Analisi geologico-strutturale dell'area di Pietrafitta-Tavernelle (Umbria occidentale, Italia centrale)

Abstract

This paper illustrates the results of a geo-structural analysis carried out in the area of the Pietrafitta-Tavernelle open-pit mine, a basin in western Umbria (Central Italy) where Pleistocene lignite-bearing continental sequences of clay and sand outcrop. The main tectonic features of these sediments are folds, faults and two sets of systematic joints. Folds in the lignite have wide limbs and the hinge line striking NNW-SSE. Main faults are NE-dipping normal faults with displacements of tens of meters. Extensional faults are cut by ENE-WSW trending sinistral and N-S trending dextral strike-slip faults. Joints are both of the extensional and shear type: extensional joints are arranged in a NW-SE direction and shear joints are aligned in a NNE-SSW direction. The surveyed tectonic features of the area can be related to different stages of the extensional tectonic phase with direction of maximum stress oriented NE-SW, which has affected western Umbria since the Late Pliocene.