Depositional Environment and Organic Geochemical Characteristics of Lower Eocene Bituminous Rocks, in the Kürnüç/Göynük-Bolu Area

Abstract

In this study, dark gray and dark brown colored, organic-carbon rich bituminous rocks (bituminous marl and bituminous shale) exposing around the Kürnüç area (Göynük, Bolu) are investigated by means of organic geochemical characteristics. In this respect, rock lithologies, depositional environments, rock source potential, kerogen and organic maturity types and hydrocarbon generation potentials of bituminous rocks were determined. For this reason, pyrolysis (Rock Eval-VI) analysis, gas chromatography (GC) and gas chromatography-mass spectrometer (GC-MS) analyses were carried out. In addition, spore color index (SCI) was determined with organic petrographic method and stable carbon analysis (δ 13 C) of the samples were also conducted. Lithology of the studied samples is of clastic source and the depositional environment is a lagoon with a partial connection to the sea. In bituminous rocks with excellent source rock potential TOC values are in the range of 2.52-8.38 wt % (average 6.08 wt %). With the exception of two samples (Type II) kerogen type of all samples is Type I. According to pyrolysis, GC and GC-MS organic maturity results, all the samples are in immature stage. Organic geochemical data indicate that bituminous rocks have an excellent oil generation potential and there is no organic contamination.