Catagenesis of Jurassic-Cretaceous coals and rocks of the Bureya basin in the Russian Far East with respect to hydrocarbon generation

The catagenesis of the Jurassic-Cretaceous deposits and coals has been comprehensively examined based on a complex of features including the reflectance (R (o) and R (a)), the qualitative properties, and the petrochemical characteristics (the density and saturation porosity) of the host rocks. The catagenesis of the Jurassic-Cretaceous deposits was studied based on the structural zones in which the coal-bearing deposits occur at different depths ranging from similar to 10 to 300 m, down to 700m, and from 5 to 3460 m in the Western, Central, and Kyndal zones, accordingly. The following regularities of the changing of the coal's catagenesis have been established: from group 3B to 1G, 2G, and GFL; from gradation PC3 to MC1-MC2; and from MC2 to MC3-MC4 with the changing of the composition of the coals from long-flame coal to gas and gasfat-lean coal. In the intrusive bodies distribution areas breaking through the coal-bearing deposits, the coal seams are metamorphosed to the marks of lean caking and lean coals. The data obtained have made possible the assessment of the hydrocarbon generation in the Jurassic-Lower Cretaceous deposits of the basin.