Mineralogical, petrographic, and geochemical characterization of colored İscehisar marbles (Afyonkarahisar, W-Turkey)

Abstract

The İscehisar marbles are located 25 km northeast of Afyonkarahisar on the Ankara highway in the vicinity of the town of İscehisar. These marbles have economic importance in the Afyon region. The purpose of this study was to reveal the mineralogical, petrographic, and geochemical characteristics of the İscehisar marbles, displaying different colors, structures, textures, and other different features. Based on polarized light microscopy investigations, the İscehisar marbles can be classified into 3 subgroups: from bottom to top 1) calcitic marbles composed of calcite minerals, 2) transition/interlayer marbles, and 3) dolomitic marbles. According to the field descriptions, each subgroup has various field classifications within itself, wherein calcitic marbles are named tigerskin, Afyon gray, Afyon white, and Afyon violet; transition/interlayer marbles are named Afyon green, and Afyon cherry, and dolomitic marbles are named Afyon pink, Afyon Porto yellow, and Afyon brown. The X-ray diffraction results showed that calcitic marbles include mainly calcite with minor amounts of mica ± quartz; transition/interlayer marbles contain mainly calcite, minor amounts dolomite ± mica; and dolomitic marbles include mainly calcite + dolomite and minor amounts of calcite ± quartz ± mica, and opaque minerals. Compared to calcitic marbles, transition and dolomitic marbles have higher SiO2, Al2O3, Fe2O3, and MgO contents. On the SiO2 vs. Mg/Ca and Mg/Ca vs. Sr diagrams, the dolomite marbles are plotted within dolostone, transitional marbles within the transition area (dolostone-limestone), and calcitic marbles within the limestone area. On the MgO vs. CaO diagram, they are plotted along the limestone-dolostone mixing line. All of the data signify a marine carbonate depositional environment for all types of the calcitic, transition, and dolomitic marbles. It can be concluded that these geochemical variations, mineral contents, and impurities played an important role in the colors of the marbles.