http://journal.uir.ac.id/index.php/JGEET E-ISSN : 2541-5794 P- ISSN : 2503-216X Journal of Geoscience, Engineering, Environment, and Technology Vol 04 No 01 2019 Mohammed, A., et al./ JGEET Vol 04 No 01/2019 7 RESEARCH ARTICLE Assessment of Geothermal Potentials In Some Parts of Upper Benue Trough Northeast Nigeria Using Aeromagnetic Data Abdulwahab Mohammed 1 , Taiwo Adewumi 2, *, Salako A Kazeem 1 , Rafiu Abdulwaheed 1 , Abbass A. Adetona 1 , and Alhassan Usman 1 1 Department of Physics, Faculty of Physical Science, Federal University of Technology, Minna, Niger State, Nigeria. 2 Department of Physics, Faculty of Science,Federal University of Lafia, Nasarawa State, Nigeria. * Corresponding author : tydon4real@yahoo.co.uk , adewumi.taiwo@fulafia.edu.ng Received: Aug 30, 2018; Accepted: Feb 11, 2019. DOI: 10.25299/jgeet.2019.4.1.2090 Abstract The assessment of geothermal potentials over part of the upper Benue trough corresponding to Kaltungo, Guyok, Lau and Dong areas, North Eastern Nigeria using spectral depth analysis of aeromagnetic data has been carried out. The study area is bounded by latitudes 9 o o o o This research work is necessitated by the need for renewable and alternative sources of energy for use in Nigeria. Regional/residual separation was carried out on the total magnetic field using polynomial fitting method of order one. The residual map was divided into nine overlapping blocks for the spectral analysis. The centroid depths and depth to top of basement were obtained from the plot of log of power spectrum against wavenumber. These two parameters were used to estimate the Curie point depth using   = 2  −  , where   ,   and   are Curie depth, centroid depth and depth to top of basement respectively. The results from the spectral analysis suggested that in the parts of the Upper Benue trough, the basement is deepest at the south western portion towards the Lau area and varies between 0.55 and 3.8 km, while the centroid depth varies from 7.26 to 18.00 km. From the same portion of the trough, the Curie- point depths vary between 12.43 and 33.91 km and the corresponding geothermal gradient and heat flow values varying from 17.10 to 46.66 0 C/km with an average of 30.75 0 C/km and 42.75 to 116.65 mW/m 2 with an average of 75.91 mW/m 2 respectively. The maximum heat flow is found around the south western portion of the study area (Lau). The entire study area with high heat flow values might probably be good sources for geothermal and thereby recommended for both geothermal exploration and exploitation. Keywords: Aeromagnetic data, Curie point, Geothermal gradient, Heat flow 1. Introduction The study involves the quantitative estimation of Curie-point depths (CPD), geothermal gradients and subsurface heat flow anomalies for the assessment of geothermal potentials in some parts of the upper Benue trough northeast Nigeria using spectral analysis of the recently acquired high resolution aeromagnetic data. The high resolution aeromagnetic data was obtained from the Nigerian Geological Survey Agency (NGSA) as part of the airborne magnetic survey data acquired betw een 2005 and 2009. Several studies have shown that regional magnetic data can be used extensively to determine the thermal environments ( Spector and Grant, 1970; Nur et al ., 1999; Bhattacharyya and Leu, 1975, 1977; Tanaka et al ., 1999; Ravat et al ., 2007; Bansal et al ., 2011, 2016; Nwankwo et al ., 2011; Eletta and Udensi, 2012; Kasidi and Nur, 2012, 2013; Nwankwo and Sunday, 2017). For example, dominant magnetic minerals in crust pass from ferromagnetic to paramagnetic state at temperature, commonly called Curie-point temperature (CPT). Magnetite (Fe 3 O 4 ) is the most common magnetic material in igneous rocks and has an approximate CPT value of 580 o C ( Nwankwo and Sunday, 2017). At temperature above CPT, the thermal agitation causes the spontaneous alignment of the various domains in the mineral to be destroyed (or randomized) to the extent that the ferromagnetic minerals become totally paramagnetic ( Nwankwo and Sunday, 2017). The Curie-point is the temperature at which the spontaneous magnetization vanishes and magnetic minerals show paramagnetic susceptibility. The Curie- point depth is known as the depth at which the dominant magnetic minerals in the crust pass from a ferromagnetic state to a paramagnetic state under the effect of increasing temperature (Nagata, 1961). For this purpose, the basal depth of a magnetic source from aeromagnetic data is considered to be the Curie-point depth. Curie point temperature varies from region to region depending on the geology and the mineralogical content of the rocks. The assessment of the variations in the Curie-point depth of an area can provide valuable information about the regional temperature distribution at depth and the potential of subsurface geothermal energy ( Tselentis, 1991). The geothermal