Two neoproterozoic crustal accretion events in the Brasília belt, central Brazil

Laux, Jorge Henrique; Pimentel, Márcio Martins; Dantas, Elton Luiz; Armstrong, Richard; Junges, Sérgio Luiz

doi:10.1016/j.jsames.2004.09.003

Cited by 134 publications

(88 citation statements)

References 29 publications

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“…The main metamorphic event took place at ca. 630 Ma, as indicated by U-Pb titanite data and Sm-Nd garnet ages (Laux et al 2005). This is similar to the regional metamorphic event observed in several other parts of the Brasília Belt, and has been interpreted as representative of the final closure of the ocean and continental collision (for a review see Cordani et al 2013).…”

Section: Introductionsupporting

confidence: 77%

“…1), the Brasília Belt includes: 1. several metasedimentary units deposited on a Paleoproterozoic sialic basement (Almeida et al 1981, Fuck et al 1993, Pimentel et al 2000; 2. one small allochthonous sialic fragment made dominantly of Archean trondhjemite-tonalite-granodiorite (TTG) terranes and greenstone belts (the Goiás Archean block of Jost et al 2013); 3. three large mafic-ultramafic complexes (Barro Alto, Niquelândia and Cana Brava;Ferreira Filho et al 2010); 4. the Neoproterozoic Goiás Magmatic Arc in the west (for a brief review see Laux et al 2005, Brito-Neves et al 2014); 5. a large Neoproterozoic high-grade terrain known as the Anápolis-Itauçu complex, interpreted as the roots of the Brasília orogen (Piuzana et al 2003.…”

Section: Geological Contextmentioning

confidence: 99%

“…900 Ma with the growth of intra-oceanic island arcs, comprising meta-basalt, meta-andesite, meta-dacite and meta-rhyolite, as well as the corresponding plutonic rocks. These rocks display primitive geochemical and isotopic characteristics with initial ε Nd values mostly ranging between +6 and +3, and Nd T DM ages between 0.8 and 1.1 Ga (Pimentel et al 1991(Pimentel et al , 1997(Pimentel et al , 2000Pimentel & Fuck 1992, Laux 2004, Laux et al 2005. Trace element and isotopic data suggest that some of the tonalites are similar to Phanerozoic adakites (Pimentel et al 1991(Pimentel et al , 1997.…”

Section: Introductionmentioning

confidence: 95%

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Granulite-facies metamorphism at ca. 570-580 Ma in the Porangatu Granulite Complex, central Brazil: implications for the evolution of the Transbrasiliano Lineament

et al. 2017

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ABSTRACT:The Porangatu Granulite Complex is exposed in the central part of the Neoproterozoic Tocantins province in central Brazil, along the boundary between the Brasília Belt to the east and the Araguaia Belt to the west. This is part of the transcontinental Transbrasiliano-Kandi shear system. The complex includes garnet-rich enderbite and charnockite, high-grade gneisses as well as lenses of garnet-bearing mafic granulite or amphibolites, and in situ anatectic charnockite, elongated in the NNE-SSW direction along the Talismã Shear Zone (TSZ). These rocks represent suites of ortho-derived rocks of calc-alkaline affinity and small contributions of tholeiitic basalts and aluminous paragneisses. The structural framework records thrust components probably related to the early stages of an oblique collision during the evolution of Neoproterozoic Brasiliano orogens, and can be understood as involving a collisional system of two crustal blocks, initially with thrust components which in its final stage evolved to a transcurrent system with dextral movement. This led to intense imbrication, generation of mylonitic foliation, stretching lineation, tectonic banding and rotation of structures and minerals. The heterogeneous and progressive ductile deformation was accompanied by metamorphic re-equilibrium in late Neoproterozoic time. Granulite facies conditions reached a metamorphic maximum at temperature and pressure above 850°C and 10 kbar, in an almost anhydrous environment, with or without anatexis. Zircon U-Pb SHRIMP analyses for two selected rock samples indicated the combined age of 580 ± 7 Ma for a charnockite and 548 ± 48 Ma for a mafic granulite from which the charnockite is throught to have been derived. The mafic granulite contains zircon grains of ca. 2.1 Ga, indicating Paleoproterozoic igneous protoliths involved in Neoproterozoic high-grade metamorphism. In addition, older inherited zircon grains of ca.

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Section: Introductionsupporting

confidence: 77%

Section: Geological Contextmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

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Granulite-facies metamorphism at ca. 570-580 Ma in the Porangatu Granulite Complex, central Brazil: implications for the evolution of the Transbrasiliano Lineament

et al. 2017

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“…Its reference age after Jackson et al (2004) For an additional test of the method, two zircon samples from our own laboratory which had previously been dated by other analytical methods were also investigated here. One is a relatively young zircon concentrate (sample HD66) from a hornblende-bearing orthogneiss of the Neoproterozoic Goiás magmatic arc which has previously been dated at 630 ± 5 Ma (2σ ) by U-Pb ID-TIMS in our laboratory (Laux et al 2005 …”

Section: Standards and Samplesmentioning

confidence: 99%

High spatial resolution analysis of Pb and U isotopes for geochronology by laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS)

Bühn

Pimentel

Matteini

et al. 2009

An. Acad. Bras. Ciênc.

