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.

Variation of arbuscular mycorrhizal fungal communities along an altitudinal gradient in rupestrian grasslands in Brazil

“…Negreiros et al (2008) reported high soil organic matter content (from 2.8 to 9.4 dag/kg) and high saturation by Al 3+ and high acidity in Serra do Cipó. The soils from the Espinhaço mountain range exhibit similar properties, with acidic soils, low levels of macronutrients, and high aluminum saturation due to the geological and geomorphological conditions (Dossin et al 1990). The low availability of nutrients and water stress caused by climatic conditions have been frequently reported in the quartzite regions of the Serra do Cipó Fig.…”

Archaeoanthrosol formation and evolution of the “Santana do Riacho” archaeological shelter: An old burial site in South America

“…The high levels of exchangeable bases (mainly in the upper bedrock platform), particularly K and Ca, corroborate the anthropogenic influence on the soil in the shelter. Although micaceous minerals occur in the quartzite of the Córrego Borges Formation (Dossin, Dossin, & Chaves, ), the release of K from the weathering of micas is inconsistent with the presence of pH H2O values higher than 5. In addition, although the mica was recognized in the microscopic analysis, the total bulk chemical composition and XRD analyses suggest that this was not the main mineral source for clay formation in the shelter.…”

Unravelling a Proterozoic basin history through detrital zircon geochronology: The case of the Espinhaço Supergroup, Minas Gerais, Brazil

“…Detail of the meatconglomerate with greenisch matrix. Dossin et al, 1990;Martins-Neto, 2000;Alkmim et al, 2006) with the sample location (*). a = after Machado et al, 1989;b = this work. Onlaping the basement highs and packages of the previously mentioned units, the Galho do Miguel Formation consists of a ca.…”