Late thrusting extensional collapse at the mountain front of the northern Apennines (Italy)

摘要: [1] Thrust-related anticlines exposed at the mountain front of Cenozoic Appenninic thrust-and-fold belt share presence hinterlandward dipping extensional fault zones running parallel to hosting anticlines. These downthrow crests and backlimbs with displacements lower than, but comparable to, uplift anticline. Contrasting information feeds a debate about relative timing between thrust-related folding beginning faulting, since several episodes, spanning from early Jurassic Quaternary, are documented in central northern Apennines. Mesostructural data were collected frontal anticline Sibillini thrust sheet, Umbria-Marche sector Apennines, aim fully constraining stress history recorded deformed multilayer. Compressional structures developed during propagation fold growth, mostly locating limbs. Extensional elements striking perpendicular shortening direction two distinct episodes: before when area by outer-arc extension peripheral bulge, late post thrusting stage. Most deformation occurred second stage, syn-thrusting erosional exhumation caused development pervasive longitudinal fracturing crestal growing anticline, which anticipated subsequent widespread Quaternary tectonics.