Late Proterozoic sediments and metasediments are present along the transition zone between the Amazonian Craton to the northwest and the Paraguay Belt to the southeast in the Cuiabá region, Mato Grosso. In the Paraguay Belt, these rocks have been affected by the BraS1liano Orogeny, characterized by increaS1ng deformation and metamorphism from the craton towards the fold belt The metamorphic evolution is determined by the illite crystallinity index. Four closely related phases of deformation (D1 to D4) are distinguished in the Paraguay Belt. The trend directions of Dl, D2 and D3 are almost identical (NE-SW) whereas D4 is transverse (NW-SE). The first phase Dl is the most preeminent, and is contemporaneous with the regional metamorphism. It produced tight and isoclinal Fl folds to the east and open folds F1 to the west, and associated S1 cleavage. The D2 and D3 phase conS1st mainly of local crenulation cleavages (S2 and S3). D4 phase is characterized by regional slight transverse folds.
