Thermal structure of the African continent based on magnetic data: Future geothermal renewable energy explorations in Africa

Abstract

The defractal method was applied to the observed magnetic data and was used to estimate Curie point depth (CPD) i.e., depth to the base of magnetic sources (DBMS), near-surface geothermal gradient (GG), surface heat production and bulk crust thermal conductivity of Africa. A range of window sizes was tested using different values of the fractal parameter (α). The calculated DBMS ranges from 19 km to 112 km in Africa, and the GG varies from 15.9 °C/km to 30 °C/km (averaging 25 °C/km). Surface heat production values vary between 0.2 μW/m2 to 5.6 μW/m2, averaging 2.5 μW/m2. The calculated bulk crust thermal conductivity ranges from 1.4 W/mK to 3.4 W/mK with an average of 2.6 W/mK. In general, shallow DBMS, high GG, and high surface heat production coincide with known geothermal, volcanic, and seismic regions in Africa. Shallow DBMS, high GG, and high surface heat production were encountered in southeastern Africa, northeastern Africa (Egypt and Red Sea), and northern Africa (Hoggar region). High bulk crust thermal conductivity values are encountered in northern Africa (Algeria, Morocco, Libya), southeastern Africa and the East African Rift (EAR) regions.