Tectónica de inversión en la Playa de Sopelana (Arco Vasco, Pirineos occidentales)

Abstract

This work analyzes the structural features of the Sopelana Fault, developed in extensional conditions during Cretaceous and Tertiary times, and inverted during the Alpine orogeny. The study area is located on the NE limb of the Biscay Synclinorium, a major structure in the Basque Arc. The Sopelana Fault bounds the northern outcrops of the Cenozoic materials in the Biscay Synclinorium. The structural analysis indicates that the inversion process related to the Alpine shortening generates folds verging towards the North and reverse faults, sometimes with a minor strike-slip component of movement. Kinematic criteria along the Sopelana Fault indicate a top to the NE shear sense, consistent with the regional compression direction, approximately NE-SW in the western area of the Basque Arc. The normal component of the Sopelana Fault was not fully recovered after the tectonic inversion that preserves younger materials of Upper Cretaceous and Tertiary times in the hanging-wall block, marked by evaporitic rocks