Tectono-stratigraphic investigation of Afyonkarahisar-Dinar-Dombayova coalsite and geological development and reserve potential of lignite deposits in the area

The study area is located 10 km to the northeast of Dinar district of Afyonkarahisar province within the horst graben system that also controls the formation of the Lakes region. The studied horst-graben system was formed by oblique slip faults along with normal faulting. The Dombayova graben in which the thesis work is carried out is a depression region of approximately 5 to 7 km in width and 20 km in length. Dombayova graben consists of generally medium-grained units such as alluvial fans and slope debris at the edges of the basin, and claystone, siltstone, sandstone, mudstone and unconsolidated clastic units at the center of the basin that has lateral and vertical transition. Due to the active tectonism in the study area, visible inclinations in the units especially in the eastern side of the area are remarkable. In addition, as observed in the cores taken from the boreholes, tight folding formed in some areas. This tectonic process, along with the formation of normal faulting in the field has led to the development of oblique slip faulting. Dombayova graben, is represented by normal and oblique slip faults sloping from the western and eastern edges towards the basin center. As observed in the drilling studies, faults in the basin caused the existing units to form at different levels over very short distances. Similar displacements have also been observed in the lignite veins. In particular, the Dinar fault, 2 km west of the study area and the Akçaköy faults to the east of the Dombayova graben are those which have caused severe earthquakes (Dinar earthquake and some historical earthquakes) in the past and have high potential to generate earthquakes in the coming periods. The drilling activities carried out in and around the villages of Uluköy, Akçaköy, Dombay, Akgün and Burunkaya and the presence of Miocene-Pliocene aged lignites formed under the Late Pliocene-Quarternary sediments with a reserve of approximately 1,525,421,287 tons (± 100 million tons) were determined. The thickness of the lignites in the field starts from a few cm on the edges of the basin and reaches to the basin center from hundreds of meters in some places. As a result of the laboratory analyzes, these lignites have an average of 1783 kcal / kg Lower thermal value, 40,57% moisture, 18,97% ash, 27,65% volatile matter, 12,81% constant carbon, 0,73% sulfur in ash, 1.25% total sulfur values.