Regional- to district-scale controls on thermal springs occurrence in South Africa: Insights from investigations of their spatial distribution and their spatial relationships with geological features

Abstract

In the study presented here, the spatial distribution of thermal springs in South Africa was investigated using point distribution analysis, fractal analysis and Fry analysis, and the thermal springs’ spatial relationships with high-heat-producing granitoids (HHPGs), groundwater yield, and structural lineaments were investigated using distance distribution analysis. The purpose of these spatial investigations was to explore the regional- to district-scale geological controls on thermal springs occurrence in South Africa. The results show that regional- to district-scale geological controls on thermal springs occurrence in South Africa involve the presence of or proximity to HHPGs (as heat source control), groundwater yield of ∼2 L/s (as water source control) and intersections of structural lineaments with particular trends (as pathways control). In southern and eastern South Africa, the pathways controls are, respectively, intersections of ENE-trending lineaments with NNW- and NW-trending lineaments and intersections of ENE- and WNW-trending lineaments. This spatial information comprises a conceptual model that can be used as a framework for regional- to district-scale predictive modeling and mapping of the prospectivity (or likelihood) of areas where geothermal resources potentially exist in South Africa.