Integrated Geophysical Mapping to Determine Depth to Basement at Awa Ijebu, Southwestern Nigeria

Abstract

Integrated surface electrical resistivity, magnetic survey and horizontal profiling were conducted at Awa Ijebu, South-western Nigeria, to delineate the probable depth of basement and determine geological anomalies therein.  Wenner resistivity profiling and magnetic data were acquired at intervals of 5.0m along four traverses of 100.0m long and five traverses of 250.0m long respectively.  The resistivity data obtained revealed three subsurface geologic layers: top soil, weathered bedrock and intrusive pegmatite rock. The distinct high resistivity zone is interpreted as the intrusive pegmatite rock while the low resistivity zone is interpreted as fault zone.  The magnetic survey result revealed that there was a high magnetic anomaly trending Southeast – Northwest direction and dipping westward.