Neogene deformations of Northern Sicily, and their implications for the geodynamics of the Southern Tyrrhenian Sea margin

The character of recent deformations along the southern Tyrrhenian Sea margin is controversial, in that it is explained either in terms of N-S convergence, or in terms of N-S extension. At odds with these extensional or contractional interpretations, analysis of kinematic data from NW-SE trending faults in northern Sicily and in the Egadi Islands reveals a dominantly right-lateral strike-slip character. Most faults are recent, but evidence is also present for an ancient fault, the Gratteri-Mt. Mufara Line, that was recently reactivated. Based on integration of these new data with available information on adjacent offshore structures, we propose that the southern Tyrrhenian Sea margin corresponds to a E-W trending dextral shear zone, namely to a strike-slip duplex, that was developed in response to a horizontal, NW-SW oriented contractional stress field.