Interpretation of Aeromagnetic Data for Geothermal Energy: Investigation of Ikogosi Warm Spring Area, Ekiti State, Southwestern Nigeria

The thermal structure of the crust at Ikogosi Warm Spring area is examined using Curie Point Depth (CPD) estimates from spectral analysis of aeromagnetic data. The CPD values from 22 sliding overlapping blocks, 55 x 55 km in size, are estimated from the data. The slope of the longest wavelength part of the radially averaged log power spectrum divided by the radial frequency produced the depth to the centroid (zo) for the deepest crustal block. The depth to the top (zt) is obtained by the slope of the second longest wavelength part of the spectrum. From these depths, the CPD is calculated by using zb = 2zo - zt. The average CPD estimates for the Ikogosi Warm Spring area is 5.8 km. Corresponding heat-flow and thermal gradient values are calculated from the CPD estimates. The shallow CPD observed at the warm spring area explains the thermal source of the Ikogosi Warm Spring. Interpretation of aeromagnetic data indicates that the warm spring source is structurally controlled. Generally, the results indicate that the area is promising for further geothermal explorations.