Turkish Journal of Earth Sciences

Abstract: The playa-mudflat facies under investigation are found in the Gemerek Basin (Sivas, Türkiye). This Miocene basin is bordered by the Akdağ Metamorphics (Paleozoic) to the N-NW, the Elmalıdağ Volcanic Rocks (Thanetian) to the E and clastic rocks and evaporites of the Cevizcik Formation (Oligocene) to the S-SW. Illite, palygorskite, smectites (montmorillonite, saponite and sauconite), chlorite (clinochlore) and serpentines had been studied using XRD analysis of mudstone samples. Illites and chlorites were found to have originated from marble, schists, granitic rocks, dioritic rocks and syenitic rocks of Akdağ Massif to the north. Palygorskite were formed in evaporitic basins by chemical sedimantation. Smectite group minerals (montmorillonite, saponite, sauconite) were derived from volcanic tuffs of the Elmalıdağ Formation to the E, and from gypsum units of the Cevizcik Formation to the SSW. One another origin of smectite group minerals is from metamorphic rocks of Akdağ Massif. Minerals of serpentine groups are derived from the ultrabasic rocks of the Sarıkaya Olistostorme