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The Central North Atlantic Basin, including most of the lower continental rise areas, should not be regarded as being prospective for hydrocarbons, because of lack of reservoirs, pervasive cementation, insufficient burial, generally low geothermal gradient, and adequate organic matter in only one of the units of the sedimentary fill. The upper parts of the continental rises and the continental slopes in the front of major Lower Cretaceous deltas appear to be prospective. The deeply buried pre-Lage Jurassic succession of shallow- water carbonates beneath the continental slopes and rises appears to offer promise, but until the Deep Sea Drilling Project provides us with better data from the lower parts of the continental margins it is not possible to assess the hydrocarbon potential of these areas.
U-series dating makes use of the tendency of the short-lived daughters of 238U and 235U to be chemically separated from their parents during sedimentary processes. Ages of samples are determined either from the decay of initial excess of daughter (Daughter Excess, DE, dating) or growth of initially deficient daughter (DD) into secular equilibrium with the parent. DE dating is applicable to marine sediments where initial excesses of "°Th and 23lPa are observed. DD dating is useful on chemically precipitated CaCOa and some biogenic carbonates. By DD dating of travertines associated with various types of geomorphic features, absolute dates for the evolution of land-forms through the Quaternary can be obtained. DD dated speleothems also yield stable isotopic records of past climate.