Magma-mixing in the genesis of Hercynian calc-alkaline granitoids: an integrated petrographic and geochemical study of the Sázava intrusion, Central Bohemian Pluton, Czech Republic

Janoušek, Vojtěch; Braithwaite, C. J. R.; Bowes, D. R.; Gerdes, Axel

doi:10.1016/j.lithos.2004.04.046

Cited by 233 publications

(116 citation statements)

References 102 publications

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“…The frequent presence of basic to intermediate igneous enclaves in granitic rocks, is considered usually as an evidence for hybridization with a mantle-derived component (Vernon, 1984;Didier, 1987;Orsini et al, 1991;Barbarin and Didier, 1992;Dias and Leterrier, 1994;Moreno-Ventas et al, 1995;Bea et al, 1999;Collins et al, 2000;Dias et al, 2002;Bonin, 2004;Janousek et al, 2004;Silva and Neiva, 2004;Renna et al, 2006;Slaby and Martin, 2008). However a simple mixing model (not shown) with a basic pole with a Sr-Nd isotopic composition close to bulk-earth values (as used by Moreno-Ventas et al, 1995) and an acid end-member corresponding to the average of lower crustal xenoliths (Villaseca et al, 1998b) suggest an enormous (Beetsma, 1995); ortogneisses, biotite gneisses and amphibolites (Noronha and Leterrier, 2000); felsic granulites (Villaseca et al, 1999).…”

Section: Discussionmentioning

confidence: 99%

Genesis and emplacement of felsic Variscan plutons within a deep crustal lineation, the Penacova-Régua-Verín fault: An integrated geophysics and geochemical study (NW Iberian Peninsula)

Martins

Sant'Ovaia

Noronha

2009

Lithos

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Multidisciplinary studies integrating, U-Pb geochronology, whole-rock geochemical data, isotope geochemistry, anisotropy of magnetic susceptibility (AMS) studies and gravimetry were carried out on the Vila Pouca de Aguiar and the Águas Frias-Chaves porphyritic biotite granite plutons. Both plutons occur independently in a distance of about 20 km. The Vila Pouca de Aguiar and Águas Frias-Chaves plutons are examples of late to post-orogenic felsic Variscan granites in northern Portugal (NW Iberian Peninsula). The U-Pb zircon analyses yield a consistent age of 299 ± 3 Ma which is considered to be the emplacement age of the two plutons. These granites are weakly peraluminous, show high HREE and Y (and low P) contents which are consistent with them being I-type. This is also supported by their weakly evolved isotopic compositions, 87 Sr/ 86 Sr i = 0.7044-0.7077 and εNd = − 2.0 to − 2.6, as well as by the whole rock oxygen isotope (δ 18 O VSMOW) ranging from + 9.7‰ to + 11.0‰. The emplacement of granite magma took place after the third Variscan deformation phase (D 3 ) in an extensional tectonic regime, large scale uplift and crustal thinning. The integration of different data suggests that both plutons have the same feeding zone aligned within the Penacova-Régua-Verin fault (PRVF) and that both have the same structure which is related to late Variscan phases. The thicker shape for the Águas Frias-Chaves pluton comparing to that of the Vila Pouca de Aguiar pluton is compatible with different depths of PRVF sectors. The available data led us to propose a model of partial melting of a meta-igneous lower crustal source rather than an open-system of mantle-crust interaction. The interaction between the continental crust and invading mafic magmas could have been limited to mere heat transfer and, perhaps, local intermingling.

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Section: Discussionmentioning

confidence: 99%

Genesis and emplacement of felsic Variscan plutons within a deep crustal lineation, the Penacova-Régua-Verín fault: An integrated geophysics and geochemical study (NW Iberian Peninsula)

Martins

Sant'Ovaia

Noronha

2009

Lithos

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“…The enriched nature of subcontinental mantle domains is also present in other sectors within the Variscan Belt (Fernández-Suárez et al, 2011;Janousek et al, 2000;Moreno-Ventas et al, 1995;Orejana et al, 2009;Pin and Duthou, 1990;Villaseca et al, 2011). Further constraints about the hybridisation process in the genesis of granitoids are given by the presence of mafic microgranular enclaves associated with granitic rocks, as they are generally considered as representing a mantle-derived component (Barbarin and Didier, 1992;Bea et al, 1999;Bonin, 2004;Cocherie et al, 1994;Collins et al, 2000;Dias and Leterrier, 1994;Dias et al, 2002;Didier, 1987;Janousek et al, 2004;Moreno-Ventas et al, 1995;Orsini et al, 1991;Renna et al, 2006;Silva and Neiva, 2004;Slaby and Martin, 2008;Vernon, 1984).…”

