The petrogenesis of Zafarghand granitoid pluton (SE of Ardestan)

The Zafarghand granitoid pluton ranging in composition from gabbro to tonalite and age of early-middle Miocene crops out about 35 km of southeast Ardestan. The pluton has intruded into the Eocene volcanic and volcanosedimentary rocks of Orumieh-Dokhtar structural zone. The pre, syn and post-plutonic dikes with mostly andesitic composition are associated with this pluton. The presence of abundant microgranular enclaves and interrupted syn-plutonic dikes are remarkable evidences of magma mixing in Zafarghand granitoid pluton. Based on the geochemical characteristics, there is a limited gap between mafic-intermediate and felsic rocks which may be the result of differences in their source rock regions. Enrichment in both LILE and Pb are indication of crustal contamination. Considering the typical negative anomaly of Ti and Nb, it can be said that this pluton is originated and produced in a volcanic arc of an active continental margin. Based on the discrimination diagrams of tectonic setting, the Zafrghand pluton can be classified as I-type, volcanic arc and continental arc granitoids (VAG and CAG). The melting of subducted Neothytian oceanic slab, it's overlay metasomatized mantle wedge and partly continental lower crust as well as fractional crystallization of generated magma, led to the formation of the studied pluton.