240

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Age determinations using the 235 U and 238 U radioactive decay series to the daughter isotopes 207 Pb and 206 Pb, respectively, using the mineral zircon (ZrSiO 4 ), are widely used to decipher geological processes. A new method developed in the last couple of years, the laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS), overcomes previous laborious sample preparation, and yields isotopic ratios and age data with a high spatial resolution of ten of microns. The present study describes the analytical set-up and data reduction process as presently applied at the Laboratory for Geochronology of the University of Brasília. It explores the precision and accuracy of the method by cross-analysing three international zircon standards. We arrive at a precision of 1.9 to 3.7% (2σ SD) and an accuracy of 0.6 to 3.8% (2σ SD) for and U isotopic ratios of the standards. We also apply the method to two natural zircon samples, which have previously been dated by other analytical methods. A comparison of the results shows a good conformity of the age data, being within the error limits. The data demonstrate the great analytical potential of the method for rapid, precise and accurate U-Pb isotopic analyses on the micron scale.

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“…Os dados geocronológicos, geoquímicos e isotópicos disponíveis sugerem que o Arco Magmático de Goiás é resultado de um sistema de arcos de ilhas intraoceânicos, caracterizados por tonalitos a dioritos cálcio-alcalinos, e vulcânicas associadas, formados por dois eventos de acreção crustal, um entre ~900 e ~800 Ma e outro entre ~670 a ~600 Ma Laux et al, 2005). Dados isotópicos e geocronológicos apresentados por Rodrigues et al (1999), Pimentel et al (2000) e Navarro et al (2004) estendem a ocorrência de rochas juvenis associadas ao Arco Magmático de Goiás até a região de Pontalina-Burití Alegre (Figura 1).…”

Section: Introductionunclassified

Geoquímica de Gnaisses do arco magmático de Goiás na Região Sul do Estado de Goiás

Navarro

Zanardo

2007

Geol. USP, Sér. cient.

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Recebido em 02 de março de 2006; aceito em 30 de outubro de 2006Palavras-chave: Faixa Brasília, Arco Magmático de Goiás, gnaisses, geoquímica. RESUMOGnaisses graníticos a trondhjemíticos da região de Pontalina, sul do estado de Goiás, mostram composição cálcica a cálcio-alcalina, metaluminosa a peraluminosa. Apresentam baixos teores em álcalis, enriquecimento em Ba, Sr, K, Rb em relação ao Nb, Y, Zr e ETR e anomalias negativas de Nb e Ti, semelhantes à composição química de magmas gerados em ambientes de arcos magmáticos. Foram anteriormente interpretados como parte do embasamento da Faixa Brasília e atribuídos ao Arqueano e Paleoproterozóico, porém novos dados isotópicos Sm -Nd sugerem que estas rochas são neoproterozóicas (T DM = 0,9 a 1,2 Ga) e os dados geoquímicos indicam que são semelhantes a rochas de outras regiões pertencentes ao Arco Magmático de Goiás.Keywords: Brasília Belt, Goiás Magmatic Arc, gneisses, geochemistry. ABSTRACTGranitic to trondhjemitic gneisses from the Pontalina region in the southern part of Goiás State, Central Brazil, have calcic to calc-alkaline, metaluminous to peraluminous compositions. They have low concentrations of alkaline elements, and are enriched in Ba, Sr, K, Rb in relation to Nb, Y, Zr and REE, and have negative anomalies of Nb and Ti, features which are similar to those of magmas generated in magmatic arc environments. Those rocks were previously interpreted as part of the basement of the Brasília Belt, attributed to the Archean to Paleoproterozoic, but new Sm -Nd isotopic data indicate a neoproterozoic age (T DM = 0,9 a 1,2 Ga), and the preliminary geochemical data reveal compositions similar to the gneisses of the other regions belonging to the Goiás Magmatic Arc.

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Two neoproterozoic crustal accretion events in the Brasília belt, central Brazil

Cited by 134 publications

References 29 publications

Granulite-facies metamorphism at ca. 570-580 Ma in the Porangatu Granulite Complex, central Brazil: implications for the evolution of the Transbrasiliano Lineament

Granulite-facies metamorphism at ca. 570-580 Ma in the Porangatu Granulite Complex, central Brazil: implications for the evolution of the Transbrasiliano Lineament

High spatial resolution analysis of Pb and U isotopes for geochronology by laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS)

Geoquímica de Gnaisses do arco magmático de Goiás na Região Sul do Estado de Goiás

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