Tectonic Setting of the Serow-Torshab Ophiolite Related Mafic Rocks, NW-Iran: Implications from Minerals and Whole-Rock Geochemistry

Abstract

In this paper, focused on the Late Cretaceous Serow ophiolite related gabbros from the Torshab area, NW Iran, to enhance our understanding on the tectonic setting of ophiolite formation in terms of pressure-temperature and fluid conditions. The applied methods encompassed field geological observations, petrographic and mineralogical analyses, and whole-rock chemistry assessments. The findings revealed that the calc-alkaline gabbros predominantly consist of hornblende gabbro, olivine gabbro, and minerals such as amphibole, ortho-/clinopyroxene, olivine, and plagioclase. According to geochemical signatures such as the depletion of high field strength elements (Hf, Zr, Nb, and Ta) and the enrichment of large ionic lithophile elements (Ba and K) the Serow-Torshab gabbro is considered in relation to an arc setting indicating their origin from a mantle wedge, potentially enriched by subducting crust-derived melts/fluids. The mineral chemical study on mafic phases also suggests a supra-subduction zone (SSZ, fore-arc) environment for the Serow ophiolite, offering valuable insights into the region's geodynamic evolution.