The rocks of the Jos-Bukuru area in North Central Nigeria is characterized by negative and positive gravity residual anomalies ranging from -25 to +20 mGals. Lineaments were extracted from the gravity residual anomaly map for the purpose of assessing the groundwater resources in the area. The region is marked by more than one set of lineaments, each with its distinctive orientation and probably spacing. Lineaments shorter than 20 km in length are shallow structures suitable for this exercise because of their importance in groundwater recharge, transmission and discharge. In a bin size of 15˚ one major and one minimum striking directions between 000˚ and 030˚ were obtained. The major type lies between 000˚ and 015˚, while the minimum one is oriented within the 015˚ and 030˚ direction. These directions correspond to the stress axis of the essentially north-south trending geological structures of Nigeria. Invasions of mineralizing fluids might had sealed some of the joints and other fractures, however where the open spaces are not sealed, weathering and erosion widen and deepened the joints paving routes for surface water flows and direct seepage into the underlying strata. On the lineament density and lineament intersection maps the closures suggest probable discontinuity of the aquifer units. On this basis of the lineament density and the lineament intersection results, the area was divided into three hydrogeological zones. Site 1 is considered most favourable for water well development, while site 3 may result in low yields or even in abortive water wells.

Magnetic data were compiled from four aeromagnetic maps. A submap for the study area was produced from the four magnetic sheets in an ILWIS environment. Magnetic intensity values vary between 32,600 and 33,160 nT. The lowest magnetic contour values closure is centred over the Kagoro granite rocks at the central part. This closure is structurally aligned along the NE -SW direction. Regional field values vary between7789.1 and 7896.6 mGal. The residual contour values range from -180 to +160 nT. The main closure of the residual map is located on the central part of the area. A slipper-shaded closure centred over the Kagoro Granite is oriented along the NNE -SSW direction. Some of the closures in the study area are aligned along the NE -SW and E -W directions. Patterns of the closures of the magnetic maps are in conformity with those of the Nigeria basement and younger granite rocks. Isolations and magnitudes of the closures suggest that the various rock bodies occur separately and at different levels. The regional fields along nine profiles were obtained by third degree polynomial fitting using OriginLab7 software so as to obtain the residuals used for the models. The residual anomalies were accounted for by Mag2dc (2.5D) algorithms. The four profiles that traversed the Kagoro younger granite complex were estimated at maximum thicknesses of 14.1, 15.2, 9.5 and 10.4 km. These suggest that the Kagoro younger granite complex was emplaced at depths between 9.5 and 15.2 km. The volcanic rocks and their associates were formed from depths between 4.7 and 13.0 km.

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