order of about 500 meters – an exception being the Dussac Fault north of Lanouaille which has a left-lateral displacement of nearly 6 kilometers! Timing of the deformations The timing of the tectonic movements is based mainly on comparisons with lithologically and structurally similar terranes in the Armorican Massif (Chantonnay Syncline in the Vendée) and in the Rouergue. In the southern Armorican Massif the dextral shearing motions are timed as Namurian and Westphalian (Serpukhovian till Moscovian), i.e. 325 till 305 million years ago. One can therefore propose for the deformations in the Thiviers-Payzac Unit of the Bas-Limousin, which is regarded as the southeastern prolongation of the Vendée, a middle to late Carboniferous age. Similar ages for the leucogranites in the northern and central Limousin seem to support this assumption. Yet some radiometric datings using the argon-method find much earlier Tournaisian ages for the intrusion of the Estivaux granite and for the motions along mylonite zones within the Saut-du-Saumon orthogneiss. These findings imply a tectonic phase in the southern Limousin already during Mississippian times (Bretonic Phase). References Sources Peterlongo, J.M. (1978). Massif Central. Guides Géologiques Régionaux. Masson. Roig, J.-Y., Faure, M. & Ledru, P.(1996). Polyphase wrench tectonics in the southern French Massif Central: kinematic inferences from pre- and syntectonic granitoids. Geologische Rundschau, 85, pp. 138–153 Geology of France