ASSETTO GEOLOGICO-STRUTTURALE DELLA DORSALE NARNESE-AMERINA A NORD DI AMELIA (APPENNINO CENTRALE)

Abstract

Structural analysis carried out in the area in the north of Amelia, in the Umbrian pre-Apennines; the aims is to define the continuity in the north of the Nami thrust structure, that characterizes more in the south the Nami-Amelia Ridge. In this area is possible to define a structural building made of a higher unit (Ul) that consists of a N 140° trending axis anticline, overthrusted onto a M. Cimarone - M. la Croce unit. The thrust plane is offset by a normal fault, trending NW­SE, between Amelia and Macchie. A tectonic element made of the overtumed pelagic sequence is localized between the han­gingwall and the footwall. The M. Cimarone - M. La Croce unit is overlie to the east on a footwall involved in minor N-S tren­ding folds, by a thrust plane cropping out between Frattucce and Sambuceto. Taking into account the structural setting of these units, is possible recognized the Nami anticline hanging­wall in the Ul unit of this area. On the base of a deformation model of a blind thrust pre­ceding the development of a thrust plane that leads to the overth­rusting of the overtumed anticline on its footwall, two geologi­cal section were restored and the value of shortening calculated. The shortening for the whole structure is about 9 km, campati­ble with the value calculated for the Nami thrust in the south.