Geochemical studies of the Miocene Onnagawa Formation of northern Japan and the Monterey Formation of California are reported.Geochemical parameters indicative of organic source are similar between the Onnagawa and Monterey Formations, suggesting marine plankton is the major source of organic matter.The degree of preservation at depositional site is a major factor influencing quality and quantity of organic matter.The total organic carbon (TOC) considerably varies among samples collected at millimeter-to centimeter-scale stratigraphic intervals, and TOC shows a distinct positive correlation with detritus content. This close relationship between TOC and detritus content suggests that the organic matter could be largely adsorbed to the surface of detritus particles which might have formed aggregates with a greater resistance to bacterial degradation.The detritus contents varied in centimeter-to decimeter-scale and control organic richness. Biomarker data indicate the Monterey Formation was deposited under more reducing condition than the Onnagawa Formation.This intensive anoxic condition could contribute to the higher contents of organic carbon and sulfur in the Monterey Formation compared to the Onnagawa Formation.

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Stable carbon isotope compositions as well as organic carbon contents and pyrolysis results of cored material are reported for the Pliocene to Pleistocene sediments from the Ocean Drilling Program (ODP) Sites 859, 860, 861, and 863. The δ 13 C values of kerogen show large variation with no downhole trend, ranging between -34.2%e and -22.6‰ with average values around -25‰, whereas the organic carbon contents in most sediment samples are consistently low (<0.5%) except for enrichment in the surface layer at Sites 859, 860, and 861. The δ 13 C values of kerogen indicate the kerogen in sediments of the Chile Margin has a predominantly terrestrial origin, and the fine-grained turbidite material is associated with terrestrial organic matter. The average δ 13 C values become lighter with increasing distance from land among three sites drilled along an east-west transect, suggesting fine turbidites with terrestrial organic matter are transported further offshore in this trench-slope setting.

Elemental analyses, Fischer assay pyrolysis, Rock-Eval pyrolysis and biomarker analyses were conducted for twenty-six lacustrine oil shales from the Lower Cretaceous Dsunbayan Group, Mongolia.