Publisher © Czech Geological Survey, ISSN: 2336-5757 (online), 0514-8057 (print)
Late Turonian and Turonian-Coniacian boundary according to study of calcareous nannofossils in the Bohemian Cretaceous Basin, Jizera development
Abstract
The evaluation of Turonian-Coniacian boundary according to study of calcareous nannofossils has not been satisfactorily solved yet. In the Bohemian Cretaceous Basin, following succession of nannofossil species has been recorded in the Upper Turonian deposits: FO (first occurrence) Lithastrinus septenarius and Marthasterites furcatus, FO Zeugrhabdothus biperforatus, FO Arkhangelskiellaceae (specimens > 5-6 |m) ?Broinsoniparca expansa, LO (last occurrence) Helicolithus trabeculatus, base of "acme" M. furcatus (closely below FO Cremnoceramus waltersdorfensis). The Coniacian nannofossil marker species were not found. Short interval with Liliasterites angularis between FO L. septenarius and FO Z. biperforatus and its probable importace for local stratigraphy is discussed. Material was sam- pled during geological research and geological mapping and from the V 800 Strelec borehole.
