Geochemical premises for petroleum formation in the Mesozoic-Cenozoic sedimentary sequence of the World Ocean

Abstract

We provide a review of the latest information on the geochemistry of dispersed organic matter in the Mesozoic-Cenozoic deposits of the World Ocean, obtained as a result of deep-sea drilling. We found that in the sedimentary sections on the ocean margin, dispersed organic matter occurs in amounts similar to those in the continental stratisphere, and in the inner region of the oceans, its content is almost five times less. On the basis of the amount and the composition, the dispersed organic matter in the deposits possesses a significant petroleum-source potential. We stablished the uneven distribution of the organic matter based on horizons of different ages in the Mesozoic-Cenozoic section. Maximum amounts were recorded in the Neogene-Quaternary and Lower Cretaceous sediments. A regular increased amount of dispersed organic matter in the oceanic stratisphere was revealed in the lithologically mixed sediments: terrigenous-carbonate and terrigenous-chert, exceeding its content in clays by 1.5 times. We enunciate the possible principal geochemical distribution patterns for the petroliferous sedimentary basins beneath the ocean floor beyond the shelf.