PETROLOGICAL STUDY OF PLAGIOGRANITES IN THE NAIN OPHIOLITE (CENTRAL IRAN)
Keywords:Plagiogranite, Nain ophiolite, Supra-Subduction Zone, Mesozoic, Central Iran
The plagiogranites from the Nain ophiolite consist of plagioclase (albite to andesine), quartz, amphibole (mostly magnesio-hornblende), apatite, titanite and oxide phases. These rocks have low K2O, Sr and high Y contents, with low Sr/Y ratios; they are geochemically similar to volcanic arc granites. The chondrite normalized REE patterns of the selected samples are characterized by negative Eu anomalies. We propose that the Nain plagiogranites formed by fractional crystallization of a low-K tholeiitic magma in a supra-subduction setting.