Comparison of Silica and Cation Geothermometers of Bath Hot Springs, Jamaica WI

Abstract

Chemical geothermometers (i.e. silica and cation) of the Bath Mineral hot springs discharged from fissures and fractures at the ground surface in eastern Jamaica were compared to estimate the temperature of the geothermal reservoir. Partial equilibrium exists between aqueous species in the reservoir fluids and the mineral assemblage quartz. The Na-K-Mg Geoindicator by Giggenbach (1988), Na-K geothermometers and the silica geothermometer based on quartz solubility appear to be the most reliable indicators of reservoir temperature. Temperatures estimated using Na-K-Ca geothermometers were either too high or low to be considered reliable. Overestimation of reservoir temperatures by the Na-K-Ca geothermometer may be due to (1) equilibration at conditions that are hotter and deeper than existing areas of mixing and circulation of groundwater and (2) conductive heat loss. Alignment of the hot springs is related to the structural and tectonic setting of a major strike-slip fault-the Plantain Garden Fault. Hydrogeochemical investigations of the hot springs resulted in reliable estimates of reservoir temperatures ranging 80ºC-102ºC at depths of 1-1.8 km. Results indicate that the localized upwelling of low enthalpy geothermal waters at Bath have sufficient heat-generating capacities and warrants further exploration using geophysical techniques and hyperspectral imaging.