Chapter C1 Integrated stratigraphy near the oligocene/miocene boundary in the piedmont basin (Italy): Biostratigraphy and geochronology

Publisher Summary This chapter discusses the biostratigraphy and geochronology of integrated stratigraphy near the Oligocene/Miocene boundary in the Piedmont basin (Italy). The Piedmont Tertiary Basin (northern Italy) is a well-suited area for location of the Oligocene/Miocene boundary. The search for the definition of a Global Stratotype Section and Point (GSSP) has been undertaken for a long time, and special attention has been focused on the Lemme section, near Carrosio, and in the surrounding palaeobasin where volcaniclastic layers have been found. In the whole region surrounding the Lemme Valley, an erosional hiatus is present at the top of “Marne di Rigoroso” formation. Usually, early or late Burdigalian sediments directly overlie the Marne di Rigoroso formation. A smaller hiatus is present in a restricted sector near Carrosio where the Aquitanian portion of the Marne di Rigoroso is not eroded. Otherwise, this chronostratigraphic interval is totally missing in adjacent areas. Therefore, the site near Carrosio is exceptional compared to the surrounding outcrops.