Geochemical Study of Thermal Springs in Eastern D.R. Congo

Abstract

Thermal water samples were collected in North and South Kivu provinces of D.R. Congo, along the western branch of the East African Rift System. Surface temperatures range from 30ºC to 100ºC and the springs are neutral to alkaline. Chemical analysis of all samples show strikingly high bicarbonate content relative to the common major anions in hot springs, i.e., chloride and sulphate. Due the unusually high CO2 content in high temperature volcanic gases of the nearby Nyiragongo volcano, and due to the huge amount of dissolved magmatic CO2 in Lake Kivu, it is suggested that the high bicarbonate content in the springs stems from a constant supply of magmatic carbon dioxide to the geothermal system. Na-K geothermometers suggests underground temperatures ranges of 150 to 270ºC in North Kivu geothermal areas and 275 to 369ºC in South Kivu.