Petrology, geochemistry and tectonomagmatism of granitoidic rocks of Taknar complex, Iran

Taknar complex is located at the Taknar structural zone in northern part of Central Iranian microcontinent. The position of this assemblage is about 20Km northwest of Bardaskan County. Taknar complex, with the Late Jurassic–Early Cretaceous age, is the result of extensive magmatism in northern part of Central Iranian microcontinent which is caused by Middle Cimmerian to Late Cimmerian orogenic events. This complex is an assemblage of leucogranite, granite, granodiorite, tonalite and granophyre. The main texture of these rocks is granular and we can see porphyroid, pertitic and granophyric textures. The major constitute minerals of these granitic rocks are orthoclase and microcline with pertitic texture and amorphic quartz. The granodioritic and tonalitic rocks of this assemblage have dark color due to frequent existence of biotite. The granophyre rocks of this assemblage are small apophysis in the old rocks. The magmatic series of rocks in this complex are calcalkaline. The chemical characteristics and tectonic environment of the studied granitoidics of the complex are completely similar to each other. From the alomine saturation point of view, the samples are in the range of meta-alomine to per-alomine. In addition to petrographic characteristics, the I-type granites are comparable with the mentioned granitoid in their geochemical features. These are Medium-K rocks and also enriched in the LILE such as Rb, Cs and Th, while depleted in the Nb and Ti. Therefore, it shows that these rocks resulted from the mixing by the lower crust. The comparison of the major and trace elements within these rocks indicates their orogenic tectonic environment. The rocks of this complex are formed at the continental margin and (VAG) environment which is related to the subduction of the Neotethys oceanic crust under Central Iranian Microcontinent.