Investigation of Magnetic Anomalies of Chibok and Damboa Areas in North Eastern Nigeria, Using High Resolution Aeromagnetic Data

ABSTRACT The aeromagnetic data of Chibok (sheet 134) and Damboa (sheet 112) areas, southern Chad basin were interpreted qualitatively and quantitatively. Spectral Analysis, Source Parameter Imaging (SPI), Standard Euler deconvolution, Forward and Inverse modelling methods were used in the quantitative interpretation with the aim of determining depth to the magnetic source bodies, magnetic susceptibilities and the possible mineralization in the area. Oasis Montaj 6.4.2, WinGlink 1.62.08, Surfer 11 and Microsoft Excel softwares were employed in the data analyses. The estimated depths from the forward and 15 15 inverse modelling methods for profiles 1-7 are 2749, 2201, 2088, 703, 521, 927 and 481 m respectively. The respective susceptibility values were 0.20407, 0.47779, 7.8043, 0.1349, 0.0889, 0.3083 and 0.4820 SI, which indicate the presence of sedimentary intrusions (basalt or limestone), few metamorphic rocks (schist) and minerals (magnetite). Spectral analysis revealed two depth sources with the deep sources ranging from 1485.3 4093.6  with an average depth value of2390.1  , while the shallow depth sources range from 405 844  with an average depth value of 567  . The temperatures at these depths range from 81.65°C to 169.16°C for the deeper sources and from 31.12°C to 32.82°C for the shallow sources. The SPI estimated depth ranges from 72.2  (shallow magnetic bodies) to 5026.4  (deep lying magnetic bodies.). The Euler depths for the four different structural indices (SI = 0, 1, 2 and 3) range from 2106.2 to 4480.3 m which are depths of shallow and deep magnetic sources in the study area. The positive numbers obtained in the Euler structural index (SI = 2) shows the magnetic sources resulting from the outcrops within the study area. Maximum depths obtained from Spectral analysis, SPI and Euler deconvolution show thick sediment that is sufficient for hydrocarbon accumulation.