ABSTRACT

 Understanding the subsurface architecture has been one of the challenges in the Benue Trough, hence this study. The study was aimed at using a combination of enhancement methods coupled with modeling to unravel the subsurface architecture through qualitative and quantitative analysis. Aeromagnetic data from six different locations from the Benue trough namely; Gboko, Otukpo, Ejekwe, Ogoja, Bansara and Abakaliki were used and the softwares used for the analysis were, oasis montaj, potent Q and ArcGis. The various maps generated are; total magnetic intensity map (TMI), residual map, reduction to equator (RTE) map, upward continuation and the SPI map. The data was equally modelled so as to obtained the magnetic susceptibility. The total magnetic intensity map (TMI) revealed areas of high magnetic intensity which are due to shallow basement or intrusions. The areas include, Gboko, Oju, Vandeikya, Bansara, Ogoja, Obubra and areas around Ezza north. The analysis showed that the study area has magnetic intensity values ranging from -75.7nT to 102.4nT. It was again noted that most ofthe anomalies ofinterest were from rock units with magnetic intensity which are either of regional origin or of localized intrusions. The basement was identified to be purely magnetic with the anomalies trending E-W, SW-NE and NE-SW directions, hence the intrusives noticed in some regions. The rose diagram shows that the mean trend ofthe structures within the area is at the angle of 52.5° which is relatively the NE-SW direction, this represents the main structural orientation ofthe area. Other variations include WNW-ESE and a very minor trend in the NW-SE direction, The regions which were recorded as having shallow depth as seen on the SPI map are Gboko, Oju, Adokwu, Ikom, Boki and Vandeikya, while areas such as Ejekwe, Bansara, Konshisha, Ushongo and Ohimin were noted as having high depth to basement. Further analysis of the models shows the presence of igneous rocks being suspected in Abakaliki and Vandeikya with susceptibility values of 0.059 and 0.0056. Also, the presence ofserpentine rocks is suspected in Bansara, Ikwo and Ohimini with susceptibility values of-0.123, -0.059 and -0.0621 respectively while Konshisha and Obudu with susceptibilities of 0.0786 and 0.0327 are suspected ofhaving the presence ofserpentine minerals and gneiss respectively. Gboko, Adokwu, Oju and Ejekwe were suspected of having the presence of limestone, siderite, calcite and siderite with susceptibilities of 0.3103, 0.01, 0.0017 and 0.01 respectively. It was however recommended that areas of shallow depth coupled with high magnetic intensity should be investigated further to ascertain the possibility of mineral deposits or other natural resources, while the areas with high depth to basement with low magnetic intensities should also be investigated further to ascertain the availability or otherwise ofother natural resourcesthat may be favored by such depth.