Geomorfologia e neotettonica nel Bacino di Tavernelle/Pietrafitta (Umbria)

Abstract

The evolution of the Tavernelle basin can be inferred from the analysis of geological, geomorphological and paleontological data. Particularly, the changes in the hydrographical net are suggestive of tectonic activity and chronological sequence. Extensional tectonics caused a progressive sinking of the area on the East of Città della Pieve, most of which was the paleoNestore basin. As a consequence, there was an inversion of the river flow and a large lake was formed. The lake persisted in this region during the whole lower Pleistocene, while at the same time, a normal-fault-system produced a general southeastward tilting. The erosive event "Aulla" favoured the drainage of the Tavernelle basin; at the same time the relict basin of Pietrafitta was left. This latter originated a wide iignitiferous deposit, which is mined out at present. A new erosive cycle ("Cassio"), giving rise to a drainage area near Castiglion della Valle, caused also the Pietrafitta basin to dry up.