Smaller gold deposits in the Archean Rio das Velhas greenstone belt, Quadrilátero Ferrífero, Brazil

Vial, D.S.; Abreu, Gustavo; Schubert, G.; Ribeiro-Rodrigues, L. C.

doi:10.1016/j.oregeorev.2005.01.004

Cited by 27 publications

(14 citation statements)

References 25 publications

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“…Hydrothermal alteration in BIF-hosted gold deposits of the Nova Lima Group are discussed by Lobato et al (1998aLobato et al ( , 1998b2001a), Junqueira et al (2007), Martins Pereira et al (2007), Ribeiro-Rodrigues (1998), Ribeiro-Rodrigues et al (2007), Vial et al (2007aVial et al ( , 2007b, and Vieira (1991). For the specific case of Lamego, Sales (1998) detailed the hydrothermal alteration of the mafic rocks.…”

Section: Structural Geology and Hydrothermal Alteration At The Lamegomentioning

confidence: 99%

“…Ribeiro-Rodrigues et al, 2007;Vial et al, 2007aVial et al, , 2007b, which are correlated in age and background characteristics with other deposits present in different cratons of the world (Goldfarb et al, 2001(Goldfarb et al, , 2005. World-class deposits as Morro Velho (> 500 ton) and Cuiabá (> 100 ton), and smaller ones as Raposos, Juca Vieira, São Bento, Córrego do Sítio and Lamego are hosted in different rocks of the Nova Lima Group, and present varying mineralization styles (Lobato et al, 1998a(Lobato et al, , 1998b(Lobato et al, , 2001b.…”

Section: Introductionmentioning

confidence: 99%

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Metal source and fluid–rock interaction in the Archean BIF-hosted Lamego gold mineralization: Microthermometric and LA-ICP-MS analyses of fluid inclusions in quartz veins, Rio das Velhas greenstone belt, Brazil

Morales

Silva

Lobato

et al. 2016

Ore Geology Reviews

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The Lamego orogenic gold deposit (440,742 Oz gold measured reserves and 2.4 million t measured resources, with an average grade of 5.71 Au g/t and the cut-off grade of 2.15 g/t Au; AGA personal communication, 2014) is located in the 5 km-long trend that includes the world-class Cuiabá deposit. It is hosted in the Neoarchean metavolcano-sedimentary rocks of the Rio das Velhas greenstone belt, Quadrilátero Ferrífero, Brazil. Mineralization is associated mainly with metachertbanded iron formation (BIF) and carbonaceous phyllites in the reclined Lamego fold, in which the Cabeça de Pedra orebody represents the hinge zone. Mineralization is concentrated in silicification zones and their quartz veins, as well as in sulfide minerals, product of BIF sulfidation. Hydrothermal alteration varies according to host rock, with abundant sulfide-carbonate in BIF, and sericite-chlorite in carbonaceous phyllite. Quartz veins classification according to structural relationships and host rocks identified three vein systems. The V1 system, mainly composed of smoky quartz (Qtz I) and pyrite, is extensional and crosscuts the S0 bedding of BIF, and is parallel to the fold axis. The V2 system, of same composition, is represented by veins that are parallel to the S1-2 foliation and S0 bedding. This system is also characterized by silicification zones in the BIF-carbonaceous phyllite contact that has its maximum expression in the hinge zone of folds. The V3 system has milky quartz (Qtz II) veins, which result from the recrystallization of smoky quartz, located mainly in shear zones and faults; these veins form structures en echelon and vein arrays. The most common ore minerals are pyrite, As-pyrite and arsenopyrite. Fluid inclusion-FI trapped in all quartz veins present composition in the H2O-CO2 ± CH4-NaCl system. Fluid evolution can be interpreted in two stages: i) aqueous-carbonic fluid trapped in Qtz I, of low salinity (~ 2% equiv. wt% NaCl), and ii) carbonic-aqueous fluid, of moderate salinity (average 9 % equiv. wt% NaCl) hosted in Qtz II. Both stages are characterized by decrepitation temperatures in the range of 200 to 300°C, and suggest a fluid of metamorphic origin. Applying the arsenopyrite geothermometer, the calculated formation temperature for the Cabeça de Pedra orebody is 300 to 375°C. The vertical intersection of the isochors allows a pressure calculation between 4 to 4.5 kbar. The composition of individual FIs of this orebody, obtained by LA-ICP-MS analyses, compared with results of FIs for the Carvoaria Velha deposit, Córrego do Sítio lineament, highlights a standard composition typical of metamorphic fluids with Na> K> Ca> Mg, which increase or decrease in concentration as a function of salinity in both deposits. Trace elements vary according to fluid-rock reactions, and are directly related to the host rock composition. The comparison of data sets of the two deposits shows that the Cabeça de Pedra FIs have a higher enrichment in Zn, while Cu, As and Sb are richer in Carvoaria Velha, suggesting influence of th...

