An attempt to estimate the Curie-point isotherm depths in the Nupe Basin, West Central Nigeria

Abstract

An estimate of Curie-point isotherm depths has been made in the northern part of the Nupe Basin, west of Central Nigeria, from the spectral analysis of aeromagnetic data. Curie-point, the temperature at which rocks lose their ferromagnetic properties, provides a link between thermal models and models based on the analysis of magnetic sources. The result of this study shows that the Curie isotherm depth varies between 12 and 30km in the study area. In the southern portion of the study area, the curie-depth was found above 28km while it was found to be less than 14km in the northern part. It had previously been discovered by earlier workers that Curie-point depths are shallower than 15km for volcanic and geothermal fields, between 15-25km for island arcs and ridges, and deeper than 20km in plateaus and trenches. Therefore, when the values for the study area are compared with these values, the areas with variations less than 15km maybe recommended for further geothermal reconnaissance studies.