Enhancing Maficity of Granitic Magma during Anatexis: Entrainment of Infertile Mafic Lithologies

Carvalho, Bruna B.; Sawyer, E. W.; Janasi, Valdecir de Assis

doi:10.1093/petrology/egx056

Cited by 25 publications

(10 citation statements)

References 57 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…As discussed Nicoli and Dyck (), the origin of S‐type granite is considerably more complex and involves multiple superimposing processes that modify the anatectic melt after its generation. These include mixing with other magmas (Schwindinger & Weinberg, ), variable entrainment of residual solids (Carvalho, Sawyer, & Janasi, ; Garcia‐Arias & Stevens, ; Milord, Sawyer, & Brown, ) and differentiation due to solidification and assimilation during migration. These limitations make direct comparison to natural magmatic rocks complex; however, the calculated melt compositions are reasonable approximation to those produced in nature (Cesare, Acosta‐Vigil, Bartoli, & Ferrero, ; White, Stevens, & Johnson, ), and the results here demonstrate that modelling allows insights into the general effects of water‐fluxed melting on melt and residual compositions.…”

Section: Discussionmentioning

confidence: 99%

“…On the scale of an anatectic section of the crust, these melts are likely to blend with each other during migration, before crystallizing (Diener, White, & Hudson, ; Schwindinger & Weinberg, ). In addition, numerous other mechanisms further modify their composition, such as fractionation (Garcia‐Arias & Stevens, ), disequilibrium partial melting (Madlakana & Stevens ; Nicoli, Stevens, Moyen, Vezinet, & Mayne, ), entrainment of peritectic minerals (Stevens, Villaros, & Moyen, ) or of residual and infertile lithologies (Carvalho et al., ), masking a clean signal of either water‐present or water‐absent melting.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Wet or dry? The difficulty of identifying the presence of water during crustal melting

Schwindinger

Weinberg

Clos

2019

Journal Metamorphic Geology

View full text Add to dashboard Cite

Partial melting of continental crust and evolution of granitic magmas are inseparably linked to the availability of H 2 O. In the absence of a free aqueous fluid, melting takes place at relatively high temperatures by dehydration of hydrous minerals, whereas in its presence, melting temperatures are lowered, and melting need not involve hydrous minerals. With the exception of anatexis in water-saturated environments where anhydrous peritectic minerals are absent, there is no

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Wet or dry? The difficulty of identifying the presence of water during crustal melting

Schwindinger

Weinberg

Clos

2019

Journal Metamorphic Geology

View full text Add to dashboard Cite

show abstract

“…The other commonly reported type of selvedge is also rich in biotite, but occurs as a much wider (up to 10 cm) and compositionally zoned rim between diatexite (melt‐rich part) and schollen within it. Mafic schollen are prone to developing this kind of selvedge (Troll & Winter, ; Carvalho, Sawyer, & Janasi, ; this study), but they also develop around schollen of marble (Figure a–d), calcsilicate, pelitic gneiss (Rocha, Moraes, Möller, Cioffi, & Jercinovic, ) and residual (Johannes, Ehlers, Kriegsman, & Mengel, ) bulk compositions. Troll and Winter () examined the composition of biotite in such a selvedge and attributed its growth to reactions and chemical exchanges between the mafic schollen and surrounding melt‐rich diatexite.…”

Section: Introductionmentioning

confidence: 67%

“…The reaction selvedges are biotite factories and sequester K 2 O and H 2 O. In a crustal melting context, erosion of reaction selvedges can be added to the growing list of processes that increase the maficity (Carvalho et al, 2017;Clemens, Stevens, & Farina, 2011) of felsic magmas.…”

Section: Recycling Of Mafic Selvedges In the Diatexitementioning

confidence: 99%

Microstructure and compositional changes across biotite‐rich reaction selvedges around mafic schollen in a semipelitic diatexite migmatite

Lin

Sawyer

2019

Journal Metamorphic Geology

View full text Add to dashboard Cite

Biotite‐rich selvedges developed between mafic schollen and semipelitic diatexite in migmatites at Lac Kénogami in the Grenville Province of Quebec. Mineral equilibria modelling indicates that partial melting occurred in the mid‐crust (4.8–5.8 kbar) in the range 820–850°C. The field relations, petrography, mineral chemistry and whole‐rock composition of selvedges along with their adjacent mafic schollen and host migmatites are documented for the first time. The selvedges measured in the field are relatively uniform in width (~1 cm wide) irrespective of the shape or size of their mafic scholle. In thin section, the petrographic boundary between mafic scholle and selvedge is defined by the appearance of biotite and the boundary between selvedge and diatexite by the change in microstructure for biotite, garnet, plagioclase and quartz. Three subtypes of selvedges are identified according to mineral assemblage and microstructure. Subtype I have orthopyroxene but of different microstructure and Mg# to orthopyroxene in the mafic scholle; subtype II contain garnet with many mineral inclusions, especially of ilmenite, in contrast to garnet in the diatexite host which has few inclusions; subtype III lack orthopyroxene or garnet, but has abundant apatite. Profiles showing the change in plagioclase composition from the mafic schollen across the selvedge and into the diatexite show that each subtype of selvedge has a characteristic pattern. Four types of biotite are identified in the selvedges and host diatexite based on their microstructural characteristics. (a) Residual biotite forms small rounded red‐brown grains, mostly as inclusions in peritectic cordierite and garnet in diatexite; (b) selvedge biotite forms tabular subhedral grains with high respect ratio; (c) diatexite biotite forms tabular subhedral grains common in the matrix of the diatexite; and (d) retrograde biotite that partially replaces peritectic cordierite and garnet in the diatexite. The four groups of biotite are also discriminated by their major element (EMPA) and trace elements (LA‐Q‐ICP‐MS) compositions. Residual biotite is high in TiO2 and low in Sc and S, whereas retrograde biotite has high Al2O3, but low Sc and Cr. Selvedge and diatexite biotite are generally very similar, but selvedge biotite has higher Sc and S contents. Whole‐rock compositional profiles across the selvedges constructed from micro‐XRF and LA‐Q‐ICP‐MS analyses show: (a) Al2O3, FeO, MgO and CaO all decrease from mafic scholle across the selvedge and into the diatexite; (b) Na2O is lowest in the mafic scholle, rises through the selvedge and reaches its maximum about 20–30 mm into the diatexite host; (c) K2O is lowest in the mafic scholle and reaches its highest value in the first half of the selvedge, then declines before reaching a higher, but intermediate value, about 20 mm into the diatexite. Of the trace elements, Cs and Rb show distributions very similar to K2O.

