GEOPHYSICAL INVESTIGATION OF OLI RIVER LODGE DAM AXIS, KAINJI LAKE NATIONAL PARK, NIGERIA
1J. B. Arubayi; 2B. D. Ako; and 2T. R. Ajayi
1Department of Physics, Federal University of Petroleum Resources, Effurun
2Department of Geology, Obafemi Awolowo University, Ile-Ife, Nigeria
E-mail: jarubayi@yahoo.com
ABSTRACT
The Kainji Lake National Park is composed of the Borgu and Zurguma sectors. The main objectives of the parks are the conservation of gene resources of indigenous wild life plants and animals and management for educational and tourist purposes. The need to complement the above objectives with a lake for recreation (boating, fishing etc) at the Oli river lodge resulted in proposing a weir across the Oli River at the camp site. Investigations using geophysical (Vertical electrical sounding, resistivity profiling and electromagnetic) methods were carried out, along geophysical traverses TS1, TS2 and Ts3 at the proposed weir across the river. The geoelectrical section along the major Weir axis varies from two to four layers. The western bank depth to basement varies from 3 to 6m. Granite exposures occur along the river channel with highly jointed features (width 80m). The eastern bank shows a more variable and compact topsoil than that of the western bank. The underlying layer is a zone of varying resistivity values, which suggest fracturing/faulting, or jointing. The geophysical result of the marked complexity at the eastern bank, show that it is underlain by conductive materials which probably are due to the presence of water saturated fracture/fault zones within the area. Depth to the fresh bedrock will however be ascertained by the drilling of two additional boreholes that will allow a seepage-free foundation to be laid.
Key words: Weir axis, resistivity, fracture/faulting and geoelectric section