Nature, Origin, and Petroleum Source Potential of Organic Matter from Deep Sea Drilling Project Sites 434, 435, 438, and 440 in the Japan Trench

Distribution, Origin, and Hydrocarbon-Potential of Organic Matter in Sediments from the Pacific Margin of Southern Mexico

“…Most of the amorphous material seems to be derived from marine organic matter. This facies is quite different from the terrestrial facies that dominates hemipelagic sediments in a similar setting on the continental margin of Japan (Gilbert et al, 1980). There the average organic assemblage is 15% structured marine, 10% amorphous, and 75% terrestrial.…”

“…The severe depletion of oxygen in the anaerobic zone at the peak of the oxygen-minimum zone along this coast explains the extensive enrichment in organic matter on the uppermost slope (Calvert, 1964;Demaison and Moore, 1980;Gilbert and Summerhayes, in press a, b). Off Japan, in contrast, the water mass (including the oxygen-minimum zone) is well oxygenated (Kester, 1975); as a result, preservation of labile marine material is poor and we are left mainly with the more refractory terrestrial components (Gilbert et al, 1980). Bacterial activity may modify diagenetically both the organic facies and the TOC, as shown, for example, by Emery (1960), who pointed out the preferential loss of nitrogenous over carbonaceous organic materials with burial in the California Borderland.…”

Distribution, Origin, and Hydrocarbon Potential of Organic Matter in Sediments from the Pacific Margin of Guatemala

“…The high productivity explains why marine-derived organic matter should be abundant in these areas; the oxygen deficiency promotes the preservation of this material once it has been deposited (Calvert, 1964;Demaison and Moore, 1980;Summerhayes and Gilbert, in press). Productivity is much lower and oxygen concentrations are much higher off Japan, where only small amounts of refractory terrestrial components remain to be incorporated into the sediment (Gilbert et al, 1980). The high productivity of the eastern side of the Pacific has led to the development of reducing conditions and consequent preservation of large amounts of organic matter (more than 4% TOC) within the oxygen minimum zone off Mexico and California (Gilbert and Summerhayes, 1981 and in press).…”

rganic Facies of Cretaceous and Jurassic Sediments from Deep Sea Drilling Project Site 534 in the Blake-Bahama Basin, Western North Atlantic

“…In many respects this study is a follow-up to earlier work on the nature and controls of deposition of the organic facies of the mid-Cretaceous "black shales" that are widespread throughout the deep North Atlantic (Summerhayes, 1981). It is also a part of Exxon's ongoing program of studies on the nature and origin of organic matter in deep-sea sediments (Mclver and Rogers, 1978;Johnson et al, 1979;Gilbert et al, 1980;Gilbert and Summerhayes, 1981, in press;Summerhayes and Gilbert, 1982, in press). This site is particularly interesting in that Jurassic "black shales" were recovered, along with the anticipated mid-Cretaceous ones.…”