Field and seismic reflection constraints for the geometric and kinematic characterization of the Quaternary extensional fault system in the Campania-Lucania arc (Southern Apennines, Italy)

The Campania-Lucania Apennines have long been a subject of significant scientific interest due to their stratigraphic-structural setting and the hydrocarbon exploration. This portion of the Apennines is also affected by recurrent and intense seismic activity, including some of the strongest historical and instrumental events, such as the “recent” Irpinian earthquake of 1980. The broad scientific literature suggests that much of this seismicity is extensional and is associated with Pleistocene-Holocene normal faults, whose deformation produced NW-SE elongated continental basins. In the north-eastern sector of the Alburni Mountains, east-dipping normal faults dominate the extensional structural setting; there are clear evidences that they represent the surface expression of a regional synthetic detachment surface. This work aims to understand if the same deformational style can be generalized to the entire internal sector of the Campania-Lucania arc from the Sele plain, to the Mt. Cervati massif, located a few tens of km south-west. The survey of key-areas provides new data to integrate into a database for the creation of a regionalscale geological-structural map, drawn up by reprocessed seismic data from literature. The area extends onland from the southern flank of the Picentini Mountains to the northwestern border of Mt. Pollino, covering approximately 9000 km2. These data constitute the surface constraint through which four shallow geological cross-sections are drawn; their integration with the logs of some calibration-wells available from literature, enables the interpretation of a grid of 12 seismic lines. The lines are provided by both the Eni and the openlyaccessible Videpi database. Their conversion to depth led to obtain a series of crustal sections that allow us to compare both the contractional and extensional structures across the entire study area. The geological sections and seismic lines, interpreted down to the top of the Apulian Platform, shed light on the following significant aspects: i) the subsurface geometry of the extensional fault systems, ii) the depth and sense of dip of their detachment surface, iii) the hierarchy between conjugate faults, iv) the relationships occurring at depth between normal faults and the main thrust surfaces, v) the shape of syn-tectonic Quaternary depressions (Auletta basin, Diano Valley and Agri Valley) and the thickness of the sedimentary infill, vi) the role of every single structure in the regional tectonic setting, and vii) the geometry of the pre-extensional state with an estimate of the elongation obtained from the restoration of the main cross-sections. The results of this work contribute to the building of a comprehensive 3D model of active extensional faults of the southern Apennines, in the context of the MUSE 4D PRIN project.