Bulnes, MayteUzkeda Apesteguia, HodeiPoblet, JosepGarcía Zuazua, Iván2025-11-242025-11-242026-01Bulnes, M., Uzkeda, H., Poblet, J., & García Zuazua, I. (2026). What do flexural normal faults tell us about fold-and-thrust belts and foredeep flexures? Cantabrian zone (Ibero-armorican orocline core) examples. Journal of Structural Geology, 202, 105564. https://doi.org/10.1016/j.jsg.2025.1055640191-814110.1016/j.jsg.2025.105564https://hdl.handle.net/20.500.14352/126433This work describes how flexural normal faults related to a flexure produced in the foredeep of a fold-and-thrust belt develop, how they can be recognized, especially when they formed in early or intermediate stages of development of the fold-and-thrust belt, what information provide about the fold-and-thrust belt and the foredeep flexure, and different procedures to obtain it. The application of these methodologies to a natural example is shown through the detailed analysis of normal faults preceding the folds and thrusts in the western part of the Cantabrian Zone, the foreland fold-and-thrust belt of the Variscan Orogen in the northwest portion of the Iberian Peninsula. These faults are interpreted as flexural normal faults formed during the fold-and-thrust belt development. The strike of the longitudinal flexural normal faults illustrates the orientation of the old fold-and-thrust belt front, resulting in an arcuate distribution consistent with the geometry of the Ibero-Armorican or Asturian Arc. The low fracturing intensity due to the longitudinal faults indicates that the flexure curvature and the flexure inclined-limb dip were very gentle, and that the flexure interlimb angle was very high. This may suggest that the fold-and-thrust belt weight was low at that time. The timing of these flexural normal faults indicate that the thrusts propagated following a forward-breaking or “piggy-back” sequence, as deduced by other authors employing different methods. Finally, the transverse flexural normal faults are interpreted as a result of large oblique/lateral thrust ramps in some thrust sheets located in the southern part of the Cantabrian Zone.engAttribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/journal article1873-1201https://doi.org/10.1016/j.jsg.2025.105564https://www.sciencedirect.com/science/article/pii/S0191814125002391open access551.24(460)Flexural normal faultFold-and-thrust beltForedeep flexureThrust propagation sequenceOblique/lateral structureCantabrian zoneGeodinámica2506.20 Geología Estructural