The origin of the Apenninic arcs

Abstract

The Apennine area is composed of a variety of arcs, some of them forming the mountain chain and some of them being submerged below the Po Plain and the Adriatic Sea. The structure of the Apennine mountain belt is that of a succession of northeast-, east- and southeastward directed arcs corresponding to single thrust sheets. Each arc is limited by N-S oriented dextral transcurrent faults. Data from volcanology, gravimetry and reflection seismic surveys show that an important section of the upper mantle is involved in these features. The geodynamic reconstruction during Neogene times i.e., the period of Apenninic up-building, suggests that a unique arc existed from Oligocene to Middle Miocene times as a result of the rotation of the Sardo-Corso continental block. This arc was successively disrupted in several segments which advanced and shortened differentially as a function of the resistance to the orogenic expansion opposed by the rigid Adriatic foreland. This new tectonic phase, which is responsible for most of the Apenninic features, has been triggered by the differential evolution of anomalous mantle domes in the Tyrrhenian area from post-Middle Miocene times onwards.