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Vol.1 , No. 3, Publication Date: May 30, 2018, Page: 124-131
 was calculated and average standard deviation of 0.89ϕ shows that the sandstones are moderately sorted and an average skewness value of -0.05ϕ implying sandstones that are strongly coarse skewed. Graphical plot of cummulative percent retained against grain size in phi shows that the sandstone sediments were predominantly deposited by saltation and traction processes as bed loads. The depositional environment is interpreted as fluvial with the aid of bivariate plot of skewness against standard deviation, but inference drawn from sedimentary structures and facies association points to deposition in delta plain environment.&picture=http://www.aascit.org/aascit/decorators/img/journal/810.jpg)
| [1] | Imoh Uchechukwu Emmanuel, Department of Geology, School of Physical Sciences, Federal University of Technology, Owerri, Nigeria. |
| [2] | Ogbonna Ndubuisi Alex, Department of Geology, School of Physical Sciences, Federal University of Technology, Owerri, Nigeria. |
Four outcrops of Nsukka Formation located in Ihube and Umuasua areas were studied and 38 sandstone samples were collected and subjected to sieve analysis. The aim of this study is to determine the textural characteristics of sandstone facies of the Nsukka Formation. Syn-sedimentary structures seen in the study area includes planner cross beds, flaser bedding and current ripples as well as vertical burrows of the scholitos ichnofacies, while post sedimentary structures seen include ferruginised hardgrounds and concretions. An average mean grain size of 1.15ϕ (medium grained) was calculated and average standard deviation of 0.89ϕ shows that the sandstones are moderately sorted and an average skewness value of -0.05ϕ implying sandstones that are strongly coarse skewed. Graphical plot of cummulative percent retained against grain size in phi shows that the sandstone sediments were predominantly deposited by saltation and traction processes as bed loads. The depositional environment is interpreted as fluvial with the aid of bivariate plot of skewness against standard deviation, but inference drawn from sedimentary structures and facies association points to deposition in delta plain environment.
Keywords
Nsukka Formation, Sandstone Facies, Depositional Environment, Granulometric Analysis
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