Petrogenesis of Mio-Peliocene Dacite-Andesite Volcanism in SE of Urumieh-Dokhtar Magmatic Belt, (NE Shahr-e-Babak)

Few More than 5 dacite to andesite volcanic masses with Mio-Pliocene age are exposed to older volcanic rocksat the south and east of the Mozahem volcano، in south-east of Urumieh- Dokhtar magmatic belt، north-east of Shahre-Babak. These rocks show hyaloporphyritic- trachytic texture and consist of pPhenocrysts of plagioclase، amphiboles and biotites. Based on geochemical data and multi elements patterns، these rocks are medium to high K calc-alkaline suite and they show LILE and LREE enriched normalized multi-element patterns، and negative Nb، Ti and Ta anomalies. Chondrite normalized REE patterns display a steep decrease from LREE to HREE without any Eu anomaly. They have higher SiO2 and Sr contents and Sr/Y and La/Yb ratios and low MgO، Y and Yb contents than the normal calc-alkaline volcanic rocks. These volcanic rocks are formed in the a subduction zone in an active margin، and showing full complete of HSA (high SiO2 adakites) characteristics. HREE and Y depleted patterns suggest the existence of garnet and amphibole as a residue in the source. The source of these rocks was probably amphibole-eclogite or garnet-amphibolite possibly generated during subduction or slab break of the Neo-Tethyan oceanic slab beneath the Central Iran microplate in Neogene.