Plio-Quaternary transpressive tectonics: a key factor in the structural evolution of the outer Apennine–Adriatic system, Italy

We used data from seismic reflection profiles and well logs from both onshore and offshore locations along the Adriatic coast to investigate the structural style and recent active deformation in the external area of the northern Apennines adjoining the Po Plain. We prepared four NE–SW sub-parallel transects based on a detailed interpretation of the available subsurface data, supported by surface geological data. Through analysis of the well logs, we identified two significant seismostratigraphic markers, together with some unconformities within the Middle Pliocene/Quaternary succession. We propose a detailed structural scheme for the area that identifies and interprets both the outcropping and buried Apennine structures. NW/NNW–SE/SSE high-angle transpressive or flower structures, referred to the recent and actual deformation history, may be responsible for surface features and features at shallow depths, with possible implications for active tectonics. We show the continuity of some of these structures towards the Conero area to the south, suggesting a wider and more regional meaning for the proposed tectonic style. These Apenninic structures close against the active NNE–SSW Cattolica fault system in the northern offshore part of the area to form an asymmetrical arch. This study contributes to the interpretation of the deformation style of the outer northern Apennines.