show abstract

“…Tabela 7-6: Histograma parcial da Figura 7.10 indicando as idades 207 Pb/ 206 Pb paleoproterozoicas obtidas em zircão detrítico da Unidade Serra do Ibituruna e os intervalos de idades U-Pb em zircão disponíveis na literatura para as prováveis áreas fontes. Referências: 1- Barbosa et al 2015;2-Seixas et al, 2013;3-Teixeira et al, 2014;4-Ávila et al, 2006;5-Teixeira et al, 2008;6-Ávila et al, 2010;7-Ávila et al, 2014;8-Teixeira et al, 2015;9-Seixas et al, 2012;10-Oliveira, 2004;11-Carvalho et al, 2017a;12-Lopes, 2013;13-Gengo et Os padrões de enriquecimento em ETR planos observados em cristais de zircão neoarqueano podem ser compatíveis com zircão do Gnaisse Candeias, que tem composição enderbítica (Oliveira, 2004), do ortopiroxêniobiotita granodiorito Santo Antônio do Amparo (Campos, 2004), ambos do Complexo Passa Tempo, e de schollens em meio ao migmatitos Kinawa, que podem apresentar clinopiroxênio + hornblenda + plagioclásio (Carvalho et al, 2017b).…”

Section: Prováveis áReas Fonteunclassified

Complexo Petúnia: Registro de múltiplos estágios evolutivos na borda sul do cráton do São Francisco

Gengo¹

View full text Add to dashboard Cite

Meus mais sinceros agradecimentos ao meu orientador, Prof. Renato de Moraes, por todo o apoio, incentivo, paciência e, principalmente, pela confiança que depositou em mim ao longo de toda minha trajetória na Geologia. Obrigada por sempre estar disposto a responder, mesmo minhas perguntas idiotas! Agora ficarão as dicas de aulas e músicas malucas.Ao Prof. Gergely Andres Julio Szabó, nosso eterno guru, por tooooda a paciência, por estar sempre disposto a me ajudar e, principalmente, por confiar a mim desvendar os mistérios do Complexo Petúnia. Eu simplesmente amei ter trabalhado nessa região, apesar de parecer o plano de fundo do Windows XP. Você me proporcionará trabalho por um bom tempo, muito obrigada! Ao Prof. Mario da Costa Campos Neto, pela ajuda com as seções, pelas discussões e pela motivação. Muito do que sou hoje como geóloga e pesquisadora, devo a você. Muito obrigada! Ao Prof. Vinicius Hector Abud Louro, pelas valiosas dicas do mundo das publicações e por topar entrar nesse balaio de gatos que é o Complexo Petúnia. Bom, se alguém tem que fazer contas, que seja o geofísico! Ao Prof. Marcos Egídio da Silva pela ajudinha com a estrutural e por proporcionar conversas sempre muito engraçadas! Ao Dr. Caio Arthur Santos (Fóóófis), por TODA a força, por me acompanhar nos trabalhos de campo, por sua infinita ajuda com as pseudosseções, por ouvir minhas lamúrias diante dos percalços com a geocron e da MP-27. Muito obrigada! À Msc. Laísa de Assis Batista pelas infinitas, produtivas e entusiasmantes discussões sobre petrocronologia (e outras coisas da vida), por estar sempre disposta a compartilhar todo o conhecimento e por finalmente ter se tornado uma amiga. Muito obrigada! A todos os demais professores do IGc-USP, por todos esses anos de convívio, em especial os professores Kabong (

show abstract

Enhancing Maficity of Granitic Magma during Anatexis: Entrainment of Infertile Mafic Lithologies

Cited by 25 publications

References 57 publications

Wet or dry? The difficulty of identifying the presence of water during crustal melting

Wet or dry? The difficulty of identifying the presence of water during crustal melting

Microstructure and compositional changes across biotite‐rich reaction selvedges around mafic schollen in a semipelitic diatexite migmatite

Complexo Petúnia: Registro de múltiplos estágios evolutivos na borda sul do cráton do São Francisco

Contact Info

Product

Resources

About