V. Spina

Neogene tectonostratigraphic evolution of allochthonous terranes in the eastern Calabrian foreland (southern Italy)

Along the Ionian side of the Calabrian Arc, Neogene-Quaternary successions overlie the Hercynian basement made up of crystalline-metamorphic tectonic units and their Mesozoic-Tertiary cover. The Neogene successions rest unconformably along the eastern border of the Sila Massif and form the Neogene basin fills. In the external portion of basins, Oligocene-Lower to Middle Miocene clastic successions, overling the variegated clay of the Sicilide Complex, outcrop. The Miocene-Quaternary evolution of the northern Calabria was mainly associated with the accrectionary processes creating Miocene wedge-top depozones onto the growing orogenic belt and flexed Adria passive margin. Middle Miocene deposits accumulated in longitudinal wedge-top depozones of the Calabrian foreland-basin system, partitioned into three depocentres: the Rossano, Ciro, and Crotone basins. The surface, subsurface and aerial-photo analyses has provided new geological data, which better define the architecture and development of the allochthonous terranes outcropping in the northeastern wedge-top basins of the Calabrian Arc. The main onland outcrop of allochthonous units is represented by the so-called Cariati Nappe. Structural investigations allowed to characterize the surface and subsurface tectonic structures detailing the style and timing of the Cariati Nappe emplacement. This structure consists of a complex NW-SE oriented back-thrust (top to the west) propagated starting from the late Tortonian time. During Messinian-Pleistocene the allochthonous terranes were involved and reworked by left-lateral NW-SE oriented transpressive fault zones. Progressive propagation of these transpressive structures compartmentalised pre-Messinian formerly continuous basin, creating distinct asymmetric depocentres during the Messinian and Pliocene. The entire Ionian Calabrian margin experienced accretion during the Neogene in consequence of which portion of Varicoulered Clays, overlain by Oligocene-Miocene successions, were extruded and emplaced into the wedge-top basins.