Petrography and geochemistry of Mio-Pliocene volcanic masses in the north of Shahre-Babak, insight on neogene adakitic magmatism

The Mio-Pliocene volcanic rocks are exposed in the north and the northwest of Shahre-babak (Trishkuh، Miduk and Sara masses) Kerman province. These rocks formed a part of Uromieh-Dokhtar magmatic belt and consist of andesites and dacites. The rocks studied have porphyritic texture and Phenocrysts wiht plagioclase، sanidine، amphibole، biotite and quartz. Based on geochemical data and multielements pattern، these rocks are medium to high K calc-alkaline suite and show LILE and LREE enriched normalized multi-element patterns، and Nb and Ti deplated. Chondrite normalized REE patterns of the studied volcanic rocks display a decrease from LREE to HREE without any Eu anomaly and formed in subduction zone in an active continental margin. They have higher SiO2، Sr content، Sr/Y and La/Yb ratios and lower MgO، Y and Yb contents in compare to those of normal calc-alkaline volcanic rocks and show characteristics of HSA (high SiO2 adakites). 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 garnet-amphibolite possibly generated during subduction of the Neo-Tethyan oceanic slab beneath the Central Iran zone.