Geochemistry of Dofan-Fentale Geothermal Prospect

Abstract

Dofan-Fantale geothermal prospect is one of the geothermal fields in Ethiopia that w recommended for further study by UNDP (1973). Currently detailed geological, geochemical a geophysical studies are going on. Dofan-Fantale area is located in the Southern Afar Region, Ethiopian Rift Valley, which is about 200km NE of the capital, Addis Ababa. Twenty-eight wa samples from thermal springs, boreholes, lakes, rivers, and dug wells were collected in the a under study. Water chemistry suggests the existence of NaHC03, CaRC03 and NalClRC03 wa types. The reservoir temperature as indicated from the geothermometry results of Rabilo spring (Sp-4) is close to -250°C. Water - mineral equilibria study has shown that most of t common geothermal minerals are over saturated at .... 100Co at atmospheric pressure. Howev they are found to be in equilibrium with the reservoir rock at a temperature of -250°C at dep The 02H versus 0180 plot has revealed .. 180 - shife of 1.4 %0 for Habilo thermal feature (Spwhich might indicate higher water-rock interaction than the other hot springs.