Study of A-type granite from the South of Lake Urmia, Sanandaj-Sirjan Zone: implications for the Neotethys opening in Iran

The magmatic evidence of the Neotethys opening in Iran, such as the Late Paleozoic A-type granitoids, was mainly discovered along the Sanandaj-Sirjan Zone and parallel to the Neotethys suture. Therefore, they may provide important clues about the geodynamic evolution of the Sanandaj-Sirjan Zone. The South of Lake Urmia (SLU) granite is situated near the Khalifan A-type pluton (315±2 Ma) with a cover of the Permian sediments. The rock-forming minerals of the SLU granite consist of quartz, alkali-feldspars (K-rich and microperthitic), sodic plagioclases, biotite (Fe-rich), zircon, apatite, and Fe-Ti oxides. The chemical composition of the SLU granite is characterized by high FeOt/MgO and (Na2O+K2O)/CaO ratios, which are typical features of A-type granites. Furthermore, the studied rocks exhibit the chemical characters of the A1 subgroup of A-type granites with peraluminous and K2O-rich affinities. On the multi-element spider plot, the SLU granite shows distinct negative Ba, Sr, P, and Ti anomalies and positive Pb anomalies. Moreover, the Chondrite-normalized rare earth elements (REE) patterns display slope downwards from LREE to HREE, with flattening at the HREE end and distinct negative Eu anomalies. The ratios of trace elements provide evidence for the contribution of the OIB-like mafic melts with crustal interactions to generate the granitic magmas of the SLU pluton. The compositional and stratigraphic features of the SLU granite are also consistent with an extensional setting during the Late Paleozoic in Iran. Therefore, the genesis of the SLU granite can be attributed to the syn-rift magmatism of the Cimmerian terranes. A comprehensive review of the Late Paleozoic rocks occurrence shows that they mainly are emerged in the northeast margin of the Sanandaj-Sirjan Zone and around the structural depressions such as Lake Urmia (so-called Tertiary fore-arc or Mesozoic back-arc).