Evolutionary transformations of the composition and structure of asphaltenes in different types of organic matter (OM) of sediments and rocks at different lithogenesis stages were studied. Insight into the main steps and processes controlling the transformation of OM asphaltenes in different steps of thermal maturation was gained, and new opportunities for using parameters of the asphaltene structure for constructing geochemical models were revealed. The following trend in variation of bitumen asphaltene parameters in the course of catagenesis was revealed for both genetic forms of OM: directional carbonization of asphaltenes, accompanied by a decrease in the content of hydrogen and an increase in the relative content of aromatic (including condensed) structures and by a decrease in the role of aliphatic substituents. Linear relationship was revealed between the parameters of the composition and structure in the course of thermocatalytic transformations. Three successive stages of thermal maturation of asphaltenes were distinguished.
