Thick organic-rich lacustrine sediments of the onshore rift basins of eastern North America constitute a new and potentially important source of hydrocarbons that heretofore have neither been reported nor described in the literature.

In the Newark basin of New Jersey, for example, lacustrine deposits comprise a major part of the Triassic-Jurassic stratigraphic section and yield up to 8% organic carbon. Like the Late Cretaceous, nonmarine, producing strata of the Cabinda and Gabon basins of the West African passive margin, these sediments formed along plate margins in wrench-faulted rift basins with deep-water lakes and anoxic bottom conditions. Laterally they interfinger with fan deltas along the border fault and fluvial-deltaic sequences along the tilted margin of the basin. Organic-rich laminated siltstones and carbonates, the result of depressed ecologic efficiency in highly productive lakes, contain (like the Eocene Green River Shale) amorphous algal kerogen, pollen and spores, plant cuticles, and whole fish. einlets and blebs of gilsonitelike deposits locally fill joints and fault surfaces. On the basis of organic maturation and depth of burial, these lacustrine rocks and their contained organics fall within the "hydrocarbon window." Having formed in pull-apart basins on the passive margin, these rocks display a variety of structural and stratigraphic traps, and should be given serious consideration in future exploration programs.

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