Analysis of thrust shear zones in curve-shaped belts: Deformation mode and timing of the Olevano-Antrodoco-Sibillini thrust (Central/Northern Apennines of Italy)

► We analyze shear zones associated with the external thrust of the Northern Apennines (Italy). ► We document SC and S tectonites associated to NW-SE- and NNE-SSW-trending ramps of the thrust. ► We perform quantitative vorticity analyses to determine the component of pure and simple shear. ► We propose the analysis of shear zones to constrain modes and timing of curved belt's development.