Geology of the Irpinia sector of southern Apennines: new data for the analysis of the tectono-stratigraphic evolution

The Irpinia area, located between Sele and Ofanto river valleys, represents a key sector for analyzing the paleogeographic conditions and the tectono-stratigraphic evolution of the southern Apennine thrust belt. The geology of this area is described with new stratigraphic, petrographic and structural data. Subsurface geological data have been collected during the studies for the excavation works of the Pavoncelli bis hydraulic tunnel, developing between Caposele and Conza della Campania in an area that was highly damaged during 1980 Irpinia earthquake. Our approach includes geological, stratigraphic, structural studies, and petrological analyses of rock samples collected along the tunnel profile and in outcropping stratigraphic sections. Stratigraphic studies and detailed geological and structural mapping were carried out in about 200 km2 wide area. The main outcropping units have been studied and correlated in order to document the effects of tectonic changes during the orogenic evolution of the foreland basin systems and related sandstone detrital modes variations. In particular, the presence of quartzolithic arenaceous successions with volcanoclastic composition, related to the Early Miocene arenaceous successions of the Corleto/Albanella Sandstone Formations, and quartz-feldspathic arenaceous successions, related to the late Miocene Castelvetere Formation, have been documented in an exhaustive way both in the outcrops and in the tunnel underground sectors. The multi-disciplinary and updated datasets have allowed getting new insights on the tectono-stratigraphic evolution and stratigraphic architecture of the southern Apennines foreland basin system and on timing of kinematic evolution of the Apennines tectonic units. They also allowed to better understand the relationships between internal and external basin units within the Apennine thrust belt and its tectonic evolution.