The Sanandaj–Sirjan Zone in the Neo-Tethyan suture, western Iran: Zircon U–Pb evidence of late Palaeozoic rifting of northern Gondwana and mid-Jurassic orogenesis

Fergusson, C. L.; Nutman, Allen P.; Mohajjel, Mohammad; Bennett, Vickie C.

doi:10.1016/j.gr.2016.08.006

Cited by 72 publications

(41 citation statements)

References 75 publications

(184 reference statements)

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“…a -Simplified geological map of the Dorud-Azna region and sample locations of mafic dykes. Ages given in Ma: Data sources: (1) Shakerardakani et al 2015;(2) Fergusson et al 2016. Map is updated and modified after Mohajjel & Fergusson (2000).…”

Section: Geological Settingmentioning

confidence: 99%

“…A laser-ablation ICP-MS U-Pb zircon age of 314.6 ± 3.7 Ma has been reported for the Dare-Hedavand metagabbro from this complex (Shakerardakani et al 2015) testifying a Late Carboniferous age of gabbro formation. Recently, Fergusson et al (2016) reported an age of 336 ± 9 Ma for a metagabbro, which was previously undated and considered to be part of the isotropic Darijune gabbro (Shakerardakani et al 2015).…”

Section: Geological Settingmentioning

confidence: 99%

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Geochemical and isotopic evidence for Carboniferous rifting: mafic dykes in the central Sanandaj-Sirjan zone (Dorud-Azna, West Iran)

Shakerardakani¹,

Neubauer²,

Bernroider³

et al. 2017

Geologica Carpathica

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Abstract:In this paper, we present detailed field observations, chronological, geochemical and Sr-Nd isotopic data and discuss the petrogenetic aspects of two types of mafic dykes, of alkaline to subalkaline nature. The alkaline mafic dykes exhibit a cumulate to foliated texture and strike NW-SE, parallel to the main trend of the region. The 40 Ar/ 39 Ar amphibole age of 321.32 ± 0.55 Ma from an alkaline mafic dyke is interpreted as an indication of Carboniferous cooling through ca. 550 °C after intrusion of the dyke into the granitic Galeh-Doz orthogneiss and Amphibolite-Metagabbro units, the latter with Early Carboniferous amphibolite facies grade metamorphism and containing the Dare-Hedavand metagabbro with a similar Carboniferous age. The alkaline and subalkaline mafic dykes can be geochemically categorized into those with light REE-enriched patterns [(La/Yb) N = 8.32-9.28] and others with a rather flat REE pattern [(La/Yb) N = 1.16] and with a negative Nb anomaly. Together, the mafic dykes show oceanic island basalt to MORB geochemical signature, respectively. This is consistent, as well, with the (Tb/Yb) PM ratios. The alkaline mafic dykes were formed within an enriched mantle source at depths of ˃ 90 km, generating a suite of alkaline basalts. In comparison, the subalkaline mafic dykes were formed within more depleted mantle source at depths of ˂ 90 km. The subalkaline mafic dyke is characterized by 87 Sr/ 86 Sr ratio of 0.706 and positive ɛ Nd (t) value of + 0.77, whereas 87 Sr/ 86 Sr ratio of 0.708 and ɛ Nd (t) value of + 1.65 of the alkaline mafic dyke, consistent with the derivation from an enriched mantle source. There is no evidence that the mafic dykes were affected by significant crustal contamination during emplacement. Because of the similar age, the generation of magmas of alkaline mafic dykes and of the Dare-Hedavand metagabbro are assumed to reflect the same process of lithospheric or asthenospheric melting. Carboniferous back-arc rifting is the likely geodynamic setting of mafic dyke generation and emplacement. In contrast, the subalkaline mafic sill is likely related to the emplacement of the Jurassic Darijune gabbro.

