On the origin of incompatible element enrichment in the Venda Nova pluton, State of Espı́rito Santo, southeast Brazil

Ludka, Isabel Pereira; Wiedemann, Cristina Maria; Töpfner, C

doi:10.1016/s0895-9811(98)00028-5

Cited by 27 publications

(26 citation statements)

References 13 publications

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“…The almost circular horizontal section reveals a slightly westward tilted cylinder-like intrusion . The internal core of the Venda Nova Pluton is off-centered and consists of high-K calc-alkaline rocks, including alkali-gabbro and norite Figure 2 Geological map of the Venda Nova Pluton (modified after Ludka et al, 1998;Mendes et al, 2002).…”

Section: Geology Of the Venda Nova Pluton E A Summarymentioning

confidence: 99%

Norite and charnockites from the Venda Nova Pluton, SE Brazil: Intensive parameters and some petrogenetic constraints

Mendes

Campos²

2012

Geoscience Frontiers

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The Venda Nova Pluton (VNP) is a zoned ring structure emplaced in the southern portion of the Neoproterozoic Araçuai Belt, in Esp ırito Santo, Brazil. It is a slightly westward tilted cylinder-like intrusion, with an almost circular horizontal section. In the center of this structure, an off-centered gabbro-noritic core, surrounded by syeno-monzonitic rocks, intrudes an outer ring of charnockites and norite. These envelop the syeno-monzonitic and gabbro-noritic center, as a narrow discontinuous belt. While, in the core intrusion, mingling and mixing processes are widespread and well documented in the literature, in the outer ring, the norite and charnockite layers show predominantly homogeneous and isotropic internal structures. Nevertheless, smaller interaction zones between charnockites and norite denote a comparatively more restricted mingling process. The norite is a fine-grained rock with hypidiomorphic granular to intergranular texture. The charnockites are medium-grained and made up of: (a) orthopyroxene-tonalite, (b) orthopyroxene-quartz-diorite, and (c) orthopyroxene-granodiorite with hypidiomorphic granular to porphyritic textures. In all lithotypes both ortho-and clinopyroxene are replaced by hornblende and biotite. Two contrasting compositional sequences have been recognized, based on whole rock geochemistry: (1) a basic, with tholeiitic affinities (norite) and, (2) an intermediate, GEOSCIENCE FRONTIERSjournal homepage: www.elsevier.com/locate/gsf GEOSCIENCE FRONTIERS 3(6) (2012) 789e800 medium-K calc-alkaline, comprising the charnockites. Estimated crystallization temperatures, which have been calculated from micro-probe analysis of pyroxenes, range from 915 AE 25 C to 960 AE 50 C. Re-equilibration temperature (ilmenite-magnetite calibration) is around 600 AE 50 C. This indicates oxygen fugacities four order of magnitude below the FMQ-buffer and a reduced environment. Coeval pressure conditions estimated from the Al-content in hornblende range from 5.5 AE 0.6 kbar. Data obtained for the norite point toward an evolution from the partial melting of an anhydrous tholeiitic mantle magma. The charnockites may correspond to the differentiation of a calc-alkaline parental magma. The later could be the hybrid product from the contamination and mixing between the anhydrous tholeiitic magma with other deeper crustal sources. Further the magmatic system evolved through fractionation of orthopyroxene, clinopyroxene, plagioclase and ilmenite. Our results support the hypothesis for the evolution of the Venda Nova Pluton through a mantle-crust delamination process probably related to the collapse of the Araçuai orogeny. ª 2012, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. All rights reserved.

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Section: Geology Of the Venda Nova Pluton E A Summarymentioning

confidence: 99%

Norite and charnockites from the Venda Nova Pluton, SE Brazil: Intensive parameters and some petrogenetic constraints

Mendes

Campos²

2012

Geoscience Frontiers

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“…2), o que sugere que este elemento substitui o K em outra fase mineral além do feldspato, provavelmente a biotita, uma vez que para o K 2 O há nítida correlação positiva. Vale ressaltar os altos conteúdos de Ba do Granito São Pedro, similar ao que tem sido detectado para rochas ígneas de ampla variação composicional desta porção da Faixa Ribeira (Ludka et al 1998, Mendes et al 2002, Gimenez Filho et al 2000. Relevantes são também valores elevados de Zr e Th, contrapondo a baixos teores de MgO e CaO, em comparação com conteúdos médios de granitos (Winter 2010).…”

Section: As Rochas Encaixantesunclassified

Assinatura isotópica de Sr e Nd do magmatismo cálcio-alcalino de alto-K na Faixa Ribeira central: o exemplo do Granito São Pedro em Lumiar, RJ

