Micropalaeontological including palynomorphs studies of Cretaceous to Tertiary Sequences in the straddled areas of the northern Anambra and southern Mid-Niger Basins: Implications for palaeoenvironment and depositional settings

Abstract

In order to determine its palaeoenvironments and the depositional settings inherent therein, the straddled area in northern Anambra Basin as well as southern Mid-Niger Basins has been examined for its palynomorphs and other micropalaeontological contents. The examined units are the Lokoja Formation, Patti Formation, and Agbaja Formation in the southern Mid-Niger Basin, and the Mamu Formation and Ajali Formation in the northern Anambra Basin. The Mamu Formation of the northern Anambra Basin is composed primarily of claystones, siltstones, shale, and coal units with the presence of palynomorphs such as Cleistosphaeridium cf.,  Leptolepidite major, Triporites sp., Lycopodiacidites asperatus, Retitricolporites cf., Milforda sp., Ephredites sp., which are all palynomorphs, and a number of plant cuticles and megaspores indicating some kind of a continental environment of deposition in that part of the basin. Phytoclasts, plant fragments, megaspores, and palynomorphs predominate in the southern Mid-Niger Basin assemblages, which are in a moderate to good state of preservation and represent a continental to shallow marine environment. Palynomorphs and foraminifera are primarily Maastrichtian in age. Echitriporites triangulate, Longaprtites marginantus,  Barculatisporites sp., Cingulatisporites sp., Ephredites sp., Stephanocolporate zonorate, and Florentina sp. are some examples of the palynomorphs that were equally recovered and points corresponding to marshy-swampy environments for the straddled part of the southern Mid-Niger Basin which has some evidence of marine transgressive events.