ABSTRACT The Pamplona Fault at the SE Basque‐Cantabrian Basin is one of the most notable and controversial transverse faults of the Pyrenees. Previous studies of this structure have been based on the analysis of single geological and geophysical datasets, which has resulted in a variety of interpretations regarding its origin and role during the Mesozoic rifting and Cenozoic inversion of the Pyrenean orogen. In this study, a 3D model integrating all the geological and geophysical information available for the transition between the Basque‐Cantabrian, Jaca‐Pamplona and Ebro foreland basins has been built to provide an updated, comprehensive view of the Pamplona Fault. We have found strong conclusive evidence for its presence in the Palaeozoic basement, as part of a widespread NNE‐SSW fault network that extends across the study area. Further evidence for the activity of the fault during the Mesozoic rifting derives from the geometry and sedimentary evolution of the overlying, allochthonous Cretaceous sedimentary units. Overall, our results indicate that the Pamplona Fault represented the easternmost boundary of the Basque‐Cantabrian basin during Hauterivian‐Barremian times, was active during the beginning of the hyperextension process that led to the eastward propagation of the basin across the fault during the Aptian‐early Albian and acted as an accommodation structure during the rest of the Cretaceous. By the integration of these results with those from surrounding areas, we identify this fault not as a single structure but as a ~65 km‐wide strip labelled Pamplona Transfer Zone that includes the neighbouring Hendaya and Oroz‐Betelu faults and represented a diffuse transfer linkage between the Basque‐Cantabrian and Mauléon segments of the Pyrenean rift. This wide transfer zone also exerted a clear role during the Cenozoic inversion of the rift, for it had an impact on the style of deformation and the local configuration of the Pyrenean thrust front.
Bravo et al. (Thu,) studied this question.