Lower Miocene deformation in the hanging wall of the Internal-External Zone boundary of the Betic Cordillera: deformation at the edges of vertical-axis rotation domains in oblique convergent margins

Abstract

AbstractIn the eastern Betic Cordillera, non-cylindrical doubly plunging folds deform the Subbetic Zone (the hanging wall of the Internal-External Zone boundary). Their hinges define an arc from north-south trends in the east to ENE-WSW in the west. These folds began to form during the Early Burdigalian with a NNE-SSW trend. Middle Burdigalian rocks define progressive unconformities in the cores of the synforms, recording the tightening of the folds and an increase in the plunge of the fold hinges. All these folds experienced verticalaxis rotations during the Early Miocene, acquiring the present-day arcuate pattern. During the Middle Burdigalian, the thrusting of the External Zones over the Internal Zones occurred with a top-to-the-SE sense of movement. Upper Burdigalian deposits seal the tectonic windows eroded in these thrust surfaces. This deformational history records a constrictional deformation with area reduction in the Subbetic Zone during the Early Miocene, which can be correlated with the dextral oblique convergence between the Internal and the External Zones.