The REE Characteristics of Oil Shales in the Lower Eocene Celtek Formation (Yozgat, Turkey) and their Relation to Tectonic Provenance

İngilizce (OpenAlex)

The Lower Eocene Celtek Formation is located in the Sorgun district of thecity of Yozgat in Turkey. In the study area, Paleozoic, Campanian‐Maastrichtian, Eocene, Miocene and Quaternary units are exposed. The Celtek Formation is noteworthy with its coal and oil shale deposits. Samples were collected from one exposure (YC ÖSK) and two boreholes (SJ and Ç boreholes) at the facility operated by the Yeni Celtek Coal Management. Concentrations of REE in oil shales from these localities were determined using the ICP‐MS technique. REE and total organic carbon (TOC) values of a total of 32 samples were compared with normalized REE contents of various environments. TOC contents of the samples ranged from 1.37wt% to 11.8wt% (mean 4.96wt%). The averages of all samples for the all normalized values show similar patterns. Normalized REE patterns are represented by the enrichment in the order of LREE>MREE>HREE and display negative Ce and positive Eu anomalies. ΣREE vs. TOC were compared. ΣREE vs. TOC showed a weak positive correlation, whereas ΣLREE vs. (M+HREE) and ΣLREE vs. ΣREE were positively correlated. Regarding tectonic provenance characteristics, the Celtek Formation oil shales were formed in microenvironments with physicochemical conditions changing in character from oxic to euxinic, representing a transitional terrestrial–marine environment.