Mineralogy and Geochemistry of Coal-Bearing Tunçbi̇lek Formation i̇n the Tunçbi̇lek-Tavşanli Coalfield (Kütahya, W-Turkey)

Abstract

Tunçbilek-Tavşanlı (Kütahya) Basin is among the most important Neogene coal deposits of Turkey. This study aims to determine the mineralogical and geochemical properties of the rocks (coal, roof, floor and parting) in the Tunçbilek-Tavşanlı coal field. The main abundant minerals in Tunçbilek-Tavşanlı coals are quartz, kaolinite, illite-smectite and siderite. Dolomite, illite, smectite, mica, feldspar, pyrite, chlorite and jarosite are less abundant minerals. The mineralogy of non-coal rocks is similar to that of coals, but pyrite is absent. The most abundant major oxides in the studied samples are SiO2, Al2O3 and Fe2O3, respectively. The SiO2, Al2O3 and MgO are the most abundant major oxides, respectively, in the claystone samples representing partings. Trace element concentrations of Tunçbilek-Tavşanlı coal samples mostly showed higher concentrations (excluding Ba, Sr, Pr, Tb, Dy, Ho, Tm, As, Cd and Bi) compared to the world low-rank coal average. According to the relative enrichment of the elements, the concentration coefficients (CC) of the coal samples are generally in the range of slightly enriched-normal; The CC of the non-coal samples mainly indicate the normal. The average REY concentration in the studied samples is higher than the world low-rank coal concentration and mostly showed L-type enrichment. Moreover, the REY concentration of the supercritical groups constitutes a significant part of the REYtotal concentration in the samples taken from the coal horizon. However, the studied samples are in the unpromising area according to the low cut-off grade value and the relationship between cut-off grade-Coutl. The high correlation coefficient between ash content and REY concentrations also indicates a mineral substance relationship. Al2O3/TiO2 (between 12.5-31.7) ratios of Tunçbilek-Tavşanlı samples show intermediate and felsic source rocks.