Paleo-Environmental Deductions from Grain size Analysis: A Case Study of the Eocene - Oligocene Sand Facies in Osumenyi and Ukpor areas of South-Eastern, Nigeria
Received Date: Nov 04, 2018 / Accepted Date: Mar 14, 2019 / Published Date: Mar 21, 2019
Abstract
The Eocene–Oligocene sand facies is well exposed around Osumenyi and Ukpor areas in the Anambra Basin of southeastern Nigeria. Outcrop sections were located, measured, described in detail and sampled so as to decipher the paleoenvironment of deposition, using an integration of sedimentary facies and grain size analyses. The sedimentary facies study suggests that the Eocene– Oligocene age in this area consist mainly of three facies association; sandstone, lignite and clay facies. The fine-grained sandstone sub-facies is indicative of shoreface, the medium grained sandstone sub-facies is indicative of estuarine, while the coarse-grained sandstone sub-facies suggests a fluvial environment. The lignite facies indicate a continental origin (swamp environment) while the clay facies are interpreted as fluvially intercepted shallow marine environment. Results of grain-size analysis for the Eocene– Oligocene age show that the sands are medium grained, moderately to poorly sorted, very negatively to positively skewed and very platykurtic to very leptokurtic. Bivariate plots of mean size against standard deviation and skewness against standard deviation support a fluvially dominated shallow marine environment with tidal crosscuts. Result of multivariate functions showed a fluvially intercepted shallow marine environment. This study is significant in providing evidence for the reservoir potentials and aquifer characteristics of the Eocene – Oligocene sand facies for petroleum accumulation and prolific water bearing units within the basin.
Keywords: Eocene–Oligocene sand facies; Anambra Basin; Paleoenvironment; Grainsize analysis; Reservoir potentials; Petroleum accumulation
Citation: Chidera Ikechukwu V, Egbunike Michael E, Okpoko Ephraim I, Okpala Emmanuel C, Onwuka Chisom J (2019) Paleo-Environmental Deductions from Grain size Analysis: A Case Study of the Eocene – Oligocene Sand Facies in Osumenyi and Ukpor areas of South-Eastern, Nigeria . J Earth Sci Clim Change 10:512.
Copyright: © 2019 Chidera Ikechukwu V, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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