First evidence for the Homerian (late Wenlock, Silurian) positive carbon isotope excursion from peri-Gondwana: new data from the Barrandian (Perunica)

摘要

The Homerian (late Wenlock, Silurian) carbon isotope excursion is documented for the first time from peri-Gondwana based on new data from the Barrandian (Perunica). It is also the first time that this excursion has been found outside of the palaeoplates that subsequently formed the supercontinent Laurussia (i.e., Laurentia, Baltica and Avalonia). The typical two-peaked Homerian δ13C excursion is documented from a highly fossiliferous shallow-water limestone succession formally established here as the Kozel Limestone Member of the Motol Formation. Application of δ13C chemostratigraphy considerably improves the stratigraphic resolution within the Kozel Limestone Member and enables more precise dating of its very diverse fauna. The present data reveal recovery of benthic communities after a series of mid-Homerian extinction events (i.e., the Mulde conodont and the end lundgreni graptolite bioevents) started much earlier than has been hitherto described from other world occurrences.