High temperature – low pressure metamorphism during subduction of Neo-Tethys beneath the Iranian plate: evidence for mafic migmatite formation in the Alvand complex (western Iran)

P–T–t path of the Boroujerd Complex, north‐west Sanandaj–Sirjan Zone, western Iran: Insights from phase equilibrium modelling and thermobarometry

“…In Boroujerd region, the tectonometamorphic evolution resembles that proposed by Mahmoudi and Baharifar (2019) probably pluton emplacement, especially the relatively hot mafic magmatic component of the complex (Jafari et al, 2020); this is a similar to the scenario proposed for the Hamedan region (Baharifar et al, 2019;Mahmoudi & Baharifar, 2019;Monfaredi et al, 2020;Saki et al, 2020;Sepahi et al, 2019). Therefore, the Hamedan and Boroujerd metamorphic sequences experienced a similar metamorphic evolution in the Lower to Middle Jurassic, which suggests along-strike metamorphic histories at this time are similar along the Sanandaj-Sirjan Zone.…”

“…Studies of the metamorphic history of the Sanandaj-Sirjan Zone in Iran have mainly focused on the Hamedan region where low-to medium-grade metamorphic rocks are intruded by felsic to mafic bodies from the Middle to Late Jurassic Alvand Plutonic Complex (ca. 154-167 Ma; e.g., Sepahi & Fadavi, 2009;Sepahi, Jafari, Osanai, Shahbazi, & Moazzen, 2019;Shahbazi et al, 2010;Mahmoudi & Baharifar, 2019;Saki, Miri, & Oberhänsli, 2020;Monfaredi et al, 2020 and references therein). In Hamedan, poly-metamorphic (e.g., Monfaredi et al, 2020;Saki et al, 2020;Saki, Moazzen, & Baharifar, 2012) or a single counterclockwise metamorphic evolution (e.g., Baharifar, Whitney, Pang, Chung, & Iizuka, 2019;Mahmoudi & Baharifar, 2019) were proposed; these have significantly different tectonic implications for the Sanandaj-Sirjan Zone.…”

Genesis of trondhjemite by low-pressure low-melt fraction anatexis of hornblende-gabbro at Alvand Plutonic Complex (Hamedan, NW Iran): insights from geochemical modelling

“…1a), a distinctive ≈1000km long and ≈150 km wide NW-SE trending crustal terrane (Stöcklin 1968), tectonically delimited by the Urumieh-Dokhtar Magmatic Belt (UDMB) and by the Zagros suture zone, at its northeastern and southwestern ends, respectively. The SaSZ is characterized by a Cadomian (≈500-600 Ma) basement (e.g., Stöcklin and Nabavi 1973;Ghasemi and Talbot 2006;Hassanzadeh et al 2008;Malek-Mahmoudi et al 2017;Azizi and Stern 2019;Moghadam et al 2020Moghadam et al , 2021 consisting of greenschist to amphibolite metamorphic rocks intruded by Jurassic-Cretaceous magmas (Mohajjel et al 2003;Ghasemi and Talbot 2006;Hassanzadeh and Wernicke 2016;Azizi et al 2018a, b;Saki et al 2020). It has been interpreted as the southwestern portion of the Iranian microcontinent (Hassanzadeh et al 2008;Hosseini et al 2015;Azizi et al 2016Azizi et al , 2018a.…”

“…The C-SaSZ, where the Alvand plutonic complex and the study area are located, is characterized by (i) Cadomian basement dominated by metagranites and amphibolites (Badr et al 2018;Azizi and Stern 2019); (ii) the Jurassic metamorphic complex (Mohajjel and Fergusson 2000;Mohajjel et al 2003;Agard et al 2005;Hassanzadeh and Wernicke 2016;Azizi and Stern 2019) with protoliths interpreted as mafic to felsic volcanic rocks interbedded with carbonates and siliciclastic materials deposited over a thin Cadomian crust in a marine basin setting (e.g., Mohajjel et al 2003;Baharifar et al 2004;Hassanzadeh and Wernicke 2016;Azizi et al 2018a, b); and (iii) the Jurassic to Early Cretaceous gabbro to granite intrusive complexes (Saki et al 2021 and references therein). The latter magmatic activity heated the pre-existing rocks and generated Buchan-type thermo-metamorphic contact aureoles characterized by Al 2 SiO 5bearing hornfels up to migmatization (e.g., Baharifar et al 2004;Agard et al 2005;Sepahi et al 2009Sepahi et al , 2018Sepahi et al , 2019Sepahi et al , 2020Shahbazi et al 2010Shahbazi et al , 2014Mahmoudi et al 2011;Hassanzadeh and Wernicke 2016;Saki et al 2020).…”

“…With the goal of contributing to the understanding of the genesis of trondhjemite leucosomes through partial melting of hornblende-bearing mafic rocks, this paper is focused on the role of the dominant protolith-forming minerals during incipient crustal anatectic events. In particular, this work is intended as a companion paper of Saki et al (2021) and uses part of its geochemical dataset from the Cheshmeh-Ghasaban (CG) mafic migmatite suite (Hamedan, NW Iran) where the connection between a gabbro protolith and in situ trondhjemite leucosomes has been demonstrated (Saki et al 2020(Saki et al , 2021. Results are discussed in the context of the existing literature.…”