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Section: Structural Geology and Hydrothermal Alteration At The Lamegomentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Metal source and fluid–rock interaction in the Archean BIF-hosted Lamego gold mineralization: Microthermometric and LA-ICP-MS analyses of fluid inclusions in quartz veins, Rio das Velhas greenstone belt, Brazil

Morales

Silva

Lobato

et al. 2016

Ore Geology Reviews

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“…However, in addition to schists of the Nova Lima Group, the sedimentary units of the Rio das Velhas Supergroup also include banded iron formations (BIFs), carbonate rocks and siliciclastic rocks. In contrast, the top of the Rio das Velhas Supergroup consists of the Maquiné Group which includes quartzites, conglomerates and phyllites (Vial et al 2007).…”

Section: Geologymentioning

confidence: 99%

“…The age of the base of the Minas Supergroup is approximately 2.65 billion years (Renger et al 1994). It is noteworthy that the occurrence of gold is also sometimes linked to the Caraça Group (Vial et al 2007). The Itabira Group, present above the Caraça Group, is 2.42 billion years old (Babinski et al 1993) and composed of iron formations (Cauê Formation), whose roughly quadrangular cartographic distribution gave rise to the name of the Iron Quadrangle region and carbonate Adapted from Alkmin and Marshak (1998) formations (Gandarela Formation).…”

Section: Geologymentioning

confidence: 99%

‘Quadrilátero Ferrífero’: A Beautiful and Neglected Landscape Between the Gold and Iron Ore Reservoirs

Salgado

Carmo²

2015

World Geomorphological Landscapes

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Located in the central-south region of Brazil (State of Minas Gerais), 'Quadrilátero Ferrífero' is a region of immense historical, economic and cultural significance for Brazil. This region is also characterised by its beautiful mountain scenery and unique biodiversity, thus attributing their existence to a complex lithology and a rich geotectonic framework. Therefore, Quadrilátero Ferrífero is an excellent example of how lithostructure can create and scale a beautiful, rich and varied landscape, despite its location in a region of tropical and humid climate.

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“…Em função de sua importância científica, econômica e história o QF tem sido alvo de grandes investimentos exploratórios, mapeamentos governamentais e de diversos estudos acadêmicos, como dissertações de mestrado, teses de doutorados, trabalhos de graduação e mapas geológicos; na busca do entendimento dos padrões estruturais e estilos de mineralização aurífera (e. g. Lobato et al 1998, Lobato et al 2001a, b, 2007, Pereira et al 2007, Baltazar e Zucchetti 2007, Junqueira et al 2007, Vial et al 2007. O avanço do conhecimento dos depósitos orogênicos e a busca de modelos quantitativos exigem novos parâmetros, atualmente inexistentes ou insuficientes, tais como dados de isótopos estáveis (C, S, O), isótopos radiogênicos, incluindo aqueles com objetivo geocronológico, estudos de inclusões fluidas e determinações de elementos químicos tanto em grãos de mineraisminério como em inclusões fluidas.…”

Section: Introductionunclassified

Estudo De Inclusões Fluidas Em Veios De Quartzo E Carbonato (± Sulfetos-Sulfossais) Do Depósito Carvoaria Velha, Lineamento Aurífero Córrego Do Sítio, Santa Bárbara, Quadrilátero Ferrífero, Mg

