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Samples from Sites 379 and 380 (DSDP Leg 42B) in the Black Sea have been analyzed for their organic content. Subbottom depth of samples ranges from 4 meters to 621 meters at Site 379 (ages to 600,000 years B.P.) and from 600 meters to 1063 meters at Site 380 (ages from 750,000 to 3 × 10 years B.P. or more). The main organic fractions consist of humic compounds and of alkali-insoluble material, called humin, including its non-hydrolyzable fraction, kerogen. The genetic properties of humic acids show great variety in the sedimentary columns suggesting important changes in the input of parental organic matter (autochthonous versus allochthonous [land derived] balance) during the course of sedimentation. Moreover it is observed that organic matter changes as a function of burial, i.e., we observe: a decrease in the hydrolyzable fraction, a decrease in humic compounds content, a decrease in proteinaceouslike material in humic acids (amide bond vibrations in IR spectra disappear with increasing sample depth) and a decrease in the oxygen content in the more autochthonous-derived humic acids, while the more land-derived humic acids undergo burial without such a decrease. This fact suggests various ways of oxygen incorporation in the different kinds of humic acids. All these changes lead the bulk of the organic matter towards the kerogen status as it is found in ancient sediments. As a result, from the comparison between Sites 379 and 380 we might claim that kerogen formation has terminated at the deepest samples of Site 380, while it is still occurring at Site 379.

Humic Compounds and Kerogens in Cores from Black Sea Sediments, Leg 42BHoles 379A, B, and 380A

Humic Compounds and Kerogens in Cores from Black Sea Sediments, Leg 42BHoles 379A, B, and 380A