Conference paperOpen access
Low-enthalpy thermal waters within Khoja-Obi-Garm field (Republic of Tajikistan)
https://doi.org/10.1051/e3sconf/20199801011
Highlights
- Water temperature in springs and boreholes: 57–93 °C.
- Estimated subsurface temperature: 140–156 °C (silica geothermometers) and 193–197 °C (K/Na geothermometer).
- Estimated circulation depth: 2–3 km.
- pH up to 8; total dissolved solids below 0.5 g/L.
- H₂SiO₃ about 140 mg/L, fluoride up to 18 mg/L, radon up to 814 Bq/L.
- Field at 1,740–1,960 m altitude, 48 km north of Dushanbe.
Abstract
This paper presents data on the composition of the low-enthalpy thermal waters from the unique Khoja-Obi-Garm field located at the central part of the southern slope of the Gissar Range, in the gorge of the Khoja-Obi-Garm River, at an altitude of 1740-1960 meters. In this place, the eponymous SPA-center was built. Groundwaters from springs and boreholes of Khoja-Obi-Garm SPA has temperatures from 57 to 93°C, high pH (up to 8) and low TDS (less than 0.5 g/l). The estimated subsurface temperatures for the same thermal waters vary from 140°C to 156°C and 193-197°C based on the silica and K/Na geothermometer temperatures consequently. These waters belong to Na–SO₄–HCO₃ type with high content of H₂SiO₃ (~140 mg/l), F (up to 18 mg/l) and Rn (up to 814 Bq/l). Thermodynamic speciation indicated that these groundwaters are supersaturated with clay minerals and low-temperature zeolites and undersaturated with carbonate and main alumosilicate minerals.
English abstract as published with the paper. The authors’ abstract, reproduced under CC BY 4.0.
In plain English
The Khoja-Obi-Garm field lies in the central part of the southern slope of the Gissar Range, in the gorge of the Khoja-Obi-Garm River, 48 km north of Dushanbe, at 1,740–1,960 m. A spa centre has been built there. The thermal waters rise through a zone of crushed granite along the latitudinal Khoja-Obi-Garm regional fault.
Water from the springs and boreholes is 57–93 °C, with a pH of up to 8 and total dissolved solids below 0.5 g/L. It is of the Na–SO₄–HCO₃ type, rich in silica, fluoride and radon. The waters are strongly enriched in lithium, rubidium, caesium and beryllium; rare-earth elements stay below 1 µg/L. Borehole samples were taken in 2015–2016.
Silica geothermometers give subsurface temperatures of 140–156 °C, and the K/Na geothermometer 193–197 °C. The authors estimate that the water circulates to depths of 2–3 km. The water temperature has changed little over more than 50 years. The waters are supersaturated with clay minerals and low-temperature zeolites and undersaturated with carbonates and the main aluminosilicate minerals.
How to cite
A. Demonova, N. Kharitonova, I. Bragin, G. Chelnokov and V. Ivanov (2019). Low-enthalpy thermal waters within Khoja-Obi-Garm field (Republic of Tajikistan). E3S Web of Conferences 98, 01011 (WRI-16). https://doi.org/10.1051/e3sconf/20199801011