Geochemistry, petrogenesis, and tectonic setting of the Almogholagh batholith in the Sanandaj–Sirjan zone, western Iran

The Almogholagh–Dehgolan region is in the North Sanandaj–Sirjan zone of NW Iran. The granites of the region are metaluminous and display geochemical and textural characteristics of transitional granites between ferroan (A-type) and I-type granites. In geotectonic discrimination diagrams, the Almogholagh–Dehgolan granites plot mainly in the fields of within-plate granites and volcanic arc granites. With the exception of the Qalaylan granites, parts of other granites resemble A2-type granites. Granites of the Qalaylan intrusive body have petrographic and geochemical features close to I-type granites and are not A-type. Primary mantle and chondrite-normalized spider diagrams show enrichments in light rare earth elements relative to heavy rare earth elements. For an age of 150 Ma, the initial 87Sr/86Sr and 143Nd/144Nd ratios vary from 0.702769 to 0.706545 and from 0.512431 to 0.512558, respectively. Epsilon Nd values vary in a relatively limited range between −0.3 and +2.2, which corresponds to a mixed mantle–crustal source. On the basis of new geochemical and isotopic data, we suggest a geodynamic model involving partial melting of lower crustal rocks with the contribution of mantle magmas in a weakly extensional tectonic setting for the generation of the A-type granites of the region. The occurrence of ferroan (A-type) granites in this region of the Sanandaj–Sirjan zone indicates the existence of a partly extensional tectonic environment in a mainly compressional subduction-related regime in Late Jurassic time.

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“…2015; Amiri et al . 2017; Jamshidibadr et al . 2018) have studied the mafic rocks of the Qorveh region and adjacent areas in the NSaSZ.…”

Section: Discussionmentioning

confidence: 99%

Geochemistry and Sr–Nd isotopic characteristics of ferroan-magnesian metaluminous granites of the NW Sanandaj–Sirjan zone, Iran: granite formation in a compressional–extensional setting during Late Jurassic time

et al. 2023

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“…The present zircon U–Pb dating establishes that the Bardkish syenite crystallized in the Turonian (91.1 ±0.8 Ma), forming the subduction‐related unit. The oldest unit is late Jurassic to early Cretaceous A‐type syenites exposed in areas of Dehgolan (Sarjoughian et al, 2015) and Almogholagh (Amiri et al, 2017; Jamshidi‐Badr et al, 2018). Their generation is controversial and is generally inferred to be generated during extensional strain in an intra‐arc setting.…”

Section: Discussionmentioning

confidence: 99%

“…Almogholagh (Amiri et al, 2017;Jamshidi-Badr et al, 2018). Their generation is controversial and is generally inferred to be generated during extensional strain in an intra-arc setting.…”

Section: Petrogenesismentioning

confidence: 99%

“…Syenitic rocks are a minor component of the igneous suite. Most of these are located in the northwest of the SSZ, in places such as Urumieh (Jafari, Fazlnia, & Jamei, 2018), Piranshahr (Mazhari et al, 2009), Sardasht (Fazlnia, 2018), Saqqez (Sepahi & Athari, 2006), Almogholagh (Amiri et al, 2017; Jamshidi‐Badr, Collins, Salomao, & Costa, 2018), Golpaygan (Davoudian, Hamedani, Shabanian, & Mackizadeh, 2007), and Dehgolan (Sarjoughian, Kananian, Haschke, & Ahmadian, 2015). Most of them have been assumed to have formed mainly in an extensional tectonic setting because of their A‐type nature and or occurring in association with A‐type granitoids (Amiri et al, 2017; Davoudian et al, 2007; Mazhari et al, 2009; Sarjoughian et al, 2015; Sepahi & Athari, 2006).…”

Section: Introductionmentioning

confidence: 99%

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The age and geochemistry of the Bardkish syenite, northwest Iran: Syenite formation during Neo‐Tethyan subduction

2020

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SHRIMP U-Pb dating of zircon from two representative samples of the Bardkish syenitic pluton, Urumieh plutonic complex, northwestern Iran, yielded a Late Cretaceous weighted mean 206 Pb/ 238 U age of 91.1 ±0.8 Ma (Turonian). The pluton is characterized by high K 2 O content, Ti-Nb-Ta depletion, enrichment in light rare earth elements and large ion lithophile elements compared to high field strength element, Mg-rich biotite and calcic amphibole, suggesting a shoshonitic affinity. Geochemical features of the Bardkish syenite are consistent with derivation by fractional crystallization of initial mafic parent magmas. It is most likely that primary magma of the syenite originated from a metasomatized subcontinental lithospheric mantle source with minor crustal component, and underwent a fractional crystallization process during its emplacement. The estimates of trapping pressures and temperatures suggest that crystallization began at the middle crustal level (less than 11 km) near 700-730 C. The generation of the Bardkish syenite could be related to the subduction of Neo-Tethyan oceanic crust beneath the Central Iranian microcontinent and it possibly marks a major magmatic episode prior to the final closure of the Neo-Tethyan ocean in northwest Iran.

