Alpine reactivation of variscan folds and faults in the Iberian Chain: Examples of the Sierra de la Demanda and the Serrania de Cuenca

[Abstract] The structure of the Variscan basement of the Iberian Chain conditioned the geometry and orientation ofstructures formed during the Alpine compression. In the Sierra de la Demanda, located in the north-western part of the Iberian Chain, the E-W Variscan folds re-activated during the Tertiary compression, bringing about the folding of the mesozoic rocks uncomformably lying on them. In sorne sites this folds broke, forming high-angle thrusts. In the Boniches anticline (Serranía de Cuenca), Tertiary folding was conditioned by the existence of NW-SE basement faults, that moved under transpression. Variscan folding directions did not influence here the Tertiary deformational geometry