Hybridization between felsic and mafic magmas in calc-alkaline granitoids — a case study in northern Sardinia, Italy

Zorpi, M.J.; Coulon, Christian; Orsini, Jean-Baptiste

doi:10.1016/0009-2541(91)90049-w

Cited by 93 publications

(30 citation statements)

References 44 publications

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“…Magma mixing is an accepted mechanism for the origin of microgranular enclaves (e.g., Frost and Mahood, 1987;Poli and Tommasini, 1991;Castro et al, 1991;Zorpi et al, 1991;Barbarin and Didier, 1992;Erlburg, 1996;D'Lemos, 1996;Maas et al, 1997;Collins et al, 2000;Silva et al, 2000;Waight et al, 2001) and for the origin of large intrusions (e.g., Neves and Vauchez, 1995;Collins, 1998;Barnes et al, 2001). This process ranges from magma mingling when original components maintain most of their characteristics, through partial mixing with the production of a heterogeneous hybrid magma to complete and homogeneous mixing (D'Lemos, 1996).…”

Section: Introductionmentioning

confidence: 99%

Geochemistry of the Rio Espinharas hybrid complex, northeastern Brazil

Campos

Neiva

Nardi

2002

Lithos

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The Rio Espinharas pluton, northeastern Brazil, belongs to the shoshonitic series and consists mainly of syenogranite, quartz -monzonite and porphyritic quartz -monzonite, but diorite, quartz -monzodiorite, quartz -syenite and microsyenogranite also occur containing microgranular enclaves, except for the diorite. Most variation diagrams of rocks, amphiboles, biotites and allanites show linear trends, but K, Zr, Sr and Ba of rocks display curved scattered trends. The rocks ranging from diorite to syenogranite define a pseudo-errorchron and have similar REE patterns. Syenogranite and microsyenogranite are derived from two distinct pulses of granite magma with initial 87 Sr/ 86 Sr ratio of 0.7083 F 0.0003 and 0.7104 F 0.0007, respectively. Modelling of major and trace elements shows that the syenogranite evolved by fractional crystallization of plagioclase, microcline, edenite, biotite and titanite, whereas quartz -monzonite, porphyritic quartz -monzonite, quartz -monzodiorite and quartz -syenite resulted from simple mixing between an upper mantle-derived dioritic magma and the upper crust-derived syenogranite magma. Dioritic enclaves are globules of a mafic magma from the upper mantle. D

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Section: Introductionmentioning

confidence: 99%

Geochemistry of the Rio Espinharas hybrid complex, northeastern Brazil

Campos

Neiva

Nardi

2002

Lithos

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“…Detailed examination of such enclave suites in granites and rhyolites has shown that they are typically more evolved than either associated mafic plutons or lavas (Bacon, 1986;Stimac et al, 1990;Zorpi et al, 1991). ME are depleted in compatible elements such as Mg, Ni, Cr, Ca and Sc relative to associated mafic rocks.…”

Section: Microgranular Enclaves and The Mafic End-member In Cornubianmentioning

confidence: 99%

“…Protracted chemical exchange between enclaves and their granitic hosts renders interpretation of enclave chemistry problematic (Eberz and Nicholls, 1990;B arbarin, 1991 ;Orsini et al, 1991 ;Zorpi et al, 1991 ;van der Laan and Wyllie, 1993). Chemical modification may occur through numerous processes, summarized by Barbarin and Didier (1992).…”

Section: Chemical Exchange Between Enclaves and Granitic Magmamentioning

confidence: 99%

Enclaves and their bearing on the origin of the Cornubian batholith, southwest England

Stimac

Clark²,

Chen³

et al. 1995

Mineral. mag.

