Pliocene foraminifera of Piedmont (north-western Italy): a synthesis of recent studies

A synthesis of recent biostratigraphical and palaeoenvironmental studies on foraminifera assemblages of he Piedmont Pliocene (north-astern Monferrato, Astigiano, Langhe and Monregalese) is discussed. In the region, biozone MPl1 is documented by typical Sphaeroidinellopsis assemblages only in its central area. Rich and diversified assemblages of MPl2 biozone, with Globorotalia margaritae Bolli & Bermudez, and MPl3 biozone, with G. margaritae and G. puncticulata (Deshayes), are indicative of the upper epibathyal zone, and suggest palaeoenvironmental conditions similar to those of coeval pelagic successions of Sicily and the Tyrrhenian Sea. Already along biozone MPl3, and chiefly biozone MPl4, with G. puncticulata, less diversified assemblages become more widespread, indicating shelf palaeoenvironments, subject to heavy transport of displaced foraminifera from more inner neritic zones. In the study area most inner neritic and shallow outer neritic microfaunas are devoid of biostratigraphic markers; only few silty sediments yield Bulimina basispinosa Tedeschi & Zanmatti and Globobulimina ovula (d’Orbigny), reported from the Middle Pliocene, and can be correlated to the MPl5 biozone.