Imaging the roots of a post-collisional pluton: Implications for the voluminous Cambrian magmatism in the Araçuaí orogen (Brazil)

2021 ◽  
pp. 229146
Author(s):  
G.F. Souza Junior ◽  
R.I.F. Trindade ◽  
F.A. Temporim ◽  
U.D. Bellon ◽  
L.P. Gouvêa ◽  
...  
Keyword(s):  
Araçuaí Orogen

Late Neoproterozoic-Cambrian granitic magmatism in the Araçuaí orogen (Brazil), the Eastern Brazilian Pegmatite Province and related mineral resources

2011 ◽  
Vol 350 (1) ◽  
pp. 25-51 ◽  
Author(s):  
A. C. Pedrosa-Soares ◽  
Cristina P. De Campos ◽  
Carlos Noce ◽  
Luiz Carlos Silva ◽  
Tiago Novo ◽  
...  
Keyword(s):  
Mineral Resources ◽  
Granitic Magmatism ◽  
Late Neoproterozoic ◽  
Araçuaí Orogen

Chapter 49 The Neoproterozoic Macaúbas Group, Araçuaí orogen, SE Brazil

2011 ◽  
Vol 36 (1) ◽  
pp. 523-534 ◽  
Author(s):  
A. C. Pedrosa-Soares ◽  
Marly Babinski ◽  
Carlos Noce ◽  
Maximiliano Martins ◽  
Gláucia Queiroga ◽  
...  
Keyword(s):  
Se Brazil ◽  
Araçuaí Orogen

scholarly journals Neoproterozoic glacial deposits from the Araçuaí orogen, Brazil: Age, provenance and correlations with the São Francisco craton and West Congo belt

2012 ◽  
Vol 21 (2-3) ◽  
pp. 451-465 ◽  
Author(s):  
M. Babinski ◽  
A.C. Pedrosa-Soares ◽  
R.I.F. Trindade ◽  
M. Martins ◽  
C.M. Noce ◽  
...  
Keyword(s):  
Glacial Deposits ◽  
Araçuaí Orogen

scholarly journals The hot back-arc zone of the Araçuaí orogen, Eastern Brazil: from sedimentation to granite generation

2014 ◽  
Vol 44 (1) ◽  
pp. 155-180 ◽  
Author(s):  
Camila Gradim ◽  
Jorge Roncato ◽  
Antônio Carlos Pedrosa-Soares ◽  
Umberto Cordani ◽  
Ivo Dussin ◽  
...  
Keyword(s):  
Eastern Brazil ◽  
Back Arc ◽  
Araçuaí Orogen

scholarly journals AGE OF THE RIBEIRÃO DA FOLHA OPHIOLITE, ARAÇUAÍ OROGEN: THE U-PB ZIRCON (LA-ICPMS) DATING OF A PLAGIOGRANITE

2013 ◽  
Author(s):  
Gláucia Nascimento Queiroga ◽  
Antônio Carlos Pedrosa-Soares ◽  
Carlos Maurício Noce ◽  
Fernando Flecha de Alkmim ◽  
Márcio Martins Pimentel ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Inductively Coupled ◽  
Inductively Coupled Mass Spectrometry ◽  
Araçuaí Orogen

