Source Depth Determination of the Ningi-Burra Younger Granite Complex North-Eastern Nigeria from Aeromagnetic Data

Source Parameter Imaging (SPI) of aeromagnetic data covering an area within Birnin-Kudu Sheet 105 SE, Gwaram Sheet 106 SW, Kalatu Sheet 127 NE and Kaffin Madaki sheet 128 NW, bounded between Latitudes 10o 55’ N to 11o 10’ N and Longitudes 9o20’ E to 9o 35’ E. The application of Source Parameter Imaging (SPI) method revealed depth ranging from 64.704m to 538 to 777m, map of the depth estimates obtained from the SPI solution plot superimposed on the residual magnetic field intensity map of the area. The blue to cyan colours (64.704m to 111.520M) indicates the shallowest portions of the basement, the Green to Yellow colours (115.773m to 187.186m) represent the intermediate depth, while the Red to Pink coloured (201.698m to 538.77m) represent the highest peak of the area which are the deepest areas. The results from the SPI study indicate that deep seated bodies (dykes) dominated the area. Other Euler deconvolution solutions were also obtained by first selecting a magnetic structural index of zero (i.e., SI=0), followed by SI=0, SI=1, SI=2, and SI=3. This is based on the concept of Euler homogeneity, a description of scaling behavior in potential-field depth analysis. The magnetic structural index (SI=0) represents the depth of the contact with basement, which is as low as -131.093m and the highest is at 329.960m The best clustering solution was obtained by selecting a structural index of one (i.e., SI = 1) shows that the solution plotted as clustered in the region where the geological structures are located in the depth range of 8.707m to 1370.815m, which indicates that the deep magnetic bodies are concentrated at the peripheral side of the ring complex. The deeper magnetic sources are at the depth of -163.723m to the basement, while the highest depth to the shallower magnetic source in the area is 700.594m and represents the extrusive bodies in the area.