Recent models support the view that the Pyrenees were formed after the inversion of a previously highly extended continental crust that included exhumed upper mantle rocks. Mantle rocks remain near to the surface after compression and mountain building, covered by the latest Cretaceous to Paleogene sequences. 3‐D lithospheric‐scale gravity inversion demands the presence of a high‐density mantle body placed within the crust in order to justify the observed anomalies. Exhumed mantle, having ~50 km of maximum width, continuously extends beneath the Basque‐Cantabrian Basin and along the northern side of the Pyrenees. The association of this body with rift, postrift, and inversion structural geometries is tested in a balanced cross section across the Basque‐Cantabrian Basin that incorporates a major south‐dipping ramp‐flat‐ramp extensional detachment active between Valanginian and early Cenomanian times. Results indicate that horizontal extension progressed ~48 km at variable strain rates that increased from 1 to ~4 mm/yr in middle Albian times. Low‐strength Triassic Keuper evaporites and mudstones above the basement favor the decoupling of the cover with formation of minibasins, expulsion rollovers, and diapirs. The inversion of the extensional system is accommodated by doubly verging basement thrusts due to the reactivation of the former basin bounding faults in Eocene‐Oligocene times. Total shortening is estimated in ~34 km and produced the partial subduction of the continental lithosphere beneath the two sides of the exhumed mantle. Obtained results help to pinpoint the original architecture of the North Iberian Margin and the evolution of the hyperextended aborted intracontinental basins.

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A P wave seismic velocity model has been obtained for the Central Iberian Zone, the largest continental fragment of the Iberian Variscan Belt. The spatially dense, high-resolution, wide-angle seismic reflection experiment, ALCUDIA-WA, was acquired in 2012 across central Iberia, aiming to constrain the lithospheric structure and resolve the physical properties of the crust and upper mantle. The seismic transect, 310 km long, crossed the Central Iberian Zone from its suture with the Ossa-Morena Zone to the southern limit of the Central System mountain range. The energy generated by five shots was recorded by~900 seismic stations. High-amplitude phases were identified in every shot gather for the upper crust (Pg and PiP) and Moho (PmP and Pn). In the upper crust, the P wave velocities increase beneath the Cenozoic Tajo Basin. The base of the upper crust varies from~13 km to~20 km between the southernmost Central Iberian Zone and the Tajo Basin. Lower crustal velocities are more homogeneous. From SW-NE, the traveltime of PmP arrivals varies from~10.5 s to~11.8 s, indicating lateral variations in the P wave velocity and the crustal thickness, reflecting an increase toward the north related with alpine tectonics and the isostatic response of the crust to the orogenic load. The results suggest that the high velocities of the upper crust near the Central System might correspond to igneous rocks and/or high-grade metamorphic rocks. The contrasting lithologies and the increase in the Moho depth to the north evidence differences in the Variscan evolution.

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