Resumen de Evolución estructural paleozoica de los materiales de la Cerdanya y del Alt Urgell

Josep Maria Casas, J. Cirés, Francisco Domingo Poveda, O. Fernández, J. Picart

• Geologic mapping in the Cerdanya-Alt Urgell area has provided new insights into the Paleozoic structural evolution o f the Central Pyrenees. Three main deformational events has been distinguished: an Upper Ordovician extension, the Hercynian crustal shortening event, and a late Carboniferous normal faulting episode. Upper Ordovician extension is depicted by km scale half grabens bounded by normal faults. The Hercynian deformation corresponds to a Namurian to early Westphalian period o f crustal shortening, a widespread crenulation cleavage and a pile of south directed thrust sheets are the main Hercynian structures. Upper carboniferous normal faulting is related to the collapse of the Hercynian orogen and is achieved by km scale moderately dipping normal faults; extension occurs shortly after compression, during late Westphalian, prior to the emplacement of the Hercynian granodiorite plutons.