The significance of mafic microgranular enclaves in the petrogenesis of the Dehno Complex, Sanandaj–Sirjan belt, Iran

Rajaieh, M.; Khalili, Mohammad Mahdi; Richards, I. J.

doi:10.1016/j.jseaes.2010.02.006

Cited by 11 publications

(4 citation statements)

References 71 publications

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“…MMEs resulting from different origins could coexist in a single granitoid pluton (e.g., Grout, 1937;Didier, 1987;Fornelli, 1994;Stimac et al, 1995;Elburg, 1996b;Schödlbauer et al, 1997;Kadioğlu and Güleç, 1999;Waight et al, 2001b;Yang et al, 2004;Barbarin, 2005;Ilbeyli and Pearce, 2005;Esna-Ashari et al, 2011;Clemens and Elburg, 2013). Among the two popular models proposed for the origin of the MMEs in granitic rocks, the magma mixing and mingling model of mantle-and crust-derived magmas accounts for the igneous textural features, finer grain size, and chilled margins of the enclaves and isotopic differences between enclaves and their host granitoids (e.g., Holden et al, 1987Holden et al, , 1991Elburg and Nicholls, 1995;Metcalf et al, 1995;Maas et al, 1997;Altherr et al, 1999;Yang et al, 2004Yang et al, , 2007Chen et al, 2009a;Shaw and Flood, 2009;Shin et al, 2009;Rajaieh et al, 2010;Qin et al, 2010;Zhao et al, 2010;Cheng et al, 2012;Jiang et al, 2013;Liu et al, 2013). The cognate origin model for crystallization of the MMEs from a coeval magma that gave rise to the host granitoids accounts for similar mineral assemblage and similarities in chemical and isotopic compo- sitions between enclaves and their hosts (e.g., Borodina, 1977, 1991;Dodge and Kistler, 1990;Pin et al, 1990;Dorais et al, 1997;…”

Section: Implications For Origin Of the Mmes In Calc-alkaline Granitoidsmentioning

confidence: 99%

Cogenetic origin of mafic microgranular enclaves in calc-alkaline granitoids: The Permian plutons in the northern North China Block

Zhang

Zhao

2017

Geosphere

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Mafic microgranular (microgranitoid) enclaves (MMEs) with fineto medium-grain-size igneous microstructures are abundant in Permian gran itoid plutons in the northern North China Block (NCB). They are mainly dioritic in composition with SiO 2 contents from 51.0 wt% to 62.7 wt% and are contiguous with their host granitoids (SiO 2 = 60.4-68.4 wt%). Their main mineral assemblage of plagioclase (oligoclase and andesine), hornblende, biotite, K-feldspar, and quartz is similar to that of their host granitoids but with different mineral proportions. Zircon laser ablation-inductively coupled plasma-mass spectrometer (LA-ICP-MS) U-Pb dating, hornblende-plagioclase thermobarometry, and Ti-in-zircon thermometry results show that the crystallization ages and pressure-temperature (P-T) conditions of the MMEs in each Permian granitoid pluton are very similar to those of their host granitoids, indicating simultaneous crystallization at the middle to upper crustal levels. Petrographical, geochemical, and Sr-Nd-Hf isotopic data show that the source areas of the Permian granitoid plutons in the northern NCB are temporally and spatially different and magma mixing was likely involved during formation of some granitoid plutons. However, the whole-rock Sr-Nd and zircon Hf isotopic compositions of the MMEs in each pluton are very similar to those of their host granitoids, indicating complete isotopic equilibration between the host granitoids and their enclaves. Combined with similar mineral assemblage and mineral chemistry between the MMEs and their host granitoids and absence of coeval mantle-derived rocks in or nearby the plutons, we confirm that the MMEs were crystallized from a coeval magma that gave rise to the host granitoids, and not by mixing and/or mingling between mantle-derived mafic and crustal-derived felsic magmas or by synplutonic injections of mafic magma into the host granitoid magma. We conclude that magma isotopic equilibration between host granitoids and their enclaves was achieved prior to emplacement and the magma mixing process during formation of some Permian granitoid plutons occurred mainly in the melting, assimilation, storage, and homogenization (MASH) zone in the lowermost crust or mantle-crust transition, not in the magma conduits or chambers at middle to upper crustal levels. A two-stage model that includes rapid cooling within the cogenetic host granitoid magma operating at pluton margins to form solid to sub-solid dioritic rocks and crystal accumulations of the host granitoid magma at the bottom of the pluton to form cumulates, and dioritic rocks and cumulates then fragmentated and interacted with progressive evolved host granitoid magma to change their shapes and orientations is proposed for origin of the MMEs in the Permian granitoid plutons in the northern NCB. This model may be more widely applicable to the generation of many MMEs in granitic rocks, especially where no direct evidence exists for the presence of mafic magmas coeval with granitoids and where there is a lack of isotopic contrast between...

