Coexistence of fault-propagation and fault-bend folding in curve-shaped foreland fold-and-thrust belts: examples from the Northern Apennines (Italy)

Terra Nova, 24, 396406, 2012 Abstract Fault-bend and fault-propagation folds have unique profiles in foreland fold-and-thrust belts that are caused by different fault-related folding models and controlled by the mechanical characteristic of the multilayer and/or by reactivation of normal faults in a positive inversion tectonics context. In this work, NNESSW- and NWSE-trending anticlines, related to the Neogene curve-shaped Olevano-Antrodoco-Sibillini thrust (Northern Apennines, Italy), are investigated to reconstruct fault-related folding mechanisms. Geological and structural analysis allows us to interpret the NNESSW-trending anticlines as fault-bend reactivation folds and the NWSE-trending anticlines as fault-propagation shortcut anticlines. The coexistence of fault-bend and fault-propagation folding processes involving the same multi-layered succession in different arms of a curve-shaped thrust is explained in an inversion tectonics context. This along-strike variation of different folding mechanisms might be recognised in similar curve-shaped orogenic thrust-belts controlled by structural inheritance.