Depositional Environment of the Kerri-Kerri Formation Around Alkaleri in the Gongola Sub Basin of the Northern Benue Trough

Abstract

The depositional environment of the Kerri-Kerri Formation around Alkaleri area in 
the Northern Benue Trough was determined using lithologic sections and grain size 
parameters in which nine sandstone samples were subjected to granulometric and 
eight samples for petrographic analysis. The graphic mean size for the various 
samples from the data analyze ranges from -1.03ϕ to 5.10ϕ which indicate very fine 
to very coarse sand. sorting for the analyzed samples ranges from 0.90ϕ to 4.450ϕ 
indicating a moderate to extremely poorly sorted. The value of skewness for various 
samples ranges from -0.15ϕ to 4.40ϕ indicating strongly fine skewed to- coarse 
skewed. The value of kurtoses from the analyzed sample ranges from 0.91ϕ to 
2.20ϕ indicating mesokurtic to very leptokurtic. For the discrimination between 
aeolian and littoral (intertidal zone) environments, the Y1 equation is used and 
beach environment was inferred, since 100% of the values of Y1 are greater than – 
2.7411 The facie characterization and evaluation indicate that the occurrence of 
five lithofacies that consist of: Through cross bedded sandstone, Planar cross 
bedded sandstone, massive sandstone, massive siltstone and Mudstone facies. The 
association of these lithofacies give rise to two facies assemblage; Intercalated 
cross bedded sandstone and mudstone facies association (FAK1) and Bedded 
sandstone facie association (FAK2); these assemblages are characteristics of Fluvial 
environment.