Airborne Geophysical Survey

Index map of the airborne survey blocks flown between 2003 and 2010 for the Nigerian Geological Survey Agency (electromagnetic surveys not shown). In the background is the Geological Map of Nigeria (NGSA, 2006).
Courtesy of the NGSA and PGW

Geophysical responses over the central Benue Trough (250 km x 230 km). Top left: Ternary image of radiometric data (RGB = K-Th-U) Top right : Reduced-to-equator magnetic field. Bottom left: SRTM digital elevation model. Bottom right: First vertical derivative of the total magnetic field.
Courtesy of the NGSA and PGW
By Graham Chandler