Oysu Grafitinin Jeolojik Konumu, Kimyasal ve Petrografik Özellikleri, Altıntaş-Kütahya

Abstract

This thesis aims to examine the formation of the graphite deposit located around Oysu (Altıntaş-Kütahya), determine formation conditions, and find out whether the Mount Murat granite intrusion in the region has any impact on the graphite formation. The investigated Oysu graphite field is the most important graphite field in Türkiye. The graphite zone with approximately 50 m thickness is located within the metamorphic rocks of the Late Triassic–Middle Jurassic Kıyır Formation, and it is exploited using open-pit mining methods. After grinding, the raw graphite ores are enriched using chemical leaching processes on site in order to concentrate graphite. In this thesis, a total of 119 graphite and 4 rock samples, including open-pit mine, drill cores, and leached and concentrated graphite samples, were obtained and evaluated. Proximate (moisture, ash and volatile matter), ultimate (total C and S), mineralogic (XRD-TK, XRD-KF, SEM-EDS), petrographic, micro-Raman spectroscopy, and FTIR analyses were performed from selected samples, and all analytical results were evaluated within the scope of the thesis. Quartz, carbonate minerals (calcite, dolomite, and a trace amount of siderite), clay minerals (illite, chlorite, and kaolinite), pyrite, and a minor amount of feldspar minerals were detected in the studied samples according to whole-rock X-ray powder diffractogram (XRD-TK) analysis. Besides XRD results, SEM-EDS analyses performed on eight samples revealed that ankerite, apatite, arsenopyrite, galena, chalcopyrite, monazite, sphalerite, Ti-oxide, zircon, and margarite? are accessories in the samples. Illite crystallinity values of X-ray clay-fraction diffractogram (XRD-KF) analysis from twelve-drill core samples are from 0.25-0.29 ∆ °2θ. According to the organic/coal petrography analyses performed on the polishing blocks, the samples had a brecciated texture, and the carbonaceous (organic/amorphous) substances mostly consisted of dispersed and anisotropic grains smaller than <200 µm. In a few samples, possible meta-vitrinite grains, which preserve primary textures, are also observed barely. According to vitrinite reflectance measurements, the highest %R’max and the lowest %R’min values are measured as 11.00, and 0.55, respectively. The micro-Raman spectroscope analyses of three selected samples show that the average positions of the D1 band are 1348 cm-1 and the G band are 1603 cm-1 in the first-order Raman spectra. Moreover, the intensity of the D1 band is detected between 63 and 181 (a.u.), while the intensity of the G band varies from 34 to 91 (a.u.). In addition, no D2 band is detected in the analyzed samples. The peak metamorphism temperatures are calculated as 313 °C or 342 °C according to the micro-Raman data. Thus, the Oysu graphite is derived from organic-rich sedimentary rock, which was developed under lower greenschist metamorphic facies. For the first time in this study, based on all analytical data, it has been determined that Oysu graphite is in the semi-graphite (amorphous graphite) stage. On the other hand, no direct contact was observed between the studied graphites and the Paleocene-Early Eocene-aged monzogranite (Baklan Granite) intrusion on Mount Murat, where the study area is located. Therefore, it can be concluded that contact metamorphism does not have any direct effect on the studied graphites.