A TYPOLOGY OF TEXTURES IN SOUTH NAGHADEH INTRUSIVE ROCKS, NORTHWESTERN IRAN

Abstract

South Naghadeh is abundant in intrusive rocks. The region is part of Laramide magmatism in the Sanandaj–Sirjan zone and, from a petrological point of view, consists of syenogranite and monzogranite, granodiorite, quartz diorite, quartz monzodiorite, quartz monzonite, quartz syenite, and olivine gabbro. Available textures in local granitoid rocks include granular, granophyric, graphic, perthitic, and myrmekitic. The textures represent the formation conditions of the minerals, their layout in the rocks, and their physiochemical transformations during or after crystallization. The textures of local plutonic rocks (such as perthitic and granophyric) and lack of metasomatic aureoles and primary biotite are suggestive of high water vapor pressure and low emplacement depth of these rocks. The corona texture found in olivine gabbros was of the magmatic type.