The Apennines constitute part of the main mountain system of the Mediterranean region (Fig. 1). The chain evolved within the framework of the convergent motion between the African and European plates and related microplates since Late Cretaceous time (Mazzoli & Helman, 1994; Critelli, 1999; and references therein). They are formed by a fold and thrust belt–foredeep system that records east-thrust transport directions and accompanied by the development and deformation of progressively younger turbiditic deposits to the east. These features indicate tectonic accretion due to a westward dipping subduction slab since at least Oligo-
Miocene time. As a result, the back-arc development of the Western Mediterranean basins (e.g. Algero-Provencal and Tyrrhenian Basins) are linked to the eastward rollback of the Adriatic slab (Fig 1).

Figure 1 – Geological map of the main mountain system iof the Mediterranean region.

The early configuration of the subduction system (Late Cretaceous– Oligocene interval) is still a matter of debate, particularly for the segment of chain between the southern Apennines and the Sicilian Maghrebids, commonly known as Calabria– Peloritani Arc, where crystalline basement and ophiolitic nappes crop out (Fig. 1). Since Late Oligocene-Early Miocene time convergence occurred between the Corsica–Sardinia–Calabria block, to the west, and the Apulia (or Adria) block, of African affinity, to the east (Fig. 2). The subduction and collision produced the structure of belt characterized by an imbricate thrust system propagating towards the foreland and accompanied by several syntectonic sedimentary successions (Figs.3-4).

Figure 2 - Palinspastic restoration of the Central Mediterranean region in the late Oligocene (about 30 Ma) showing the distribution of the Central and Southern Apennine platforms and basins before their incorporation in the mountain chain. 1) European foreland. 2) Paleogene mountain chains. 3-6) African foreland: 3) shallow-water carbonate platforms; 4) deeper-water basins floored by oceanic or thinned continental crust; 5) basinal areas with isolated structural highs; 6) wide pelagic plateau; 7) fronts of the orogenic belt, (from Patacca & Scandone, 2007).

Figure 3 - Schematic representation of the geometric relationships between the tectonic units of the southern Apennines (from Patacca & Scandone, 2007).

At the boundaries of northern Calabria and southern Basilicata, the Meso-Cenozoic carbonate successions of the Apennines are in contact with the crystalline Calabrian Arc (Fig. 1). According some Authors, the stratigraphic and structural lineaments of the Pollino area showed the occurence of three main imbricate carbonate units; from bottom to top, they are:

• the metamorphic "S. Donato Unit", which consists of a lower terrigenous interval (Werfen facies with organogenic carbonate, buildups, Early Triassic-Permian in age) and an upper carbonatic interval to which a genetic Triassic age could be assigned;
• the "Carbonate Platform Unit" formed by two tectonic subunits both ranging from Triassic to Eocene (Verbicaro and Pollino Units). These two elements are mainly constituted of neritic carbonate and of eteropic pelagic deposits which show the same kinematic evolution.

In the northern part of this region, three main groups of nappes may be distinguished: (1) crystalline basement nappes (Calabride Complex in Fig. 5 ); (2) ophiolite-bearing nappes (Liguride Complex in Fig. 5); (3) mostly calcareous nappes (Panormide Complex in Fig. 5) derived from the inner part of the Apulia continental margin. Group (1) includes Hercynian metamorphic and crystalline rocks and Mesozoic deposits of the Sila Unit. These Paleozoic units overlie ophiolite-bearing units, ranging from greenschist- facies (Malvito Unit), showing in some cases (Reventino– Gimigliano Unit) evidence of an earlier HP–LT metamorphic event, to blueschist-facies metamorphism (Diamante–Terranova Unit). Some of these units, the HP–VLT (very low temperature) Frido Unit and the unmetamorphosed Calabro- Lucanian Flysch Unit. The latter crop out NE of the Pollino Massif, in Calabria– Lucania border area (Figs. 4-5). This metasedimentary or sedimentary cover includes the uppermost Oligocene and Aquitanian units, respectively.