Neogene tectonostratigraphy and kinematics of Calabrian basins; Implications for the geodynamics of the Central Mediterranean
A new structural model for the Calabrian Arc (Southern Italy) is presented, based on a systematic analysis of basin kinematics combined with a review of the literature on basement structure. Three tectonic patterns can be distinguished: (A) NW-SE trending oblique thrust zones, determining a set of N130 trending segments, (B) SW-NE to E-W trending thrust zones, and (C) radial and concentric tensional fault systems in the southern Tyrrhenian back-arc area. These faults, combined with dome-shaped uplift centres determine the actual arc. Patterns A and B can be regarded as the on-shore representation of the Calabrian accretionary-wedge system. The kinematics of various types of basins such as piggy-back, pull-apart and complex-oblique-strike-slip basins are connected to these patterns. The patterns A and B can be linked to the Middle Miocene-Early Pliocene development of oblique, convergent crustal shear zones ("strike-slip cycle"), whereas pattern C can be linked to the Pleistocene collapse of the Southern Tyrrhenian basin and concentric uplift of the arc. Our structural model has considerable implications for the understanding of the kinematic evolution of the Central Mediterranean. We propose a model in which the evolution is characterized by an alternation of the translation of the Calabrian lithosphere element either to the southeast (gravitationally) or to the northeast (compression). Combining (a) our analyses of basin evolution, (b) the structural model and (c) some considerations concerning kinematics of the Central Mediterranean, with the geodynamic mechanisms as proposed in literature, we present a model which consists of a geodynamic cycle comprising the following three stages: (1) a tension stage with back-arc basin opening related to the diapiric inflow of asthenosphere material and roll-back of the subducted Ionian slab, resulting in gravitational displacement of the Calabrian Element to the southeast, (2) a transpression stage with oblique overthrusting towards the northeast upon the Southern Apennines, and (3) a compression stage with NE-SW compression due to oblique dextral shear along the North African margin, plate rupture/lithosphere split and back-arc basin collapse.