Palyno-maceral and lithological analysis was carried-out on Mamu Formation, northern Anambra Basin, Nigeria. Analyses of the palyno-maceral composition of the exposed shale unit of the Mamu Formation in the northern Anambra Basin at Ojuwo-Olijo revealed that PM-1 and PM-2 were numerous and poorly sorted, as well as medium to small-sized PM-3 and PM-4, accompanied by Structureless Organic Matter (SOM). This scenario suggests predominantly terrestrial deposition conditions, with possible variations towards coastal and lagoonal environments in certain samples.