Anomalous geothermal gradients and heat flow in the Limpopo Province, South Africa: Implications for geothermal energy exploration

The crustal rocks of South Africa are generally regarded as too old and cold for utilisation of geothermal energy. However, demands for alternative energy and the introduction of new technology have instigated a number of research projects in this and surrounding countries. Higher than average heat flow and the occurrence of several thermal springs in the northern Limpopo Province suggest that this region is a potential target area. Geothermal measurements in the eastern part of the Province yield anomalously high rock temperatures, thermal gradients (up to 90 K/km) and heat flow (up to 200 mW m(-2)). The anomalies are attributed to deep-seated circulation of meteoric water that provides an effective mechanism for concentrating geothermal heat. Heat flow studies of this kind may reveal more extensive potential geothermal fields elsewhere in South Africa.