Original and economic investigation of lignite coals (lower eocene Çeltek formation) found in Suluova (Amasya, Türkiye) surroundings

This thesis study, is aimed to investigate the organic geochemical properties of the bituminous and coal-bearing lithologies of the Early Eocene Çeltek Formation cropping out around Suluova (Amasya, Turkey) and to reveal the origin of the coals in the formation, the amount of organic matter, the type of organic matter, the degree of maturation and what kind of contribution they will make to the economy. The mineral assemblage of the Çeltek claystone consists of kaolinite-chlorite-illite-smectite-mixed clay (smectite-chlorite). The total organic carbon values of the Çeltek coals are high and represent an excellent source rock. The Çeltek coals indicate Type II and Type III kerogen, and show more gas and less oil-prone properties. The presence of gamaserans in the examined coals indicates the effect of the marine environment in the sedimentation of the Çeltek Formation. The observation of oleane in the Çeltek coal samples is an indicator of high plant material accumulated in a deltaic environment and shows that the maturation stage has not been reached. The waxiness index values calculated in Çeltek coals indicate the terrestrial organic matter input provided by higher plants during the sedimentation process. The fact that the C23 tricyclic peak is the main peak in these coals emphasizes the carbonate source rock and the marine environment effect. The C24 tetracyclic ratio in the studied coal samples is 0,69 in one sample and indicates the shale source rock; it is 2,19 and 3,19 in two samples and indicates the carbonate source rock. The C29 norhopane/C30 hopan ratios in the Çeltek coals are 4,74 in one sample and represent the carbonate source rock, while they are 0,48 and 0,58 in two samples and emphasize the shale source rock. The C31/C30 hopan ratios observed in the analyzed coals are low (<0,25) in all three samples (0,11; 0,12 and 0,13) and indicate the lacustrine source rock. Again, since the C35/C30 hopane ratios in these coals have values ranging between 0,013 and 0,014, they indicate fluvial/deltaic and lake-fluvial/deltaic depositional environments. Since the C23/C30 hopane ratios in the coals collected from the field are at high values (4,29; 4,34 and 4,59), they indicate marine influence in the studied basin. Since the C35/(C31-C35) homohopane index observed in the studied coals is at low values such as 0,023-0,025, it indicates suboxic and/or oxic environmental conditions and paleodeposition developed in a clastic environment. Again, since the C35 (R+S)/C34 (R+S) ratios in these coals are <1 in all three samples (0,15; 0,16, and 0,15), they indicate suboxic environmental conditions. Since the moretan/hopane ratios vary between 0,53–0,61 in the Çeltek coal samples, they indicate a source rock in the immature-early mature stage. Since the Ts/Tm ratios in the coals we studied are <1 (0,0185–0,1810), they indicate that the paleodeposition environment was anoxic. In addition, since the Ts/(Ts+Tm) ratios (0,0181–0,153) are low in these samples, they indicate that the coals are not mature. The C29/C27 sterane ratios are >1 (7,2; 10,7; 11,6) in all samples, representing a terrestrial plant source. The coals contain high amounts of C29 (%71-74) and C28 (%16-23) steranes and low amounts of C27 (%6-10) steranes. Again, these coals have low concentrations of diasterane/sterane ratios (0,349-0,415) and reflect the presence of carbonate-rich source rock. Our samples with low sterane/hopane ratios (<1) indicate terrestrial and/or microbial organic matter input. Since the (C29) ββ/(ββ+αα) sterane ratios in our samples are lower than the C29 ββ steranes than the C29 αα steranes, we can say that the Çeltek coals reflect deposition in a freshwater environment rather than a saltwater environment. As a result, it can be said that the studied formation was deposited in a shallow marine-delta transition and freshwater lacustrine environment; the organic matter sources are both carbonate and shale rocks, the organic matter is in the immature and early mature stages; We can suggest that it was under the influence of oxic-suboxic-anoxic environmental conditions and that there was a contribution of higher terrestrial plants and lesser contributions of herbaceous plants, lacustrine algae, bacteria and fungi. The reserve of the Eski Çeltek coals that constitute the material of the study is 10 million tons and we can suggest that it has economic and workable properties.