Organic geochemical characteristics of the bituminous Eocene units in the Corum-Suluova Basin, central Anatolia, Turkey

Abstract

In the Corum-Suluova Basin (central Anatolia) the Eocene Celtek and Armutlu formations consist of conglomerate, sandstone, siltstone, marl, mudstone, shale, limestone, clayey limestone, bituminous shale and coal. Total organic carbon (TOC) values in the Celtek Formation range between 0.1 and 8%. Rock-Eval analyses on core samples with the highest TOC values give hydrogen index (HI) values from 45-846 mgHC g(-1) TOC and oxygen index (OI) values from 9-64 MgCO2 g(-1) TOC. The organic matter can be classified as Type I and Type II kerogen on the modified van Krevelan diagram. T-max values vary between 428degrees and 440degreesC, with an average of 436degreesC, indicating the catagenesis stage. Based on the microscopic studies, organic matter is composed of predominantly autochthonous algal and amorphous material, with a minor contribution of terrestrial material. The Celtek Formation can be regarded as a source rock for hydrocarbons. The TOC content of the Armutlu Formation is poor. Samples consist of terrestrial and reworked organic matter. Vitrinite reflectance values are between 0.27% and 0.43%, with an average of 0.34%. T-max values are between 433degreesC and 436degreesC, with an average of 435degreesC. The HI value is between 29 mgHC g(-1) TOC and 39 mgHC g(-1) TOC. Considering the data, the Armutlu Formation cannot be the source rock.