Tethyan subduction and Cretaceous rift magmatism at the southern margin of Eurasia: Evidence for crustal evolution of the South Caspian Basin

Monsef, Iman; Zhang, Zhiyong; Shabanian, Esmaeil; Roux, Petrus le; Rahgoshay, Mohammad

doi:10.1016/j.earscirev.2022.104012

Cited by 13 publications

(3 citation statements)

References 157 publications

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“…Subsequently, northeastward subduction of the Neo-Tethys oceanic lithosphere beneath the Iranian Plateau was initiated in the Cretaceous and continued to the Eocene–Oligocene, leading to mantle metasomatism beneath the overriding plate (e.g. Shafaii Moghadam & Stern, 2021; Monsef et al 2022). Neo-Tethyan ophiolites of Iran determine the location of ancient suture zones of the Iran–Cimmerian continental blocks (e.g.…”

Section: Regional Geologymentioning

confidence: 99%

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Neo-Tethyan subduction triggered Eocene–Oligocene magmatism in eastern Iran

et al. 2022

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Eocene–Oligocene magmatic rocks are well exposed in the region south of Birjand, eastern Iran. The ages, geochemistry and petrogenesis of these rocks are important to understand eastern Iran’s magmatic and geodynamic history during the Cenozoic. Detailed field investigations show that numerous intrusive, intermediate to felsic units are intruded into a thick sequence of Eocene–Oligocene lava flows and their accompanying pyroclastic rocks. The volcanic rocks are mainly basaltic andesitic to rhyolitic, whereas intrusive rocks are characterized by dioritic to granitic composition. Previously compiled U–Pb geochronological data indicate that Eocene–Oligocene magmatism in eastern Iran formed continuously from ∼46 Ma to ∼25 Ma. Our new zircon U–Pb data reveal crystallization ages of 43.6 ± 0.4 Ma to 39.5 ± 0.6 Ma, consistent with the upper end of this age range. Geochemically, the igneous rocks have high-K calc-alkaline to shoshonitic signatures. Rare-earth and trace element patterns show enrichment in LREEs, K, Rb, Cs, Pb, Th and U and depletion in HFSEs such as Nb, Zr and Ti, typical of a subduction-related environment. 87Sr/86Sr(i) and ϵNd(i) values range from 0.7051 to 0.7064 and −0.1 to +0.2, respectively. We postulate that the Cretaceous northeastward subduction of the Neo-Tethyan oceanic lithosphere underneath the Iranian Plateau caused sub-continental lithospheric mantle (SCLM) metasomatism by slab-derived fluid components. Subsequently, slab roll-back of the Neo-Tethyan oceanic lithosphere associated with asthenospheric upwelling led to lithospheric thinning and melting of the metasomatized SCLM. The resulting parental magmas probably interacted with upper continental crust during magma ascent to form Eocene–Oligocene magmatism in eastern Iran.

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Section: Regional Geologymentioning

confidence: 99%

“…beneath the overriding plate (e.g. Shafaii Moghadam & Stern, 2021;Monsef et al 2022). Neo-Tethyan ophiolites of Iran determine the location of ancient suture zones of the Iran-Cimmerian continental blocks (e.g.…”

Section: Regional Geologymentioning

confidence: 99%

Neo-Tethyan subduction triggered Eocene–Oligocene magmatism in eastern Iran

et al. 2022

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“…It is intruded by several plutonic bodies, particularly from Jurassic to Early Cenozoic times, through the northward subduction of the Neotethys Oceanic plate beneath the Central Iran microcontinent (e.g., Berberian & Berberian, 1981; Hassanzadeh & Wernicke, 2016; Moinvaziri, 1996; Yang et al, 2018). According to the published geochronological data, the Jurassic–Cretaceous granitoids are the most voluminous subduction‐related intrusions in the SSZ (e.g., Ahmadi‐Khalaji et al, 2007; Azizi, Najari, et al, 2015; Davoudian et al, 2007; Esna‐Ashari et al, 2012; Fazlnia et al, 2009; Ghasemi‐Siani et al, 2021; Gholipour et al, 2020; Mahmoudi et al, 2011; Masoudi et al, 2002; Mazhari et al, 2011; Monsef et al, 2022; Sepahi, 2008; Shakerardakani et al, 2020; Torkian et al, 2008; Yajam et al, 2015; Zhang et al, 2023). The magmatic source and tectonic setting of the Mid‐Jurassic (e.g., Deevsalar et al, 2017; Shahbazi et al, 2010), Early Cretaceous (Gholipour et al, 2020; Molaei Yeganeh et al, 2018; Rahimzadeh et al, 2021) and Late Eocene (Deevsalar et al, 2017) mafic igneous rocks in the northern SSZ are extensively studied using geochronological and isotopic geochemistry data.…”

Section: Introductionmentioning

confidence: 99%

Petrography, U–Pb geochronology and geochemistry of Varcheh intrusions: Insight into younging trend of mid‐Cretaceous subduction in the northern Sanandaj–Sirjan Zone, western Iran

Shomali,

Ghorbani,

Ghassemi

et al. 2024

Geological Journal

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The Neotethyan Sanandaj–Sirjan Zone of western Iran has recorded major magmatic activities due to its continental arc tectonic setting during the Mesozoic. The Varcheh mafic intrusions were less‐studied plutons in the northern Sanandaj–Sirjan Zone (SSZ). Field evidence, petrography, geochemistry and U–Pb geochronological data were used to determine petrographic composition, geochemical nature, crystallization age and also to suggest a conceptual tectonomagmatic model for their emplacement. Small plutonic bodies are dominantly composed of monzogabbro that have intruded into the Cretaceous sedimentary rocks. Based on U–Pb zircon datings, these rocks have crystallized at 125–118 Ma in late Early Cretaceous (Barremian–Aptian), and are older than the supposed ages reported on geological maps. Varcheh rocks are not just typical calc‐alkaline rocks and some show alkaline affinity. Negative anomalies in Nb–Ta–Ti and enrichments in some large‐ion lithophile elements on spider diagrams are consistent with a subduction‐zone setting. Potential deep source for magma generation is partial melting of subcontinental lithospheric mantle wedge above a subducting slab of oceanic lithosphere. The spaces for the Varcheh mafic intrusions are accommodated by dominant dextral strike‐slip movement in a continental arc experiencing extension during late Early Cretaceous subduction. According to the zircon U–Pb geochronology results in this paper and previous U–Pb ages in the northern part of the SSZ, the mid‐Cretaceous magmatism reveals a significant NW‐ward younging trend and migration of the magmatic arc from the Barremian–Aptian in south‐east to the Albian–Cenomanian in the north‐west.

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