New U–Pb ages and lithochemical attributes of the Ediacaran Rio Doce magmatic arc, Araçuaí confined orogen, southeastern Brazil

Gonçalves, Leonardo; Farina, Felicia; Lana, Cristiano; Pedrosa-Soares, Antônio Carlos; Alkmim, Fernando Flecha de; Nalini, Hermínio Árias

doi:10.1016/j.jsames.2014.02.008

Cited by 49 publications

(51 citation statements)

References 45 publications

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“…1b and c), previously investigated by Gonçalves et al (2014), Mondou et al (2012), Nalini (1997), Nalini et al (2000Nalini et al ( , 2005Nalini et al ( , 2008 and Vauchez et al (2007). The study area covers ca.…”

Section: Resultsmentioning

confidence: 99%

“…charnockites) and orthopyroxene-free granites and granodiorites, the latter forming the so-called Galiléia Batholith and displaying variable amounts of mafic microgranular enclaves (MME) (e.g. Gonçalves et al, 2014). The batholith extends roughly northsouth for ca.…”

Section: The Galiléia Batholithmentioning

confidence: 99%

“…1a) (Gonçalves et al, 2014;Pedrosa-Soaeres et al, 2011;Pedrosa-Soares et al, 2001;Vauchez et al, 2007). Based on field evidence, mineral textural studies and geochemical features, Gonçalves et al (2014) have recently further subdivided the Galiléia batholith into a suite of enclave-rich tonalitegranodiorite rocks and a suite of enclave-poor tonalitic to granitic rocks. These two suites, appear to occur throughout the whole batholith ( Fig.…”

Section: The Galiléia Batholithmentioning

confidence: 99%

“…Geochemically, the opx-free granitoids resemble medium-to high-K metaluminous Cordilleran-type granitoids, and are interpreted as being produced during the Rio Doce arc-related magmatism; they are suggested to be derived from the partial melting of the Paleoproterozoic basement due to underplating of mantle derived magmas (e.g. Gonçalves et al, 2014). However, assimilation of host rocks, fractional crystallization during the ascent of mantle-derived magmas, or mixing between mantle derived magma with felsic magmas of crustal origin have also been proposed as possible processes that might have shaped the Galiléia igneous rocks (e.g.…”

Section: The Galiléia Batholithmentioning

confidence: 99%

“…However, assimilation of host rocks, fractional crystallization during the ascent of mantle-derived magmas, or mixing between mantle derived magma with felsic magmas of crustal origin have also been proposed as possible processes that might have shaped the Galiléia igneous rocks (e.g. Gonçalves et al, 2014).…”

Section: The Galiléia Batholithmentioning

confidence: 99%

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Magmatic garnet in the Cordilleran-type Galiléia granitoids of the Araçuaí belt (Brazil): Evidence for crystallization in the lower crust

Narduzzi

Farina

Stevens

et al. 2017

Lithos

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Magmatic garnet, together with epidote, is a rare mineral association in cordilleran-I-type granitoids and of special petrogenetic significance. The metaluminous to slightly peraluminous (ASI = 0.97-1.07) Galiléia batholith (Brazil) is a large (ca. 30,000 km 2 ), Neoproterozoic (ca. 632-570 Ma) weakly foliated calc-alkaline granitoid body, characterized by the widespread occurrence of garnet (grossular 25-43 mol%) and epidote (pistacite 9.3-22.7 mol%). Field, petrographic and mineral chemical evidence indicates that garnet, epidote, biotite as well as white mica crystals (low-Si phengite), are magmatic. There is no difference in bulk rock major and trace element composition between the Galiléia granitoids and other garnet-free cordilleran-type granitoids worldwide. This evidence strongly suggests that the origin of the uncommon garnet + epidote parageneses is related to the conditions of magma crystallization, such as pressure, temperature and water content. Comparison between the mineral assemblages and mineral compositions from this study and those recorded in crystallization experiments on metaluminous calc-alkaline magmas, as well as within garnet-bearing metaluminous volcanic rocks and granitoids, indicates that the supersolidus coexistence of grossular-rich garnet, epidote and white mica is consistent with magma crystallization at pressures greater than 0.8 GPa (above 25 km depth) and at temperatures below 700°C, i.e. near the water saturated solidus. Furthermore, resorption textures around garnet (plagioclase ± quartz coronas) and epidote suggest that these minerals have been partially consumed prior to complete crystallization. These findings demonstrate that at 630 Ma the crust underneath the Araçuaí Orogen was already at least 25-30 km thick and relatively cool. However, this contrasts with the marked high heat flow registered from the neighbour Carlos Chagas Batholith located 50 km to the east. In fact such granitoids record granulite-facies metamorphism at the same pressure and time (ca. 570 Ma) of Galiléia granitoids crystallization. Thus, a more suitable geodynamic scenario is required in order to explain these two contrasting thermal regimes within the same orogen. Eventually, field, petrographic and mineral chemical analogies with similar garnet-bearing granitoids located in the fore-arc settings of the British Columbia subduction zone, possibly imply that the Galiléia granitoids represent "rare" garnet-and epidote-bearing metaluminous Cordilleran-Itype granites which can only form in a fore-arc setting.

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Section: Resultsmentioning

confidence: 99%

Section: The Galiléia Batholithmentioning

confidence: 99%

Section: The Galiléia Batholithmentioning

confidence: 99%

Section: The Galiléia Batholithmentioning

confidence: 99%

Section: The Galiléia Batholithmentioning

confidence: 99%

See 3 more Smart Citations

Magmatic garnet in the Cordilleran-type Galiléia granitoids of the Araçuaí belt (Brazil): Evidence for crystallization in the lower crust

Narduzzi

Farina

Stevens

et al. 2017

Lithos

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The Araçuaí Belt

Alkmim

Kuchenbecker

Reis

et al. 2016

São Francisco Craton, Eastern Brazil

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The Araçuaí belts extends along the curved southeastern margin of the São Francisco craton between the Brazilian coast and Lat 21°S, where it merges with the Ribeira belt. It represents the external, basement-involved fold-thrust belt of the Araçuaí-West Congo confined orogen (AWCO), which formed due to the closure of the terminal branch of the Adamastor ocean during the amalgamation of West Gondwana in the Ediacaran and beginning of the Cambrian. Bounded to the east and southeast by the high grade and granitic core of the AWCO, the Araçuaí belt involves a basement assemblage older than 1.8 Ga, the 1.7-0.9 Ga rift to rift-sag successions of the Espinhaço Supergroup, the Tonian-Edicaran rift-passive margin Macaúbas Group, as well as the syn-orogenic Salinas Formation and crustal derived granitic intrusions. The Macaúbas Group, the type unit of the belt, contains a glaciomarine sequence made up of thick diamictites, sandstones and Rapitan-type banded iron formations. The units exposed along the belt were metamorphosed under greenschist to amphibolite facies conditions and affected by thrusts, reverse faults and cratonward verging folds, developed between 575 and 530 Ma. The Araçuaí orogenic front propagates into the craton interior and interacts with preexistent rift structures. This chapter describes the stratigraphic framework and overall structure of the Araçuaí belt, emphasizing the paleogeographic and tectonic significance of its sedimentary and volcanic assemblages.

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