RARE EARTH ELEMENT (REE) GEOCHEMISTRY AND GENESIS OF OIL SHALES AROUND DAGHACILAR VILLAGE, GOYNUK-BOLU, TURKEY

The study area is located in the south of Daghacilar village of Goynuk town in Bolu Province, Turkey. This study is a pioneering work in Turkey on the genesis and environmental characteristics of oil shales and other shallow marine-type sedimentary rocks regarding their major and rare earth element contents. The abundances of SiO2, Al2O3, TiO2, K2O and Fe2O3 decrease in the following order: claystone > oil shale > marl. CaO and MgO abundances are ranked in the decreasing order as follows: marl > oil shale > claystone. These results reveal the presence of two different genetic groups - detrital and marine. The same groups were also established in the correlation studies of elements. TOT/C and TOC contents of rocks observe the following order: oil shale > marl > claystone, and as a result of variations in redox conditions they also vary in a wide range. Total carbon and total organic carbon are positively correlated with the group representing clays and negatively correlated with CaO, MgO and MnO. That is why TOT/C and TOC are associated with clays. The positive correlations between some major oxides (e.g. SiO2, Al2O3, Fe2O3, TiO2 and K2O) and REE might indicate that clays and iron oxy-hydroxyls play an important role in transportation and deposition processes. The only slight negative Ce and positive Eu anomalies and Ce/Ce* and Eu/Eu* values recorded in the depositional environment indicate low oxygenated and anaerobic (reducing) conditions.