Panafrican basement and Mesozoic gabbro in the Zagros orogenic belt in the Dorud–Azna region (NW Iran): Laser-ablation ICP–MS zircon ages and geochemistry

Shakerardakani, Farzaneh; Neubauer, Franz; Masoudi, Fariborz; Mehrabi, Behzad; Liu, Xiaoming; Dong, Yunpeng; Mohajjel, Mohammad; Monfaredi, Behzad; Friedl, Gertrude

doi:10.1016/j.tecto.2015.02.020

Cited by 78 publications

(82 citation statements)

References 95 publications

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“…In addition, the mafic rocks of the Amphibolite-Metagabbro unit exhibit sub-alkaline to alkaline basaltic compositions, and have an E-MORB geochemistry (Shakerardakani et al 2015). 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.…”

Section: Geological Settingmentioning

confidence: 90%

“…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%

Section: Geological Settingmentioning

confidence: 99%

“…To the southeast, these units are intruded by the Darijune gabbro (Shakerardakani et al 2015). The existence of a Panafrican basement in this part of SSZ has been proposed based on recent U-Pb dating of the granitic Galeh-Doz orthogneiss that yielded ages of 608 ±18 Ma and 588 ± 41 Ma, respectively (Shakerardakani et al 2015). The calc-alkaline granitoids of the Panafrican basement were formed during subduction of the Proto-Tethys and are similar to those exposed in Central Iran (Shakerardakani et al 2015).…”

Section: Geological Settingmentioning

confidence: 99%

“…1, 2) (Shakerardakani et al 2015). The Galeh-Doz orthogneiss and similar nearby granitic gneisses derive from a calc-alkaline, metaluminous granite, and is, according to recent U-Pb age dating, Panafrican in age (Nutman et al 2014;Shakerardakani et al 2015).…”

Section: Introductionmentioning

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: 90%

Section: Geological Settingmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

Section: Introductionmentioning

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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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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Geochemistry and apatite U–Pb geochronology of alkaline gabbros from the Nodoushan plutonic complex, Sanandaj–Sirjan Zone, Central Iran: Evidence for Early Palaeozoic rifting of northern Gondwana

et al. 2018

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The Zagros Orogen formed during the Cenozoic collision of Arabia with Eurasia and resulted in the closure of the Neo‐Tethys Ocean. Collision was preceded by a complicated tectonic history involving Pan‐African orogenesis, Late Palaeozoic rifting and the formation of Neo‐Tethys, and subsequent Mesozoic convergence on the northern margin of the ocean contemporaneous with ophiolite obduction on its southern margin. The Sanandaj–Sirjan Zone (SaSZ) is a metamorphic belt within the Zagros Orogen of Gondwanan provenance. U–Pb zircon geochronology has revealed the presence of Pan‐African igneous and metamorphic basement complexes, in addition to minor late Palaeozoic plutons and abundant Jurassic plutonic rocks. This study presents a LA‐ICP‐MS U–Pb apatite age of 440.7 ± 3.7 Ma from a gabbroic body on the central north‐eastern margin of the SaSZ (Nodoushan region). Based on petrography and geochemistry, en route fractional crystallization of ascending magma was an important process in the evolution of the intrusive rocks. Geochemical characteristics imply that the south‐west Nodoushan alkaline gabbroic magma was originated from the asthenospheric mantle source, whereas the high ratios of (La/Yb)N and (Dy/Yb)N are related to the low degree of partial melting from the garnet‐bearing mantle source. Enrichment pattern of Nb, Ta, and Ti and depletion of Rb, Th, and Y are similar to the OIB pattern and intraplate alkaline magmatic rocks. High εNd(t) values (+1.29 to +1.50), low initial Sr isotopic ratios (0.703679–0.704098), and trace element ratios (e.g., Nb/La, Ce/Pb, Ba/Nb, and Th/Nb) indicate that crustal contamination was insignificant in its petrogenesis. The petrogenesis of the Nodoushan alkaline gabbroic rocks could be related to the presence of extensional phase, upwelling and decompressional melting of asthenospheric mantle in the rift basin which was associated with the opening of the Paleo‐Tethys Ocean in Late Ordovician to Silurian times.

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Panafrican basement and Mesozoic gabbro in the Zagros orogenic belt in the Dorud–Azna region (NW Iran): Laser-ablation ICP–MS zircon ages and geochemistry

Cited by 78 publications

References 95 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)

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

Geochemistry and apatite U–Pb geochronology of alkaline gabbros from the Nodoushan plutonic complex, Sanandaj–Sirjan Zone, Central Iran: Evidence for Early Palaeozoic rifting of northern Gondwana

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