f Carbon Isotope (δC13) Characteristics of Bituminous Shales in Middle Miocene Hırka Formation (Beypazarı, Ankara / Turkey)

Studied samples were collected from bituminous shales of Middle Miocene Hırka Formation in Beypazari Basin. These samples were rich in organic matter (2.08 to 48.48% TOC%) and the C13 isotope is very important delivered data for environmental review due to effective especially biological processes of carbon isotopes. Carbon isotope data obtained from the study area ranged from -24.6 ‰ to -33.52 ‰ (average ‰ -28,85). When samples have compared with δ13C datas from various geological environments, it has also been identified to be similar with C-3 plants, sedimentary rocks, metamorphic rocks and igneous rocks of in terms of samples distribution ranges. C isotope fractions changes depending on temperature (Park and Epstein 1960). The fractions are higher values in cold water plankton but on the contrary, it has less dissolved CO2 due to increase the effect solubility with temperature increase and therefore C isotopes shows the lowest values. When we have considered the origin and the physicochemical conditions of C-3 plants, it can be concluded to occure in terrestrial environment and in the warm waters of Hırka formation bituminous shales in Beypazari basin.