Maastrichtian climate changes – the calcareous nannofossil record from flysch deposits of the Outer Carpathians

Abstract

The Maastrichtian, last of the Cretaceous stage, was ended by Cretaceous/Palaeogene (K-Pg) extinction event, recognized as one of the five most severe extinctions throughout the entire Phanerozoic. Therefore, this event marks also beginning of a new era (the Cenozoic). Naturally, such a phenomenon focused the attention of many scientists, leading over time to the enunciation of two main hypotheses explaining possible causes of the event, i.e. an asteroid impact (Alvarez et al., 1980) or intense volcanism (MacLean, 1985).However, these two possible circumstances, which could have led to the end-Cretaceous catastrophe, differ basically in the time of duration, i.e. the rapidness of change, and the stratigraphic position of their record. Thus, the evidence of a sudden and very short-lived extraterrestrial bolide impact ending the Maastrichtian would have been recorded in post-impact deposits belonging stratigraphically to the youngest Danian, or the Cenozoic. In contrast, volcanism during some period before the extinction event should have left its footprint below the K-Pg boundary.Indeed, many studies of the uppermost Maastrichtian deposits revealed their individual geochemical feature that may be linked to phase 2 of Deccan volcanism, initiated