LAKE BOGORIA HOT-SPRINGS (KENYA) - GEOCHEMICAL FEATURES AND GEOTHERMAL IMPLICATIONS

Many boiling springs and fumaroles are present along the shores of Lake Bogoria, which is a closed-basin alkaline saline lake typical of African Rifts. Two different geothermal waters, both of Na-HCO3 type have been recognized. The first, discharged by the boiling springs located along the western shores of the lake, comes from a shallow steam-heated thermal aquifer. Its temperature is close to 100-degrees-C, as indicated by chalcedony solubility, while the chloride content of these waters is slightly higher than 200 mg L-1. The second, recognizable in the southernmost boiling springs, is representative of a deeper and hotter geothermal reservoir. The occurrence of mixing and boiling processes complicates the interpretation of geochemical data. Nevertheless, a chloride content of about 660 mg L-1, an equilibrium temperature close to 170-degrees-C and a high carbon dioxide partial pressure, at least 10-20 bar, have been estimated for the deep geothermal reservoir.