Volcano-sedimentary beds of Oligocene age from the Tertiary Piedmont Basin (NW Italy): biostratigraphy and mineralogy

Biostratigraphy (planktic foraminifers and calcareous nannofossils) and mineralogy of volcano-sedimentary beds found in Oligocene hemipelagic marls outcropping in the SE margin of the Tertiary Piedmont basin have been studied. Two distinct volcano-sedimentary types were discriminated according to their mineralogical composition. The first type derive from alkaline volcanism and is Early Oligocene in age. The second type shows a calcalkaline affinity and is close to the Paleogene-Neogene boundary. In both types minerals suitable for radiometric age determinations occur.