Dinoflagellate cysts and palynofacies across the Cretaceous-Paleogene boundary interval of the Vrancea Nappe (Eastern Carpathians, Romania)

Abstract

A palynological study of uppermost Maastrichtian to Lower Paleocene deposits from a stratigraphic section of the Vrancea Nappe (Eastern Carpathians), reveals the presence of diverse and well-preserved dinoflagellate cyst assemblages. The biostratigraphic interpretation of these dinocyst assemblages suggests that (1) the Cretaceous-Paleogene boundary lies within a ~8 m thick sedimentary interval, between the Lepşa Formation (uppermost Maastrichtian) and Putna-Piatra Uscată Formation (Lower Danian), based on the Last Appearance Datum of latest Maastrichtian markers such as Pterodinium cretaceum and Palynodinium cf. grallator and on the First Appearance Datum of Danian markers such as Senoniasphaera inornata, Xenicodinium lubricum, Tectatodinium rugulatum and Eisenackia circumtabulata, and (2) a discontinuity between the two formations. The palynofacies analysis from this geological section indicates an abundance of continental organic matter (mainly opaque phytoclasts), deposited in a distal setting of the sedimentary basin. The occurrences in the palynological assemblage of some oceanic dinocyst taxa such as Impagidinium and Pterodinium suggest the same depositional environment for the geological formations analysed.