Geochemical Studies of Cenozoic Shale Beds of the Western Cis-Caucasian Region

Abstract

Geochemical parameters of the Cenozoic shale strata of the western Ciscaucasia have been analyzed. Oil source strata were identified in the study. The geochemical characteristics of organic matter (OM) of the Kumian rocks revealed high oil source potential of the rocks. The formation and emigration of hydrocarbons (HCs) were inferred from qualitative and quantitative changes. Sapropelic OM generated large amounts of hydrocarbons in the Kuma Sequence, with the value increasing from the top to the bottom of the profile. Para-autochthonous and migratory bitumoids were registered on the PC3 gradation and well-developed on the MK2 gradation (at a depth of 4.6–5.0 km). A comprehensive study of OM from Khadumian rocks by pyrolysis, bituminology, and chromatography showed that all kerogen types were developed in the rocks, but mixed OM with moderate oil source potential predominated. Maximal organic carbon (C_org) concentrations and genetic potential were observed within the Western Kuban trough, as well as in the strip of outcrops in the Adygei ledge area. The improvement in geochemical parameters in these areas is due to a decrease in the terrigenous component in the crude OM in the same direction.