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Detailed geological work has concentrated on three main geothermal areas of southwest Uganda: Katwe-Kikorongo, Buranga and Kibiro hot springs. This has included geochemical exploration, isotope hydrology, geological mapping and geophysics. Using resistivity measurements, anomalies were located in Katwe and Kibiro, thought to delineate a geothermal reservoir. However, drilling of geothermal gradient wells gave no sign of geothermal activity. Hence, there is a need to expand the previously targeted areas for drilling and to probe deeper. In this project, a study was carried out to correlate different geothermal hot springs with the aim of grouping them into geothermal fields. The characteristics of the geothermal fluids were studied using Cl-SO4-HCO3, Na-K-Mg, Cl-Li-B ternary diagrams, speciation using the WATCH program, isotopes, and ratios between conservative elements and mixing models. The Cl-SO4-HCO3 ternary diagram was employed to classify Amoropii, Okumu, and Kibiro as chloride waters, Kitagata and Kanangorok as steam heated waters, Kibenge, Kabuga and Rwagimba as volcanic waters, but Amuru, Amuru (Pakele) and Avuka as peripheral bicarbonate waters. The source of geothermal fluids is old base rock rather than underlying sediments and the fluids are partially or fully equilibrated. The δ2H versus δ18O plots and the Cl/B, Cl/Li, Na/K, Na/Cl ratios show that Kibenge, Rwagimba and Kabuga are correlated to Buranga with fluids of similar origin while Kibiro and Panyamur appear to be linked, with Avuka at the periphery of the Kibiro-Panyamur geothermal area. SiO2-CO2 mixing models show that there was no boiling in the hot springs studied but there was some evidence of mixing. The log Q temperature plots for minerals show that Kanangorok, Kabuga, Kibenge, Rwagimba, and Okumu are saturated with calcite and could be prone to scaling if utilised. |
