Summit low‐angle faults in the Central Apennines of Italy: Younger‐on‐older thrusts or rotated normal faults? Constraints for defining the tectonic style of thrust belts

摘要: Low-angle faults that juxtapose younger rocks over older ones are widely documented in fold-thrust belts, and reconstruction of tectonic style is strictly dependent on their interpretation. Various modes exist for generating hinterland-dipping low-angle with younger-on-older relationships. Indeed, the Central Apennines Italy, faults, which rest summits major anticlines (i.e., summit faults), have been interpreted variously as thrusts within out-of-sequence thrust systems, postorogenic normal gravity-driven slides, or rotated prethrusting faults. In this study, we provide a new robust structural-geological data set, corroborated stratigraphic timing constraints balanced geological cross sections, bringing an essential contribution to interpretation preexisting shortcut during Neogene thrust-related fold emplacement. A detailed structural characterization carried out four remarkable examples from allowed reconstructing inversion tectonics model. The lack reverse reactivation here analyzed consistent fault bend propagation folding models associated break forward in-sequence implying more conservative estimates shortening system, compared previous models. Taking into account various possible causes development presented study results achieved could be critically applied when examining similar structures other belts.