Metapelites and add orthogneisses from the Lower Unit of the Tormes Gneissic Dome, NW Salamanca, contain high-grade mineral assemblages with characteristics diffusional zoned garnets, The P-T path deduced for this unit from combined studies based on TWEEQU thermobarometry in core-rim garnets, retrograde reaction analysis and mineral zoning, shows an important isothermal decompression of several kilobars. This decompression is the record of the tectonic exhumation of the unit, caused by a D2 extenslonal event related with the collapse of the previously thickened Variscan crust