Abstract
The evolution of the Mediterranean area since the Oligocene-Lower Miocene has been driven by the convergence of the surrounding plates. This implies that the observed deformation pattern in that region must be the most convenient shortening pattern, i.e. the one controlled by the minimum action principle. To understand why the fulfilment of such condition has required a complex spatio-temporal distribution of major tectonic events, such as uplift, lateral displacement and bending of orogenic belts, consumption of large lithospheric domains and formation of back arc basins, it may be very useful to take into account a basic tectonic concept, which helps to identify the process that can minimize the resistance of tectonic forces. Such concept starts from the fact that the most convenient consumption process is the one that involves low buoyancy oceanic lithosphere (Tethyan domains). However, such process is highly favoured where the oceanic lithosphere is stressed by vertical forces, a situation that develops when orogenic wedges are forced to over thrust and load the oceanic domain to be consumed. This interpretation can provide plausible and coherent explanations for the complex pattern of the observed deformations. In this view, the generation of back arc basins is taken as a side effect of an extrusion process, as suggested by numerical and mechanical experiments.
Highlights
We argue that a geodynamic context which can plausibly and coherently account for the major features of that tectonic event, such as starting and ending times, location and configuration of the stretched zone, trend of crustal extension, spatio-temporal distribution of magmatism, etc., may be identified by taking into account the large scale tectonic setting and boundary conditions that preceded the opening of the Northern Tyrrhenian basin
Since the resistance that acts in tectonic processes is mainly related to buoyancy forces, one might expect that the shortening required by plate convergence would be best accommodated by the sinking of oceanic lithosphere, which is characterized by the lowest buoyancy
We argue that the lateral escape of orogenic wedges in constricted contexts has played a basic role in the evolution of the study area, since this kind of process has made possible the consumption of large remnants of the Tethys ocean, which could have hardly developed if such structures were stressed by horizontal compression due to plate convergence
Summary
The structural/tectonic setting of the Central Mediterranean region (Figure 1) has undergone a drastic change since about the middle Miocene, mainly due to the formation of three basins (Northern, Central and Southern Tyrrhenian) with distinct locations and timings, strong deformation, migration and fragmentation of the previously formed peri-Adriatic orogenic belts (Alps, Apennines, Hellenides and Maghrebides), new accretionary activity at those belts, formation of a major discontinuity crossing the Ionian oceanic domain (Medina-Victor Hensen fault system) and the Hyblean-Pelagian African zone (Sicily Channel), stop of old subduction processes and activation or acceleration of new consuming boundaries, etc. Since at that time the only sector of the belt which was still facing oceanic lithosphere was the Calabrian arc (Figure 4), one may expect (in the minimum-action view) that the lateral escape of that buoyant orogenic wedge at the expense of the adjacent low buoyancy Ionian lithosphere was the most viable tectonic process
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
