraptus delicatus n. sp. and Arienigraptus balticus n. sp. from the basal Darriwilian, are described as new species.

KEYWORDS:

• Ordovician
• Dapingian
• Darriwilian
• graptolites
• biostratigraphy
• Krapperup
• Scania
• Sweden

Acknowledgments

The research by JM was possible through grants from the Wenner-Gren Foundations (grant 2008-11-28 to Maletz in 2008), the Gyllenstierna Krapperup’s Foundation (grants KR2010-0024, KR2012-0079, 2014–0100 and 2017–0108 to Ahlberg) and the Royal Physiographical Society of Lund (grants to Ahlberg). Kristina Lindholm (Kävlinge, Sweden) provided invaluable information on the lower part of the Krapperup drill core from her unpublished thesis (Lindholm 1981) and helped to trace core boxes and additional fossil material. Zhang Yuandong and Ma Xuan (NIGPAS Nanjing, China) are thanked for access to NIGPAS type collection. We are also indebted to the journal reviewers (Guillermo L. Albanesi and one anonymous reviewer) for useful comments on the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Wenner-Gren Foundations [grant approved 2008-11-28] and the Gyllenstierna Krapperup’s Foundation [KR2010-0024, KR2012-0079].