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Article: Baltoscandian conodont biofacies fluctuations and their link to Middle Ordovician (Darriwilian) global cooling

Palaeontology Cover Image - Volume 61 Part 3
Publication: Palaeontology
Volume: 61
Part: 3
Publication Date: May 2018
Page(s): 391 416
Author(s): Jan A. Rasmussen, and Svend Stouge
Addition Information

How to Cite

RASMUSSEN, J.A., STOUGE, S. 2018. Baltoscandian conodont biofacies fluctuations and their link to Middle Ordovician (Darriwilian) global cooling . Palaeontology, 61, 3, 391-416. DOI: 10.1111/pala.12348

Author Information

  • Jan A. Rasmussen - Fossil and Moclay Museum Museum Mors Skarrehagevej 8 Nykøbing Mors DK‐7900 Denmark
  • Svend Stouge - Natural History Museum of Denmark University of Copenhagen Øster Voldgade 5–7 København K DK‐1350 Denmark

Publication History

  • Issue published online: 19 April 2018
  • Manuscript Accepted: 25 November 2017
  • Manuscript Received: 10 July 2017

Funded By

Carlsberg Foundation

Online Version Hosted By

Wiley Online Library
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The Middle Ordovician conodont genera that are suitable for palaeoenvironmental interpretations from the epicontinental Baltoscandian platform have been identified and evaluated to establish and describe conodont biofacies and their relationship to global cooling. The construction of biofacies was based on multivariate statistical analyses of more than 375 700 conodont specimens from 520 samples and 21 localities across Baltica. Three distinct, recurrent and laterally extensive conodont biofacies existed across the Baltoscandian platform of the Baltica continent during the Dapingian and early to middle Darriwilian stages (Middle Ordovician). A relatively shallow water conodont assemblage named the Baltoniodus–Microzarkodina Biofacies characterized the inner shelf localities in central Sweden, Estonia, Russia and Ukraine. In the distal shelf areas, patterns are more complex. Here, genera of the Periodon Biofacies characterized the shelf margin areas of the Scandinavian Caledonides facing the relatively warm Iapetus Ocean towards the north, whereas the Protopanderodus Biofacies dominated the distal shelf areas facing the cooler Tornquist Sea towards the south‐west. Although these three main biofacies continued to dominate during the succeeding Darriwilian stage, distinct changes in the distribution of biofacies took place during the transition from the Dapingian Stage to the Darriwilian. We argue that the biofacies change was triggered by a regressive event related to early Darriwilian cooling, and that the palaeoclimatological changes influenced the Baltic conodont faunas near the Tornquist Sea margin before those of the Iapetus margin (early vs middle Darriwilian).

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