Considerazioni sul significato paleoclimatico di una serie lacustre pleistocenica inferiore presso Tavernelle (Perugia, Umbria)

New data on the paleoclimatic and geodinamic significance of a lacustrine lower Pleistocene series near Tavernelle (Perugia, Umbria)

Abstract

In this work a lower Pleistocene lacustrine series, located near Tavernelle (Umbria), is examined. The series is horizontal and has been affected by a system of parallel faults at the western margin of the basin. It is made up by clays and travertine silts rich in freshwater mollusks of Villafranchian tradition. At the West the series is overlain by detritical coarse sediments and in the middle of the basin by Pietrafitta lignitic level. Before the setting of the lignitic facies, which ends with the Cassio erosional phase, a renewed tectonic activity is pointed out. It is also testified by sedimentological evidences and is referred to the “Aulla phase”, to which a beginning of a climate worsening corresponds, testified by the extinction of the “warm” Villafranchian species. The 50 % of mollusk species extinguish at the end of lower Pleistocene. The whole association shows a climatic transition phase to the middle Pleistocene cold phases.