Garnet composition from felsic pegmatitic rocks in North of Golpayegan (Ochestan), Iran

Editorial

Abstract

The felsic pegmatitic rocks are exposed in the north of Golpayegan. The dominate mineral assemblage is quartz, K-feldspar, plagioclase, muscovite, tourmaline and garnet. The elevated spessartine content of the garnets in the studied rocks along with their idiomorphic shape, the absence of resorption feature and garnet-free country rocks may point to their magmatic origin and crystallization at a fairly low pressure (less than 3 Kbar). A significant geochemical criteria is the absence of chemical zoning which suggest their crystallization at temperatures above ∼ 700 °C. Apparently at these temperatures, the Mn diffusion becomes sufficiently rapid to eliminate compositional zoning. The overall petrographical and geochemical data indicate that these phases generated from peraluminous S-type melts.

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