Mendes

Medeiros

Chaves

2011

RBG

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Resumo Na porção centro-norte da Faixa Ribeira, no Estado do Rio de Janeiro, ocorrem muitos corpos intrusivos de formas diversas e variação composicional predominantemente granodiorítica a granítica, que defi nem uma província magmática tardi a pós-colisional, com assinatura geoquímica Cálcio-alcalina tipo I cordilheirano. O Granito São Pedro é um desses corpos, ocorrendo como pequenos corpos pós-colisionais na região serrana do Rio de Janeiro, caracterizando-se por sua estrutura isotrópica, textura equigranular a inequigranular seriada e concentração local de allanita, o que confere sutil variação composicional e de textura à rocha. Trata-se de magmatismo ácido cálcio-alcalino de alto K/álcali-cálcico, fracamente peraluminoso e com pequena variação na sua composição química. Relevantes são os conteúdos elevados de Ba, Zr e Th e baixos teores de MgO e CaO. São altas as concentrações de ETR, que conferem padrão bastante fracionado, com conspícuas anomalias negativas de Eu. Determinações isotópicas de Nd e Sr apontam para o granito caráter crustal revelado por valores de Є Nd muito negativos (até -13,9) e Є Sr muito positivos (até 133,9), além de altas razões iniciais 87 Sr/ 86 Sr variando entre 0,718 e 0,740. Idades T DM indicam fonte paleoproterozoica para esse granito, coincidente com período de extensa geração de crosta continental. Palavras-chave:Granito pós-colisional, Faixa Ribeira central, Isótopos Nd-Sr. Abstract Sr and Nd isotopic signature of the high-K calc-alkaline magmatism of the central Ribeira belt: the São Pedro Granite in Lumiar, RJ.In the central-northern Ribeira belt there are many granitic to granodioritic bodies showing varied shape and size, characterizing a late-to post-collisional Ca-alkaline, cordilleran I-type province. The São Pedro Granite occurs in the mountain region of Rio de Janeiro State as small post-collisional bodies. It presents isotropic fabric, equigranular to seriate inequigranular texture, as well as local concentration of allanite, which gives discrete composition and texture variation to the rock. The granite has a high-K calcalkaline to alkali-calcic character and weakly peraluminous nature. Despite its short geochemical variation, high Ba, Zr and Th contents besides low concentrations of MgO and CaO are noticeable. High REE contents are associated with fractionated REE patterns showing strong negative Eu anomalies. A crustal origin for the granite can be assumed by its very negative and positive Є Nd and Є Sr values, respectively, as well as by 87 Sr/ 86 Sr initial ratios ranging from 0,718 to 0,740. T DM ages point to paleoproterozoic source, which agrees with geological time of intensive crust generation.

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“…Poucos são os trabalhos de síntese regional sobre os granitoides brasilianos da região do vale do rio Doce, sendo mais comuns trabalhos relacionados ao estudo de maciços isolados e que abordam em geral aspectos petrográficos, litogeoquímicos, e mais raramente geocronológico e estrutural (Siga Jr., 1986;Wiedemann et al, 2002;Wiedemann, Mendes, Ludka, 1995;Figueiredo e Campos Neto, 1993;Wiedemann, 1993;Ludka, Wiedemann, Töfner, 1998;Mendes et al, , 2005Nalini, 1997;Bilal et al, 1998; Pedrosa Soares e Wiedemann-Leonardos, 2000;Martins, 2000;Martins et al, 2004;Nalini, Machado, Bilal, 2005.…”

Section: Granitoides Brasilianos Do Vale Do Rio Doceunclassified

“…A série cálcio-alcalina, a mais expressiva dos plútons estudados (de ~90%), é meta-aluminosa, alto-K, e foi originada numa crosta continental, porém com importante contribuição de um manto enriquecido Mendes, Wiedemann, McReath, 1999;Ludka, Wiedemann, Töfner, 1998;Medeiros, Wiedemann, Mendes, 2001;Wiedemann et al, 2002 …”

Section: Granitoides Brasilianos Do Vale Do Rio Doceunclassified

Petrografia e geoquímica do Complexo Charnockítico de Aimorés: um exemplo de plutonismo pós-orogênico do Cinturão Araçuaí/Ribeira

Mello

Machado

2011

Geol. USP, Sér. cient.

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On the origin of incompatible element enrichment in the Venda Nova pluton, State of Espı́rito Santo, southeast Brazil

Cited by 27 publications

References 13 publications

Norite and charnockites from the Venda Nova Pluton, SE Brazil: Intensive parameters and some petrogenetic constraints

Norite and charnockites from the Venda Nova Pluton, SE Brazil: Intensive parameters and some petrogenetic constraints

Assinatura isotópica de Sr e Nd do magmatismo cálcio-alcalino de alto-K na Faixa Ribeira central: o exemplo do Granito São Pedro em Lumiar, RJ

Petrografia e geoquímica do Complexo Charnockítico de Aimorés: um exemplo de plutonismo pós-orogênico do Cinturão Araçuaí/Ribeira

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