Microphytoplankton biozonation of late Albian - Turonian succession in Famo-1 well, Gongola Sub Basin, Upper Benue Trough, Nigeria

Abstract

A comprehensive palynological (Dinoflagellate Cyst) study of 35 ditch cutting samples recovered from Late Albian to Turonian succession penetrated by Famo-1 well in the Gongola sub Basin, Upper Benue Trough, North East, Nigeria, generated biostratigraphically important dinoflagellate cyst species. Intervals (8300 ft. – 8330 ft.) in the lower part of the studied section were barren of dinoflagellate cysts. Interpretation of the first and last (FAD and LAD) appearance datum of the recovered dinoflagellate cyst assemblages allowed the erection of four informal dinoflagellate cyst assemblage biozones. The biozones in stratigraphically ascending order and their ages are as follows: Late Albian-Cenomanian (Biozone I & II), Turonian (Biozone III) and undiagnostic (Biozone IV). The ages of these zones based on stratigraphic positions and series of first occurrences of key species are from Late Albian-Turonian. An inner neritic palaeoenvironment was delineated based on the dominance of Peridinacean cysts over Gonyaulacacean cysts.

Keywords: Turonian, Cenomanian, Biozone, palaeoenvironment