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Geochemical studies of sandstones from the three lithostratigraphic successions in the southern Benue Trough of Nigeria were undertaken for a geochemical characterization of the sandstones, and to assess their stratigraphic and source evolution.Major and trace elements data were obtained from outcrop sandstone samples. The SiO 2 /Al 2 O 3 , Fe 2 O 3 /K 2 O ratios and CaO contents have been used to characterize the Cretaceous sandstones into Al-rich and high and low Fe 2 O 3 /K 2 O ratio sandstones. Results indicate that there are geochemical features that display stratigraphic trends across the succession from the Asu River Group, Eze-Aku Group to the proto-Niger Delta succession which may imply a discontinuous evolution from different source terrains of Precambrian and Mesozoic ages that supplied the sediments. The Asu River Group sandstones have lower SiO 2 , Al 2 O 3 , Fe 2 O 3 and higher MgO; the Eze-Aku sandstones have higher TiO 2 , CaO, alkalis and lower MgO while the proto-Niger Delta sandstones have higher SiO 2 , Al 2 O 3 , Fe 2 O 3 and lower alkalis and CaO. These discontinuities signify the influence of tectonic impulses that affected the southern Benue Trough during the Cretaceous time. Changes in ratios of TiO 2 /Al 2 O 3 , Fe 2 O 3 , Cr and Zr suggest an increasingly mafic contribution to the depositional basin with time. The chemical index of alteration increases with time, possibly suggesting that a more intense weathering regime in the hinterland developed with time.

A subsurface study of the Agbada Formation in the Akpor and Apara oilfields in the eastern Niger Delta was undertaken in order to determine the depositional development of the reservoir sand‐bodies. In the study area, the formation comprises a maximum of 29 relatively thick sandstones, cyclically interbedded with shales of varying thicknesses. The lowest tow sand units, separated by a shale unit and located near the base, produce petroleium from ten wells in both fields. Each sand‐body exhibits a coarsening‐upward textural gradient. The lower sand‐body (Unit A), which is oval‐shpaed, moderately‐ to poorly‐sorted, fine‐ to very coarse‐grained, carbonaceous, with clay and lignite horizons, is interpreted as a deltaic sand. The unit appears to have migrated landwards (north) (destructive delta), probably as a result of localized transgression, and developed maximum thickness between the two fields. The upper sand (Unit B) is fine‐to‐pebbly in grain size, well‐sorted and glauconitic. Maximum development occurred slightly east of the delat. As the unit prograded in a predominantly southerly direction, genetic currents simultenously caused it to be channelized. This sand‐body is interpreted as an offshore marine bar. The intervening carbonacous shale is thought to be of logoonal origin. Since the geometries of these sand‐bodies are not conclusively delimited by the existing well density, their pinch‐out edges to the north, east and west may constitute prolific stratigraphic traps.