Key sequence-stratigraphic markers define intervals recognised in outcrops and wells in the Aptian-Albian Mfamosing Limestone Formation in SE Nigeria. These markers aid in outcrop-to-subsurface correlation. The influx of siliciclastics and sea-level fluctuations controlled carbonate production. Peritidal, lagoonal and reefal carbonates rim the igneous Oban Massif and reflect an initial relative sea-level high stand. Subsequent sealevel fall was accompanied by the progradation of carbonates away from the exposed, siliciclastic-shedding hinterland, and maximal carbonate production took place during a sea-level lowstand, when an open-marine carbonate shelf and a mixed carbonate siliciclastic shoal co-existed side by side. In the Ituk area, wave action abraded the sea floor which was occasionally exposed, and hardgrounds and leached horizons were formed Bed- and matrix-selective dorag dolomitisation improved the reservoir potential of the carbonates in certain intervals.