Section: Nature Of the Granite Sourcesmentioning

confidence: 99%

“…Although controversial, the type and nature of the processes responsible for the genesis of different granitic magmas can involve partial melting of distinct source rock materials, hybridisation of magmas with contrasting compositions, fractional crystallization, crustal contamination and more complex models, such as assimilation-fractional crystallization process (Bea et al, 1999;Bonin, 2004;Castro et al, 1999;Collins et al, 2000;Dias and Leterrier, 1994;Dias et al, 2002;Janousek et al, 2004;Moreno-Ventas et al, 1995;Patiño-Douce, 1999;Renna et al, 2006;Silva and Neiva, 2004;Slaby and Martin, 2008;Villaseca et al, 1998Villaseca et al, , 2008Villaseca et al, , 2009). Thus, their study offers an important contribute to a better knowledge of the mechanisms of magma genesis and the deep continental crust evolution, giving together insights about the nature of source rocks that are melted.…”

Section: Introductionmentioning

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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“…Poli, Tommasini & Halliday, 1996;Janousek et al 2004), or cognate enclaves, suggesting that they represent accumulations of fractionated phases (e.g. Nitoi et al 2002;Donaire et al 2005).…”

Section: A Qmzdmentioning

confidence: 99%

“…Symbols as in Figure 3. assimilation (AFC process;De Paolo, 1981) An alternative hypothesis could be a model of mixing plus fractional crystallization (MFC; e.g. Wei, Congqiang & Masuda, 1997;Poli & Tommasini, 1999;Janousek et al 2004;Gagnevin et al 2007), with a mathematical formulation analogous to AFC (De Paolo, 1981). A reasonable approximation for the felsic end-member could be the composition of GDS rocks, whereas an average composition of minettes/leucominettes from the Veliki Majdan area could be a proxy for the mafic end-member.…”

Section: A Qmzdmentioning

confidence: 99%

Petrogenetic and tectonic inferences from the study of the Mt Cer pluton (West Serbia)

et al. 2010

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-The Mt Cer Pluton, Serbia, is a complex laccolith-like intrusion (∼ 60 km 2 ), situated along the junction between the southern Pannonian Basin and northern Dinarides. It intrudes Palaeozoic metamorphic rocks causing weak to strong thermal effects. Based on modal and chemical compositions, four rock-types can be distinguished: (1) metaluminous I-type quartz monzonite/quartz monzodiorite (QMZD); (2) peraluminous S-type two-mica granite (TMG), which intrudes QMZD; (3) Stražanica granodiorite/quartz monzonite (GDS); and (4) isolated mafic enclaves (ME), found only in QMZD. 40 K-39 Ar dating and geological constraints indicate that the main quartz monzonite/quartz monzodiorite body of Mt Cer was emplaced not later than 21 Ma, whereas the emplacement ages of the Stražanica granodiorite/quartz monzonite and two-mica granites are estimated at around 18 and 16 Ma, respectively. The Mt Cer pluton is similar to the Mt Bukulja pluton, some 80 km southwestwards. Genesis of QMZD cannot be interpreted by fractional crystallization coupled with mixing or assimilation. It is best explained by a convection-diffusion process between mantle-derived minette/leucominette magmas and GDS-like magmas followed by two end-member magma mixing. The composition of GDS rocks suggests that GDS-like magmas could have formed by melting of lower crustal lithologies similar to amphibolite/metabasalts. The geochemistry of TMG is reproduced by an Assimilation/Fractional Crystallization model with a ratio of rate of assimilation to rate of fractional crystallization of 0.4, using the compositions of the least evolved TMG of the Bukulja pluton and adjacent metamorphic rocks as proxies for the parental magma and contaminant, respectively. The origin and evolution of the Mt Cer and adjacent Mt Bukulja plutons provide new constraints on the Tertiary geodynamics of the northern Dinarides-southern Pannonian region. The quartz monzonite/quartz monzodiorite is interpreted as a result of the Oligocene post-collisional Dinaride orogen-collapse, which included a limited lithosphere delamination, small-scale mantle upwelling, and melting of the lower crust. By contrast, the two-mica granite magmas formed through melting in shallower crustal levels during the extensional collapse in the Pannonian area.

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Magma-mixing in the genesis of Hercynian calc-alkaline granitoids: an integrated petrographic and geochemical study of the Sázava intrusion, Central Bohemian Pluton, Czech Republic

Cited by 233 publications

References 102 publications

Genesis and emplacement of felsic Variscan plutons within a deep crustal lineation, the Penacova-Régua-Verín fault: An integrated geophysics and geochemical study (NW Iberian Peninsula)

Genesis and emplacement of felsic Variscan plutons within a deep crustal lineation, the Penacova-Régua-Verín fault: An integrated geophysics and geochemical study (NW Iberian Peninsula)

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

Petrogenetic and tectonic inferences from the study of the Mt Cer pluton (West Serbia)

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