A NEW RECORD OF THE LP-HT LATE-VARISCAN M ETAMORPHISM - THE PEYRE-ARGUET UNIT (HAUT-DAUPHINE)

The petrologic study of the Peyre-Arguet metabasites (Haut-Dauphine), allows us to constrain the P-T evolution of these rocks from an upper amphibolitic stage (P = 7 +/- 1 kbar, T = 650 +/- 50 degrees C) to a l ow-pressure granulitic stage (P = 5 +/- 1 kbar, T = 800 +/- 50 degrees C) followed by a high-temperature amphibolitic stage (P = 3 +/- 1 kba r, T = 700 +/- 50 degrees C) toward the green schist facies (P < 2 kba r, T < 500 degrees C). The temperature increase during decompression i s compatible with the migmatization of the surrounding gneisses, proba bly during the Carboniferous. The tectonometamorphic evolution of this unit is similar to those observed in the French Massif Central and co uld correspond to a new witness of the late Variscan LP-HT evolution.