COMPARISION CHARACTERTIZATION AND INTERPRETATION
OF GEOTHERMAL FLUID GEOCHEMISTRY IN SEDIMENTARY ENVIRONMENTS
OF KIBIRO, PANYIMUR AND ÖXARFJÖRDUR
Grace Lajwe
Ministry of Energy and Mineral Development
Department of Geological Survey and Mines
P.O. Box 9 Entebbe
UGANDA
gracelajwe@yahoo.com
ABSTRACT
Geochemical data interpretation of representative chemical analytical and isotopic results for
geothermal waters and gas in sedimentary environments obtained by standard analytical
methods were studied in this research work. Techniques like: - Chemical geothermometers
(silica and cation geothermometers) and gas geothermometers were used in the prediction of
variation of temperatures in these geothermal systems. The speciation programme WATCH
was used to calculate the different species of anions and cations, Na/K, Quartz and
Chalcedony temperatures, Ternary diagram for Na/1000-K/100-√Mg based on the
equilibration conditions for these cations in these waters at particular temperatures, and a ClSO4-HCO3 ternary plot constructed. Different mixing models and plots of different
constituent relationships were used in the comparison characterization and interpretations of
the geochemistry of these different geothermal areas. The geochemistry of magmatically
driven geothermal systems may be used to develop effective exploration techniques for the
geothermal systems that are driven by temperature gradients like the East African Rift
System (EARS) the western branch of which Kibiro and Panyimur are part.
The chemical and isotopic composition of the water samples from Kibiro, Panyimur and
Öxarfjördur, suggest mixing of cold ground water with geothermal waters. Major ions and
isotope parameters were used to characterize the waters from Kibiro and Panyimur as Na-ClHCO3 waters and waters from Öxarfjördur as Na-Cl waters. The main processes affecting
the geothermal system in the sedimentary geological environment are:-dilution and
conductive cooling