Petrographical and geochemical features of the granite-pegmatite transition in the Velasco Pegmatitic District, NW Argentina

Sardi, Fernando Guillermo; Murata, Mamoru; Grosse, Pablo

doi:10.1127/0077-7749/2010/0085

Cited by 4 publications

(14 citation statements)

References 13 publications

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“…Major elements were determined by XRF, and trace elements by ICP-MS/AES. The analyses are shown in table 1, and include our new data (n=8) together with previously unpublished analyses of Grosse (2007;n=7) and published data of both Grosse et al (2009;n=5) and Sardi et al (2010;n=15).…”

Section: Geochemistrymentioning

confidence: 99%

“…The geochemical evolutionary trend from the main facies of the Huaco granite towards the Be-pegmatites has been studied by Sardi et al (2010Sardi et al ( , 2011. The Huaco granite consists of several facies and associated rocks which are described in the next section.…”

Section: Huaco Granite Plutonmentioning

confidence: 99%

“…Be-pegmatites (BeP): they are lens-shaped with the main axis length up to 140 m (Sardi et al, 2015 Sardi et al, 2010) is in sharp contact with the APG and usually grades inward towards the Be-pegmatite zone. It commonly consists of aplites or more rarely of muscovite-rich equigranular leucogranites.…”

Section: The Coeval-to-late Facies (Bep and Og)mentioning

confidence: 99%

“…Following Sardi et al (2010), we name the main facies Regional Porphyritic Granite (RPG). This main facies transitions towards two coeval facies, at the margins of the pluton (Border Granite; BG) and around Be-pegmatites (Adjacent porphyritic granite; APG) (Figs.…”

Section: Occurrence and Petrographymentioning

confidence: 99%

“…It is formed predominantly of porphyritic syeno-to monzogranites and contains several distinct subordinate facies and associated magmatic rocks with variable morphologies, compositions, textures and temporal relations. Several previous studies have described the main features of this pluton and some of its minor facies Grosse et al, 2009;Sardi et al, 2010Sardi et al, , 2011Dahlquist et al, 2010Dahlquist et al, , 2013 as well as some of the associated rocks, for example, Be-pegmatites (Cravero, 2005;Sardi et al, 2015), an orbicular granite (Quartino and Villar Fabre, 1962;Grosse et al, 2010) and the La Chinchilla stock (Grosse et al, , 2009Macchioli Grande et al, 2015). However, none of these previous studies have Two pulses of magmatism are found in the Velasco range, Ordovician and Lower Carboniferous (Pankhurst et al, 2000;Toselli et al, 2007;Dahlquist et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

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Internal framework and geochemistry of the Carboniferous Huaco granite pluton, Sierra de Velasco, NW Argentina

