Petrogenesis of the Orthogneisses of the Mantiqueira Complex, Central Ribeira Belt, SE Brazil: An Archaean to Palaeoproterozoic Basement Unit Reworked During the Pan-African Orogeny

Duarte, Beatriz Paschoal; Valente, Sérgio de Castro; Heilbron, Mônica; Neto, M.C. Campos

doi:10.1016/s1342-937x(05)70795-4

Cited by 42 publications

(5 citation statements)

References 7 publications

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“…3 C and D). Geochemical data are available for selected regions in the state and the nearby Minas Gerais State (Duarte et al 1997, Heilbron et al 1998, Duarte et al 2004, Fernandes André et al 2009). The felsic rocks comprise two of intermediate to high-K calcalkaline compositional groups, mostly with juvenile magmatic arc signatures (Duarte et al 1997, Heilbron et al 1998 (Machado et al 1996, Fernandes André et al 2009, Silva et al 2002, Ragatky et al 1999, Noce et al 2007, Degler et al 2017.…”

Section: Juiz De Fora Complexmentioning

confidence: 99%

Proterozoic to Ordovician geology and tectonic evolution of Rio de Janeiro State, SE-Brazil: insights on the central Ribeira Orogen from the new 1:400,000 scale geologic map

et al. 2020

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Section: Juiz De Fora Complexmentioning

confidence: 99%

Proterozoic to Ordovician geology and tectonic evolution of Rio de Janeiro State, SE-Brazil: insights on the central Ribeira Orogen from the new 1:400,000 scale geologic map

et al. 2020

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“…Alkmin & Teixeira 2017;Heilbron et al, 2017;Peres et al, 2004). Compiled U-Pb data from: Cardoso et al, 2019;Pinheiro et al, 2019;Moreira et al, 2018;Teixeira et al, 2015;Seixas et al, 2013;Seixas et al, 2012;Corrêa Neto et al, 2012;Heilbron et al, 2010;Ávila et al, 2014;Noce et al, 2007;;Duarte et al, 2004;Quéméneur et al, 2003;Silva et al, 2002). (Pearce, 1982).…”

Section: Discussionunclassified

Evidence for a complex accretionary history preceding the amalgamation of Columbia: The Rhyacian Minas-Bahia Orogen, southern São Francisco Paleocontinent, Brazil

et al. 2021

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“…The studied samples come from the Mantiqueira Complex, a unit that forms a belt at the southeastern margin of the São Francisco Craton, southeastern Brazil (Figure 1) and is interpreted to correspond to a portion of the São Francisco Craton reworked during the Neoproterozoic Brasiliano orogenic cycle (Brueckner et al., 2000; Cutts et al., 2018; Figueiredo & Teixeira, 1996; Noce et al., 2007). The Mantiqueira Complex is composed of intensely foliated migmatites and banded gneisses with granite to tonalite compositions, among which amphibolite lenses and boudins occur (Baltazar & Raposo, 1993; Duarte et al., 2004). These rocks record crystallization ages from 2,203 to 2,041 Ma (Brueckner et al., 2000; Figueiredo & Teixeira, 1996; Noce et al., 2007; Silva et al., 2002).…”

Section: Geological Settingmentioning

confidence: 99%

The gabbro to amphibolite transition along a hydration front

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et al. 2020

Journal Metamorphic Geology

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In most metamorphic terrains the transition to the preserved mineral assemblage can be established to have occurred during progressive metamorphism through lowergrade facies involving fluid saturated conditions. However, in some circumstances metamorphism can occur in a non-progressive way as a distinct overprint of either igneous protoliths such as gabbro, or of earlier higher-grade metamorphic rocks such as granulites. In this contribution we use thermodynamic modelling, together with petrographic and mineral chemistry analysis, to study a suite of amphibolite facies metamafic rocks that were variably affected by metamorphism, with the objective of explaining the textures and mineral assemblages observed. The study samples form a continuum in terms of textural relationships and mineral compositions, but they can be divided into three main types: metagabbro, lineated metagabbro, and amphibolite. Metagabbro samples preserve both relict igneous and metamorphic textures and a combination of igneous and metamorphic mineralogy. They preserve a variety of reaction textures, such as coronas of garnet around ilmenite, double coronas of low-Al (actinolitic) and high-Al (pargasitic) hornblende around clinopyroxene and limited degrees of recrystallization of igneous plagioclase. Lineated metagabbro samples preserve similar reaction textures as the metagabbro but show a strong lineation and have higher proportions of pargasitic hornblende and polygonal plagioclase combined with lower proportions of clinopyroxene, igneous plagioclase and actinolitic hornblende. Amphibolite samples are composed of pargasitic hornblende and polygonal plagioclase, presenting little igneous plagioclase and practically no garnet and clinopyroxene, and they preserve none of the reaction textures of the other two types. These samples are interpreted to be near chemically equilibrated on a hand sample scale, although with some mineral zoning preserved. P − X H 2 O and T − X H 2 O pseudosections show that the main mineral assemblage differences between the amphibolites and the other two types are primarily controlled by the amount of H 2 O that equilibrated with the rocks. While all rocks experienced an influx of fluid, only the amphibolites represent thermodynamically fluid-saturated conditions, the metagabbro and lineated metagabbro having equilibrated under H 2 O undersaturated conditions, allowing the presence of garnet. In parallel with the variation in fluid influx, the variation in microstructure appears to be the result of varying length scales of diffusion. The complex corona structures in the metagabbros are interpreted to reflect the pre-existing igneous texture and the apparent low mobility of Al during metamorphism. Here, igneous clinopyroxene is largely pseudomorphed by the actinolitic

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Petrogenesis of the Orthogneisses of the Mantiqueira Complex, Central Ribeira Belt, SE Brazil: An Archaean to Palaeoproterozoic Basement Unit Reworked During the Pan-African Orogeny

Cited by 42 publications

References 7 publications

Proterozoic to Ordovician geology and tectonic evolution of Rio de Janeiro State, SE-Brazil: insights on the central Ribeira Orogen from the new 1:400,000 scale geologic map

Proterozoic to Ordovician geology and tectonic evolution of Rio de Janeiro State, SE-Brazil: insights on the central Ribeira Orogen from the new 1:400,000 scale geologic map

Evidence for a complex accretionary history preceding the amalgamation of Columbia: The Rhyacian Minas-Bahia Orogen, southern São Francisco Paleocontinent, Brazil

The gabbro to amphibolite transition along a hydration front

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