Development of the Integrated Approach to Stratigraphic Subdivision and Correlation of Middle–Upper Jurassic Deposits in Southeastern West Siberia

Abstract

On the basis of integrated paleobotanic, lithogeochemical, IR-spectrometric, and thermochemical studies, stratigraphic subdivision and correlation of productive Middle–Upper Jurassic sediments represented by the Tyumen and Naunak formations in the Dvoinaya and Snezhnaya areas (southeastern part of West Siberia, central Tomsk oblast) are carried out. A reliable basis is created for an optimal correction of reserves calculation and effective development of hydrocarbon deposits. It is found that the index species among paleobotanic remains of the Tyumen Formation are the ferns Coniopteris vialovae and Raphaelia diamensis and Czekanowskiales Czekanowskia irkutensis, Cz. rigida, and Phoenicopsis mogutchevae; for the Naunak Formation, it is Czekanowskia tomskiensis. This is due to the paleoclimatic environment which predetermined the compositions of plant communities and the species of coal-forming plants. For reliable correlation, a lithogeochemical study of sediments is carried out taking into account the analysis of coal origin. The difference in composition of plant complexes in the studied formations is confirmed by the difference in genetic properties of the marking coal-bearing deposits: degree of biochemical stability of the organic mass of the peat, gelification, and floristic restorability of the organic mass in coals, as well as yields of light and heavy hydrocarbons.