Kinematics of a kilometric recumbent fold: The Courel syncline (Iberian massif, NW Spain)

The Courel recumbent syncline is one of the best examples of a regional scale recumbent fold outcropping in the NW Iberian massif. A strain, microfabric and minor fold analysis of this structure has been integrated in an evolutionary model that begins with an episode of layer shortening, buckling and body rotation associated with deformation dominated by simple shear. Subsequently, the fold was flattened by dominant irrotational strain with maximum shortening perpendicular to the axial surface and maximum stretching parallel to the fold axis. This occurred during the first phase of the Variscan deformation, and gave rise to a fold with an axial surface dipping moderately towards the hinterland (SSW). The recumbent character of the fold was increased during the third phase of the Variscan deformation, which produced a large-scale open structure with a subhorizontal limb.