The ancestry and magmatic evolution of Archaean TTG rocks of the Quadrilátero Ferrífero province, southeast Brazil

Abstract

h i g h l i g h t sWe have analysed the mineral sturmanite. Formula Ca 6 (Fe, Al, Mn) 2 (SO 4 ) 2 (B(OH) 4 )(OH) 12 Á26H 2 O. The mineral is unusual as it contains both sulphate and hydroxyborate anions. Chemical analysis shows a homogeneous phase, composed by Ca, Fe, Mn, S, Al and Si. Bands attributed to sulphate and hydroxyborate anions are identified.

Evolution of arc magmatism in the Carmópolis de Minas Layered Suite, Minas Gerais, Brazil: Sm-Nd and Rb-Sr isotope geochemistry

“…In metamorphic complexes of the Quadrilátero Ferrífero, the climax of this event is recorded by episodes of granitogenesis correlated to a crustal relaxation phase, resulting from orogenic collapse, represented by the granites Mamona ), Santa Luzia (Noce et al 1998) and Brumadinho . Recent LA-ICP-MS work by Romano et al (2013) and Lana et al (2013) have provided a large number of U-Pb zircon ages that confirm previous studies by , Teixeira et al (1998) and Machado & Carneiro (1992). According to these authors the TTG rocks were emplaced during tree main magmatic phases, referred to as the Santa Bárbara (3220-3200 Ma), Rio das Velhas I (RV I; 2930-2900 Ma) and Rio das Velhas II (RV II; 2800-2770 Ma) events.…”

“…The Archean crust in the Southern São Francisco Craton (SSFC), records a polyphase evolution dating back to the formation of one of the first continental nuclei in South America at about 3.2 Ga Machado & Carneiro 1992;Machado et al 1992;Romano et al 2013;Lana et al 2013). Early studies by Teixeira et al (1996;1998), indicate that an acrescionary event at circa 3.0-2.9 Ga amalgamated several crustal segments that currently constitute the TTG metamorphic complexes in the surroundings of the Quadrilátero Ferrífero mining district.…”

Petrography and geochronology of the Furquim Quartzite, an eastern extension of the Itacolomi Group (Quadrilátero Ferrífero, Minas Gerais)

“…The Santa Bárbara Complex corresponds to an Archean TTG gneiss terrain considered to be the basement of the Rio das Velhas Supergroup in the eastern portion of the Quadrilátero Ferrífero. Geochronological U-Pb SHRIMP and LA-ICP-MS dating by Lana et al (2013) indicate crystallization ages of 3.2 Ga. The Mantiqueira Complex is composed of TTG ortogneisses thrusted over the southern margin of the São Francisco Craton during the 2.1 Ga Transamazonian event (Silva et al, 2002, Noce et al, 2007.…”

Processos de acresção e retrabalhamento continental no embasamento do Orógeno Brasília Meridional

“…3.20 and 2.93 Ga (e.g. Lana et al, 2013;Farina et al, 2015). Previous data from the Archean complexes in the basement of the southern Brasília Orogen are very scarce but indicate igneous crystallization ages between 3.02 and 2.75 Ga with TDM ages from 3.3 to 3.0 Ga (Fetter et al, 2001;Tassinari and Nutman, 2001;Santos, 2014).…”

“…Dados publicados na literatura sugerem quatro períodos principais de magmatismo na crosta arqueana na porção sul do Cráton do São Francisco (Teixeira et al, 2000;Lana et al, 2013;Farina et al, 2015): (1 Ma, dentro da margem de erro das idades paleoproterozóicas obtidas em um neossoma do Complexo…”