Structural analysis and 3D geological modelling of the Santerno transect in the Northern Apennines (Italy)

We present preliminary results of a structural analysis and 3D modelling project carried out along a transect in the Santerno Valley, between Firenzuola (Tuscany) and the outskirts of Imola. The aim of the project is to combine surface geological and structural data (available thanks to the national geological mapping CARG project and original surveys), with the available subsurface data (2D seismics and a few wells), and obtain a comprehensive 3D framework for deformation in this key area of the Northern Apennines. In addition, by combining geodetic, seismicity and interferometric data with the 3D structural model, we are able to obtain a better picture of the active structures in the area. Our analysis shows that the studied transect is at the northern periclinal hinge of a regional anticline/window where the Marnoso-Arenacea Formation crops out and is crosscut by several regional-scale thrusts. Subsurface data suggest that these relatively shallow thrusts are rooted at the top of Mesozoic carbonates, that do not crop out in the area. Different balancing algorithms confirm a relevant along-strike variation of slip along these thrusts, that reduce their offset towards the periclinal hinge to the west. In the more external part of the transect, towards the lower hills and the plain around Imola, a regional-scale pop-up, evidenced by the late-Messinian unconformity, is the main feature in subsurface datasets. This structure is rooted at the base of Mesozoic carbonates and is characterized by large and continuous ramps that can be considered candidates for recent earthquakes in the area.