The extent of the Middle Ordovician Dapingian Stage in peri-Gondwanan Europe and north Africa: stratigraphic record, biostratigraphic tools and regional chronostratigraphy

Abstract

The boundaries and subdivisions of the global Dapingian stage cannot be adequately characterized in the extensive south-polar Gondwana continental shelves. Correlatable sediments, dated to some extent by palynomorphs, are generally highly condensed in shale facies ( < 10 m thick) or are entirely lacking, whereas in shallow-water sandstones they may locally reach more than 100 m thick. In the absence of valuable data derived from key macrofossils (graptolites and conodonts), the regional chitinozoan biostratigraphy has gone through numerous conceptual variations in the last 20 years, which has not helped a precise definition of the base of the Dapingian, provisionally included in the “upper” Arenigian regional stage of peri-Gondwana.

Keywords::

• Ordovician
• Dapingian
• Gondwana margin
• regional chronostratigraphy
• Chitinozoan biostratigraphy
• Europe

Acknowledgements

We would like to thank Esther Asselin (Québec) and Enrique Villas (Zaragoza) for their careful review of the paper. This work has been supported by the Spanish Ministry of Economic Affairs and Competitivity project “Iberian Ordovician chronostratigraphy and correlation with the global scale” (IBEROR, number CGL2012-39471/BTE) and is also a contribution to the IGCP Project 591 “The Early to Middle Paleozoic Revolution”.