| Title | Sulfate-Water Isotopic Equilibrium Temperatures for Thermal Springs and Wells of the Great Basin |
|---|---|
| Authors | Nehring, Nancy L.; Mariner, Robert H. |
| Year | 1979 |
| Conference | Geothermal Resources Council Transactions |
| Keywords | Geochemistry; Geothermometers; Base Temperature; Brine Chemistry; USA; Great Basin; Hot Springs; Isotopes; Sulfate Minerals; Regional Evaluation; Silica; Mixing Models; Reservoir Temperature; Temperature Logging; Geothermal Wells; USGS |
| Abstract | Temperatures estimated assuming oxygen isotopic equilibrium between water and dissolved sulfate agree with measured temperatures in the four deep geothermal well sin the Great Basin for which measured temperatures are available. However, when temperatures estimated from spring samples using silica, Na-K-Ca and sulfate water geothermometers are compared, considerable scatter is observed with sulfate water generally predicting the higher temperatures. Probable causes for the scatter include: (1) a practical upper limit for the silica geothermometer of about 180°C in most hot spring systems; (2) chemical but not isotopic equilibrium being established in shallow secondary reservoirs; (3) contamination of the thermal water by dissolution of isotopically enriched marine sulfate minerals or isotopically depleted hydrothermal sulfate minerals: (4) oxidation of sulfide to sulfate; and (5) different rates of oxygen isotope exchange between water rock and water sulfate systems. |