摘要
Since approximately forty years ago, the equation relating the oxygen isotope fractionation between bisulfate and water has been extensively used as a geothermometer for acidic and high-enthalpy hydrothermal systems (T > 150 ¡ãC). Its application to near-neutral or basic, low-enthalpy (T < 150 ¡ãC) systems was considered to be unreliable. Recently, empirical and theoretical geothermometric equations were formulated for the (SO42 ?-H2O) oxygen isotope system, opening new perspectives on isotope geochemistry applied to geothermal research. In the present paper, these geothermometers are applied while revisiting a variety of hydrological case studies. In addition to the equilibrium fractionation, isotopic effects on geothermometric estimates due to mixing-dilution, salinity, sulfide oxidation, sulfate reduction, standardization of the analytical results and aqueous speciation are also discussed.