Mineralogy and Mineral Chemistry of Xenoliths from the Felsic Dykes Swarm in the Southwest of Bayazeh, South of Khur (Isfahan province)

The felsic dyke swarm with the Late Cretaceous age is situated in the southwest of the Bayazeh village (South of Khur, Isfahan Province). This dyke swarm, with northeast- southwest trend, cross cut the Lower Cretaceous sedimentary rocks of the Biabanak Formation in the eastern margin of the Yazd block (Central East- Iranian Microcontinent). The Bayazeh dykes host the amphibolite and granulite xenoliths. Based on the mineral paragenesis, the amphibolite xenoliths are subdivided into the amphibolite, clinopyroxene amphibolite and garnet clinopyroxene amphibolite. Mineralogical study of these amphibolites indicates that they belong to the para-amphibolite type. Rock-forming minerals of the granulitic xenoliths in these dykes consist of plagioclase, phlogopite, spinel, garnet, sillimanite and staurolite. Mineralogical studies show that these xenoliths consist of Al-rich and Ca-, K-, H2O-poor minerals (except of phlogopite). Mineral chemistry of phlogopites in these granulites indicates their similarity to the micas from the lower crust xenoliths. According to the geothermobarometry calculations and mineral paragenesis, amphibolite and granulite xenoliths in the Bayazeh dyke swarm were derived from 21 to 32 km depths. Based on the Moho depth (approximately 40 km) in this part of the Yazd block, these xenoliths are fragments of the lower continental crust that have been carried to the surface by the felsic melts