Structural and metamorphic criteria allow us to distinguish two units (Cneissic and Porphyroid) belonging to the Olio de Sapo formation in the Sanabria región. The high-grade gneissic unit and the lower Ordovician metasediments were brought together by a top-to-east extensional detachment with related flat-lying foliation. The low grade porphyroid unit, only affected by vertical foliation, intruded along subvertical faults that cross-cut the detachment. These Upper Ordovician tectonic and magmatic processes in the Sanabria area seem to be related to the extension in the continental margin of Condwana that permitted the formation of deep basins and the addition of huge volumes of granitic magma to the crust