The molecular composition of hydrocarbons and heteroatomic compounds of the lube stock of Ivanovskoe asphaltite has been studied. The results obtained allow for the conclusion that the source material for the formation of the asphaltite deposit was crude oil generated in the catagenesis stages corresponding to the beginning of the main phase of oil generation by marine carbonates, whose sedimentation and diagenesis had occurred in coastal marine environments under anoxic conditions upon euxinia in the benthic zone. The asphaltite composition bears no signs of deep biochemical oxidation of the original oil.