Mariusz Kędzierski

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

Abstract In 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 species Abathomphalus mayaroensis. It appears that the LO of A. mayaroensis, which has been used previously in the studied section as the possible K/Pg boundary indicator is located below the boundary. The disappearance of A. mayaroensis along 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 foraminiferid Rzehakina fissistomata, because it first appears together with the nannofossil Ceratolithoides kamptneri (zonal marker for the latest Maastrichtian UC20cTP Zone). According to the present study, the whole studied section represents the lower Upper to the upper Upper Maastrichtian UC20bTP and UC20cTP nannofossil zones, so that it corresponds to the lower-middle part of the planktonic foraminiferal A. mayaroensis Zone, which, according to the scheme by Caron (1985), should extend up to the K/Pg boundary.