Outcrop of the month – August 2017 by Manuel de Paz (Amsterdam)
The Cantabrian Zone (CZ) conforms the Variscan foreland fold and thrust belt, and is located in the core of the Ibero-Armorican arc of NW-Iberia. Deformation is characterized by thin-skinned thrusts and associated folds that accommodate frontal and lateral ramps. The Villazón-Reigada Syncline is located in the Somiedo Nappe, the most internal nappe of the CZ. It is associated with a paired fault-propagation anticline, and is characterised by an open interlimb angle and a subvertical axial plane. The erodibility of the Silurian shales of the Formigoso Fm. has allowed the syncline to be perfectly highlighted in the landscape by the Cambro-Ordovician quartzarenites of the Barrios Fm., as it can be appreciated in the picture. As an scale, the height of the left-hand side mountain over La Barca Reservoir is about 300 m.
Reference: Gutiérrez-Alonso, G. (1992). The Narcea Antiform and its relation with the Western Nappes of the Cantabrian Zone. PhD Thesis. University of Oviedo.