Estructura y metamorfismo de la Zona Axial pirenaica en el sector suroccidental del Macizo de Lys-Caillaouas (Huesca, España)

Resum

A geologic map and cross-section of the southwest sector of the Lys-Caillaouas Massif (Axial Zone of the central Pyrenees), have been constructed to study the structure and its relationship with the metamorphism. Cambro-Ordovician to Devonian metasedimentary rocks crop out deformed and metamorphosed during the Variscan Orogeny. Moreover, pre-Variscan and Alpine structures could be found. Several deformation phases are observated: pre-Variscan structures corresponding to a foliation, only present in the pre-Upper Ordovician rocks; Variscan D1 structures which are north-facing folds with the main foliation (S1) associated; and Variscan D2 structures that are a subvertical creanulation cleavage associated with upright, tight and E-W trending folds. The Eriste-Vallarties fault corresponds to a D2 thrust, and separates two domains: in the northern one, the main structures are D1 folds and S1 cleavage. In the southern part of the study area, D2 structures dominate. The peak of the metamorphism produces the growth of minerals formed in high-temperature and lower-pressure metamorphism conditions, which show pressure shadows and weak rotation in some cases, probably due to the granite of Lys-Caillaouas emplacement.