Structural evolution of the SW margin of the Basco-Cantabrian basin

The SW margin of the Basco Cantabrian basin (as the whole basin itself) is a clear example of inversion tectonics. During Mesozoic times a main extensional event is recognized. Rifting began in Upper Jurassic triggering an important haloldnesis; both progressed until Middle Albian controlling the deposit of synrift sediments which can be grouped in four megasecuences separated by major uncomformities. The Utrillas Fm. and the overlying Upper Cretaceous carbonate deposits represent the postrift sediments linked with the thermal subsidence subsequent to the aforementioned mechanical stretching. Coaxial Tertiary compression tightened the Mesozo c geometry and allowed the thrusting of the Cantabrian Mesozoic and Tertiary cover over the Duero basi