Geodynamic evolution of the San Vitero basin, a foreland-type basin developed in the hinterland of the Variscan Orogen (Zamora, NW Spain)

Abstract

The Alcañices region, located in the internal zones of the Variscan Orogen of the Iberian Peninsula, is composed of the autochthonous Paleozoic succession of the Central Iberian Zone (CIZ), the allocthonous Schistose Domain of the Galicia-Tras-OsMontes Zone (GTOMZ) and the unconformable synorogenic fysch-type deposits. A new detailed geological map and the analysis of the structure at all scales contribute to establishing the geological relationships between the diferent paleo-geographic units, and in particular of the synorogenic sediments, that given their location in the hinterlands provide further insights into the tectonic evolution of the orogen. The partial restoration of the Variscan structures suggests a model of imbricate thrust-system and an associated foreland-type basin. A reconstruction of the basin allows estimating its width in c.100 km, with a depth of c.1500 m in its depocenter. During the Early Carboniferous the basin developed ahead in relation with the emplacement of the large allochthonous units linked to the D2 deformation event. The evolution of the basin ends with the formation of out-of-sequence thrusts involving their basement and associated folds during the third Variscan deformation event (D3).