From a deformed Peri-Tethyan carbonate platform to a fold-and-thrust-belt: an example from the Central Apennines (Italy)

In the Central Apennines of Italy, the relationships between the foreland deformation of a Peri-Tethyan carbonate platform (Lazio–Abruzzi domain) and the subsequent contractional pattern have been clearly documented by means of stratigraphic and structural evidence. Stratigraphic and structural data point out the occurrence of pre-thrusting normal fault systems, and allow us to define their relationships with contractional structures. Miocene normal faults are particularly well documented by thickness and facies variation of foredeep deposits and by structural evidence. These faults controlled sedimentation during Tortonian–Early Messinian times (foredeep stage), and produced most of the accommodation space for clastic deposits in their hanging-walls. On the contrary, the subsequent positive inversion appears to be quite limited, and generally the hanging-wall sequences are not uplifted above the regional. Clear evidence that normal faults formed first and were later cut and/or rotated during thrusting is supported by analyses carried out along the main fault surfaces. The restoration of a balanced geological section across the study area, based on the inference of an extended foreland affected by later contraction, provided a total, small shortening value. This is lower than the previous estimated by several authors, for the same foreland-fold-and-thrust-belt.