Gravity and magnetic investigations are undertaken to determine the structure in the Gongola arm of the Upper Benue Trough. The area is characterized by negative Bouguer anomalies ranging from -75 to -10 mGal. The residual gravity anomalies range from -28 to +20 mGal. Results of 2.5-D modeling of the residual gravity anomalies along selected profiles reveal the presence of horst and graben structures. Some of these grabens are as wide as 80 km and are filled by sediments as thick as 4.8 km. The interpreted results also suggest the presence of basic intrusives (of density about 2800 kg m^-3) as shallow as 0.5 km extending upto 8 km. Magnetic data interpretation along some profiles coinciding with interpreted gravity profiles also reveal the existence of high magnetic susceptibility rocks (about 0.0476 SI units) of basic to ultrabasic composition at 7 to 8 km depth. A prominent magnetic lineament identified was interpreted in terms of a geosuture zone at depth beneath the Gongola Arm of the Benue Trough.

The Gongola arm of the Upper Benue Trough (Figure 1), a part of the Benue linear rift structure, developed closely with the separation of Africa from South America and the opening of South Atlantic Ocean. The Benue trough is about 250 km wide in its southern portions consisting of the Anambra Basin, Abakaliki Anticlinorium and Afikpo syncline (Figure 1). Towards the Northeast, the width of the trough varies between 80 and 150 km. The total length of Benue trough is about 1000 km.

Interpretation of Gravity and Aeromagnetic Anomalies in the Gongola Arm of the Upper Benue Trough, NE Nigeria, Gravity, Magnetic, Geosuture, Benue trough, Nigeria,interpreted, anomalies, residual, presence, magnetic, composition, developed, extending, geosuture, Afikpo, interpretation, investigations, lineament, Magnetic, Anticlinorium, sediments