The Duero foreland basin is characterized by a large synformal geometry formed by the lithospheric flexure and northward subduction of the Iberian crust underneath the Cantabrian-European crust. Basin structure is represented by high-angle faults that involve both basement and cover units, and that did not generate large amounts of horizontal displacement. The northern deformation front is represented by a series of S-directed faults that probably sole into middle-lower crustal levels. Growth strata within the basin interior indicate that basement faulting occurred during the uppermost Cretaceous to Paleocene, previous to the onset of the foreland stage, while the Orogen uplift and the northern deformation front activity took place mainly between the Eocene-Oligocene, locally protracting until Miocene times. The Duero Basin behaved as an orogenic scale buttress due to the lack of an inherited Late Jurassic-Early Cretaceous extensional architecture associated with the opening of the Bay of Biscay. Hence, most of the Alpine contraction had a major impact where Mesozoic extension was more important, like the North Iberian Margin and the system of Mesozoic extensional basins of the Pyrenean rif
