Reconstruction and comparison of P-T paths in the Andrelândia Nappe System, southern Brasília Fold Belt, MG

The Andrelândia Nappe System consists of three main nappes, from bottom to top: the lower Andrelândia nappe, themiddle Liberdade nappe and the upper Três Pontas-Varginha nappe and associated klippen, Pouso Alto, Aiuruoca, Carvalhosand Serra da Natureza. In the Andrelândia Nappe System, metamorphism increases from north to south and east to west, withthe highest temperatures and pressures recorded in rocks of the Três Pontas-Varginha nappe and associated klippen. Samplesof pelitic and mafic rocks were selected from the three nappes to determine the conditions of metamorphism using the programThermocalc. In this study, peak metamorphic conditions were calculated for the following samples: one sample of theAndrelândia Nappe (688 ± 35 °C and 5.63 ± 0.9 kbar), one sample of the Liberdade Nappe (648 ± 23°C and 7.41 ± 1 kbar), andthree samples of the Carvalhos Klippe (845 ± 53ºC and 15.7 ± 5.2 kbar, and 847 ± 45oC and 13.6 ± 5.8 kbar for two samplesof pelitic granulites respectively, and 854 ± 71ºC and 15 ± 1.4 kbar for one sample of mafic granulite). P-T paths inferred onthe basis of the observed textures are clockwise and typical of collisional belts.