Constraining the Origin and Age of the Thermal and Cold Water in the Lake Natron Basin, Northern Tanzania

Authors

  • Edista A. Abdallah Department of Geosciences, University of Dar es Salaam, P.O. Box 35052, Dar es Salaam, Tanzania.
  • Charles H. Kasanzu Department of Geosciences, University of Dar es Salaam, P.O. Box 35052, Dar es Salaam, Tanzania.
  • Crispin P. Kinabo Department of Geosciences, University of Dar es Salaam, P.O. Box 35052, Dar es Salaam, Tanzania.
  • Akira Imai Department of Earth Resources Engineering, Kyushu University, Japan
  • Mike J. Butler iThemba Laboratory, Private Bag 11, Wits, 2050, Johannesburg, South Africa

DOI:

https://doi.org/10.4314/tjs.v48i4.8

Abstract

Springs on the eastern and western shores of Lake Natron Basin (LNB), located within the eastern branch of the East Africa Rift System (EARS) in Northern Tanzania had a discharge temperature that ranged between 34.0 °C and 51.2 °C, while the pH varied from 8.0 to 10.7. The electrical conductivity (EC) ranged between 5,007 µS/cm and 49,200 µS/cm. Cold waters had a temperature of 31.9 °C to 32.5 °C, while the pH ranged between 8.0 and 8.3, and the EC ranged between 1,401 µS/cm and 3,806 µS/cm. The stable isotope composition varied between -2.4 €° and -5.3 €° for δ18O, and -15.5 €° to -29.3 €° for δ2H. The isotopic composition of thermal and cold water of LNB indicates a significant contribution of meteoric water in the recharge of the hydrothermal system. However, thermal water is affected by evaporation, water-rock interaction, carbon dioxide (CO2) exchange and condensation processes. Tritium analysis indicated that the spring water in the LNB hydrothermal system has a residence time of more than 50 years.

Keywords:  thermal water; Lake Natron Basin; stable isotopes; springs.

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Published

2022-12-31

Issue

Vol. 48 No. 4 (2022)

Section

Articles