Last occurrence of Abathomphalus mayaroensis (Bolli) foraminiferid index of the Cretaceous–Paleogene boundary: the calcareous nannofossil proof

Abstract

AbstractIn the Gaj section (Polish Carpathians, Skole Nappe, Ropianka Formation), the Late Maastrichtian calcareous nannofossil biostratigraphy is compared with foraminiferal zonation based on the occurrence of the planktonic foraminiferid index speciesAbathomphalus mayaroensis. It appears that the LO ofA. mayaroensis, which has been used previously in the studied section as the possible K/Pg boundary indicator is located below the boundary. The disappearance ofA. mayaroensisalong with other planktonic foraminiferids before the Cretaceous–Paleogene (K/Pg) boundary mass extinction event may be a consequence of the Late Maastrichtian rapid warming pulses. Moreover, the Paleogene age cannot be supported by the FO of the benthic foraminiferidRzehakina fissistomata,because it first appears together with the nannofossilCeratolithoides kamptneri(zonal marker for the latest Maastrichtian UC20cTPZone). According to the present study, the whole studied section represents the lower Upper to the upper Upper Maastrichtian UC20bTPand UC20cTPnannofossil zones, so that it corresponds to the lower-middle part of the planktonic foraminiferalA. mayaroensisZone, which, according to the scheme by Caron (1985), should extend up to the K/Pg boundary.