Geochemistry of microgranular enclaves in Aligoodarz Jurassic arc pluton, western Iran: implications for enclave generation by rapid crystallization of cogenetic granitoid magma

Esna-Ashari, Amir; Hassanzadeh, Jamshid; Valizadeh, M V

doi:10.1007/s00710-011-0149-7

Cited by 23 publications

(11 citation statements)

References 53 publications

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“…While the majority of the granitoids are I‐type, some A‐type examples have been identified throughout the zone [e.g., Sarjoughian et al ., , and references therein]. The more deeply eroded plutonic systems (e.g., in the Alvand batholith in the Hamadan region and the Aligoodarz batholith) expose mafic bodies of the same age that have been interpreted either as cognate cumulates [ Shahbazi et al ., ; Esna‐Ashari et al ., ] or as separate magmas [ Ghalamghash et al ., , ].…”

Section: Plutonismmentioning

confidence: 99%

The Neotethyan Sanandaj‐Sirjan zone of Iran as an archetype for passive margin‐arc transitions

2016

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The Sanandaj-Sirjan zone of Iran is a northwest trending orogenic belt immediately north of the Zagros suture, which represents the former position of the Neotethys Ocean. The zone contains the most extensive, best preserved record of key events in the formation and evolution of the Neotethys, from its birth in Late Paleozoic time through its demise during the mid-Tertiary collision of Arabia with Eurasia. The record includes rifting of continental fragments off of the northern margin of Gondwanaland, formation of facing passive continental margins, initiation of subduction along the northern margin, and progressive development of a continental magmatic arc. The latter two of these events are critical phases of the Wilson Cycle that, elsewhere in the world, are poorly preserved in the geologic record because of superimposed events. Our new synthesis reaffirms the similarity between this zone and various terranes to the north in Central Iran. Late Paleozoic rifting, preserved as A-type granites and accelerated subsidence, was followed by a phase of pronounced subsidence and shallow marine sedimentation in Permian through Triassic time, marking the formation and evolution of passive margins on both sides of the suture. Subduction and arc magmatism began in latest Triassic/Early Jurassic time, culminating at~170 Ma. The extinction of arc magmatism in this zone, and its shift northeastward to form the subparallel Urumieh-Dokhtar arc, occurred diachronously along strike, in Late Cretaceous or Paleogene time. Post-Cretaceous uplift transformed the zone from a primarily marine borderland into a marine archipelago that persisted until mid-Tertiary time.

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Section: Plutonismmentioning

confidence: 99%

The Neotethyan Sanandaj‐Sirjan zone of Iran as an archetype for passive margin‐arc transitions

2016

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“…The similar mineral assemblages and isotopic compositions of the MMEs and host granitoids in both plutons, which are considered further in Section 6.2, are commonly used to indicate that the microgranular enclaves crystallized from coeval, cognate host magmas via accumulation (Dahlquist, 2002;Dodge and Kistler, 1990) or chilled margins processes (Donaire et al, 2005;Esna-Ashari et al, 2011;Pascual et al, 2008). The cumulate model has been criticized because it would not be compatible with the small grain size and the fine-grained margins of many enclaves (Donaire et al, 2005;Esna-Ashari et al, 2011).…”

Section: Magma Mixing For Generating the Mafic Microgranular Enclavesmentioning

confidence: 99%

“…The cumulate model has been criticized because it would not be compatible with the small grain size and the fine-grained margins of many enclaves (Donaire et al, 2005;Esna-Ashari et al, 2011). In the chilled margin scenario, microgranular enclaves have high SiO 2 contents (commonly N58 wt.%) (Donaire et al, 2005;Esna-Ashari et al, 2011;Pascual et al, 2008), can be classified as intermediate-felsic microgranular enclaves (Didier and Barbarin, 1991) and the major mafic mineral is biotite (Donaire et al, 2005;Esna-Ashari et al, 2011;Pascual et al, 2008).…”

Section: Magma Mixing For Generating the Mafic Microgranular Enclavesmentioning

confidence: 99%

Overlapping Sr–Nd–Hf–O isotopic compositions in Permian mafic enclaves and host granitoids in Alxa Block, NW China: Evidence for crust–mantle interaction and implications for the generation of silicic igneous provinces

Wei

Wang

et al. 2015

Lithos

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“…Among them the most popular issue is the magma mixing and/or mingling model, and in many cases, MMEs are widely used as main evidence for magma mixing and/or mingling between mantle-derived mafic and crustal-derived felsic magmas during formation of calc-alkaline granitoids (e.g., Vernon, 1983Vernon, , 2014Poli and Tommasini, 1991;Wiebe et al, 1997;Yang et al, 2004Yang et al, , 2007Barbarin, 2005;Kocak, 2006;Kumar and Rino, 2006;Kaygusuz and Aydınçakır, 2009;Zhao et al, 2010;Cheng et al, 2012;Dan et al, 2015). In some granitoid plutons, MMEs from different origins coexist and have provided important constraints on formation processes of the granitoid plutons in continental crust (e.g., Grout, 1937;Tindle and Pearce, 1983;Didier, 1987;Didier and Barbarin, 1991;Fornelli, 1994;Stimac et al, 1995;Elburg, 1996b;Schödlbauer et al, 1997;Yang et al, 2004;Barbarin, 2005;Ilbeyli and Pearce, 2005;Esna-Ashari et al, 2011;Clemens and Elburg, 2013). Using MMEs as one of the most important indicators of mixing and/or mingling between mantle-derived mafic and crustal-derived felsic magmas, most researchers considered magma mixing as a common phenomenon in generation of intermediate magmatic rocks such as andesites and diorites (e.g., Cantagrel et al, 1984;Ussler and Glazner, 1989;Castro et al, 1990a;Cole et al, 2001;Janoušek et al, 2004;Alpaslan et al, 2005;Kawabata and Shuto, 2005).…”

Section: Introductionmentioning

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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Geochemistry of microgranular enclaves in Aligoodarz Jurassic arc pluton, western Iran: implications for enclave generation by rapid crystallization of cogenetic granitoid magma

Cited by 23 publications

References 53 publications

The Neotethyan Sanandaj‐Sirjan zone of Iran as an archetype for passive margin‐arc transitions

The Neotethyan Sanandaj‐Sirjan zone of Iran as an archetype for passive margin‐arc transitions

Overlapping Sr–Nd–Hf–O isotopic compositions in Permian mafic enclaves and host granitoids in Alxa Block, NW China: Evidence for crust–mantle interaction and implications for the generation of silicic igneous provinces

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

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