Ribeiro

Silva

Lobato

et al. 2013

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RESUMO:O Lineamento Aurífero Córrego do Sítio corresponde a uma zona de cisalhamento dúctil com um trend NE-SW controlando quatorze depósitos de ouro, no qual se inclui o depósito Carvoaria Velha. A mineralização de ouro se hospeda em rochas arqueanas do greenstone belt Rio das Velhas, estas correspondem a filitos e xistos finos alterados a quartzo, carbonato e sericita. O estilo de mineralização principal ocorre em veios de quartzo-carbonato-sulfetos (±sulfossais). Os tipos de veios são classificados como: Veios V1 -quartzo-ankerita-sulfetos-berthierita-ouro -são paralelos à principal foliação Sn e estão localmente mineralizados em ouro. Veios V2 -quartzo-ankerita-pirita -são veios desenvolvidos no plano de clivagem de crenulação Sn+1, extensionais e raramente mineralizados. Veios V3 -quartzo-ankerita -são veios de preenchimento de fraturas Sn+3, geralmente não contêm sulfetos e sulfossais. Veios V4 -quartzocalcita -são veios restritos aos diques e sills metamáficos, são extensionais e sem orientação preferencial. Os minerais-minério são arsenopirita, pirita, berthierita e pirrotita. Microssonda eletrônica revela a presença de fases metálicas ricas em As, Sb e Co (boulangerita, tetraedrita, cobalita e ullmanita), que sobrecrescem aos minerais-minério. Dados de inclusões fluidas caracterizam fluido mineralizador com composição H2O-CO2±CH4-NaCl, com traços de N2, podendo conter outros cátions além de Na + , como Mg 2+ , Ca 2+ e Fe 2+ . Estes fluidos teriam pelo menos dois estágio de evolução: i) fluido inicial aprisionado em quarto fumê, com salinidade moderada (~8.5% em peso de NaCl eq.) e temperatura mínima de 280±17 o C; e ii) fluido tardio, representado por fluido aprisionado em quartzo recristalizado, menos salino (~4.6% em peso de NaCl eq.) e temperatura mínima de 315±33 o C. Os dados obtidos correspondem a valores típicos de fluido metamórfico característico de depósitos tipo orogenic gold. Palavras-chave: mineralização aurifera, inclusões fluidas, Quadrilátero Ferrífero, alteração hidrotermal Abstract: FLUID INCLUSION STUDIES IN QUARTZ-CARBONATE(± SULFIDES-SULFOSALTS)VEINS FROM CARVOARIA VELHA DEPOSIT, CÓRREGO DO SÍTIO GOLD LINEAMENT, SANTA BÁRBARA, QUADRILÁTERO FERRÍFERO, MG. The Córrego do Sítio Lineament is defined as a 16 km long, NE-SW trending ductile shear zone which controls fourteen deposits, one of them is Carvoaria Velha deposit. The mineralization is hosted in Archean rocks of Rio das Velhas greenstone belt, represented for carbonaceous phyllite and schists with carbonate, sericite, sulphide-sulphosalt and silica alteration. The main gold mineralization styles at the Córrego do Sítio lineament are quartz-carbonate-sulphide±sulphosalts veins of varied distribution. They are classified as: V1 veins -quartz-ankerite-pyrite-berthierite-gold -parallel to the main regional foliation Sn, and usually mineralized in gold; V2 veins -quartz-ankerite-pyrite -developed at the crenulation cleavage Sn+1, extensional and rarely gold mineralized; V3 veins -quartz-ankerite -filling Sn+3 fractures, usually free ...

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Smaller gold deposits in the Archean Rio das Velhas greenstone belt, Quadrilátero Ferrífero, Brazil

Cited by 27 publications

References 25 publications

Metal source and fluid–rock interaction in the Archean BIF-hosted Lamego gold mineralization: Microthermometric and LA-ICP-MS analyses of fluid inclusions in quartz veins, Rio das Velhas greenstone belt, Brazil

Metal source and fluid–rock interaction in the Archean BIF-hosted Lamego gold mineralization: Microthermometric and LA-ICP-MS analyses of fluid inclusions in quartz veins, Rio das Velhas greenstone belt, Brazil

‘Quadrilátero Ferrífero’: A Beautiful and Neglected Landscape Between the Gold and Iron Ore Reservoirs

Estudo De Inclusões Fluidas Em Veios De Quartzo E Carbonato (± Sulfetos-Sulfossais) Do Depósito Carvoaria Velha, Lineamento Aurífero Córrego Do Sítio, Santa Bárbara, Quadrilátero Ferrífero, Mg

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