Abstract : In order to better understand the tectono-metamorphic evolution of the Thiviers-Payzac-type units in the Hercynian belt, three study areas have been chosen in Rouergue-Albigeois, Quercy and Central Vendée. These petro-structural studies allow us to settle the following tectonic evolution:
During middle Devonian, a first event responsible for a south-westward thrusting of the Upper Gneiss Unit above the Lower Gneiss Unit is coeval with the emplacement of synkinematic calc-alkaline plutons. Around 360 Ma, a second top-to-the NW ductile and synmetamorphic event is responsible for the thrusting of the Thiviers-Payzac-type units on the previously structured units. A third phase occurring around 330Ma ago is characterised by a top-to-the south thrusting of the previously structured units upon the Albigeois-Montagne Noire series. The geodynamic significance of the second event is also discussed.