The tectonic evolution of the Quadrilátero Ferrífero, Minas Gerais, Brazil

Chemale, Farid; Rosière, Carlos Alberto; Endo, Issamu

doi:10.1016/0301-9268(94)90098-1

Cited by 172 publications

(68 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The alternation between hematite rich layers and martitized magnetite-hematite layers (mm to cm) is frequent ( Figure 3b) and it defines the bedding (S 0 ), which coincides with a metamorphic foliation S 1 (Endo and Nalini 1992, Chemale Jr. et al 1994, Alkmim and Marshak 1998. Quartz grains are locally present along the contact between these layers and may also be occasionally abundant in the hematite layers but were not observed in the martitized magnetite-hematite layers.…”

Section: Massive Hematite Orementioning

confidence: 99%

Microporosity of BIF hosted massive hematite ore, Iron Quadrangle, Brazil

Varajão

Bruand

Ramanaïdou

et al. 2002

An. Acad. Bras. Ciênc.

View full text Add to dashboard Cite

Massive hematite ore (MHO) is a special high-grade iron ore, used as lump ore in the process of obtaining direct reduction iron (DRI). The influence of porosity on the reducibility of MHO from the Capitão do Mato Mine (Iron Quadrangle, Brazil) was investigated using optical and scanning electron microscopes on drill core and open pit samples.Hematite is the main component of the samples and occurs as granular crystals (10 µm), microplates (1 µm) and euhedral martite (10 to 30 µm). Quartz, maghemite, kenomagnetite and goethite are minor components.Primary micropores (Å to 1 µm) are associated with microplaty crystals that fill cavities between granular hematite. Secondary micropores (Å to 5 µm) related to euhedral martite crystals, are the most important.The total porosity of weathered samples, measured using nitrogen adsorption and mercury injection, attains values up to 11%, whereas unweathered samples have a porosity less than 2.5%. Reducibility is strongly enhanced by porosity, but inhibited by structure (bedding).

show abstract

Section: Massive Hematite Orementioning

confidence: 99%

Microporosity of BIF hosted massive hematite ore, Iron Quadrangle, Brazil

Varajão

Bruand

Ramanaïdou

et al. 2002

An. Acad. Bras. Ciênc.

View full text Add to dashboard Cite

show abstract

“…A estrutura regional é o resultados da superposição de dois eventos deformacionais principais (Chemale Jr. et al 1994). O primeiro produziu a nucleação de sinclinais regionais nas supracrustais e o soerguimento de domos granito-gnáissicos durante a Orogênese Transamazônica (2.1 -2.0 Ga) resultando em uma estruturação semelhante à encontrada preservada nas bacias de Transvaal e Hamersley.…”

Section: Principais Estruturas Tectônicas: Dbs -Sinclinal De Dom Boscunclassified

“…-domínio oriental de alta deformação (DAD), que cobre principalmente as zonas metamórficas da actinolita (AZ) e da tremolita -antofilita (TAZ) (Pires 1995) e é dominada por cavalgamentos e zonas transcorrentes . gerando dobras apertadas a isoclinais e espessas zonas de milonitização (Chemale Jr. et al 1994). Evidências de retrometamorfismo de ocorrência descontínua estão aparentemente associadas às fases finais da tectônica compressiva.…”

Section: Principais Estruturas Tectônicas: Dbs -Sinclinal De Dom Boscunclassified

Itabiritos E Minérios De Ferro De Alto Teor Do Quadrilátero Ferrífero – Uma Visão Geral E Discussão

