U–Pb age of the Qobadlu Intrusive body -Evidence for Cretaceous subduction related Magmatism, Northern Sanandaj – Sirjan Zone, NW Iran

The Qobadlu intrusive body in the northern part of the Sanandaj – Sirjan Zone (SaSZ) has been recognized as a remnant of Cretaceous magmatic activity in the NW Iran. The Qobadlu gabbroic body has a calc-alkaline affinity. Based on the zircon dating (U-Pb), the coarse grained Qobadlu gabbro were crystallized at 99 Ma. The Low SiO2 and high Mg # Cr and Ni contents of the Qobadlu rocks can be indicate the upper mantle source for parental magma. Positive anomalies of the LILE and LREE, coupled with negative anomalies of Nb and Ti, and high ratios of La/Nb (1.3-3.3) and Ba/Nb (20-90) can be indicate that the samples are sourced from an amphibole-enriched spinel lherzolitic mantle and developed through Neo-Tethyan subduction regime. Variations in incompatible elements suggest the crustal assimilation and fractionation crystallization during magma ascent. Considering the Cretaceous magmatic activity of the calc-alkaline, these rocks have seemingly formed in the extensional basin related to the Neotethys subduction.