Genesis of Peraluminous Granites I. Experimental Investigation of Melt Compositions at 3 and 5 kb and Various H2O Activities

Holtz, François; Johannes, Wilhelm

doi:10.1093/petrology/32.5.935

Cited by 209 publications

(107 citation statements)

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“…Thus we see no evidence that the studied granites could represent the more evolved fractionates from a calc-alkaline system. The composition of these monzogranites is different from that of melts obtained experimentally from pelitic protoliths, rather suggesting a major involvement of metaigneous protoliths or metagreywacke sources (Conrad et al, 1988;Holtz, 1989;Holtz and Johannes, 1991;Johannes and Holtz, 1996;Patiño-Douce and Johnston, 1991). The VMG shows mineralogical and geochemical features that are characteristic of crustal-derived magmas.…”

Section: Nature Of the Granite Sourcesmentioning

confidence: 67%

Late-Variscan emplacement and genesis of the Vieira do Minho composite pluton, Central Iberian Zone: Constraints from U–Pb zircon geochronology, AMS data and Sr–Nd–O isotope geochemistry

Martins

Ovaia

Noronha

2013

Lithos

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In the Central Iberian Zone synorogenic (syn-and late-D 3 , the last deformation phase) composite batholiths of biotite-rich granitods with peraluminous character are well represented. We report here U-Pb zircon and monazite ages, geochemical, Sr-Nd-O isotopic data and Anisotropy of Magnetic Susceptibility (AMS) studies for the late-D 3 Vieira do Minho pluton, in northern Portugal. AMS reveals the paramagnetic behaviour of these granites and the magnetic fabric enhances the major role of NW-SE regional anisotropies on controlling the ascent and emplacement of the magmas. Magnetic anisotropy and medium temperature microstructures also point out the evolution of regional tectonics during crystallization of the magma. U-Pb zircon and monazite analyses yield consistent ages of 310 ± 2 Ma and 312 ± 2 Ma, interpreted as emplacement age. The Vieira do Minho pluton consists of two peraluminous monzogranites, the VMG and the MRG. Both have similar ε Nd values (VMG= −5.2 to −5.7; MRG =−4.98 to −5.96) but the VMG is slightly enriched in 87 Sr/ 86 i = 0.7087-0.7098 as well as in δ 18 O in the range of 10.6‰ to 11.0‰ than the MRG with 87 Sr/ 86 i =0.7064-0.7075 and δ 18 O=9.9‰-10.5‰. These granites are associated with coeval scarce grabroic intrusions and/or mafic microgranular enclaves which are not considered as mafic precursors of the associated granitic magmatism. Instead, a lower metaigneous crustal source, at different levels, is proposed based on the available data set.

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Section: Nature Of the Granite Sourcesmentioning

confidence: 67%

Late-Variscan emplacement and genesis of the Vieira do Minho composite pluton, Central Iberian Zone: Constraints from U–Pb zircon geochronology, AMS data and Sr–Nd–O isotope geochemistry

Martins

Ovaia

Noronha

2013

Lithos

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“…Described correlation between X Fe and Ti in biotite and geochemical composition of the whole rocks (e.g. Ba, SiO 2 ) is typical of magmatic biotite crystallizing from peraluminous granitic melt (Holtz and Johannes 1991;Villaseca and Barbero 1994). The behaviour of biotite in the samples suggests that the chemical composition changed throughout the recrystallization in a relatively chemically isolated system.…”

Section: Discussionmentioning

confidence: 99%

Ordovician metagranites and migmatites of the Svratka and Orlice-Sněžník Units, northeastern Bohemian Massif

Buriánek¹,

Verner²,

Hanžl³

et al. 2012

J. Geosci.

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Metagranites and migmatites of the Svratka and the Orlice-Sněžník units, northeastern Bohemian Massif, exhibit a number of similarities in their lithological, mineralogical and geochemical features. Both of these units were affected by intense migmatitization accompanied by intrusion of peraluminous granites during the Cambrian to Ordovician. The chemical composition and mineralogy of all the studied rocks correspond to crustal melts. From the geochemical point of view, both rock groups (migmatites and metagranites) exhibit progressive geochemical fractionation (increase in the SiO 2 , Rb, X FeO , W and Sn contents, accompanied by a decrease in the concentrations of Ba, Sr, Mg and Ca) as a result of varying degrees of partial melting and fractional crystallization. The main rock-forming minerals are influenced by metamorphic recrystallization under amphibolite-facies conditions during the Variscan orogeny.

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“…Due to involvement of plagioclase, wet melting tends to generate a rather-calcic melt, whereas melts originated during dehydration melting, owing to involvement of only micas, have more alkali composition (Patiño Douce & Beard 1995). The melting with added H 2 O will increase the CaO/Na 2 O ratios (0.1-0.36) of peraluminous granites (Holtz & Johannes 1991). The role of muscovite (or biotite) -breakdown in the source should be apparent from strong peraluminosity (Whitney 1988 Harris et al (1990).…”

Section: Petrologymentioning

confidence: 99%

Petrology and mineral chemistry of peraluminous Marziyan granites, Sanandaj-Sirjan metamorphic belt (NW Iran)

Darvishi¹,

Khalili²,

Beavers³

et al. 2015

Geologica Carpathica

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Abstract:The Marziyan granites are located in the north of Azna and crop out in the Sanandaj-Sirjan metamorphic belt. These rocks contain minerals such as quartz, K-feldspars, plagioclase, biotite, muscovite, garnet, tourmaline and minor sillimanite. The mineral chemistry of biotite indicates Fe-rich (siderophyllite), low TiO 2 , high Al 2 O 3 , and low MgO nature, suggesting considerable Al concentration in the source magma. These biotites crystallized from peraluminous S-type granite magma belonging to the ilmenite series. The white mica is rich in alumina and has muscovite composition. The peraluminous nature of these rocks is manifested by their remarkably high SiO 2 , Al 2 O 3 and high molar A/CNK ( > 1.1) ratio. The latter feature is reflected by the presence of garnet and muscovite. All field observations, petrography, mineral chemistry and petrology evidence indicate a peraluminous, S-type nature of the Marziyan granitic rocks that formed by partial melting of metapelite rocks in the mid to upper crust possibly under vapour-absent conditions. These rocks display geochemical characteristics that span the medium to high-K and calc-alkaline nature and profound chemical features typical of syn-collisional magmatism during collision of the Afro-Arabian continental plate and the Central Iranian microplate.

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Genesis of Peraluminous Granites I. Experimental Investigation of Melt Compositions at 3 and 5 kb and Various H2O Activities

Cited by 209 publications

References 0 publications

Late-Variscan emplacement and genesis of the Vieira do Minho composite pluton, Central Iberian Zone: Constraints from U–Pb zircon geochronology, AMS data and Sr–Nd–O isotope geochemistry

Late-Variscan emplacement and genesis of the Vieira do Minho composite pluton, Central Iberian Zone: Constraints from U–Pb zircon geochronology, AMS data and Sr–Nd–O isotope geochemistry

Ordovician metagranites and migmatites of the Svratka and Orlice-Sněžník Units, northeastern Bohemian Massif

Petrology and mineral chemistry of peraluminous Marziyan granites, Sanandaj-Sirjan metamorphic belt (NW Iran)

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