La fábrica de las rocas miloníticas de la Zona de Cizalla de Los Llanos (Calzadilla de los Barros, Badajoz)

Abstract

The Los Llanos Shear Zone bounds the Cabeza Gorda and Zafra units located in the Ossa-Morena Zone (SW Iberian Massif). Within the Cabeza Gorda unit two peridotitic massifs crop out, named Sierra Cabeza Gorda and Cerro Cabrera. The mylonitic rocks consist of metamorphic and peridotitic rocks extensively deformed that exhibit a penetrative foliation. Mylonitic fabrics are characterized by s and d structures and S-C and S-C’ band. Some examples show a crenulation cleavage that points out the existence of at least two deformation stages. Kinematic criteria are widespread, but dextral-reverse movement prevails both in outcrop and thin section. Los Llanos Shear Zone orientation is NW-SE, similar to variscan structures trend in the area, and deforms precambrian and paleozoic rocks. Los Llanos Shear Zone represents a dextral-reverse structure of Variscan age.