scholarly journals The Glória quartz-monzodiorite: isotopic and chemical evidence of arc-related magmatism in the central part of the Paleoproterozoic Mineiro belt, Minas Gerais State, Brazil

2006 ◽  
Vol 78 (3) ◽  
pp. 543-556 ◽  
Author(s):  
Ciro A. Ávila ◽  
Wilson Teixeira ◽  
Umberto G. Cordani ◽  
Héctor R. Barrueto ◽  
Ronaldo M. Pereira ◽  
...  
Keyword(s):  
Minas Gerais ◽  
Crustal Material ◽  
Calc Alkaline ◽  
Isotopic Data ◽  
Zircon Age ◽  
Quadrilátero Ferrífero ◽  
Minas Gerais State ◽  
Tectonic Relationship ◽  
Mineralogical Assemblage ◽  
Chemical Evidence

The Glória quartz-monzodiorite, one of the mafic plutons of the Paleoproterozoic Mineiro belt, is intrusive into banded gneisses, amphibolites, schists and phyllites of the Rio das Mortes greenstone belt, in the southern portion of the São Francisco Craton, State of Minas Gerais, Brazil. The Glória quartz-monzodiorite yields a SHRIMP U-Pb zircon age of 2188 ± 29 Ma, suggesting a tectonic relationship with the pre-collisional phase of the Mineiro belt. According to the Nd isotopic evidence (epsilonNd(T) = -3.4; T DM = 2.68 Ga) the original magmas was formed by a mixture among Archean crustal material and Paleoproterozoic juvenile magma. The Glória quartz-monzodiorite shows metaluminous and calc-alkaline tendency with intermediate K content, comparable to that of volcanic-arc rocks. The primary mineralogical assemblage was partly modified by metamorphism, dated between 2131-2121 Ma in nearby coeval plutons. Such metamorphism is significantly older than the reported metamorphic episodes of the Mineiro belt in the Quadrilátero Ferrífero region (2059-2041 Ma) in the eastern portion of the study area. This evidence, together with chemical and isotopic data from other mafic and felsic plutons coeval with the Glória quartz-monzodiorite, indicate a tectonic and magmatic migration within the Mineiro belt from west to east.

Monazite-(Ce) and xenotime-(Y) microinclusions in fluorapatite of the pegmatites from the Volta Grande mine, Minas Gerais state, southeast Brazil, as witnesses of the dissolution–reprecipitation process

2019 ◽  
Vol 83 (4) ◽  
pp. 595-606 ◽  
Author(s):  
Felipe Emerson André Alves ◽  
Reiner Neumann ◽  
Ciro Alexandre Ávila ◽  
Fabiano Richard Leite Faulstich
Keyword(s):  
Electron Probe ◽  
Minas Gerais ◽  
Compositional Variation ◽  
Partial Removal ◽  
Hydrous Fluid ◽  
Southeast Brazil ◽  
Pegmatite Body ◽  
Minas Gerais State ◽  
Fluorapatite Structure ◽  
Mineralogical Assemblage

AbstractFluorapatite with monazite-(Ce) and xenotime-(Y) microinclusions occurs in the lithium–caesium–tantalum pegmatite body A of the Volta Grande mine, Minas Gerais state, Southeast Brazil. The fluorapatite displays faint zoning, detected mainly by cathodoluminescence. Electron probe and laser ablation analyses indicate that zoning in the fluorapatite corresponds to variation in Mn and rare-earth element (REE) content. Such compositional variation is attributed to partial removal of the REE from the fluorapatite structure during a dissolution–reprecipitation process, forming monazite-(Ce) and xenotime-(Y) microinclusions in the REE-depleted zones of the fluorapatite. These inclusions exhibit an inherited geochemical signature, manifested by low Th and U concentrations when compared to monazite and xenotime crystallised from melts. Rhodochrosite and calcite inclusions are also associated with monazite-(Ce) and xenotime-(Y) and are probably products of the same process, recycling Ca, Mn, and CO32− from the fluorapatite through the following reaction: [Ca(5–2a–b–½x),Naa,(Y + REE)a,Mnb][(PO4)3–x(CO3)x(F)] + Fluid[a(2Ca2+ + P5+) + (x–b)(Ca2+) + H2O)] → [Ca5(PO4)3(F,OH)] + a[(Y + REE)PO4] + b[Mn(CO3)] + (x–b)[Ca(CO3)] + Fluid a[Na+].On the basis of new fluid-inclusion analyses, we propose that a hot (T > 204.5°C), salty (16 wt.% eq. NaCl, attributed to LiCl), hydrous fluid mediated the dissolution–reprecipitation of the fluorapatite. This fluid corresponds to similarly described Li-rich fluids which were suggested to have re-equilibrated the mineralogical assemblage at the Volta Grande mine.

