The Canastra Group in the type-area, Tapira region, southwest of Minas Gerais State, Brazil

This work aimed at describing the Neoproterozoic evolution of a Southern Brasília Fold Belt segment, in Tapira area(southwest of Minas Gerais state, Brazil), using detailed geologic mapping. This area, the Canastra Group type-area, hasshowed great tectonic and stratigraphic complexities unlike the simplicity suggested in previous works. From recognizingthe main tectonic discontinuities, it was possible to subdivide the area into some domains. In the west domain, they wereindividualized in tectonic sheet I, marked by pelitic rocks and pelitic-graphite rocks with psammitic intercalations, and II,pelitic rocks with psammitic and mafic-ultramafic intercalations overlapped by gneisses. In the east domain, a group ofthree tectonic sheets was defined, in which, in the two lower tectonic sheets, pelitic and pelitic-graphite rocks with psammiticrock intercalations prevailed, which is different in metamorphic conditions. The lower tectonic sheet is marked bymineralogical associations with muscovite + chlorite + quartz ± graphite ± albite, without biotite; however, the superior oneis with muscovite + quartz + garnet ± chlorite ± biotite ± chloritoid ± graphite ± albite. In the upper tectonic sheet, peliticrocks with local contributions of psammitic and ultramafics rocks occur. In the south domain, psammitic rocks basically occur with contributions of pelitics and rudaceous rocks, where the preservation of textures and sedimentary structures is common.Rocks of the several domains are interpreted as part of a passive continental margin basin, located in the western margin of the S oFrancisco paleocontinent. Thus, the south domain rocks would represent the facies of proximal platform; rocks of the lower and middle tectonic sheets (east domain) and of the tectonic sheet I (west domain) are of facies distal platform; and the ones from the upper tectonic sheet (east domain) and tectonic sheet II (west domain) were acknowledged as deposited in an environment of continental shelf and/or oceanic seafloor.