Original paper

Age and geotectonic position of the Malayer granitoids: Implication for plutonism in the Sanandaj-Sirjan Zone, W Iran

Ahadnejad, Vahid; Valizadeh, Mohammad-Vali; Deevsalar, Reza; Rezaei-Kahkhaei, Mehdi

Abstract

New Sr and Nd isotopic data and LA-ICP-MS U-Pb zircon ages of the Malayer pluton, Sanandaj-Sirjan Zone (SSZ) are presented. Initial Sr ratios range from 0.70797 to 0.71087, εNd(t) from -2.3 to -4.9 and TDM from 955 to 1.33 Ga. The depleted-mantle model age indicates a dominant Neoproterozoic-Paleozoic crustal component in the granites and suggest an involvement of Central Iran components in the production of the Malayer rocks. Zircon ages for 8 studied plutonic rocks yielded data between 162 Ma and 187 Ma (Middle-Jurassic). The vast majority of ages, at least from the Hamadan-Shahrekord section of the SSZ, indicate a Middle Jurassic age suggesting an extreme plutonism at this time. The equivalent age for diorite indicates the contemporaneity of the granitic and basaltic magmas, and confirm dioritic rocks as origin of hybridization and magma mingling.

Keywords

malayersanandaj-sirjan zoneirangranitoidsu-pb agend-sr isotopes