Издатель: ИГ Коми НЦ УрО РАН , Место издания: Сыктывкар , Год издания: 2020

The features of the transition zone (members I-IV) between the Bazhenovo and Kulomzino horizons in the central and southeastern West Siberia have been determined based on a comprehensive analysis of lithology, geochemistry of rocks and organic matter, and geophysical well logging data. The composition and structure of the transition zone in the southeastern region differ significantly from those in the central region, where four members are fairly confidently distinguished: the upper part of the Bazhenovo Formation, the lower part of the sub-Achimovo member and two transitional whose composition reveals the boundary of changing redox conditions. The transitional part (members II and III) of the studied sections in the southeastern region is interpreted as uniform, inasmuch as the transitional members differ slightly in lithological-geochemical and geophysical characteristics of rocks, and differentiate only slightly by the organic matter geochemistry. Defining the upper limit of the Bazhenovo Formation in the southeastern region will additionally require paleontological studies.