Sardi

Grosse

Murata

et al. 2018

andgeo

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ABSTRACT. The A-type Huaco granite pluton of the Velasco range (Sierras Pampeanas of northwest Argentina) is formed by three coeval granitic facies and contains subordinate coeval-to-late facies, as well as enclaves, dikes and stocks that show different temporal relations, textures and compositions. The dominant facies (Regional Porphyritic Granite; RPG) is a porphyritic two-mica monzo-to syenogranite, with abundant microcline megacrysts up to 12 cm in size. It was emplaced in a dominant extensional setting and has a mainly crustal source but with participation of a mantle-derived component. The RPG transitions towards two coeval and co-genetic granite facies, at its margins (Border Granite; BG) and around Be-pegmatites (Adjacent Porphyritic Granite; APG). These two facies have a finer-grained texture and smaller and less abundant megacrysts. They are also monzo-to syenogranites, but a slight decrease in the biotite/muscovite ratio is observed from the BG to the RPG to the APG. Trace element modeling suggests that the RPG, BG and APG differentiated from the same magma source by fractional crystallization. Temporally older mafic (ME) and felsic (FE) enclaves are common in the pluton. The ME can be considered partially assimilated remnants of a mafic component in the genesis of the RPG, whereas the FE seem to be remnants of premature aplites. Other subordinate rocks intrude the RPG and are, hence, temporally younger: felsic dikes (FD), dioritic dikes (DD) and equiganular granites (EqG) are clearly posterior, whereas coeval-to-late Be-pegmatites (BeP) and orbicular granites (OG) formed during the final stages of crystallization of the pluton. The BeP, OG and FD indicate the presence of abundant water and volatiles. The EqG form small stocks that intrude the RPG and were possibly originated from purely crustal sources. The DD probably correspond to a younger unrelated episode of mafic magmatism. Keywords: Granitic facies, REE and LIL composition,Fractional crystallization model, Huaco granite, Velasco range, Sierras Pampeanas.RESUMEN. Estructura interna y geoquímica del plutón granítico carbonífero de Huaco, Sierra de Velasco, NW de Argentina. El Plutón Huaco, ubicado en la sierra de Velasco (en Sierras Pampeanas del noroeste de Argentina), es de afinidad granítica A y está conformado por tres facies graníticas y contiene varias rocas ígneas subordinadas, las que muestran diferentes relaciones temporales, texturas y composiciones. La facies granítica dominante (Granito Porfírico Regional; RPG) es un monzo-sienogranito de dos micas, de textura porfírica con abundantes megacristales de microclino que pueden alcanzar hasta 12 cm de longitud. Ha sido emplazado en un marco tectónico dominantemente extensional y habría tenido una fuente de origen cortical pero también con participación de componentes mantélicos. En los bordes del Plutón Huaco y envolviendo a pegmatitas de berilo contenidas en el mismo (BeP), se reconocen las facies cogenéticas BG y APG respectivamente, las cuales tienen contacto transicional con el RPG. E...

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Section: Geochemistrymentioning

confidence: 99%

Section: Huaco Granite Plutonmentioning

confidence: 99%

Section: The Coeval-to-late Facies (Bep and Og)mentioning

confidence: 99%

Section: Occurrence and Petrographymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Internal framework and geochemistry of the Carboniferous Huaco granite pluton, Sierra de Velasco, NW Argentina

Sardi

Grosse

Murata

et al. 2018

andgeo

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Chemical evolution and origin of the Luumäki gem beryl pegmatite: Constraints from mineral trace element chemistry and fractionation modeling

Michallik

Wagner

Fußwinkel

et al. 2017

Lithos

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Age and petrogenesis of the beryl-bearing granitic magmatism of the Velasco Pegmatite District, Pampeana Province, NW Argentina

2021

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Two porphyritic granitoids (Huaco and Sanagasta) in the Velasco district of the Pampeana Pegmatite Province in Northwestern Argentina are recognized. They are considered the fertile granites of the beryl-bearing pegmatites and can be described as post-orogenic and peraluminous A-type granites formed in an intraplate tectonic setting during an extensive regime, whose magma source is predominantly of cortical origin and to a lesser extent, mantle-derived. The pegmatites are classified as Rare Elements of the beryl type and beryl-columbite-phosphate subtype, while the entire district shows characteristics related to the NYF (Nb-Y-F) petrogenetic family. From rocks and cogenetic minerals of an individual 'Ismiango' pegmatite of the Velasco district, two Rb/Sr isochrons have been constructed. They define an age of 330.3 ± 8.3 and 331.7 ± 2.3 Ma and fall in the Lower Carboniferous period, consistent with the age of the parental and host-rock, the Huaco granite. As the Ismiango pegmatite has a similar composition and structure to the other beryl mineralized pegmatites of the Velasco district, the obtained age is attributed extensively for the entire district. According to the initial 87 Sr/ 86 Sr value obtained of 0.713, the pegmatite-magmatism of the Velasco District might be mainly derived from the crust with some minor participation of mantle materials.

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Petrographical and geochemical features of the granite-pegmatite transition in the Velasco Pegmatitic District, NW Argentina

Cited by 4 publications

References 13 publications

Internal framework and geochemistry of the Carboniferous Huaco granite pluton, Sierra de Velasco, NW Argentina

Internal framework and geochemistry of the Carboniferous Huaco granite pluton, Sierra de Velasco, NW Argentina

Chemical evolution and origin of the Luumäki gem beryl pegmatite: Constraints from mineral trace element chemistry and fractionation modeling

Age and petrogenesis of the beryl-bearing granitic magmatism of the Velasco Pegmatite District, Pampeana Province, NW Argentina

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