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Section: Geological Settingmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

Geochemical and isotopic evidence for Carboniferous rifting: mafic dykes in the central Sanandaj-Sirjan zone (Dorud-Azna, West Iran)

Shakerardakani¹,

Neubauer²,

Bernroider³

et al. 2017

Geologica Carpathica

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“…1c), which is tectonically overlain by a Panafrican basement with the Gondwanan affiliation of orthogneiss and various in part Carboniferous-aged amphibolites and metagabbros (Nutman et al 2014;Shakerardakani et al 2015Shakerardakani et al , 2017Fergusson et al 2016).…”

Section: Geological Settingmentioning

confidence: 99%

“…c Simplified lithostratigraphic section of Triassic and Jurassic sedimentary units of the Dorud-Azna region (after Mohajjel et al 2003) metasedimentary units are imbricated with older, highergrade metamorphic units. These are from footwall to hangingwall: (1) Permian Marble and overlying Triassic Complex metamorphosed within greenschist facies conditions and, to the southeast, intruded by the Jurassic Darijune gabbro, tectonically overlain by (2) amphibolite-facies Panafrican orthogneiss and (3) Carboniferous Amphibolite-Metagabbro unit (Mohajjel et al 2003;Shakerardakani et al 2015;Fergusson et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Tectonic significance of Triassic mafic rocks in the June Complex, Sanandaj–Sirjan zone, Iran

et al. 2017

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This study concentrates on the petrological and geochemical investigation of mafic rocks embedded within the voluminous Triassic June Complex of the central Sanandaj-Sirjan zone (Iran), which are crucial to reconstruct the geodynamics of the Neotethyan passive margin. The Triassic mafic rocks are alkaline to sub-alkaline basalts, containing 43.36-49.09 wt% SiO 2 , 5.19-20.61 wt% MgO and 0.66-4.59 wt% total alkalis. Based on MgO concentrations, the mafic rocks fall into two groups: cumulates (Mg# = 51.61-58.94) and isotropic basaltic liquids (Mg# = 24.54-42.66). In all samples, the chondrite-normalized REE patterns show enrichment of light REEs with variable (La/Yb) N ratios ranging from 2.48 to 9.00, which confirm their amalgamated OIB-like and E-MORB-like signatures. Enrichment in large-ion lithophile elements and depletion in high field strength elements (HFSE) relative to the primitive mantle further support this interpretation. No samples point to crustal contamination, all having undergone fractionation of olivine ? clinopyroxene ? plagioclase. Nevertheless, elemental data suggest that the substantial variations in (La/Sm) PM and Zr/Nb ratios can be explained by variable degrees of partial melting rather than fractional crystallization from a common parental magma. The high (Nb/Yb) PM ratio in the alkaline mafic rocks points to the mixing of magmas from enriched and depleted mantle sources. Abundant OIB alkaline basalts and rare E-MORB appear to be linked to the drifting stage on the northern passive margin of the Neotethys Ocean.

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“…The metamorphic belt of the SSZ consists mainly of various metamorphic, igneous, and Sedighian et al, 2017); S.J = Sirjan; (b) Simplified geological/structural map of the Dehsard (Bazar) (modified from Geological map of the Dehsard (Bezar), Scale 1/100,000, Nazemzadeh and Rashidi, 2006). sedimentary rocks of Late Neoproterozoic to Neogene age that are unconformably overlain by the Barremo-Aptian Orbitolina limestones, characteristic of Central Iran sedimentation Berberian et al, 1982;Temizel and Arslan, 2008;Shahbazi et al, 2010;Fergusson et al, 2016). The SSZ was deformed and partly unearthed during the Cretaceous-Paleogene continental collision of the Afro-Arabian with Central Iran (Şengör and Natal'in, 1996;Mohajjel and Fergusson, 2000;Mohajjel et al, 2003).…”

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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The Sanandaj–Sirjan Zone in the Neo-Tethyan suture, western Iran: Zircon U–Pb evidence of late Palaeozoic rifting of northern Gondwana and mid-Jurassic orogenesis

Cited by 72 publications

References 75 publications

Geochemical and isotopic evidence for Carboniferous rifting: mafic dykes in the central Sanandaj-Sirjan zone (Dorud-Azna, West Iran)

Geochemical and isotopic evidence for Carboniferous rifting: mafic dykes in the central Sanandaj-Sirjan zone (Dorud-Azna, West Iran)

Tectonic significance of Triassic mafic rocks in the June Complex, Sanandaj–Sirjan zone, Iran

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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