Isotopic and geochemical study of the Domuyo Geothermal field, Neuquén. Argentina.

PANARELLO, H.0.; SIERRA, J. L.; D AMORE, F.; PEDRO, G

Iaea Technical Document Tecdoc

INTERNATIONAL ATOMIC ENERGY AGENCY

Lugar: Viena, Austria; Año: 1992 vol. 641 p. 31 - 56

1011-4289

Environmental isotopes, deuterium, oxygen-18 and Sulphur-34 as well as chemical analyses of dissolved solids and gases have been performed in order to establish a circulation model and reservoir temperature according to tritium levels and isotope content, recharge occurs 2900 m above sea level on the west slope of the Domo volcano. Water from a geyser, "El Humazo", has been recognized as the most related to the primary deep geothermal fluid, although with a minor proportion of fresh water.  Reservoir temperature as estimated by the Na-K- Ca geothermometer on this manifestation yield a value of 225ºC. A shallower reservoir with temperatures of about 176º C (Na-K- Ca -geothermometer) is evidenced in "Las Olletas" and 'Los Tachos" also affected by dilution and steam loss processes. Finally, temperate manifestations as "Aguas Calientes" and "Baños de aguas Calientes" are the result of mixing between Las Olletas type waters with fresh meteoric shallower waters. Gas thermometry and computation of fluid and mineral equilibria yield temperatures between 220-248ºC for the deep reservoir, in agreement with more classical techniques and suggest a value near to zero for the vapor fraction at depth, and confirm the liquid state of the fluid into the reservoir.