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“…For most of the second half of the Mesozoic, the SSZ manifested an active Andean-type margin where its calc-alkaline magmatic activity constantly moved northward (Berberian and King, 1981). The SSZ and its metamorphic-plutonic complexes were the subject of numerous petrological, geochemical, structural, and geochronological studies (Baharifar et al, 2004;Ahmadi Khalaji et al, 2007;Arvin et al, 2007;Shahbazi et al, 2010;Esna-Ashari et al, 2012, Fergusson et al, 2016Amiri et al, 2017;Sedighian et al, 2017). The aim of the present contribution is to present detail petrographic and wholerock geochemical analysis of mafic volcanic rocks in the SSZ, which are exposed in the south of the Dehsard area southwest of Kerman (Figure 1b), in order to examine their origin and tectonic settings in the context of the Neo-Tethys evolution.…”

Section: Introductionmentioning

confidence: 99%

Geochemistry and source characteristics of Dehsard mafic volcanic rocks in the southeast of the Sanandaj–Sirjan zone, Iran: implications for the evolution of the Neo-Tethys Ocean

Nazemei¹,

Arvin²,

Dargahi³

2018

Turkish J Earth Sci

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The Late Jurassic-Early Cretaceous Dehsard mafic volcanic rocks crop out in the southeastern Sanandaj-Sirjan Zone (SSZ), composed primarily of basalts and basaltic andesite with subordinate dolerite. They are influenced to some degree by hydrothermal alteration under zeolite-greenschist facies. Using fairly immobile trace elements, the mafic volcanic rocks show subalkaline (tholeiitic) affinities. They commonly have similar designs with somewhat strong enrichment in light rare earth elements (LREEs) and large ion lithophile elements (LILEs) and depletion in high field strength elements (HFSEs; e.g., Nb, Ta, Ti) and nearly flat heavy rare earth element (HREE) patterns. The negligible or absence of negative Eu anomalies indicate that plagioclase played an insignificant role during magma evolution. The low La/Nb (1.03-2.31) and Nb/Y (0.12-0.46) ratios, relatively high Zr/Y (4.03-8.18) and Th/Ta (2.25-9.64) ratios, steady enhanced normalized patterns, and moderate La/Nb ratios hint at an island arc and most likely a back-arc basin environment for the formation of Dehsard mafic volcanic rocks. The arc magma resulted from partial melting of depleted mantle source that experienced assimilation and fractional crystallization and was enhanced by melts of subducted sediments or contribution of slabderived fluids in an intraoceanic subduction environment in the Neo-Tethyan Ocean. Therefore, the presence of an island arc setting (Dehsard island arc) must be investigated in the south of the SSZ prior to the Late Jurassic-Early Cretaceous as the Neo-Tethys oceanic crust was subducting north beneath the southern margin of the Central Iranian Microcontinents. The later collision of the arc with SSZ led to tectonic proximity of the Dehsard mafic volcanic rocks to SSZ components.

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Geochemistry, petrogenesis, and tectonic setting of the Almogholagh batholith in the Sanandaj–Sirjan zone, western Iran

Cited by 12 publications

References 67 publications

Geochemistry and Sr–Nd isotopic characteristics of ferroan-magnesian metaluminous granites of the NW Sanandaj–Sirjan zone, Iran: granite formation in a compressional–extensional setting during Late Jurassic time

Geochemistry and Sr–Nd isotopic characteristics of ferroan-magnesian metaluminous granites of the NW Sanandaj–Sirjan zone, Iran: granite formation in a compressional–extensional setting during Late Jurassic time

The age and geochemistry of the Bardkish syenite, northwest Iran: Syenite formation during Neo‐Tethyan subduction

Geochemistry and source characteristics of Dehsard mafic volcanic rocks in the southeast of the Sanandaj–Sirjan zone, Iran: implications for the evolution of the Neo-Tethys Ocean

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