نوع مقاله : علمی -پژوهشی
عنوان مقاله [English]
Studied area which is introduced as Ayoub Ansar volcanic dome, located about the 25 km southeast of the Takab, in the central part of the Takab 1:100000 geological map. This area is a part of Central Iranian Zone at the junction of Sanandaj- Sirjan and Central Iranian Zones. Ayoub Ansar volcanic dome intruded into the marl and sandstones of Miocene. In this base, post Miocene age could be considered to it. This volcanic dome croups out in E-W trend with length about 4.5 km and 2.5 km width. Based on petrographic studies, Ayoub Ansar volcanic dome has dacitic- rhyodacitic composition. These rocks have porphyritic, felsophyritic and golmero- porphyritic texture with plagioclase, Amphibole and quartz phenocrysts. Based on geochemical evidences, these rocks are high- K calc-alkaline, metaluminous to peraluminous and classified as I-type granitoids. These rocks demonstrate REE patterns with enrichment in LREE, high LREE/HREE ratio and without negative Eu anomalies which indicate that plagioclase didn’t underwent fractionation. Enrichment in K, Rb and Ba and negative anomalies for HFSEs such as Nb, Ta and Ti in the spider diagrams indicative for influence of the continental crust in formation of parent magma. Based on tectonic setting discrimination diagrams, these rocks formed at the volcanic arc and Syn-collisional to post- collisional setting. The studied dacites demonstrate geochemical features like Adakites.