Structural architecture and tectonic evolution of the Campania-Lucania arc (Southern Apennines, Italy): Constraints from seismic reflection profiles, well data and structural-geologic analysis

This paper sheds light on the structural architecture and tectonic evolution of the Campania-Lucania segment of the Southern Apennines orogen through an integrated analysis of mostly unpublished and partly published (CROP-04 line) seismic reflection profiles, exploratory well logs and geologic-structural relations among the lithostratigraphic units of this region. The pre-orogenic Mesozoic-Neogene carbonate platform, margin-slope and basinal units that compose the upper orogenic level (Apennines fold and thrust belt) were detached from their basement during Miocene thrusting and form a heterogenous multilayer that was thrust above the Apulian foreland platform. The Apulian Platform itself was involved in Pliocene thick-skinned thrusting that controlled the style and localization of Quaternary transtension and extension. The velocity data from sonic logs, the well stratigraphy, and the seismic reflection facies were integrated through an accurate well-to-seismic tie, allowing the building of a specific velocity model for the time-to-depth conversion. We identified different seismic units with distinctive reflections attributes, which were assigned to the lithostratigraphic units logged in the wells. Our analysis documents the stratigraphic-structural arrangement of the thin-skinned thrusts sheets (Liguride Basin, Apennine Platform and Lagonegro-Molise Basin units) that form the Apennines fold and thrust belt. These units show strong lateral thickness changes because of both the original depositional environments and the non-coaxial deformation stages. In contrast, the underlying Apulian Platform is characterized by a regional anticlinorium (~30–50 km wavelength) that, based on our new reconstruction, extends further west than hitherto known. The anticlinorium exhibits shorter-wavelength (<10 km) anticlines limited by N- to NE-verging thrust ramps, whose high dip (~45°) suggests they root in the crystalline basement. Our work provides a sound link between surface and subsurface structural setting and an improvement of the geometry of the Apulian Platform, with important implications for structural and seismotectonic models of the region.