Geology of the Pitangui greenstone belt, Minas Gerais, Brazil: Stratigraphy, geochronology and BIF geochemistry

Stratigraphy of the Pitangui Synclinorium, northwest of the Quadrilátero Ferrífero mineral province - Brazil: magmatism and sedimentation from Archean to Neoproterozoic

“…The southern region of the São Francisco Craton, in which the Pitangui Synclinorium is located (Figure 1), is composed of Meso-to Neoarchean complexes represented by TTG (tonalite-trondhjemite-granodiorite) gneisses and migmatites, Neoarchean medium-and high-K granitoids, and Mesoto Neoarchean greenstones belts covered by Proterozoic supracrustal rocks (Machado et al 1996;Alkmim and Marshak 1998;Romano 2007;Lana et al 2013;Romano et al 2013;Farina et al 2015;Brando-Soares et al 2017;Araújo et al 2020).…”

“…Recently, Brando-Soares et al (2017) divided the Pitangui greenstone belt (PGB) into three informal units: lower, intermediate and upper. The lower unit consists of mafic metavolcanic rocks represented by metabasalts, komatiitic metabasalts and metaultramafic rocks, with intercalations of banded iron formations (BIFs), metacherts and carbonaceous phyllites.…”

“…These lithologies are characterized by an aphanitic to fine-grained, yellowish to reddish groundmass involving fine kaolinized phenocrysts of K-feldspar. The felsic-intermediate metavolcanic rocks are classified as metadacites and meta-andesites by Brando-Soares et al (2017).…”

“…Later, Romano (2007) defined it as a metasedimentary sequence, predominantly metapelitic with thin lenses of BIFs, carbonaceous phyllites and magnetitites. More recently, Brando-Soares et al (2017) placed this formation at the base of the intermediate section of the greenstone.…”

Geochemistry of komatiites and basalts from the Rio das Velhas and Pitangui greenstone belts, São Francisco Craton, Brazil: Implications for the origin, evolution, and tectonic setting

“…The youngest detrital zircon population in two metasedimentary rocks (slate and phyllite) indicated an average age of 2720 Ma (n = 8 grains) and three other grains showed an average age of approximately 2670 Ma. Recently, Soares et al (2017) divided the belt into three units: a lower unit of predominantly metavolcanic ultramafic and mafic rocks interbedded with thinner metasedimentary intervals of BIFs, turbiditic metasandstones and metapelites; a middle unit of turbiditic metasediments interbedded with metavolcanic intermediate rocks, minor BIFs, and quartzites; and an upper unit composed of quartzites and polymictic metaconglomerates. According to Soares et al (2017), the rocks from all three units were metamorphosed under upper-greenschist to lower-amphibolite facies and are bounded by domes composed of Tonalite-Trondhjemite-Granodiorite (TTG) and late-to post-tectonic alkaline granitoids.…”