Global Advanced Research Journal of Physical and Applied Sciences (GARJPAS)

September 2015 Vol. 4(1), pp. 064-071
Copyright © 2015 Global Advanced Research Journals

Original Research Paper

Subsurface Resistivity Structures of Some Parts of Southern Upland Area of River Kaduna, North Central Nigeria

Alkali SC

Department of Geology, University of Maiduguri, P. M. B. 1069, Maiduguri, Nigeria

Email: samcrah@gmail.com, Tel: +2348069263114

Accepted 29 September, 2015

Abstract

Shallow subsurface electrical resistivity images of Southern Upland area of River Kaduna defined fresh geoelectric basement at different levels. While some parts of the bedrock topography outcropped on the surface, others are buried beneath weathered sediments.  Fracturing probably split and displaced the bedrocks into individual granite blocks along weak zones. The blocks that resisted weathering stood as isolated hill summits. Where the bedrock nears the surface, effect of fracturing is low. Development of deep fractures is however, pronounced along weak zones.  At some locations the fractures extended to the surface and in others, they assumed the structural shapes initiated by the fresh basement. Formation of ridge structures and characteristic dome-tops is probably due to resistance of the fresh bedrocks to conditions they were subjected to. The main weathered products of the profiles are gravels with some gravelly sands, sands and clays. Some of these sediments are exposed on the surface and constitute the main capping units. At some locations they occupy existing structures of the underlying fractures and inclined diagonally along their directions. Depression of underlying rock units housed considerable quantity of arenaceous sediments around some localities. Thickness of weathered regolith within two major fractured zones exceeded 30 m. Minimum thickness of the overburden is estimated at 7 m. Within the highly fractured zones clay matrix constitute minor constituents of the overburden. Clay sands occurred in patches and are enveloped by thin layers of sandy fractions in some locations.

Keywords: Dipole-dipole, resistivity, profile, bedrock, structures, fractures,