Penetrative conditions and tectonomagmatic setting of the Takht granitic batholith, Sirjan

The Takht granitic batholith of Sirjan contains gabbro-diorite to alkali-feldspar granite in composition. The batholith was emplaced in the south of the Urmia-Dokhtar magmatic belt in the Oligo-Miocene. The depth and temperature of the emplacement of the batholith is between 5. 5 and 10. 5 km and 750 to 900°C، respectively. The crystallization conditions of the rocks were examined on the base of chemical composition of minerals using the thermometers and barometers description diagrams provided by previous researchers. Hydrous minerals such as biotite and amphibole crystallized along with plagioclase، quartz، clinopyroxene، titanite، apatite، and magnetite under subsolidus condition. The nature of the batholith is calc-alkaline and cordilleran I- type. Lithological changes in the batholith are due to fractional crystallization. The injection of the Takht batholith is related to the last stages of Neotethys subduction activity under neath the Central Iranian plate. Oblique subduction created appropriate spaces in the edge of the Central Iran. Hence، partial melting occurred due to decompression in the mantle wedge or base of the lower crust. The melts، which were gabbro-diorite to granite in composition، were injected into these spaces.