Of the Jurassic oil shales (Bolshoi Vosim river outcrop, Yarengsk shale-bearing area, Arkhangelsk region, Russian Federation)

Geological and geochemical features at the observation point in the Yarengsk oil shale region in its southern part were investigated. According to the results of the micropaleontological studies and the study of ammonites, the deposits belong to the Middle Volgian substage of the Upper Jurassic. The paper presents the bulk characteristics of the organic matter of the investigated oil shale sequence, as well as data on the distribution of polycyclic biomarkers. The share of oil shales in the section is small. The organic matter has a very low degree of ma- turity because hopanes have mostly  configuration and  steranes are absent. The distribution of regular  20R steranes predominate at the expense of hydrocarbons of composition C27 and C29, with the latter more. The original organic matter is represented by both marine phytoplankton residues and terrigenous impurities.