Areal And Depth Estimation Of Subsurface Anomalous Structures Of Oyandega And Environs, Part Of The Anambra Basin Using 2d Modelling Of Magnetic Data

This study employed spectral analysis, Source Parameter Imaging (SPI), and Euler deconvulation techniques on two aeoromagnetic data sheets (Illushi 286 and Nsukka 287) to assess the depth to sub-surface structures and estimate the depth to magnetic sources at the transition region of Oyandega Area, Ibaji local government of Kogi state, part of lower Benue Trough (Anambra Basin). SPI techniques show minimum to maximum depth to anomalous source as 25.765m to 2533.293m. Euler deconvolution for contact body (Structural Index=1), indicate depth ranges from -473.70m to 751.11m, for extrusive body like thin layer, dyke (Structural Index =2) ranges from -619.74 to 1122.25m and for sphere (Structural Index =3), the depth to magnetic source obtained ranges from -800m to 1494.12m. From the spectral analysis, depth to the first layer (D1) in the study area varies from 1.3100 km to 5.6700 km with an average depth of 3.4900 km while second layer depth (D2) varies from 0.15300 km to 1.3200 km with the average depth of 0.7365 km. This result therefore indicates that the average basement depth of the study area as deduced from power spectrum inversion is 2.11325 km. The results favour the accumulation of petroleum around Agnosi, Annegbette, ijankuta and Uhro of the study area. The shallow magnetic sources around Nwajala, Adani, and Ogbo-uvuru are believed to be the resultant of basement rocks that were tectonically uplifted into the sedimentary overburden.