Petrogênese das rochas Pré-Cambrianas da região Itabira/Morro do Pilar, borda sudeste da Serra do Espinhaço Meridional-MG

Guimarães, Marcelo L.V.

doi:10.11606/d.44.1992.tde-05102015-134750

Cited by 3 publications

(5 citation statements)

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“…TTG-type orthogneisses that crop out in the surroundings of the MER area are correlated with the Archean Guanhães/Dona Rita Complex (Guimarães, 1992) and interpreted as part of the basement of the metasedimentary rocks of the MER sequence. These rocks exhibit a medium grain size (0.01e1 mm), with granoblastic to granolepidoblastic fabric.…”

Section: The Archean Gneissic Complexmentioning

confidence: 98%

“…The Guanhães Complex stretches over the central-eastern part of the state of Minas Gerais and is comprised mainly of an undivided assemblage of TTG (tonaliteetrondhjemiteegranodiorite) gneisses, migmatites and granitic bodies, commonly displaying mylonitic fabric, together with discontinuous strings of metasedimentary and metavolcanic rocks (Dussin et al, 2000;Noce et al, 2007). The Dona Rita Complex is a similar lithostratigraphic unit, indistinguishable from the Guanhães Complex, which crops out on the eastern border of the Craton (Guimarães, 1992;Grossi-Sad et al, 1997).…”

Section: The Crystalline Basementmentioning

confidence: 99%

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The Statherian itabirite-bearing sequence from the Morro Escuro Ridge, Santa Maria de Itabira, Minas Gerais, Brazil

Braga

Rosière

Queiroga

et al. 2015

Journal of South American Earth Sciences

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The itabirite-bearing metasedimentary sequence from Morro Escuro Ridge comprises the basal units of the Espinhaço Supergroup and makes up a small tectonic inlier developed during one of the Brasiliano orogenic events (800-500 Ma), amongst horses of the Archean TTG gneisses, including sheared granites of the anorogenic Borrachudos Suite (~1700 Ma). The metasedimentary rocks are comprised of low-to intermediate-amphibolite facies schists, quartzites, conglomerates and banded iron formation (itabirite) correlatable with the sequences of the Serro Group, which underlies the metasedimentary rocks of the Espinhaço Supergroup in the Serra da Serpentina Ridge. A maximum Statherian deposition age (1668 Ma) was established using SHRIMP UePb isotopic constraints on zircon grains from conglomerate and quartzite units overlying the itabirite. The itabirite is predominantly hematitic and its geochemical characteristics are typical of a Lake Superior-type BIF deposited in a platformal, suboxic to anoxic environment distant from Fe-bearing hydrothermal vents. Close to the contact zone with amphibolites of the Early Neoproterozoic Pedro Lessa mafic suite, an increase of the magnetite content and crystallization of metasomatic Mg-hornblende and Ce-allanite can be observed. These mineralogical changes developed preferentially along the igneous contact zone but are probably co-genetic with the formation of alteration haloes in zircon grains during the Neoproterozoic Brasiliano orogeny (506 ± 6 Ma).

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Section: The Archean Gneissic Complexmentioning

confidence: 98%

Section: The Crystalline Basementmentioning

confidence: 99%

The Statherian itabirite-bearing sequence from the Morro Escuro Ridge, Santa Maria de Itabira, Minas Gerais, Brazil

Braga

Rosière

Queiroga

et al. 2015

Journal of South American Earth Sciences

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show abstract

“…Por outro lado, corpos intrusivos básicos de idade mais recente, não apresentando sinais de metamorfismo, tem sido descritos na região (e.g. Bastos Neto 1982;Herrgesell 1984;Guimarães 1992). Idades K/Ar apresentadas por Dossin et al (1993) confirmam o posicionamento Mesozóico já admitido, entre outros, por Herrgesell (1984) e Knauer (1990).…”

Section: Magmatismo Básicounclassified

Espinhaço - Quo Vadis ? (Onde Está? - Aonde Vai?) a Evolução Dos Conhecimentos Sobre a Cordilheira Do Espinhaço Meridional Em Minas Gerais Entre 1979 E 1995

Renger¹,

Knauer²

1995

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In this paper a brief review is given of master and doctoral thesis as well of articles published duringthe last 16 years, concerning the geology of the Serra do Espinhaço in Minas Gerais, Brazil. The differentproposals of a subdivision of the Archean basement and sedimentary sequences of Pre-Espinhaço age arereviewed. The existing geochronological data are insufficient for a complete understanding of these units.The Espinhaço rift started its evolution about 1800 Ma ago with continental sediments with intercalationof acidic and basic volcanics evolving in the upper part of the sequence to shallow marine sedimentation.Aspects of stratigraphy and sedimentology of the Espinhaço Supergroup as well as those of structuraland economic geology are briefly discussed. Diamonds washed in the Sopa-Brumadinho conglomeratesand in alluvials remains the principal mineral resource as about 160 years ago predicted by L.W. vonEschwege. In recent years exploration work was successful to identify the gold deposit at Riacho dosMachados in the northern extension of the Serra do Espinhaço.A chapter resumes the geodymamic models presented during the considered period. Finally, suggestionsfor future investigations are listed.

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“…Datações de minerais e rochas de corpos de metagranitóides Borrachudos apresentaram idades amplamente variáveis, arqueanas até neoproterozóicas (Herz, 1970;Dussin et al, 1997;Noce et al, 2007). Entretanto, análises litoestruturais regionais indicam serem os corpos de metagranitóides Borrachudos arqueanos devido à inuência que exerceram na conformação sedimentar e tectônica dos depósitos paleoproterozóicos (Guimarães, 1992;Schorscher, 1992).…”

Section: Metagranitóides Borrachudosunclassified

“…Entretanto, algumas dessas propostas são bastante problemáticas, já que incluem (como demonstrado, entre outros, por Guimarães (1992)), rochas típicas do Supergrupo Minas, paleoproterozóicas, no Supergrupo Espinhaço (Grupo Serro), que consideram de idade mesoproterozóica.…”

Section: Supergrupo Espinhaçounclassified

Quartzitos e metaconglomerados auríferos da Sequência da Serra da Boa Vista, borda leste do Quadrilátero Ferrífero, MG, Brasil

Rossi¹

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Petrogênese das rochas Pré-Cambrianas da região Itabira/Morro do Pilar, borda sudeste da Serra do Espinhaço Meridional-MG

Cited by 3 publications

References 1 publication

The Statherian itabirite-bearing sequence from the Morro Escuro Ridge, Santa Maria de Itabira, Minas Gerais, Brazil

The Statherian itabirite-bearing sequence from the Morro Escuro Ridge, Santa Maria de Itabira, Minas Gerais, Brazil

Espinhaço - Quo Vadis ? (Onde Está? - Aonde Vai?) a Evolução Dos Conhecimentos Sobre a Cordilheira Do Espinhaço Meridional Em Minas Gerais Entre 1979 E 1995

Quartzitos e metaconglomerados auríferos da Sequência da Serra da Boa Vista, borda leste do Quadrilátero Ferrífero, MG, Brasil

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