scholarly journals ASPECTOS LEGAIS DA SEGURANÇA DE BARRAGENS DE REJEITO DE MINÉRIO: IMPLICAÇÕES PARA A QUALIDADE AMBIENTAL E USOS MÚLTIPLOS DA ÁGUA NO ALTO RIO DAS VELHAS (MG)

GEOgraphia ◽  
2019 ◽  
Vol 21 (45) ◽  
pp. 32
Author(s):  
Guilherme Eduardo Macedo Cota ◽  
Nayara Mariana Gonzaga Rosa ◽  
Camila Esteves Romeiro ◽  
Izabela Aparecida da Silva Mendes ◽  
Antônio Pereira Magalhães Júnior
Keyword(s):  
Environmental Quality ◽  
National Policy ◽  
Legal Aspects ◽  
Minas Gerais ◽  
Environmental Risks ◽  
Mining Tailings ◽  
Tailings Dams ◽  
Iron Quadrangle ◽  
Quadrilátero Ferrífero ◽  
Minas Gerais State

: A construção de barramentos para a contenção de rejeitos provenientes da exploração mineral é uma prática comum em Minas Gerais, principalmente no Quadrilátero Ferrífero. Os riscos ambientais associados ao colapso destas estruturas favoreceram a elaboração de parâmetros legais que regulam as barragens de rejeito de minério no Brasil, estabelecidos através da Política Nacional de Segurança de Barragens e do Sistema Nacional de Informações sobre Segurança de Barragens. A bacia do Alto Rio das Velhas está totalmente inserida no Quadrilátero Ferrífero, onde a mineração se sobressai em diferentes contextos de uso e ocupação do solo no entorno dos cursos d’água. Deste modo, destaca-se a importância da realização de estudos que abordem os aspectos e instrumentos legais tocantes à segurança de barragens de rejeitos, fomentando reflexões acerca das implicações e dos riscos inerentes à instalação e à manutenção deste tipo de estrutura na região. Neste sentido, este artigo apresenta um panorama dos aspectos jurídicos, legais e administrativos que envolvem a segurança de barragens de rejeito de minério instaladas na região do Alto Rio das Velhas e faz uma reflexão sobre o seu contexto espacial, apontando os problemas, riscos e consequências para a qualidade ambiental e a manutenção de usos múltiplos da água na bacia.Palavras-chave: Mineração. Riscos ambientais. Quadrilátero Ferrífero. LEGAL ASPECTS ON SAFETY OF MINING REJECT DAMS: IMPLICATIONS FOR AN ENVIRONMENTAL QUALITY AND MULTIPLE WATER USES IN THE UPPER RIO DAS VELHAS BASIN (MINAS GERAIS STATE, BRAZIL)Abstract: The construction of dams to store and contain mineral tailings is a common practice in the Minas Gerais state, Brazil, mainly in the so-called “Quadrilátero Ferrífero” geological region (iron quadrangle). The environmental risks associated with the collapse of these structures favored the elaboration of legal parameters that regulate this sector in Brazil. These parameters are established through the national policy on dam’s safety and the national information system on dam’s safety. The Alto Rio das Velhas basin is totally inserted in the “Quadrilátero Ferrífero”, where mining excels in different contexts of land use and occupation around the water courses. Therefore, it is important to carry out studies that address the legal aspects and instruments related to the safety of mining tailings dams, motivating reflections about the implications and risks inherent to the their installation and maintenance in the region. In this sense, this article presents an overview of the juridical, legal and administrative aspects that involve the safety of mining tailings dams installed in the region and reflects on their spatial context, pointing out the problems, risks and consequences for environmental quality around maintaining commitment of water multiple uses in the basin.Keywords: Mining. Environmental risks. “Quadrilátero Ferrífero” (iron quadrangle).

