CROP 03: Structure of the Montecalvo in Foglia - Adriatic Sea Segment

A detailed study of the in-land and off-shore areas around the easternmost segment of the CROP 03 deep seismic reflection profile, in the Romagna-Marche borderland area, has been carried out integrating geological (field mapping), structural and biostratigraphic analyses with sub-surface data (seismic reflection profiles and composite well logs). In the on-shore part of the study area, the thrust anticlines of Montefiore Conca-Serrungarina, Mombaroccio and Gabicce-Pesaro are th result of deformation of the sedimentary cover, detached at its base and along some other detachment levels within the multilayer, and also of the basement, involved in the deformation by thrust faulting and presumably through the reactivation of pre-existing extensional faults related to Mesozoic rifting and/or Neogene flexure of the foreland lithosphere. Three balanced geological sections across the study area show a relatively simple structural style at depth, consisting of major anticlines mostly faulted by thrusts and backthrusts defining pop-up structures, separated by wide synformal structures. Restoration of these cross-sections indicates low shortening values which are comprised between 11% and 20%, increasing from north to south. The forward migration of the thrust system is dated by the shift of the foredeep and the development of satellite (thrust-top) basins showing a quite complex deformation history from the Messinian (on-shore structures) up to the Middle Pleistocene (unconformities occurring in off-shore deposits), with estimated average shortening rates ranging from 1.5 to 2.5 mm/y.