Microphytoplankton and Geological Boundaries in Maastrichtian to Lutetian Succession of Ajire-1 Well Anambra Basin, Nigeria

Lucas F. A.

Department of Geology

University of Benin, Benin-City, Nigeria

E-mail: drfalucas@gmail.com

ABSTRACT

Dinocysts and acritarchs recovered from Ajire-1 well were evaluated and appraised for their palynostratigraphic utilities. Interpretation of their bio-events allows the recognition, delineation and numerical age dating of five stage boundaries in the well section. These are from oldest to youngest Maastrichtian / Danian, Danian / Selandian, Selandian / Thanetian, Thanetian / Ypresian and Ypresian / Lutetian boundaries respectively. The last appearance datum [LAD] of Paleocystodinium australinium allows the recognition of early/late Selandian boundary. Comparison of the bio-events identified in this study with internationally established planktonic foraminiferal zonal schemes suggests numerical age estimates of the five stage boundaries as 65.0Ma, 60.9Ma, 59..2Ma 54.8Ma and 49.0Ma respectively. The early /late Selandian boundary is 60.0Ma.It is envisaged that the information documented in this paper would enhance the interpretation and age characterization of sub-surface sequence stratigraphic events in the southern Nigeria sedimentary basins.

Keywords: Microphytoplankton; Boundaries; Maastrichtian; Lutetian; Ajire-1 Well; Anambra Basin.