O Orógeno Araçuaí, de idade neoproterozóica, se estende da margem sudeste do Cráton do São Franciscoao Oceano Atlântico, entre os paralelos 15° e 21° S. O estágio rifte da bacia precursora do Orógeno Araçuaíé balizado pela idade U-Pb SHRIMP de ca. 875 Ma dada por granitos anorogênicos. A evolução orogênicaé subdividida nos estágios pré-colisional (ca. 630-585 Ma), sin-colisional (ca. 585-560 Ma), tardi-colisional(ca. 560-530 Ma) e pós-colisional (ca. 530-490 Ma). Remanescentes de rochas magmáticas de assoalhooceânico, localizados no setor central deste orógeno, têm sido descritos na literatura geológica desde 1990.O mais completo destes registros oceânicos é o ofiolito de Ribeirão da Folha, situado nos arredores da vilahomônima, no município de Minas Novas, MG. O ofiolito de Ribeirão da Folha é uma associação litológicatectonicamente desmembrada, composta por fatias de rochas meta-ultramáficas e metamáficas que foramembutidas por empurrões em pacotes da Formação Ribeirão da Folha (unidade distal do Grupo Macaúbas).Esta formação, na área enfocada, consiste de micaxistos e cianita-grafita xistos (pelitos pelágicos), comintercalações de metacherts sulfetados, diopsiditos sulfetados, corpos de sulfetos maciços, formaçõesferríferas bandadas dos tipos óxido, sulfeto e silicato, e orto-anfibolitos finos (metabasaltos), metamorfisadosnas zonas da cianita da fácies anfibolito médio. Dados geotermobarométricos dos micaxistos peraluminososrevelaram condições metamórficas em torno de 550º C a 5,5 kbar. As assinaturas litoquímicas das rochasmetamáficas e meta-ultramáficas revelam afinidade ofiolítica e origem em assoalho oceânico. Os dadosisotópicos Sm-Nd destas rochas mostram valores positivos de epsilon Nd (+3 a +7), e as idades modelo eisocrônica sugerem desenvolvimento de litosfera oceânica durante o Neoproterozóico. Todas as tentativasanteriores de recuperação de zircão a partir de volumosas amostras das rochas metamáficas foram infrutíferas.Contudo, corpos leucocráticos semelhantes a plagiogranito foram reconhecidos poucos anos atrás e setornaram um dos principais alvos da tese de doutorado da primeira autora. Estes corpos ocorrem sob aforma de veios irregulares com dimensões milimétricas a centimétricas (até 50 cm), e são encaixados pororto-anfibolito bandado de granulação média a grossa (metadolerito a metagabro). Os corpos leucocráticosconsistem de metaplagiogranito foliado, composto essencialmente por plagioclásio cálcico com bordasalbíticas, quartzo, hornblenda e epidoto, com titanita, sulfeto, apatita e zircão como os principais mineraisacessórios. Os cristais de zircão da amostra de plagiogranito são euédricos e muito límpidos, e mostrammorfologia prismática elongada (3:1), sugerindo origem magmática. Análises U-Pb por LA-ICPMS (LaserAblation Inductively Coupled Mass Spectrometry) foram realizadas em dezoito cristais de zircão e mostramresultados concordantes, indicando idade de cristalização magmática de 660 ± 29 Ma. Esta idade baliza aépoca de geração de crosta oceânica na bacia precursora do Orógeno Araçuaí. O espalhamento de algumasdas análises ao longo da curva concórdia sugere perda de Pb devido ao metamorfismo de fácies anfibolitoem ca. 580 Ma. A idade de ca. 660 Ma plagiogranito precede a maior idade U-Pb (ca. 630 Ma) de tonalitosdeformados do arco magmático pré-colisional, bem como a idade U-Pb (ca. 582 Ma) dos granitos sincolisionaismais antigos. 

scholarly journals ORÓGENO ARAÇUAÍ: SÍNTESE DO CONHECIMENTO 30 ANOS APÓS ALMEIDA 1977

2013 ◽  
Author(s):  
Antônio Carlos Pedrosa-Soares ◽  
Carlos Maurício Noce ◽  
Fernando Flecha de Alkmim ◽  
Luiz Carlos da Silva ◽  
Marly Babinski ◽  
...  
Keyword(s):  
Oceanic Crust ◽  
Detrital Zircon ◽  
Volcanic Rocks ◽  
Oceanic Lithosphere ◽  
Continental Rift ◽  
Passive Margin ◽  
Iron Formation ◽  
Calc Alkaline ◽  
Magmatic Arc ◽  
Araçuaí Orogen

