A portion of new seismic reflection/refraction data collected over the Iberia margin were processed and interpreted, resulting in the recognition of two previously unknown normal faults in the deep crust. These faults, named Q and R, formed during the Triassic-Cretaceous rifting of Pangea, and formation of the Atlantic basin. Previous studies have shown a third surface, the low-angle S reflector, in the area. S has previously been interpreted as a detachment surface or as a velocity interface. A model is proposed where extension was accommodated along Q, R and S during the rifting of Pangea. R and S acted as detachment surfaces as the hangingwall block moved westward. Late in the rifting process, the geometry of R and S was altered by motion of underlying serpentinized mantle material. This upwelling of the mantle controlled the shape of Sin three dimensions. Total extension across the margin is estimated at 1.67.