Resumen
Cataclastic bands from the eastern border of Tambillo Pluton are studied. Two band systems are observed: one northeast and the other northwest in strike. The northeast system is the most conspicuous and its kinematic analysis shows dextral displacement. The two directions of bands form right angle and this suggest that they formed from joints in the Tambillo Puton. A number of granodioritic dykes intruded along the bands and thus they constitute weak zones for dyke emplacement. The age of the cataclasis is undoubtely Ordovician and occurred during the Arenigian in a maximum span of time of only 11 m.y. It is assigned to the Ocloyic orogenesis.