Stratigraphy and facies of the southern serra do Espinhaco, Minas Gerais, Brazil

The first stratigraphic concepts of the Serra do Espinhaco were introduced by Eschwege (1822) and Derby (1882, 1906), although still influenced by geological concepts of their time. Some local or specific stratigraphic terms were proposed during the first half of the 2011, century. Pflug (1968) proposed for the first time a stratigraphic column for the southern Serra do Espinhaqo, which was improved and adapted to modem geological concepts during the 1970/80s. Studies of the regional distribution of individual units and its possible geotectonic setting during the last 15 years, combined with basin analysis and geochronology, allowed to establish a new stratigraphic model of the Espinhaqo System within the southern Serra do Espinhaqo. The Espinhaqo System comprises all geological units deposited during formation and evolution of the basin, as well as during the tectonic inversion, which built up the Espinhaqo Orogen, comprising five groups. The regional distribution of the five groups corresponds to different geotectonic setting, whereas the formations refer to the individual compartments of the Espinhaqo Basin and Orogen. Units of the Desembargador Otoni Group represent the pre-rift phase, the Serro Group comprises units of the marine basin, the Guinda Group is formed by sediments of the alluvial plain adjacent to the marine basin, the Conselheiro Mata Group represents the western foredeep trough and the Inhai Group corresponds to the molasse of the Espinhaqo System. Geochronological data indicate a time span between 1.75 and 1.3 Ga for the evolution of the Espinhaqo System.