Notes on some lateral spreading phenomena around Roccalbegna – Mt. Labbro (Tuscany, Italy)

Abstract

In the area around Roccalbegna up to Mt. Labbro competent calca-reus rocks (Calcareniti di Dubba and Calcareniti di Montegrossi) overlie lithotypes with duclite behaviour (Marne del Sugame and Argilliti di Bro-lio) with sub-horizontal setting. Lateral spreading phenomena are indicated by the trenches observed on the different calcarenitic slabs; these tranches are the consequence of tectonic fractures evidently opened up in recent times by gravitational movements. The activity of slope movements is connected to the recent uplitft due to the magmatic chamber setting in the Quaternary M. Amiata volcano. Toppling and rock falls are widespread along the edges of the calcarenitic slabs producing talus of debris at the base of the slopes; the talus are later removed by debris flows or landslips.