The Araçuaí Fold Belt was defined as the southeastern limit of the São Francisco Craton in the classicalpaper published by Fernando Flávio Marques de Almeida in 1977. This keystone of the Brazilian geologicliterature catalyzed important discoveries, such as of Neoproterozoic ophiolites and a calc-alkaline magmaticarc, related to the Araçuaí Belt and paleotectonic correlations with its counterpart located in Africa (the WestCongo Belt), that provided solid basis to define the Araçuaí-West-Congo Orogen by the end of the 1990thdecade. After the opening of the Atlantic Ocean in Cretaceous times, two thirds of the Araçuaí-West-CongoOrogen remained in the Brazil side, including records of the continental rift and passive margin phases ofthe precursor basin, all ophiolite slivers and the whole orogenic magmatism formed from the pre-collisionalto post-collisional stages. Thus, the name Araçuaí Orogen has been applied to the Neoproterozoic-Cambrianorogenic region that extends from the southeastern edge of the São Francisco Craton to the Atlantic coastlineand is roughly limited between the 15º and 21º S parallels. After 30 years of systematic geological mappingtogether with geochemical and geochronological studies published by many authors, all evolutionary stagesof the Araçuaí Orogen can be reasonably interpreted. Despite the regional metamorfism and deformation, thefollowing descriptions generally refer to protoliths. All mentioned ages were obtained by U-Pb method onzircon. The Macaúbas Group records rift, passive margin and oceanic environments of the precursor basinof the Araçuaí Orogen. From the base to the top and from proximal to distal units, this group comprises thepre-glacial Duas Barras and Rio Peixe Bravo formations, and the glaciogenic Serra do Catuni, Nova Auroraand Lower Chapada Acauã formations, related to continental rift and transitional stages, and the diamictitefreeUpper Chapada Acauã and Ribeirão da Folha formations, representing passive margin and oceanicenvironments. Dates of detrital zircon grains from Duas Barras sandstones and Serra do Catuni diamictitessuggest a maximum sedimentation age around 900 Ma for the lower Macaúbas Group, in agreement withages yielded by the Pedro Lessa mafic dikes (906 ± 2 Ma) and anorogenic granites of Salto da Divisa (875 ±9 Ma). The thick diamictite-bearing marine successions with sand-rich turbidites, diamictitic iron formation,mafic volcanic rocks and pelites (Nova Aurora and Lower Chapada Acauã formations) were depositedfrom the rift to transitional stages. The Upper Chapada Acauã Formation consists of a sand-pelite shelfsuccession, deposited after ca. 864 Ma ago in the proximal passive margin. The Ribeirão da Folha Formationmainly consists of sand-pelite turbidites, pelagic pelites, sulfide-bearing cherts and banded iron formations,representing distal passive margin to oceanic sedimentation. Gabbro and dolerite with plagiogranite veinsdated at ca. 660 Ma, and ultramafic rocks form tectonic slices of oceanic lithosphere thrust onto packagesof the Ribeirão da Folha Formation. The pre-collisional, calc-alkaline, continental magmatic arc (G1 Suite,630-585 Ma) consists of tonalites and granodiorites, with minor diorite and gabbro. A volcano-sedimentarysuccession of this magmatic arc includes pyroclastic and volcaniclastic rocks of dacitic composition datedat ca. 585 Ma, ascribed to the Palmital do Sul and Tumiritinga formations (Rio Doce Group), depositedfrom intra-arc to fore-arc settings. Detrital zircon geochronology suggests that the São Tomé wackes (RioDoce Group) represent intra-arc to back-arc sedimentation after ca. 594 Ma ago. The Salinas Formation, aconglomerate-wacke-pelite association located to northwest of the magmatic arc, represents synorogenicsedimentation younger than ca. 588 Ma. A huge zone of syn-collisional S-type granites (G2 Suite, 582-560Ma) occurs to the east and north of the pre-collisional magmatic arc, northward of latitude 20º S. Partialmelting of G2 granites originated peraluminous leucogranites (G3 Suite) from the late- to post-collisionalstages. A set of late structures, and the post-collisional intrusions of the S-type G4 Suite (535-500 Ma) andI-type G5 Suite (520-490 Ma) are related to the gravitational collapse of the orogen. The location of themagmatic arc, roughly parallel to the zone with ophiolite slivers, from the 17º30’ S latitude southwardssuggests that oceanic crust only developed along the southern segment of the precursor basin of the Araçuaí-West-Congo Orogen. This basin was carved, like a large gulf partially floored by oceanic crust, into the SãoFrancisco-Congo Paleocontinent, but paleogeographic reconstructions show that the Bahia-Gabon cratonicbridge (located to the north of the Araçuaí Orogen) subsisted since at least 1 Ga until the Atlantic opening.This uncommon geotectonic scenario inspired the concept of confined orogen, quoted as a new type ofcollisional orogen in the international literature, and the appealing nutcracker tectonic model to explain theAraçuaí-West-Congo Orogen evolution. 

Contrasting oxygen fugacity of I- and S-type granites from the Araçuaí orogen, SE Brazil: an approach based on opaque mineral assemblages

2019 ◽  
Vol 113 (5) ◽  
pp. 667-686 ◽  
Author(s):  
Jordania Cristina dos Santos Dias ◽  
Leonardo Gonçalves ◽  
Cristiane C. Gonçalves
Keyword(s):  
Oxygen Fugacity ◽  
Opaque Mineral ◽  
Se Brazil ◽  
Mineral Assemblages ◽  
Araçuaí Orogen

scholarly journals Thermobarometry and electron-microprobe Th-U-Pb monazite dating in garnet metapelites from the Capelinha Formation, Araçuaí Orogen, Brazil

2016 ◽  
Vol 69 (1) ◽  
pp. 33-44 ◽  
Author(s):  
Gláucia Nascimento Queiroga ◽  
Bernhard Schulz ◽  
Maximiliano de Souza Martins ◽  
Marco Paulo de Castro ◽  
Antônio Carlos Pedrosa-Soares ◽  
...  
Keyword(s):  
Electron Microprobe ◽  
Monazite Dating ◽  
Araçuaí Orogen
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