Estimation of Curie point depth, geothermal gradient and heat flow within the lower Benue trough, Nigeria using high resolution aeromagnetic data

摘要

Aeromagnetic data have been used in estimating the Curie point depth (CPD), geothermal gradient and heat flow within the lower Benue trough, Nigeria, using the spectral analysis method. The area covered is approximately 227,225 km(2). It is bounded by latitudes 6 degrees 30 ' to 8 degrees 00 ' N and longitudes 6 degrees 30 ' and 8 degrees 00 ' E. The results of this study show that the depth to the centroid (Z(o)) varies between 6.268 and 12.556 km, and the estimated depth to top boundary (Z(t)) varies between 6.268 and 12.556 km. The depth to the top boundary (Z(t)) of magnetic sources ranges from 0.796 to 2.171 km beneath the level of the sea. Furthermore, Curie point depth obtained varies between 10.5 and 22.5 km, and the geothermal gradient ranges from 25.527 to 54.063 degrees C/km having an average value of 37.821 degrees C/km. On the other hand, the calculated heat flow values ranges from 63.818 to 135.160 mW m(-2)having an average value of 96.2198 mW m(2). The graph of Curie point depth plotted against the values of heat flow shows a linear and inverse relationship. This relationship indicates that the Curie point depth increases as the heat flow decreases in the study area. With the high geothermal gradient in the study area, there is a possibility of the geothermal energy potential in the study area. These results demonstrate that the contribution of knowledge of Curie depth point and thermal heat flow to geoscientists could be traced to the thermal history of the study area.