Tectonic Evolution of the Northern Sicanian-Southern Palermo Mountains Range in Western Sicily: Insight on the Exhumation of the Thrust involved Foreland Domains

Geological mapping and structural analysis, coupled with extensive samplings on terrigenous Tertiary covers, enable us to reconstructthe structural setting as well as the tectonic evolution of the northern Sicanian-southern Palermo Mountains range in westernSicily. The analyzed region is a segment of the Apenninic-Maghrebian Orogen characterized by the occurrence of two regional superimposed tectonic edifices; the Apenninic-Maghrebian Chain (AMC)and the Pelagian Sicilian Thrust Belt (PSTB) which constitute the uppermost and lowermost structural level respectively.The different structural associations generally suggest a multiphasetectonic history in which we distinguished three main deformational events.The oldest one is characterized by the development of low-angleforeland-verging large thrust contacts. These usually propagated along Lower-Middle Miocene terrigenous levels and leads to the staking of the AMC. As a whole the AMC structured during MiddleMiocene and tectonically overrode the Pelagian foreland since Tortoniantime.The subsequent tectonic phase developed as effect of continental collision with the propagation of south verging high-angle thrustfaults. These involve mainly the underlying Pelagian foreland giving rise to the imbrications at depth of the PSTB.The more recent tectonic phase starts since Middle Pliocene with the activation of NW-SE oriented right-lateral traspressive shear zones and associated double verging E-W striking thrust contacts.These latter occurred mainly in the overlapping area between major shear zones and are responsible for the final uplift of the previouslyimbricate PSTB. During this tectonic stage the previously E-W oriented structural features suffered local clockwise rotations in theneighbours of the main right-lateral shear zones.In this newly proposed structural framework, we interpreted the Mt. Kumeta and Rocca Busambra carbonate ridges as a Pliocene push-up type antiformal structures grown and exhumed at strainingstepovers in a contest of regional strike-slip kinematics.