Reappraisal of Heat Flow Variations in Mainland Africa

Abstract

A reappraisal of geothermal data of the mainland of Africa has been carried out based on data sets available at the IHFC website, incremented with updated information on volcanic activities of post Holocene times. Our compilation makes use of 1480 heat flow values that include 1327 observational data supplemented with 36 estimates derived from heat flow-age relation. In addition, the method of magmatic heat budget (MHB) has been employed in deriving deep crustal heat flow values for 117 for sites of recent volcanic activity, most of it located in Ethiopia. These data sets were regrouped into regular equal-area cells with dimensions of 5 x 5 degrees and subsequently employed in deriving maps of the regional distributions of heat flow and geothermal resources and interpreted on the basis of available information on tectonic setting and geological characteristics. The most prominent features are the relatively high values in the region of rift valleys in the eastern sector of the continent. High heat flow values also occur along north-south trending belts of Atlas Mountains in the north and pockets associated with the Cameroon volcanic chain on the west-central parts of the continent. The vertical distributions of temperatures were calculated for depths reaching down to 6 km. The associated resource base calculations indicate availability of high temperature resources in vast regions of the African continent.