Fluid-inclusion technique for determining maximum temperature in calcite and its comparison to the vitrinite reflectance geothermometer

Theory, laboratory experiments, and empirical observation suggest that many aqueous fluid inclusions in calcite reequilibrate during overheating, and therefore some homogenization temperatures (T_h) record a temperature close to the maximum reached by the rock. This characteristic suggests that aqueous fluid inclusions in calcite can be used to establish maximum temperature (T_peak). To test this hypothesis, we have compiled fluid inclusion T_peak, mean random vitrinite reflectance (R_m), and present-day T_peak from 46 diverse geologic systems that have been at T_peak from 10⁴ to 10⁶ yr. Present T_peak ranged from 65 to 345 °C, T_h modes and means ranged from 59 to 350 °C, and R_m data ranged from 0.4% to 4.6%, spanning the temperature and thermal maturity range associated with burial diagenesis, hydrothermal alteration, and low-grade metamorphism.