Ikoro D.O, Amajor L.C, Inyang D.O, Okereke C.N, Ekeocha N.O, Ibeneme S.O, Israel H.O, Nwagbara J.O and Essien, A.G
This study is focused on the Upper Cretaceous Maastritchtian Ajali Sandstone within the Afikpo Basin. It is aimed at determining the sedimentology, the depositional environment as well as a sedimentary model for the sandstone. The research was carried out using field relationships based on syndepositional sedimentary structures, grain size analysis and first order embedded Markov chain analysis. Field data and observations show that Ajali Sandstone is partly coarsening upward and fining upward sequences, dominantly cross bedded and highly bioturbated. Granulometric analysis shows coarse, medium to fine grained, bivariate and multivariate analyses reveal that Ajali Sandstone is predominantly fluvial but tidally influenced. Paleocurrent plots indicate that the paleocurrent direction is Southwest while the provenance is Northeast with occasional reversals suggesting that the sediments were mainly sourced from the nearby Oban Massif and partly from the Okigwe Abakaliki Anticlinorium. Application of first-order embedded Markov-chain statistics reveals that deposition do not exhibit Markovian property (cyclicity) implying that there was no memory in the depositional medium during the deposition of Ajali Sandstone.
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