Mineralogical and Geochemical characteristics of the Chah-Shur Clay Deposit, ‎Southeast of Isfahan, Iran

The Chah-Shur clay deposit is located in150 km southeast of Isfahan. Eocene igneous rocks ‎and Quaternary deposits cover the area. Eocene volcanic rocks include andesite and tuffs ‎which relating to magmatic activities of Urumieh-Dokhtar magmatic belt. Alteration of the ‎vitric and lithic tuff units has produced the clay deposit. Based on the petrographic studies, ‎the main minerals in tuff units are plagioclase, K-feldspar and quartz. The major phases in ‎clay deposit are kaolinite, illite, montmorillonite, quartz, albite and orthoclase. Also, ‎muscovite, chlorite and hematite are as minor phases. The mineralogical studies show an ‎intermediate alteration. The clay deposits can be formed by supergene or hypogene ‎processes; while the combination of both of them can result in the formation of mixed type ‎clay. The geochemical data of Chah-Shur clay deposit show scattering between hypogene ‎and supergene type genesis. The abundance of Fe2O3+TiO2 vs Cr+Nb and Zr vs TiO2, as ‎well as Sr+Ba vs Ce+Y+La suggest mixed and hypogene type. On the other hand, P2O5 and ‎SO3 plot shows the mixed type and supergene genesis. The results obtained from ‎mineralogical and geochemical studies indicate that the genesis of the Chah-Shur clay ‎deposit can be considered mixed type.‎