Plegamiento cónico en la Zona Cantábricaefectos del plegamiento oroclinal

Résumé

The Cantabrian Orocline of the Variscan Belt has been recently defined as a true orocline, based on the kinematics and the timing of deformation. This curved sector of the Variscan orogenic belt is characterized by two different fold sets: (1) one runs parallel to the strike of the main thrusts and describes a horseshoe shape concave towards the east and (2) the other is radial to the arc. A detailed geometric study of the fold interference patterns in the Cantabrian Orocline reveals the conical nature of the folds belonging to the radial set. These conical folds developed with different geometrical characteristics (semiapical angles y axis attitudes) depending on the initial orientation and the geometry of the folded surfaces. They are interpreted to result from a vertical axis rotation during oroclinal folding of the Variscan Belt in NW Iberia. This study of conical folds in the Cantabrian Orocline highlights that conical folds in curved orogenic arcs are a powerful tool for establishing the sequence of tectonic events because interference patterns due to vertical axis secondary differential rotations provide unique geometrical characteristics observed in the Cantabrian Orocline that can be extrapolated to other oroclines.