Late pre–Cambrian – early Cambrian igneous rocks of Anjiravand area of Central Iran are mostly composed of rhyolites, subvolcanic granites, doleritic dikes and rarely basic volcanic rocks. These rocks, due to lack of variation in peterographic and geochemical composition, are mainly in range of acidic and basic groups and are considered as bimodal without any intermediate terms. Basic volcanic rocks of this area with alkaline composition are originated from mantle and belong to within-plate igneous rocks, while in the same age, acidic rocks are made of calk-alkaline affinity and originated by partial melting of crustal rocks.
Granitic part of these acidic assemblage have anorgenic character and are belong to related rift group granites. In addition, bimodal characteristic of magmatic rocks imply that these rocks were formed in a within-plate rift environment. Thereby, it can be assumed that in the primarily stage of rift separation along with tensile and uplift of lithosphere, diapirs of basic alkaline from mantle, first dissociated and emplaced in lower crust section of continent and then due to high temperature gradient around these diapirs acidic magmas formed from partial melting of crustal rocks and emplaced as cap, covered basic magma chambers