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Enclaves of diverse origin are present in minor amounts in the coarse-grained biotite granites of the Cornubian batholith, southwest England. The most common enclave type is layered, rich in biotite, cordierite and aluminosilicates, and has textures and compositions that reveal variable degrees of melt extraction from metasedimentary source rocks. Rare sillimanite-bearing enclaves represent residual material, either from the region of magma generation or its ascent path, but most such enclaves were probably derived from the contact aureole closer to the present level of exposure. These non-igneous enclaves (NIE) and their disaggregation products are present in all major plutons, comprising from < 2 to 5 vol.% of the granites. Enclaves of igneous origin are also present in all major plutons except Carnmenellis, generally comprising < 1 vol.% of the granites. The most common type is intermediate in composition, with microgranular texture, and mineral compositions and textures consistent with an origin by magma mixing. Large crystals of K-feldspar, plagioclase and quartz, common in these microgranular enclaves (ME) but absent in NIE, represent phenocrysts derived from the silicic end-member during magma mixing events rather than products of metasomatism as suggested previously. Although the composition of the mafic end-member (basaltic or lamprophyric) involved in the mixing process is poorly constrained, the presence of ME in the granites, and the preponderance of mantle-derived mafic rocks in the coeval Exeter Volcanics, indicate that mafic magma injection into the crust was a factor in the generation of the batholith. Advection of sub-crustal heat provides an explanation for large-volume crustal melting in regions of relatively thin crust such as southwest England.

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“…: Putteti, Rajesh 2003). The areas delimited by dashed lines correspond to the element ratios between the granitoids and the mafic-microgranular enclaves (MME) which are not formed through melt immiscibility (see text) : Gamble 1979;Reid et al 1983;Wiebe 1984;Diethelm 1989;Eberz and Nicholls 1990;Zorpi et al 1991;Bigioggero et al 1994;Eklund et al 1994;Né dé lec et al 1995, Bolle 1996Lowell and Young 1999;Silva 2000;Xu et al 1999;Roberts et al 2000. Glassy globules, ocelli, and the Shonkin Sag intrusion plot on the trend defined by the immiscibility experiments in the basaltic system.…”

Section: Ti and P Partitioningmentioning

confidence: 99%

Experiments on silicate melt immiscibility in the system Fe2SiO4–KAlSi3O8–SiO2–CaO–MgO–TiO2–P2O5 and implications for natural magmas

Bogaerts

Schmidt

2006

Contrib Mineral Petrol

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The effect of CaO and MgO, with or without TiO 2 and P 2 O 5 , on the two-melt field in the simplified system Fe 2 SiO 4 -KAlSi 3 O 8 -SiO 2 has been experimentally determined at 1,050°-1,240°C, 400 MPa. Despite the suppressing effect of MgO, CaO, and pressure on silicate melt immiscibility, our experiments show that this process is still viable at mid-crustal pressures when small amounts (0.6-2.0 wt%) of P 2 O 5 and TiO 2 are present. Our data stress that the major element partition coefficients between the two melts are highly correlated with the degree of polymerisation (nbo/t) of the SiO 2 -rich melt, whatever temperature, pressure, or exact composition. Experimental immiscible melt compositions in natural systems at 0.1 MPa from the literature (lunar and tholeiitic basalts) plot on similar but distinct curves compared to the simplified system. These relations between melt polymerisation and partition coefficients, which hold for a large range of compositions and fO 2 , are extended to various volcanic and plutonic rocks. This analysis strengthens the proposal that silicate melt immiscibility can be important in volcanic rocks of various compositions (from tholeiitic basalts to lamprophyres). However, the majority of proposed immiscible compositions in plutonic rocks are at least not coexisting melts, but may have suffered accumulation of early crystallized minerals.

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Hybridization between felsic and mafic magmas in calc-alkaline granitoids — a case study in northern Sardinia, Italy

Cited by 93 publications

References 44 publications

Geochemistry of the Rio Espinharas hybrid complex, northeastern Brazil

Geochemistry of the Rio Espinharas hybrid complex, northeastern Brazil

Enclaves and their bearing on the origin of the Cornubian batholith, southwest England

Experiments on silicate melt immiscibility in the system Fe2SiO4–KAlSi3O8–SiO2–CaO–MgO–TiO2–P2O5 and implications for natural magmas

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