Petrology and mineral chemistry of Ochestan granitoids (south of Mahallat, Markazi province)

The Ochestan granitoids are located 60 Km South of Mahallat in Markazi province and in Sanandaj-Sirjan zone. Based on petrographic studies, these rocks are alkali feldspar-granite, granite (syenogranite and monzogranite) and granodiorite. Alkali feldspar (orthoclase and microcline), plagioclase (albite and oligoclase), quartz and muscovite are present as the major minerals and tourmaline, biotite, zircon, garnet, apatite, opaque minerals, rutile and chlorite as the secondary ones. Foliation is found in many parts of the pluton indicating mylonitization process. Geochemical studies show sub-alkaline (calc-alkaline), peraluminous and S-Type for the granitoid studied. According to spider diagrams, upper crust is considered as the magma source, and syncollision as the geotectonic setting. Partial melting of metapelites can be assumed as a source of magma generation in regard to the type of granitoids, geochemical data and metamorphic rocks exposing in this area.