Minerology and geochemistry of sedimentary units in Çavdarhisar (Kütahya) basin

In this study, it is aimed to determine the mineralogical and geochemical characteristics and formation factors of the sedimentary units in the Çavdarhisar basin, to examine their originary characteristics, and to illuminate the stratigraphic development of the basin. Çavdarhisar Basin, which has NE-SW trending extension, is a basin connected with Gediz and Emet basins. The Sarıcasu formation, consisting of Paleozoic-Middle-Upper Triassic aged marble and schists, forms the basement rocks in the basin. Marbles belonging to the Jurassic aged Arıkaya formation, conformably overly the Sarıcasu formation. The Upper Cretaceous aged Dağardi Ophilotic melange, consisting of serpentineschist, greenschist, radiolarite, talcschist, and calcshist, tectonical unconformably overlies the Arikaya formation. The Middle-Upper Miocene aged Çokköy formation, consisting of limestone, clayey limestone, dolomite, claystone, carbonated claystone and sandstone, unconformably overlies the unit. The Upper Miocene-Pliocene aged Emet formation, which consists of limestone, marl and mudstone containing claystone interlayers, conformably overlies the Çokköy formation. Quaternary aged alluviums unconformably overlie the Emet formation. In this study, samples were taken from two deep drillings with depths of 132 and 236 m made by the General Directorate of TKI and outcrops. In the drillings, 5cm and 10cm of coal were cut in several levels. Clay minerals, feldspar, quartz, calcite, dolomite, aragonite, gypsum and celestine have been determined by XRD studies. Clay minerals consist of Ca-simectite, illite, chlorite, kaolinite, paligorskite and sepiolite. In SEM examinations, growth traces were observed on the subhedral, euhedral calcite and anhedral, subhedral rhombohedral dolomite crystals. The gypsum are in the form of euhedral, subhedral, platy, fibrous and prismatic crystals, and not fully developed dolomite, illite and smectites were detected together with gypsum. Paligorskites are generally fibrous-filamentous, and sepiolites are fibrous-filamentous, floppy-looking, locally planar aggregates. It was determined that the sedimentary rocks in the study area were formed in humid, arid-semi arid climatic conditions and derived from the rock of acidic origin. δ13C stable isotope values obtained from carbonates in the Çavdarhisar basin were found between ‰0.81 and ‰-8.45 (V-PDB), and δ18O stable isotope values were between ‰-8.6 and 0.43 (V-PDB). According to isotope analyses, the study area is a basin fed by groundwater with low salinity, and then the water level in the lake continued to decrease with the dominance of arid climatic conditions. Negative δ isotope values of 13C indicate that limited ventilation conditions are effective in the lake area, and CO2 production is attributed to local biogenic sources.