Kinematic evolution of the outer zones of the Northern Apennines, Italy: the contribution of sequential cross-section balancing techniques

A geological section across the southeastern zones of the Northern Apennines, from the Umbria-Marche Range to the Adriatic Foreland Folds (Spoleto Mizar 1 well), is described. These provinces are characterized by the widely outcropping deepest portions of the Umbria-Marche sedimentary cover which, due to a marked axial plunge, are largely buried under the Neogene deposits further to the North. Restoration of the compressional structures allows for an evaluation of the shortening experienced by the Meso-Cenozoic sedimentary cover. The limited amount of contraction (about 20%) is broadly consistent with observation of thrust faults terminating both upwards and along-strike in asymmetrical fold pairs, an evidence supportive of tip-line folding processes. This interpretation, in combination with with a hinterland-to-foreland thrust propagation inferred from structural overprinting relationships, provides a key for reconstructing the kinematic evolution of the outer zones of the Northern Apennines. A systematic use of sequential restoration methods can be halpful in the interpretation of coeval structures (such as those along the CROP 03 seismic profile) whose geometry is not accessible to direct investigation.