Rosière

Chemale

2000

Self Cite

View full text Add to dashboard Cite

Itabirites are Palaeoproterozoic metamorphic banded iron formations from the Itabira Group, Minas Supergroup, that crop out in the Quadrilátero Ferrífero District, Minas Gerais, Brazil. The following compositional types occur: quartz itabirite, being metamorphic jaspilites, dolomitic itabirite, being dolomitized banded iron formations, and amphibolitic itabirite modified by the presence of pelitic sediments. These rocks are also associated to pyritic phyllites and hematitic phyllites. A multiple metamorphicdeformational history during two main tectonic events, the Palaeoproterozoic Transamazonian and the Neoproterozoic Brasiliano Event, produced a variety of mineralogical assemblages in the more impure facies and hydrothermal alteration was responsible for carbonatization, intensive oxidation and mineralization. Hypogenic iron mineralization developed in two main phases resulting in thick massive bodies with no relationship to tectonic structures, denominated non-tectonic ores; and schistose ore associated to shear zone, denominated syn-tectonic ores. The mineralizing fluids might be of metamorphic origin, but the importance of hypogenic fluids of magmatic origin is emphasized. Supergene processes on quartz and specially dolomitic itabirites are also of utmost importance in the development of giant ore bodies. INTRODUÇÃOItabiritos, dolomitos ferruginosos e filitos hematíticos compõem um conjunto de formações ferríferas metamórficas do Grupo Itabira na região do Quadrilátero Ferrífero, uma das principais regiões produtoras de minério de ferro do mundo. Metamorfismo e deformação modificaram diversas características primárias dos sedimentos originais e deram a esse conjunto de rochas um aspecto único quando comparados com outras regiões ferríferas. O entendimento desses processos e seus efeitos nas formações ferríferas permite melhor estabelecer um paralelo entre as rochas que compõem o Grupo Itabira, outras formações ferríferas bandadas de iguais características e jaspilitos anquimetamórficos tais como da Serra dos Carajás, e das Bacias de Transvaal, Hamersley, entre outras. Dessa forma podemos também melhor compreender a evolução geológica da bacia Minas, os processos de mineralização que levaram a gerar grandes corpos de alto teor e, finalmente, estabelecer critérios mais sólidos de pesquisa e prospecção de minério de ferro.As formações ferríferas do Grupo Itabira sofreram ao longo de sua evolução geológica, além de alterações mineralógicas, intensas modificações texturais entre as quais o desenvolvimento de uma orientação preferencial cristalográfica e morfológica de seus constituintes minerais (Rosière et al. 2001a, no prelo), que dificulta a identificação de estruturas e processos pré-deformacionais. A caracterização de minérios pré -e sin-tectônicos e o reconhecimento dos processos mineralizantes é de grande importância econômica não somente para auxiliar nos trabalhos de prospecção e pesquisa como também na caracterização tecnológica. O ajuste dos parâmetros dos processos metalúrgicos utilizados na...

show abstract

“…Defined as such, the Araçuaí belt would encompass the area of the southern Serra do Espinhaço in Minas Gerais and the Serra Geral along Minas Gerais-Bahia border together with its continuation up to the Atlantic coast in southern Bahia (e.g., Uhlein 1991). However, as a west-verging Neoproterozoic fold-thrust belt, the Araçuaí belt can be followed along the eastern boundary of the São Francisco craton beyond the southern termination of the Serra do Espinhaço, involving the eastern half of the Quadrilátero Ferrífero and reaching at least the region immediately south of the town of Barbacena in Minas Gerais, where it overprints the southern Brasília belt (e.g., Alkmim et al 1993, Chemale Jr. et al 1994 ( Fig. 2 and 3).…”

Section: The Araçuaí Orogen and The Araçuaí Beltmentioning

confidence: 99%

The southern Araçuaí belt and the Dom Silvério Group: geologic architecture and tectonic significance

Peres

Alkmim

Jordt-Evangelista

2004

An. Acad. Bras. Ciênc.

View full text Add to dashboard Cite

The Araçuaí belt corresponds to the external portion of the western half of the Araçuaí-West Congo Neoproterozoic orogen. The Araçuaí belt fringes the São Francisco craton to east and is separated from the crystalline core of the orogen by the Abre Campo geophysical discontinuity. The southern Araçuaí belt involves four major lithologic units: the Archean and Paleoproterozoic gneisses of the Mantiqueira Complex, the Pedra Dourada Charnockite, the Paleoproterozoic Borrachudos Granitoid, and the metavolcanosedimentary rocks of the Dom Silvério Group. The Dom Silvério Group occurs in a NNE-SSW striking belt and consists of a thick package of metapelitic rocks with intercalations of quartzites, amphibolites, meta-ultramafics, banded iron formations, gondites and marbles. All units of the southern Araçuaí belt underwent four synmetamorphic phases of deformation in the course of the Brasiliano event. The first phase, synchronous to a regional amphibolite facies metamorphism, was associated to a general tectonic transport towards north along the left-lateral Dom Silvério shear zone and its low angle segment. The second and third phases represent progressive stages of a west directed shortening, which led to the development of local thrusts and pervasive folds in several scales. The fourth phase is extensional and reflects the collapse of the orogen.

show abstract

The tectonic evolution of the Quadrilátero Ferrífero, Minas Gerais, Brazil

Cited by 172 publications

References 14 publications

Microporosity of BIF hosted massive hematite ore, Iron Quadrangle, Brazil

Microporosity of BIF hosted massive hematite ore, Iron Quadrangle, Brazil

Itabiritos E Minérios De Ferro De Alto Teor Do Quadrilátero Ferrífero – Uma Visão Geral E Discussão

The southern Araçuaí belt and the Dom Silvério Group: geologic architecture and tectonic significance

Contact Info

Product

Resources

About