Biostratigraphical correlation and geochronology of volcaniclastic horizons across the Tortonian/Messinian boundary in the Apennine foreland basin system

In northern and central Apennines several volcanogenic horizons, interbedded in different stratigraphic intervals within Neogene deposits, have been detected. This study deals with the correlability of some of this horizons deposited during Late Miocene in different sites of the Apennine foreland basin system. Two volcaniclastic levels outcropping respectively in the Peglio (northern Apennines) and the Pietrasecca (central Apennines) sections have been studied. Both the horizons have been analysed from a petrographic and biostratigraphical point of view. Moreover, a geochronological study has been performed on the Peglio layer, comparing the results with the data already obtained for the Pietrasecca layer. 40Ar-39Ar analyses failed to provide unequivocal chronological informations, due to disturbance of the isotopic system: obtained dates on plagioclases (