Geochemical evidences for quantifying crustal thickness over time in the Urumieh-Dokhtar magmatic arc (Iran)

Juvenile crust and mantle sources for the Nasrand intrusive rocks, the central Urumieh–Dokhtar magmatic arc, Iran: Insights from elemental and isotopic geochemistry

“…According to our results (Figures 6 and 13), from north‐west to south‐east in the UDMA, changes in geochemical and isotopic characteristics (e.g., Sr/Y, La/Yb, 87 Sr/ 86 Sr (i) ratios and ɛNd (t) ) could be due to crustal thickening, which is possibly due to the intrusion of magma and placement of mantle‐derived magma into a magma chamber close to the Moho after the initial collision. Based on previous studies (e.g., Chaharlang, Ducea, & Ghalamghash, 2020; Pirouz, Avouac, Hassanzadeh, Kirschvink, & Bahroudi, 2017), the crustal thickening is due to tectonic shortening after the collision initiation, which confirms our results in Figure 13. The underplated mafic rocks were converted into garnet amphibolites and (or) amphibole eclogites with adakitic affinity (high La/Yb >10) and Sr/Y > 40); thus preparing a favourable lower crustal origin for the production of adakitic magmas at pressures of 12–15 kbar (crustal thickness of 40–50 km) in the south‐east of the UDMA (Aghazadeh, Hou, Badrzadeh, & Zhou, 2015; Asadi et al, 2014).…”

“…Chaharlang et al (2020) suggested, based on temporal changes in the crust thickness during the Tertiary, from the Eocene to the Middle Miocene, so that the crustal thickness remained constant during the Eocene to Oligocene (likely of normal thickness ~35 km), which related to slab roll back and back‐arc extension along the Eurasian active margin. Crustal thickening began in the Early Miocene (~40 km) and culminated in the Middle Miocene (~50 km).…”

Petrogenesis and geochemical characteristics of Plio-Quaternary alkali basalts from the Qorveh–Bijar volcanic belt, Kurdistan Province, NW Iran

“…Several geological and geophysical studies attribute Iranian and East Anatolian magmatism to the break-off of the southern Neo-Tethyan oceanic slab beneath the Bitlis–Zagros suture and/or delamination of part of the lower lithosphere (e.g. Keskin, 2003; Şengör et al 2003; Molinaro et al 2005; Omrani et al 2008; Hatzfeld & Molnar 2010; Agard et al 2011; Chaharlang et al 2020, Kettanah et al 2021). Priestley and McKenzie (2006) suggest that lithosphere thickness in the study area is 150–200 km.…”

“…11d), QBB rocks manifested the effects of sediment components in the mantle source. This is an excellent indicator of the type of sedimentary component because sediment-bound Pb is not mobilized by hydrous fluid, whereas it is incompatible during the melting of pelagic sediments (Class et al 2000;Johnson & Plank, 2000). Moreover, high Th levels are commonly interpreted as reflecting the predominance of a component of subducted pelagic sediments in the magma source (Kirchenbaur et al 2009;Kirchenbaur & Munker, 2015).…”