Upper Cretaceous Deep-Water Agglutinated Foraminifera from the Contessa Highway Section, Umbria-Marche basin, Italy: Taxonomy and Biostratigraphy

The taxonomy and biostratigraphy of deep-water agglutinated foraminifera (DWAF) are documented in a 299 m thick section collected from the Upper Cretaceous (Turonian to Maastrichtian) of the Scaglia Bianca and Scaglia Rossa Formations in the Contessa Highway section of Italy. A total of 94 species belonging to 48 genera are documented from the section, including two new species: Subreophax longicameratus n.sp., and Hormosinella fusiformis n.sp.. The DWAF assemblages display a general trend of increasing abundance and diversity from the Cenomanian/Turonian boundary to the Cretaceous/Paleogene boundary. The biostratigraphy of DWAF in the Upper Cretaceous part of the Contessa Highway section is calibrated to the 2008 ICS timescale by means of the calcareous nannofossil biostratigraphy. Nine calcareous nannofossil biozones are determined in the interval CC10 to CC26, but some of the Upper Cretaceous nannofossil biozones could not be determined owing to poor preservation or the absence of index taxa. The first occurrences of biostratigraphically important DWAF species are compared with the first occurrences in the Upper Cretaceous of the Carpathians and the North Atlantic. The agglutinated foraminiferal biozones of the Carpathian schemes of Geroch & Nowak (1984) and Neagu et al. (1992) and the North Atlantic zonation of Kuhnt et al. (1992) cannot be applied in their entirety to the Contessa Highway section owing to the scarcity of some index taxa. Four Upper Cretaceous DWAF biozones described from the Atlantic and Western Tethys are recognised in the Scaglia formations at Contessa: the lower Turonian Bulbobaculites problematicus Zone, the upper Turonian to Coniacian Uvigerinammina jankoi Zone, the Santonian to Campanian Caudammina gigantea Zone, and the Maastrichtian Remesella varians Zone. However, some of the cosmopolitan index taxa, such as Bulbobaculites problematicus and Uvigerinammina jankoi have truncated stratigraphic ranges. The oligotrophic palaeoenvironmental conditions represented by the red deep-water Scaglia Rossa limestones cause flysch-type species such as Uvigerinammina jankoi and Caudammina gigantea to be rare, and in the case of Rectoprotomarssonella rugosa, an index species for the Lower Campanian, to be absent. Nevertheless, the Uvigerinammina jankoi Zone in Contessa can be correlated with the Carpathian Basins and the North Atlantic. Agglutinated foraminiferal assemblages are similar in taxonomic composition to those of the Carpathian Basins but in addition, a series of small abyssal type Haplophragmoides species known from the North Atlantic DSDP/ODP sites are present in the Contessa Highway section, probably as a result of oligotrophic conditions in the central Tethys. The abundance of agglutinated foraminifera at Contessa displays mimima during sea level high stands in the late Turonian, late Coniacian, late Santonian, early Campanian. These low abundance assemblages likely indicate enhanced oligotrophy as result of sediment starvation. The foraminiferal abundance and diversity values generally increase upsection, and typical "flysch-type" species appear in the record, indicating more detrital influx and a change to more mesotrophic conditions in the Campanian.