Alpine superposed buckle folds in Aliaga

The Aliaga area exhibits a complete inventory of large-scale examples of superposed buckle folds deforming the Mesozoic-Cenozoic cover. They resulted from successive, diversely oriented contractional episodes developed during the Alpine Orogeny, which caused inversion of a series of extensional Mesozoic basins and built the intraplate Iberian Chain (NE Spain).
ENE-WSW trending buckle folds (Early Miocene in age) are superposed to a large NNW-SSE anticline (Eocene-Oligocene). North of Aliaga, the earlier hinge zone in the competent unit controlling buckling (Urgon facies, Lower Cretaceous marine limestones) constituted a mechanical obstacle to refolding. This induced development of conical second-generation folds that buckle the hinges and axial surfaces of the former ones in a complex manner. On the contrary, to the south, erosional removal of the hinge zone allowed the vertical eastern limb to behave almost independent, being refolded into cylindric, nearly vertical folds, as La Olla anticline. Lower Miocene conglomerates adjacent to the earlier NNW-SSE trending anticline contain pebbles of Jurassic origin, whose source area was the fold core. This evidences that the latter had been effectively exhumed before refolding.