It is shown that microscopic algae dominate in source material of organic matter of black shales, and admixture of residues of organisms and terrestrial humic material is contained. The main direction of source material transformation during syngenesis and sedimentogenesis is associated with jellofication resulting to formation of organic matter of significantly sapropelic type. Low reflectance of vitrinite and alginite from organic matter refer to the primary and secondary lignite stages of its carbonification. Significantly sapropel type of organic matter and low stage of carbonification are reliable criteria for assigning black shales to the category of potential oil source strata.

Supplement to: Bogolyubova, L I; Timofeev, Pyotr P (1978): Composition of organic matter from black shales of the Cape Verde Basin (Eastern Atlantic) and their oil source potential. Litologiya i Poleznyye Iskopaemyye (Lithology and Mineral Resources), 13(5), 3-17