Spectral Analysis Aimed at Delneating the Curie Point Depth and Geothermal Potentials in Parts of Lower Benue Trough

Abstract

The need to increase power generation in Nigeria necessitates the quest for alternative sources of energy which are green, renewable and durable at large. Our aim in this research is to explore zones with geothermal prospects so as to alleviate the nations dwindling hydrocarbon dependence.  This research utilized the aeromagnetic technique to investigate the subsurface properties in parts the lower Benue Trough with respect to its sediments, basement rocks and geothermal potentials. Twelve sheets of the aeromagnetic data were used covering Nsukka, Igumale, Ejekwe, Ogoja, Udi, Nkalagu, Abakaliki, Bansha, Okigwe, Afikpo, Ugep, and Ikom areas. These Twelve data sheets covered areas within latitude 5˚30΄N to 7˚00΄N and longitude 7˚00΄E to 9˚00΄E. Composite aeromagnetic data was merged to produce a merged map for the study area using Oasis Montaj8.3. The Total Magnetic Intensity (TMI) of the study area depicted intensities ranging from – 47.2 nT to 143.1 nT on merging. This was followed by spectral analysis to generate spectral depths of the deeper and shallow sources from which we calculated the Curie point depth and other geothermal parameters. Spectral analysis results show that the deep depths and shallow depths of the suspected magnetic bodies have an averavge value of 7,035 m and 350 m respectively. Curie depths show that the magnetic rock materials in the study area lose their magnetism due to temperature increase at depths between 4 km to 21 km which suggests that the source of the magnetic anomaly in those areas are highly magnetic. The geothermal gradient of the study area ranges from 25 ⁰Ckm^-1 to 125 ^oCkm^-1   while the heat flow of the study area range from 80 mWm^-2 to 365 mWm^-2 which suggests that the study area is a good source of geothermal energy with areas like Okoroba and Okorroba showing the highest potential.