Lowermost Cretaceous limestones from the Kučaj zone (Carpatho–Balkanides, Eastern Serbia): new data on their age assignment

Abstract The lowermost Cretaceous carbonate deposits of the Carpatho–Balkanides (Eastern Serbia), which crop out in the Kucaj zone, were studied in three sections: Kamenica, Prekonozi and Jerma River Canyon. The identified micropalaeontological assemblages generally consist of calcareous green algae (mainly dasycladaleans), benthic foraminifera (mainly orbitolinids, cyclaminids, pfenderinids), and scarce calpionellids. The dasycladalean algal association comprises mostly species known from the Berriasian–lower Valanginian. The same age is also indicated by the majority of the identified benthic foraminifera, except for the orbitolinids from the upper parts of the sampled successions that hitherto were only known from the upper Hauterivian–lower Aptian of Southern France and Northern Spain. The co-occurrence of Berriasian–lower Valanginian algae and benthic foraminifera with Hauterivian–Aptian orbitolinids challenges establishment of the age of the sampled succession and, potentially, other carbonate successions too. The recognition of rare calpionellid specimens in samples containing orbitolinids can resolve this dilemma. Calpionellids are planktonic microfossils with a well-defined stratigraphic distribution within the Neotethyan realm; consequently, the identified species belonging to Calpionellopsis zone confirm a late Berriasian age. In addition, it should be emphasized that some of the orbitolinids known until now only from upper Hauterivian–lower Aptian deposits were already present in the studied region from the base of the upper Berriasian.