Petrogenesis of Tarom high-potassic granitoids in the Alborz–Azarbaijan belt, Iran: Geochemical, U–Pb zircon and Sr–Nd–Pb isotopic constraints

Zircon U–Pb ages, geochemical and Sr–Nd–Pb–Hf isotopic constraints on petrogenesis of the Tarom-Olya pluton, Alborz magmatic belt, NW Iran

“…1). The SSZ is considered as the main magmatic arc resulting from Neo-Tethyan subduction during the Mesozoic (Azizi et al, 2011;Berberian and King, 1981), whereas the UDMA and AMB are interpreted to be associated with early to late Cenozoic subduction-related magmatism on the Zagros hinterland (Berberian and King, 1981;Berberian et al, 1982;Stöcklin, 1971), slab break-off (Agard et al, 2011;Ghasemi and Talbot, 2006;Haschke et al, 2010), slab roll-back (Jahangiri, 2007;Verdel et al, 2011) and post-collisional relaxation (Castro et al, 2013;Nabatian et al, 2014). Several petrogenetic models have been proposed for some of the magmatic segments in the UDMA and AMB including continental arc magmatism Hassanzadeh, 1993) to continental rifting (Amidi et al, 1984) and post-collisional tectonic setting (Aghazadeh et al, Ahmadian et al, 2009;Berberian and King, 1981;Castro et al, 2013;Honarmand et al, 2013;Nabatian et al, 2014).…”

“…The AMB is divided into western and eastern segments by the N-S trending Rasht-Takestan Fault. The eastern part of the AMB consists of basic and acidic tuff and lava with alkaline to shoshonitic affinity, while the western part (western Alborz-Azarbayjan magmatic belt) comprises andesiticdacitic lava, and many granitoid bodies with calc-alkaline to alkaline affinity (Aghazadeh et al, 2011;Castro et al, 2013;Moayyed, 2001;Nabatian et al, 2014). These volcanic and plutonic rocks with calcalkaline and potassic alkaline affinity are interpreted as arc and backarc magmatism in an extensional (post-collisional) tectonic setting (Allen et al, 2003;Asiabanha and Foden, 2012;Berberian, 1983;Castro et al, 2013;Hassanzadeh et al, 2002;Mirnejad et al, 2010;Nabatian et al, 2014).…”

“…In the Tarom area outcrops mainly exhibit Paleogene volcanic and plutonic rocks (Fig. 2) mostly comprising lava flows and pyroclastic rocks (the Karaj Formation with an Eocene age) intruded by late Eocene plutonic rocks (Castro et al, 2013;Nabatian et al, 2014) (Fig. 2).…”

“…The Eocene Alborz magmatic assemblage such as the Karaj Formation was deposited in the central and western Alborz within an extensional regime (back-arc basin) (Allen et al, 2003;Asiabanha and Foden, 2012;Ballato et al, 2011;Berberian, 1983;Hassanzadeh et al, 2002). The Eocene marine volcanism includes pyroclastic and lava flows of trachyte, trachy-andesite, andesite, basaltic andesite, olivine-basalt, porphyritic and non-porphyritic rhyodacite with high-K calc-alkaline to alkaline affinity (Asiabanha and Foden, 2012;Moayyed, 2001;Nabatian et al, 2014). These rocks are potassic and show shoshonitic affinities (Asiabanha and Foden, 2012;Moinvaziri, 1985).…”

“…1). Decompression melting of a metasomatized mantle source in a post-collisional tectonic setting is the most favorable explanation for the generation of high-potassic and shoshonitic magmas in Iran (Aghazadeh et al, 2011;Ahmadian et al, 2009;Castro et al, 2013;Nabatian et al, 2014;Torabi, 2011). Other authors (e.g.…”