Dinoflagellate cyst biostratigraphy of Upper Cretaceous turbiditic deposits from a part of the Bąkowiec section in the Skole Nappe (Outer Carpathians, southern Poland)

Abstract

Dinoflagellate cysts from turbiditic deposits of the Ropianka Formation in an interval of the Bąkowiec section (Skole Nappe, Outer Carpathians, southern Poland) have been analyzed. This interval, previously attributed to the Cretaceous–Paleogene boundary transition based on planktic and benthic foraminifera, contains organic-walled dinoflagellate cysts (dinocysts) of a latest Campanian age. The difference in age, revealed here between foraminifera and dinocyst findings, is considered as an unresolved dilemma, which is pending some explanations, probably on the basis of further multidisciplinary studies envisaged in the same outcrop. The palynological content is well preserved and rich in dinocyst cyst taxa, including 37 upper Campanian index species among 92 species in total. The dinocyst assemblages observed in this interval are similar to those previously recognized in biostratigraphically well-calibrated sections of Western Europe. The dinocyst marker events enabled a correlation of the studied interval with the Samlandia mayi dinocyst Zone of Slimani (2001a), which is an equivalent to the Belemnitella minor Zone in the northwestern Europe. These dinocyst events include the first occurrences (FOs) of Kleithriasphaeridium truncatum, Nematosphaeropsi philippotii, Samlandia carnarvonensis, Samlandia mayi and last occurrences (LOs) of Corradinisphaeridium horridum, Raetiadinium truncigerum, Odontochitina operculata and Xenascus ceratioides subsp. ceratioides. The palynological content shows significant reworking of Campanian dinocyst taxa and a richness in palynodebris of continental origin, which are likely related to deposition by turbiditic currents.