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Section: Implications For Origin Of the Mmes In Calc-alkaline Granitoidsmentioning

confidence: 99%

Cogenetic origin of mafic microgranular enclaves in calc-alkaline granitoids: The Permian plutons in the northern North China Block

Zhang

Zhao

2017

Geosphere

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“…In order to evaluate analogies and differences in magma composition, evolution and time of emplacement, the AGC is compared with available literature data from the major intrusive bodies of the central SSZ: i.e., the Dehno granitoid complex (Rajaieh et al, 2010), the Boroujerd granitoid complex (Ahmadi-Khalaji et al, 2007) and the Alvand granitoid complex Shahbazi et al, 2010).…”

Section: Comparison With Other Granitoids Of the Central Sszmentioning

confidence: 99%

“…Data for Dehno(Rajaieh et al, 2010); Boroujerd(Ahmadi-Khalaji et al, 2007) and Alvand complexes are reported for comparison.…”

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confidence: 99%

Geochemistry and zircon U–Pb geochronology of Aligoodarz granitoid complex, Sanandaj-Sirjan Zone, Iran

Esna-Ashari

Tiepolo

Valizadeh

et al. 2011

Journal of Asian Earth Sciences

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“…However, the granitoidhosted enclaves display an identical composition to that of the metavolcanic rocks. The mineralogical and geochemical features of the enclaves and metavolcanics support the idea that the granitoid rocks developed through variable degrees of mixing/mingling between a basic magma and granitic melt during subduction, when blobs of basic to intermediate parental magma became trapped in the granitic magma (Hassen et al 2008;Rajaieh et al 2010). The gabbro and andesite enclaves most likely represent the nearest composition to the original, more basic, magma.…”

Section: B Petrogenesis Of the Metavolcanic Rocks And Enclavesmentioning

confidence: 63%

Origin and tectonic significance of the metavolcanic rocks and mafic enclaves from the Palaeoproterozoic Birimian Terrane, SE West African Craton, Ghana

Sakyi

Manu

et al. 2020

Geol. Mag.

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The Palaeoproterozoic Birimian Supergroup of the West African Craton (WAC) consists of volcanic belts composed predominantly of basaltic and andesitic rocks and intervening sedimentary basins composed predominantly of wackes and argillites. Mafic metavolcanic rocks and granitoid-hosted enclaves from the Palaeoproterozoic Lawra Belt of Ghana were analysed for geochemical and Sr–Nd isotopic data to constrain the geological evolution of the southeastern part of the WAC. The metavolcanic rocks display mainly tholeiitic signatures, whereas the enclaves show calc-alkaline signatures. The high SiO2 contents (48.6–68.9 wt%) of the enclaves are suggestive of their evolved character. The high Th/Yb values of the samples relative to that of the mantle array may indicate derivation of their respective magmas from subduction-modified source(s). The rocks show positive εNd values of +0.79 to +2.86 (metavolcanic rocks) and +0.79 to +1.82 (enclaves). These signatures and their Nd model ages (TDM2) of 2.31–2.47 Ga (metavolcanic rocks) and 2.39–2.47 Ga (enclaves) suggest they were probably derived from juvenile mantle-derived protoliths, with possible input of subducted pre-Birimian (Archean?) rocks in their source(s). Their positive Ba–Th and negative Nb–Ta, Zr–Hf and Ti anomalies may indicate their formation through subduction-related magmatism consistent with an arc setting. We propose that the metavolcanic rocks and enclaves from the Lawra Belt formed in a similar island-arc setting. We infer that the granitoids developed through variable degrees of mixing/mingling between basic magma and granitic melt during subduction, when blobs of basic to intermediate parental magma became trapped in the granitic magma to form the enclaves.

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The significance of mafic microgranular enclaves in the petrogenesis of the Dehno Complex, Sanandaj–Sirjan belt, Iran

Cited by 11 publications

References 71 publications

Cogenetic origin of mafic microgranular enclaves in calc-alkaline granitoids: The Permian plutons in the northern North China Block

Cogenetic origin of mafic microgranular enclaves in calc-alkaline granitoids: The Permian plutons in the northern North China Block

Geochemistry and zircon U–Pb geochronology of Aligoodarz granitoid complex, Sanandaj-Sirjan Zone, Iran

Origin and tectonic significance of the metavolcanic rocks and mafic enclaves from the Palaeoproterozoic Birimian Terrane, SE West African Craton, Ghana

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