Stratigraphical and structural constraints in the Lucanian Apennines (southern Italy): tools for reconstructing the geological evolution

The southern Apennines are characterized by the presence of tectonic units of internal derivation (Liguridi/Sicilidi Units) that have suffered several phases of tectonic transport. For this reason relies of such units rest now on the extreme front of the chain and they are often confused with tectonic units of more external derivation. The attribution of the different units to their original paleodomains needs different geological aspects to be considered: geometrics of the tectonic contacts, petrographical and stratigraphical characters; this in order to unequivocally distinguish apparently similar sequences which, on the contrary belong to different tectonic units. In three areas of the Southern Apennines (Lucanian sector) selected for the present study two tectonic wedges are distinguishible, both characterized by compressive deformation tied up to a thin-skinned tectonic context. The more ancient accretionary wedge (Late Oligocene-Early Miocene) is connected with the subduction of the Tethys oceanic crust (Liguride/Sicilide Units) which stopped at the collision between the European margin and the Maghrebide crust, a continental-type crust that separates the Tethys from the Ionian. The subduction of the Ionian oceanic crust took place since the Middle Miocene and continued in southern Apennines up to the Late Pliocene-Early Pleistocene. This tectonic phase resulted in the structuration of the accretionary wedge formed by the basinal Lagonegrese Units and by the External Flysch that overthrust upon the Pliocene foredeep deposits, as is clearly shown in well logs. The stratigraphic, petrographic and structural constraints lead us to the reconstruction of a geologic frame that takes into account the field evidence and provides a fruitful tool for understanding the geodynamic evolution of the Southern Apennines. (C) 2002 Published by Elsevier Science Ltd.