Infrazonal biostratigraphy of the Upper Cretaceous in the East European province based on benthic foraminifers, Part 2: Santonian-Maastrichtian

Abstract

A chart of infrazonal biostratigraphic subdivisions in the Cenomanian-Coniacian succession of the East European paleobiogeographic province is substantiated based on distribution of benthic foraminifers. The suggested chart characterizes successive trend of changes in ecologic assemblages of benthic foraminifers and morphologic evolution of certain agglutinated (Gaudryina, Ataxophragmium, Ataxoorbignyina, Arenobulimina, Novatrix, Voloshinovella, Orbignyina, Bolivinopsis) and secretory (Neoflabellina, Globorotalites, Stensioeina, Osangularia, Eponides, Gavelinella, Pseudovalvulineria, Pseudogavelinella, Brotzenella, Cibicides, Cibicidoides, Angulogavelinella, Falsoplanulina, Anomalinoides, Coryphostoma, Bolivinoides, Praebulimina) foraminiferal genera. The chart includes 23 biostratigraphic units (zones and subzones), most of which are recognizable over the vast territory from the Mangyshlak to southern Baltic areas. It is correlated with the acknowledged belemnite, inoceramid, ammonoid and echinoid zonations. Eight stadia of taxonomic changes in foraminiferal assemblages, which are distinguished in this work, show that principal biotic events took place across the middle-late Santonian and Santonian-Campanian boundaries, in the earliest Campanian, at the early-late Campanian boundary time, during the late and terminal Campanian, and in the mid-early Maastrichtian.