COMPARTIMENTAÇÃO ESTRATIGRÁFICA DO SUPERGRUPO ESPINHAÇO EM MINAS GERAIS - OS GRUPOS DIAMANTINA E CONSELHEIRO MATA

Abstract

THE STRATIGRAPHICAL ARRANGEMENT OF THE ESPINHAÇO SUPERGROUP IN MINAS GERAIS-THE DIAMANTINA AND CONSELHEIRO MATA GROUPS. The quartzitic sequences which build the Espinhaço Range in the center-north of Minas Gerais and in Bahia, constitute the Espinhaço Supergroup. In the Southein Espinhaço Region, the unit is composed of eight formations which can be assembled into two distinct groups based on the depositional evolution of the sedimentary basin. The Diamantina Group corresponding to three Espinhaço Supergroup basal formations, occurs in the central and east portion of the range and is made up of continental meta-sediments corresponding to a period of great crustal unstability. The more frequent rocks are quartettes, meta-conglomerates locally diamond-bearing (Sopa-Brumadinho Formation), phyllite and bimodal metavolcanics. The Conselheiro Mata Group contains the upper formations, is characteristically marine, transgressive on that took place tendencies in under a stable tectonic phase. The unit is a sucession of quartzits ad phyllites, without synsedimentarv volcanism. The deposition of the Supergroup occured during Mid Proterozoic, in a rift-type intracratonic basin, whose main axis was located west of Diamantina. Deformation of the unit is related to the Brasiliano Cycle and was triggered by a continental collision east ward from the cordillera, responsible for a contractional orogen which affected all the region toward the São Francisco Craton and under simple progressive shearing regime.