Le superfici relitte della regione fucense (Appennino centrale) ed il loro possibile significato nella ricostruzione dell'evoluzione geologica

Abstract

Remnant surfaces are a common feature of Apenninic landscapes. They are a clear indication of ancient erosiona! base levels and can be considered as significant pauses in the dissection of the uplifting chain. Successions of several orders of remnant surfaces, which are variously set into one another, may have analogous significance to that of terrace flights. This paper reports the results of a morphological study carried out to recognize and interpret the remnant surfaces of the area surrounding the Fucino Basin in order to reconstruct its geological evolution. The study was based on map analyses integrated with aerial photo interpretation and field surveys in an area of approximately 1500 km2. A large number of remnant surfaces have been identified either on the hilltops or hanging onto the slopes of present ridges and valleys at elevations between 1950 and 800 m a.s.l. Up to 12 surfaces have been identified in single successions. From the chronological point of view, available stratigraphical references allowed to attribute the surfaces to 3 chronological time intervals: The first corresponds to an undefined Pliocene time, the second ranges from the lower Pleistocene to part of the middle Pleistocene, and the third falls in a generic upper part of the middle Pleistocene. It has also been possible to subdivide the area into 4 homogeneous sectors, each of which being characterized by a given number of remnant surfaces with essentially homogeneous geometric relationships between one another. On the basis of the correlability between surfaces, it is hypothesised that the difference between surface successions is mainly due to a different vertical component in Plio-Quatemary tectonic movements. Support to this hypothesis is given by the fairly good correspondence between the boundary of identified sectors and some tectonic structures known from the literature. This correspondence is particularly evident for the Mount Velino-Magnola border structure, the "Tre Monti" fault, the "San Benedetto-San Potito" fault and for the fault along the southern flank of Mount Sirente.