scholarly journals Range extension of Anthus nattereri Sclater, 1878 (Aves: Motacillidae) in Minas Gerais, southeastern Brazil

Check List ◽  
2011 ◽  
Vol 7 (5) ◽  
pp. 598 ◽  
Author(s):  
Luiz Gabriel Mazzoni ◽  
Alyne Perillo
Keyword(s):  
Endangered Species ◽  
New Records ◽  
Minas Gerais ◽  
Range Extension ◽  
Southeastern Brazil ◽  
The North ◽  
Quadrilátero Ferrífero ◽  
Minas Gerais State

The distribution of Anthus nattereri, an endangered species, is extended at least 170 km to the north of the nearest locality in southeastern Brazil. New records of five individuals are provided from the municipality of Itabirito, within the Quadrilátero Ferrífero region, Minas Gerais state. Anthus nattereri was photographed and tape-recorded, sometimes in sympatry with Anthus hellmayri, a species it closely resembles. Records were made mostly on burnt open grasslands (“campos limpos”) making the conservation of this species a difficult task. 

scholarly journals META-KOMATIÍTOS DO MORRO DO ONÇA, UM IMPORTANTE SÍTIO GEOLÓGICO DO QUADRILÁTERO FERRÍFERO - MG

2013 ◽  
Author(s):  
Úrsula de Azevedo Ruchkys ◽  
Maria Márcia Magela Machado ◽  
Carlos Maurício Noce
Keyword(s):  
Thermal Conditions ◽  
Minas Gerais ◽  
Geological Heritage ◽  
Quadrilátero Ferrífero ◽  
Minas Gerais State

O Quadrilátero Ferrífero ocupa uma área de aproximadamente 7.000 km2 na porção centro-sudeste do estado de Minas Gerais. É internacionalmente reconhecido como importante terreno pré-cambriano e uma das maiores províncias minerais do planeta, especialmente por seus significativos depósitos de ouro e ferro. Elementos geológicos singulares e bem preservados, representativos de quase toda a evolução pré-cambriana são encontrados em diferentes conjuntos de rochas no Quadrilátero Ferrífero fazendo desta área um importante patrimônio geológico. Um dos sítios geológicos que compõem este patrimônio é o Morro do Onça, uma exposição de rochas komatiíticas arqueanas com textura spinifex e estrutura em almofada preservada. O fato das rochas komatiíticas fornecerem evidências das condições termais e composição do manto Arqueano, e portanto constituírem a memória da história evolutiva da Terra, faz do Morro do Onça um local de excepcional interesse científico e pedagógico que, como tal, deve ser divulgado e preservado.Palavras chave: Morro do Onça, Komatiítos, Patrimônio Geológico, Geoconservação.ABSTRACT: META-KOMATIITES OF MORRO DO ONÇA, GEOLOGICAL HERITAGE OF QUADRILÁTERO FERRÍFERO - MG The Quadrilátero Ferrífero covers an area of approximately 7,000 km2 in the central-southeastern portion of Minas Gerais state. It is worldwide recognized as an important pre-Cambrian terrain and as one of the world’s largest mineral province, especially by your significant deposits of gold and iron. Singular and well preserved geological elements, representative of the Precambrian evolution, are found in different sets of rocks in the Quadrilátero Ferrífero region, making this a great and important geological heritage. One of geological sites that make up this heritage is the Morro do Onça, where crops out komatiites with spinifex texture and pillow structure preserved. The fact of komatiites provide evidence of thermal conditions and composition of the Archean mantle, and so become memory of of the earth’s history, makes Morro do Onça a place of exceptional scientific and educational interest, that should be promoted and preserved.Keywords: Morro do Onça, Komatiites, Geological Heritage, Geoconservation.

scholarly journals New records of Phibalura flavirostris Vieillot, 1816 (Aves: Cotingidae) in Minas Gerais, southeastern Brazil, with notes on its natural history and a review of its historical occurrence

Check List ◽  
2013 ◽  
Vol 9 (4) ◽  
pp. 870
Author(s):  
Helberth José Cardoso Peixoto ◽  
Gustavo Bernardino Malacco ◽  
Marcelo Ferreira de Vasconcelos ◽  
Luiz Gabriel Mazzoni ◽  
Alyne Perillo ◽  
...  
Keyword(s):  
Natural History ◽  
New Records ◽  
Minas Gerais ◽  
The State ◽  
Southeastern Brazil ◽  
Breeding Behavior ◽  
Migration Patterns ◽  
Quadrilátero Ferrífero ◽  
Minas Gerais State ◽  
Plant Families

