Petrogenetic variations of the Jurassic magmatic sequences of Hoseinabad-Hajiabad regions in Sanandaj-Sirjan Zone (south of Iran)

The Jurassic magmatic sequences in the southern part of Sanandaj-Sirjan Zone show significant geochemical variations during their compositional evolution. These magmatic sequences have exposed in the Hoseinabad region with Early to Middle Jurassic age and in Hajiabad region with Late Jurassic to Early Cretaceous age. The parent magma of the first sequence in Hoseinabad region, with island arc tholeiite (IAT) affinity have been originated from the spinel lherzolite mantle source with primitive mantle (PM) composition. This mantle source is affected by liquids and sediments resulted from the subducting slab. The parent magma of the second sequence in Hajiabad region with island arc tholeiite to transitional affinity have been resulted from the garnet - spinel lherzolite mantle source with E-MORB composition. These compositional changes may be related to high sediment and hydrothermal fluxes which resulted from the deep subducted slab into the mantle wedge. These magmatic sequences are originated during the subduction of the Neo-Tethyan oceanic lithosphere under the Sanandaj-Sirjan Zone, during the Early Jurassic to Early Cretaceous time, in the island arc tectonic environment.