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

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.     

Integrated biostratigraphic and sequence stratigraphic framework for Upper Cretaceous strata of the eastern Gulf Coastal Plain, USA

Upper Cretaceous (Santonian-Maastrichtian stages) strata of the eastern US Gulf Coastal Plain represent a relatively complete section of marine to nonmarine mixed siliciclastic and carbonate sediments. This section includes three depositional sequences which display characteristic systems tracts and distinct physical defining surfaces. The marine lithofacies are rich in calcareous nannoplankton and planktonic foraminifera which can be used for biostratigraphic zonation. Integration of this zonation with the lithostratigraphy and sequence stratigraphy of these strata results in a framework that can be used for local and regional intrabasin correlation and potentially for global interbasin correlation. Only the synchronous maximum flooding surfaces of these depositional sequences, however, have chronostratigraphic significance. The sequence boundaries and initial flooding surfaces are diachronous, and their use for correlation can produce conflicting results. The availability of high resolution biostratigraphy is critical for global correlation of depositional sequences.