PALEOBATHYMETRY IN THE WESTERN PORTION OF NORTHERN DELTA DEPOBELT OF NIGER DELTA, NIGERIA

Abstract

The probable age of the onset and end of the sedimentation of the paralic Agbada unit of the three commonly described lithostratigraphic successions in some parts of the Niger delta was established in this study. The Paleobathymetry as the sea rose and fell in the area was also described in line with the concept of sequence stratigraphy using biofacies data and wire line log. The trend of the paralic sedimentation suggests that the delta built out faster in the southwestern direction than in the western direction during late Oligocene to Early Miocene. This may be as a result of a southwest-northeast current during the period. In the northern part of the study area, paralic sedimentation, which was inferred based on the identification of the top of the Akata shale started about 50.0 Ma ago. The end of its sedimentation, taken as the onset of continental deposits in the area, started about 41.0Ma ago. This was determined based on the age of the first fossiliferous shale in the area. At the southern end of the study area, the onset of the paralic sedimentation was about 38.0Ma and ended about 28.1 Ma. These suggest that the period of paralic deposition in the northern depobelt was at a relatively steady rate of about 10.0 Ma. Key words. Lithostratigraphic, Paralic, Paleobathymetry, Agbada Formation, progradeds, sedimentation.