Evolución metamórfica de las kinzigitas en facies granulita del macizo del Aglí

In the Agly massif outcrops one of the deepest parts of the Hercynian crust. Its basement is constituted by a monotonous pile of paragneisses and anatectic migmatites which presents numerous intercalations of kinzigites, marbles, calcsilicates and basic rocks. This work describes the main structural and metamorphic features of the kinzigites in order to define the P-T evolution of a granulite facies crustal segment. The main mineral metamorphic association is in equilibrium at the univariant prograde reaction biotite + sillimanite + quartz = cordierite + garnet + K-feldspar + H2O and it is formed synchronously with the development of the regional foliation (S2). Following this association and close to the climax, there is a slight pressure drop recorded in the formation of cordierite coronas around garnet porphyroblasts; finally there is a retrograde stage linked to a high grade extensional event (D3). Petrographic observations in conjunction with Schreinemakers analysis and thermobarometric calculations have enable the construction of a nearlyisobaric P-T path and determine that the metamorphic peak is reached at 790 oC and 5,5 kbar by the deepest rocks. Assuming a linear gradient it is concluded that the climax is achieved at different times and at different crustal levels and that, af ter the climax, there is an important shor tening of the lithological column consistent with an extensional unroofing.