A hidden crust beneath the central Urumieh‐Dokhtar Magmatic Arc revealed by inherited zircon ages, Tafresh, Iran

Abstract

Laser ablation ICP‐MS U–Pb dating on inherited zircons from Neogene volcanic rocks of the Tafresh area in the central part of Urumieh‐Dokhtar Magmatic Arc (UDMA) yielded Paleoproterozoic, Late Neoproterozoic–Early Cambrian, Carboniferous, and Cretaceous ages. These ages improve our understanding of the geodynamical evolution of central UDMA. The 2,379 Ma age (i.e., Paleoproterozoic) is the oldest age reported in the central UDMA and is similar to the age of detrital zircons from Central Iran. The Paleoproterozoic zircons may come from the African Craton and fed from Central Iran sedimentary sequences. The Late Neoproterozoic–Early Cambrian ages (605 ± 11 Ma to 533 ± 9.2 Ma) indicate a basement for the UDMA, which is similar to that of the Sanandaj‐Sirjan Zone, Central Iran, and northwest Iran. The Carboniferous zircon age (328.4 Ma) is interpreted as being derived from the Eurasian arc produced by northward subduction of the Paleo‐Tethys Oceanic Plate. The Late Cretaceous zircon ages (106 to 71.2 Ma) might be regarded as indicating the Late Cretaceous magmatic episode, marking the subduction of oceanic crust that followed the Neo‐Tethys subduction.

Lithospheric mantle, asthenosphere, slab and crustal contribution to petrogenesis of Eocene to Miocene volcanic rocks from the west Alborz Magmatic Assemblage, SE Ahar, Iran

“…Cretaceous volcano-sedimentary sequences are the oldest rock units that crop out near to the study area; however, the presence of older crustal rocks is suggested by the inherited zircons retrieved from volcanic rocks in the present study. Palaeoproterozoic, Neoproterozoic-early Cambrian, Palaeozoic and Mesozoic ages (Hassanzadeh et al 2008;Chaharlang & Ghorbani, 2020) obtained for inherited zircons from igneous rocks imply the presence of older crustal materials underlying the Alborz, Sanandaj-Sirjan and Central Iran tectonomagmatic zones. Igneous rocks in the study area entirely comprise Tertiary magmatic rocks, including Eocene, Oligocene and Miocene rock units (Figs 2, 3).…”

“…A few Palaeoproterozoic zircons indicate the incorporation of older crustal materials (i.e. those derived from the African craton and supplied by Central Iran sedimentary beds) in the late Neoproterozoicearly Cambrian magmatism (Chaharlang & Ghorbani, 2020). The presence of 1870 Ma detrital zircons in the Tashk Formation siliciclastic rocks (Ramezani & Tucker,Fig.…”

“…The zircons straddling the Carboniferous are regarded as being derived from the Eurasian arc, which resulted from Palaeotethyan oceanic plate subduction towards the north. The Cretaceous zircons indicate a Late Cretaceous magmatic episode that followed Neotethyan subduction (Chaharlang & Ghorbani, 2020).…”

Problemy ophiolitów Zagros i ciał bazaltowych, przykłady z Regionu Kurdystanu, północny Irak

“…Another criticism that may arise against this article is extending the volcanic activity in the Urumieh-Dokhtar Magmatic arc (UDMA) to Jurassic -Lower Cretaceous; while its exposed rocks not older than Paleocene in Iran. My justification is shown in three facts: the first is the recent conclusion of Chaharlang and Ghorbani (2020) [73] that a volcanic activity occurred on UDMA during the Cretaceous (106 m.y.). The second is the extensive erosion of the rocks of the UDMA during the Jurassic-Early Cretaceous due to the availability of large accommodation space for sediments transport to the deep basin (Fig.…”