Timing of porphyroblasts growth and their relation to deformation stages in metamorphic rocks of the Hamedan area

Structural elements of four deformation stages have been recognized in the Hamedan schists. These deformation stages were synchronous with regional and contact metamorphism events. Numerous porphyroblasts have grown in the metamorphic rocks as pre، syn and post deformation stages. Andalusites were generated Pre and syn- D2 due to regional metamorphism in the area. Andalusites were oriented in NW-SE trend and were extended، boudinaged and distances between boudins filled by quartz fibers. Garnets have been initiated pre، syn and post D1، syn and post D2 and syn and post D3 in the metamorphic rocks. Staurolites were grown pre D2 probably syn D1، pre and syn D2 and post D3. Sillimanites are found in the andalusites or as fibrolits that were produced during D4 stage. Cordierites were generated by both regional and contact metamorphism and it is found pre-syn D2 in regional metamorphic rocks.