We present new records of Phibalura flavirostris for the state of Minas Gerais, a little known and endangered species in the state, including notes on feeding and breeding behavior. We also present a review of records of the species in this state based on specimens housed in ornithological collections. It was noted the consumption of fruits belonging to five different plant families and reproductive evidence in a new state locality. The species proved to be rare in Minas Gerais, being relatively common in a few localities. P. flavirostris proved to be resident in the Quadrilátero Ferrífero region and were not found evidence of altitudinal migration. However the available records are inconsistent to affirm about the migration patterns of this species. The preservation of certain areas and new studies on the natural history are important for the conservation of the species in Minas Gerais state.

Biorremediação de solos contaminados com arsênio por meio de lavagem de solo usando biossurfactantes

2020 ◽  
Vol 25 (4) ◽  
pp. 543-553
Author(s):  
Ricardo Silva Coelho ◽  
Mônica Cristina Teixeira
Keyword(s):  
Soil Washing ◽  
Minas Gerais ◽  
Quadrilátero Ferrífero

RESUMO A mineração de ouro é uma das principais fontes de contaminação de arsênio (As) no Quadrilátero Ferrífero em Minas Gerais. O As é um elemento tóxico capaz de causar sérios danos à saúde humana. Com o objetivo de investigar formas mais ecológicas e igualmente eficientes para a remoção de As em solos, empregou-se a técnica de lavagem de solos (soil washing) com uso de extratos com biossurfactantes (BS) visando promover a mobilização do As contido em solo de mina de ouro abandonada. Para a produção dos extratos, foram selecionadas duas culturas mistas de bactérias produtoras de BS (MPCB e MPBR) tolerantes a alta concentração de arsênio (8 mg.L-1). Os tensoativos produzidos foram estáveis em ampla faixa de pH, 3-11; temperatura, 28-50ºC e salinidade, 1-5% NaCl (p.v-1). Nos testes de lavagem de solo, em pH 11, as remoções de As obtidas com os extratos MPCB (14,01 e 13,72%) e MPBR (12,04 e 12,31%) foram superiores àquelas obtidas com soluções a 1% (p.v-1) dos surfactantes comerciais SDS (0,87 e 0,71%); saponina (0,57 e 0,55%) e lecitina de soja (2,05 e 2,63%). Os resultados dos testes em coluna foram igualmente influenciados pelo pH e pela proporção sólido:líquido. As maiores remoções de As: 25,43% (MPCB) 22,43% (MPBR) foram obtidas em pH 11, na proporção 1:40 (g.mL-1), após 10 ciclos de extração. Os extratos MPCB e MPBR removeram o As solúvel em água, os íons ligados ao carbonato e aqueles adsorvidos. Ambos os extratos tiveram comportamento semelhante ao ácido etilenodiaminotetracético (EDTA) e ao extrato de cultura microbiana comercial (GorduraKlin®).

Episodic tectono-thermal activity in the southern part of the East Greenland Caledonides

2000 ◽  
pp. 42-49 ◽  
Author(s):  
A. Graham Leslie ◽  
Allen P. Nutman
Keyword(s):  
Thermal Activity ◽  
Isotopic Data ◽  
Zircon Age ◽  
East Greenland ◽  
Original Series ◽  
Age Determinations

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Leslie, A. G., & Nutman, A. P. (2000). Episodic tectono-thermal activity in the southern part of the East Greenland Caledonides. Geology of Greenland Survey Bulletin, 186, 42-49. https://doi.org/10.34194/ggub.v186.5214 _______________ Isotopic data from the Renland augen granites of the Scoresby Sund region (Figs 1, 2) provided some of the first convincing support for relicts of potentially Grenvillian tectono-thermal activity within the East Greenland Caledonides. In Renland, Chadwick (1975) showed the presence of major bodies of augen granite (Fig. 2) interpreted by Steiger et al. (1979), on the basis of Rb–Sr whole rock and U–Pb zircon age determinations, to have been emplaced about 1000 Ma ago.

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