Polyphase shear tectonics in the South Limousin (French Massif Central) and its interpretation in a polycyclic evolution model of the Hercynian belt

Structural. kinematics and thermo-barometric analyses of the ductile deform ation of the south-limousin metamorphic formations show a polyphase shear t ectonics corresponding to two different thrusting events. The older one, is a to the top-to-the-SW thrusting during middle Devonian. This deformation occurs under minimum PT conditions of 7 Kbar/700 degrees C simultaneously t o anatexis. The second event is a top-to-the-NW shearing which occurred in late Devonian - early Carboniferous under Barrovian conditions (5 kbar/600 degrees C). Diorites bodies and non-eclogitized mafic rocks allow us to arg ue for an extensional phase between the two thrusting events. These two duc tile and syn-metamorphic deformations rake place in a polycylic evolution m odel of the Hercynian belt of the French Massif Central.