%0 Journal Article
%T Petrogenesis of Quaternary Shoshonitic Volcanism in NE Iran (Ardabil): Implication for Postcollisional Magmatism
%A Habib Shahbazi Shiran
%J Journal of Geological Research
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/735498
%X Trachyandesites, trachytes, andesites, and pyrocalstic rocks, with shoshonitic signature, are the main Quaternary volcanic rocks in the Sabalan region (Ardabil). Plagiocalse, K-feldspar, biotite associated with clinopyroxene, and glass are the main constituents of these lavas. Plagioclases are andesine to labradorite while clinopyroxenes have augitic composition. The Sabalan volcanic rocks show enrichment in LREEs (relative to HREEs) and are characterized by enrichment in LILEs and depletion in HFSEs. Petrological observations, along with rare earth and trace elements geochemistry, suggest shoshonitic signature for Sabalan lavas. This signature highlights derivation from a subduction-related source. The Sabalan volcanic rocks are isotopically characterized by derivation from an enriched mantle source with a tendency to plot in the fields defined by island-arc basalts (IAB) and OIBs (in ¦ÅNd versus 87Sr/86Sr diagram). The geochemical and isotopic characteristics of the Sabalan lavas suggest that their magma has been issued via low degree partial melting of a subduction-metasomatized continental lithospheric mantle. The formation of these lavas is related to slab steepening and breakoff in a postcollisional regime. 1. Introduction Cenozoic magmatism is well known from the peri-Arabic region, north of the Bitlis-Zagros Suture Zone (Figure 1), and ranges in age from Eocene to Plio-Quaternary. The timing of the eruptions and pooling the plutons mostly coincides with and postdates a series of continental collisional events in the northern Bitlis-Zagros Suture Zone region [1, 2]. The Eocene magmatism in the peri-Arabic region (both in the Urumieh-Dokhtar magmatic belt and south of the Anatolian block) is calc-alkalic to shoshonitic, which resulted from subduction of the Neotethyan Ocean beneath the central Iranian and Anatolian blocks. The Plio-Quaternary (and Quaternary) alkaline-ultrapotassic magmatism occupies most of the Turkish-Iranian high plateau (NW Iran and NE Turkey) and is mostly characterized by within-plate and/or subduction-related geochemical characteristics [3¨C5]. The geochemical variations of late Cenozoic lavas indicate a progression from calc-alkaline to alkaline compositions with time [2]. Figure 1: Simplified tectonic map of the eastern Mediterranean-Persian Gulf region showing the active plate boundaries and post-collisional volcanic rocks in the Peri-Arabian region modified after [ 6]. Abbreviation: PSF = Pampak-Sevan Fault; EKP = Erzurum-Kars Plateau; EAF = East Anatolian Fault; IAESZ = Izmir-Ankara-Erzincan Suture Zone; EF = Ecemis
%U http://www.hindawi.com/journals/jgr/2013/735498/