Extensional tectonics in the western border of the Vasco-Cantabrian Basin (Cantabrian Mountains, NW of Spain)

A geological cross-section in the western border of the Vasco-Cantabrian Basin show extensional faults active during Permo-Mesozoic sedimentation , as well as the tectonic inversion of these faults during Alpine deformation. The hercynian basement of the Cantabrian Zone was deformed together with the Meso-Cenozoic cover during the extension and subsequent compression, without the existence of detachments betwen them. Cross-section restauration allow to reconstruct the sedimentary basins from Permian to Upper Cretaceus times. The calculated extension during this time is of about 7.5 Km and the alpine shortening of 20 Km