Petrographical and geochemical characteristics of enclaves in Astaneh area (Southwest of Arak)

The Astaneh granodiorite intrusion, located in the southwest of Arak, is characterized by rounded and rarely ellipsoid microgranular enclaves ranging in composition from gabbro to diorite and quartz diorite. The diameter of enclaves varies from a few millimeters to 40 centimeters. In the marginal part, the enclave forming-minerals are finer than that of the central parts. The fine grained enclaves are an evidence of rapid magma cooling which these rocks were surrounded by host felsic magma. Petrographical evidences such as ocellar quartz, acicular apatite, bladed biotite, poikilitic textures and pargasitic amphibole in all of the enclaves show that magma mingling occurred. The enrichment of the studied enclaves in CO, Ni, Cr and HREE display that these rocks are globules of mafic magmas mingling to felsic type.