The Nature, Origin, and Thermal Influence of the Granite Source Layer of Central Iberia

Беа, Ф.; Montero, P.; Zinger, T. F.

doi:10.1086/376767

Cited by 114 publications

(54 citation statements)

References 32 publications

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“…This is in agreement with recent thermal modelling of the Hercynian collision by thickening of the central Iberian crust, if correct it would imply that granite magmatism does not require a significant addition of heat from mantle sources (Bea et al, 2003).…”

Section: Discussionsupporting

confidence: 91%

Metaluminous pyroxene-bearing granulite xenoliths from the lower continental crust in central Spain: their role in the genesis of Hercynian I-type granites

Villaseca¹,

García²,

Paterson³

et al. 2007

ejm

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Basic and intermediate meta-igneous xenoliths are very scarce within the granulite population transported by the Per mian alkaline lamprophyric dyke swarm of the Spanish Central System (SCS). These xenoliths are metalurninous pyroxene-bearing chamockites (sensu lato). They show LREE-poor plagioclase and orthopyroxene-clinopyroxene. Crystallization conditions were estimated at about 850 to 1000 °C and 9 to 11 kbar, a slightly higher range than that estimated for the associated peralurninous granulites, but indicating derivation from the lowerrnost crust.\¥hole-rock geochemistry suggests that the chamockite samples are not a cogenetic suite. The more basic varieties have affinities with cumulates from previous calc-alkaline underplated protoliths, whereas intermediate charnockites have a restitic origin. The similarity in Sr-Nd-Pb isotopic signatures between these restitic chamockites and some SCS I-type granites suggests a genetic relationship. This study, including Pb isotopic data from the whole granulite xenolith suite, reinforces the lower-crustal derivation of the SCS Hercynian granitic batholith.

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Section: Discussionsupporting

confidence: 91%

Metaluminous pyroxene-bearing granulite xenoliths from the lower continental crust in central Spain: their role in the genesis of Hercynian I-type granites

Villaseca¹,

García²,

Paterson³

et al. 2007

ejm

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“…The lack of appropriate sources in terms of isotopic composition has led to consider several models for the origin of the peraluminous granites: (i) mixing or assimilation between crustal melts and mantle-derived magmas (Castro et al, 1999;Dias and Leterrier, 1994;Dias et al, 2002Dias et al, , 2009Moreno-Ventas et al, 1995) (ii) partial melting of essentially crustal sources either from mid-crustal levels (Bea et al, 2003;Neiva, 1998) or from infracrustal materials, namely metaigneous rocks (Dias et al, 2002(Dias et al, , 2009Martins et al, 2009;Villaseca and Herreros, 2000;Villaseca et al, 1998Villaseca et al, , 1999.…”

Section: Nature Of the Granite Sourcesmentioning

confidence: 99%

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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“…Recio et al, 1992;Pinarelli and Rottura, 1995;Villaseca et al, 1998;Villaseca and Herreros, 2000). Several models have been proposed to explain the origin of this huge batholith: a) hybridization between crustal melts and mantle-derived magmas (Pinarelli and Rottura, 1995;Moreno-Ventas et al, 1995); b) variable degrees of crustal assimilation by mantle derived magmas (Ugidos and Recio, 1993;Castro et al, 1999); and c) partial melting of essentially crustal sources, either from lower crustal derivation (Villaseca et al, 1998(Villaseca et al, , 1999 or from midcrustal levels (Bea et al, 1999(Bea et al, , 2003. Clear geochemical similarities between SCS granites and lower crustal xenoliths carried by the SCS Upper Permian alkaline dykes, suggest that the lower crust is the most likely crustal source for the formation of the SCS batholith (Villaseca et al, 1999(Villaseca et al, , 2007.…”

Section: Geological Settingmentioning

confidence: 99%

Mineral chemistry of late Variscan gabbros from central Spain: constraints on crystallisation processes and nature of the parental magmas

García

Losantos

Villaseca

et al. 2015

Journal of Iberian Geology

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Major and trace element chemistry has been determined in the main minerals (olivine, orthopyroxene, clinopyroxene, plagioclase, amphibole, phlogopite) from the Talavera and La Solanilla gabbroic intrusions (Spanish Central System). The results show a heterogeneous mineral composition illustrative of the chemical evolution of calc-alkaline basic magmas during crystallization. The formation of incompatible element-rich interstitial minerals, such as amphibole, phlogopite and accessory phases (e.g., zircon, apatite), and the presence of zoning patterns in major minerals towards a more evolved composition, point to a progressive differentiation of the parental melt. The chemical variation depicted by trace elements usually incompatible with clinopyroxene (e.g., rare earth elements (REE), Th, Zr, Nb, Ti) implies co-precipitation with phases displaying a compatible behaviour with respect to these elements (e.g., apatite, zircon, amphibole). However, the very high LILE (large ion lithophile elements) and LREE (light REE) shown by clinopyroxene can not be explained exclusively by a closed-system in-situ crystallization process. Several features of the mineral chemistry (e.g. positive correlation of (La/Sm) N with La and Na in clinopyroxene and plagioclase, respectively) support the involvement of an external component (wall-rock assimilation or hybridization with an evolved melt). The petrography and mineral chemistry of the gabbros, in conjunction with bulk rock data from previous studies, favour a calc-alkaline affinity for the parental melts. Thus, metasomatism in the mantle sources related with this basic magmatism might be associated with recycling of crustal components during the Variscan orogeny.Keywords: Late orogenic gabbros, late-stage crystallization, Spanish Central System, Variscan Orogeny, calc-alkaline magmas Resumen Se ha caracterizado la composición química de elementos mayoritarios y trazas en los minerales principales de las intrusiones gabroideas de Talavera y La Solanilla (Sistema Central Español). Los resultados muestran una composición mineral heterogénea que es ilustrativa de una evolución química de los magmas básicos calco-alcalinos durante la cristalización. La formación de minerales intersticiales con elevados contenidos en elementos incompatibles, como por ejemplo el anfíbol, la flogopita y algunos minerales accesorios (circón, apatito...), y la presencia de zonados en los minerales principales, con tendencia a desarrollar una composición más evolucionada hacia el borde, indican la diferenciación progresiva del fundido parental. La variación química de elementos traza normalmente incompatibles en el clinopiroxeno (e.g., REE, Th, Zr, Nb, Ti) implica la co-precipitación de fases con un comportamiento compatible con dichos elementos (e.g., apatito, circón, anfíbol). Sin embargo, las elevadas concentraciones de LILE y LREE del clinopiroxeno no se pueden explicar exclusivamente por un proceso de cristalización en un sistema cerrado. Varias características de la química mineral (e.g., corr...

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The Nature, Origin, and Thermal Influence of the Granite Source Layer of Central Iberia

Cited by 114 publications

References 32 publications

Metaluminous pyroxene-bearing granulite xenoliths from the lower continental crust in central Spain: their role in the genesis of Hercynian I-type granites

Metaluminous pyroxene-bearing granulite xenoliths from the lower continental crust in central Spain: their role in the genesis of Hercynian I-type granites

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

Mineral chemistry of late Variscan gabbros from central Spain: constraints on crystallisation processes and nature of the parental magmas

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