Geophysical Survey as a useful Instrument for Determining Subsurface Lithology in Igarra, Edo State, Nigeria

Abstract

The investigation of direct current probing of sea level for subsurface lithology in Igarra area of Edo State, Nigeria was carried out using electrical resistivity method based on schlumberger array of vertical electrical sounding (VES). The need to carry out this research became imperative in view of the fact that subsurface lithologies are of economy importance to mankind for development. Ten (10) VES, uniformly distributed was carried out at four (4) different stations. A computer iterative method of interpretation was employed using the IP12WIN and win rest software. The results were correlated with geologic and lithological data/log acquired from the survey area to obtain the desired lithologies or rock types. The various subsurface lithologies encountered were topsoil, sandstone, wet sand, sand and clay with resistivities varying from (60-300) ohm-m, (200-400) ohm-m, (200-500) ohm-m (300-600) ohm-m, (70- 130)ohm – m respectively, thicknesses raying from (0.2-2.00)m, (0.4-2.00)m,  (3.50-6.50) m (25-55)m and (1.0-3.0) m respectively, depths varying from (0.2-2.0)m, (0.6-4.0)m, (4.10- 10.50m), (29.10-65.50)m and (30.10-68.50)m. These results agreed very well with available borehole records of the area.