A concise review on the sedimentary and palynological signatures of mid-cretaceous sediments, Southern Bida Basin, Nigeria

Abstract

The southern Bida Basin is the southern arm of the Nigerian inland rift system that needs detailed investigation in terms of stratigraphic and age precision and the description of depositional environment as well as promising hydrocarbon potential. The study focuses on the review of the stratigraphic and palynological setting of the sediments of Cretaceous (Upper Maastrichtian) in the Patti Formation. This paper integrated the sedimentological and the palynological data in order to improve age determination and paleoenvironmental reconstruction. Lithologic descriptions, and palynological analyses were done on dark grey to black shale samples of Ahoko and Acheni outcrops respectively through field observations. The study revealed dominantly Upper Maastrichtian palynomorphs such as Monocolpites marginatus, Proteacidites cf. dehaani, Longapertites sp., Cyathidites sp., and Echitriporites trianguliformis in the study sections of the basin. Evidence of freshwater algae (Botryococcus braunii) and diatom frustules revealed a fluvio-lacustrine and low-energy as well as swampy depositional environments amidst a humid climatic condition. The presence of diagnostic marker Retimonocolpites and Zlivisporites indicates early Paleocene and this implies an uninterrupted sedimentation through the Cretaceous-Paleogene boundary. The combination of sedimentary facies and palynology addresses explicitly zonation, depositional interpretation and environmental proxies to age determination that was stated in previous work. This study also proves the value of palynology in the determination of environmental signatures of inland basins that have not received much description and attention, such as the southern Bida Basin.