Textural and Compositional Studies of Sediments from Parts of the Albian Bima Sandstone, Upper Benue Trough, Nigeria

Abstract

Studies were carried out on fresh samples of sandstones from parts of the Bima Sandstone to classify it on the basis of its textural and compositional characteristics. Grain size analysis of samples reveals that they are fine to coarse-grained, moderately sorted to poorly sorted, coarse skewed to strongly fine skewed and very platykurtic to extremely leptokurtic. Thin-section analysis reveals the sandstones to be lithic subarkoses, subarkoses, and lithic arkoses comprising averagely of 66.6% quartz, 21% feldspar and 12.4% rock fragments. The appreciable amount of feldspar, the dominance of subangular to angular grain shape and the poorly sorted nature of the sandstones suggest that they are texturally and mineralogically immature sediments. Bivariate plots of graphic mean versus standard deviation, skewness versus standard deviation and simple sorting versus simple skewness indicates a fluvial origin for sandstones deposited under a moderate to high energy level.