ORGANIC GEOCHEMICAL CHARACTERISTICS OF MIOCENE OIL SHALE DEPOSITS IN THE ESKİŞEHİR BASIN, WESTERN ANATOLIA, TURKEY

In the Eskisehir Basin, western Turkey, oil shale occurs in alternation with claystone, siltstone, conglomerate and coal (lignite) seams in lacustrine deposits of Early-Middle Miocene age. The thickness of oil shale seams drilled during the study varies between 20 and 30 m. Organic geochemical features of the shale were evaluated using TOC, pyrolysis, GC and GC-MS analyses. The Eskisehir oil shale is characterized by very high TOC contents, Hydrogen Index, Potential Yield and very low Oxygen Index values. While oil shale samples in general have low tricyclic terpane abundance, their C sub( 30) tricyclic terpane content is high. For all the oil shale samples studied C sub( 29)/C sub( 30) hopane, C sub( 31)R homohopane/hopane and moretane/hopane ratios are high and Ts/(Ts + Tm) and C sub( 29)Ts/(C sub( 29)Ts + C sub( 29)H) ratios are low. A 22S homohopanes are recorded in lower quantities in comparison to 22R epimers and the 22S/(22S + 22R) homohopane ratio is low.