Physical and Mineralogical Characteristics of Overburden on Three Common Basement Complexes

Abstract

Disturbed soil samples taken at depths 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, and 5m/to bedrock from three (3) trial pits, of common basement complexes around Minna, of granite, gneiss and schist parent rocks, were subjected to physical tests, while X-ray diffraction (XRD) method was employed for the mineralogical analysis. Variation of physical and mineralogical properties with depth of the weathering profiles was made. Index properties results for the three (3) location shows, they are clay and silt of intermediate and low plasticity with liquid limit and plasticity index ranging between 27.80 to 50.50% and 4.74 to 40.00% respectively while percentage of fines ranging between 24.67 to 63.70%. The x-ray diffraction results show the presence of quartz in all locations, while the major minerals for each of the location were identified to be kaolinite, albite; a non-clay mineral and illite in combination with other minerals. The presence of kaolinite in combination with other clay minerals, such as montmorillonite is responsible for intermediate plasticity of samples of granite parent rock.