Evoluzione geomorfologica quaternaria del bacino del Fiume Vomano (Abruzzo)

Abstract

The study area covers the entire Vomano river basin (Abruzzo, central Italy), and is located between the Gran Sasso carbonatic ridge, to the W, and the Adriatic sea, to the E. It is characterized by geological and geomorphological elements allowing a good interpretation of the phenomena which led to the morphotectonic evolution of the Adriatic basin, starting from the Middle-Upper Miocene. From the Messinian to final Lower Pliocene, a progressive eastward migration of the foredeep domain had occurred followed by its transformation into a chain. In the external part of the area, the development of a piggy-back subsident basin, which had started in the Middle Pliocene, was associated with chain orogenic processes. During the deepening of the peri-Adriatic sedimentary basin, the emersion and continuos uplift of the Apenninic area is indicated by the presence of a sequence of erosional surfaces, which can be recognised throughout the Adriatic side of the Apenninic ridge, and by a series of discontinuities in the Plio-Pleistocene marine sequence. During the final emersion of the area, an erosional phase took place as a consequence of the fast regional uplift which had started during the Lower Pleistocene. This is confirmed by the presence of an erosional surface extending from the ridge to the Adriatic sea, and which cuts also the Sicilian deposits. Due to the effect of alternations of cold and temperate climatic phases, the low relief landscape was deeply cut through by an articulated hydrographic system, producing several orders of fluvial terraces, which are located at various elevation from the thalweg. The effects of the Middle-Upper Pleistocene extensional tectonics are highlighted by the dislocation of superficial deposits and paleosurfaces, by triangular or trapezoidal slopes, new scarps and steps, with the development of land irregular forms, sharp captures and deviations in the hydrographic network, and, by the activation of huge landslides in correspondence with recent faults.