Update on the fluid geochemistry monitoring time series for geothermal systems in Dominica, Lesser Antilles island arc: 2009–2017

Abstract

With updated geochemical and isotopic compositions obtained over the period 2009 to 2017, this study presents revised fluid characterizations for the active volcanic-hydrothermal systems on the island of Dominica in the Lesser Antilles, which were first reported in 2011. Hydrothermal waters of Dominica cover a wide spectrum of pH, temperatures and chemical composition. The pH of the thermal waters ranges from acidic to neutral (pH values of 1–7.8) and the waters are predominantly Na-SO4 in character (Na = 14–2127 mg/L; SO4 = 1–1725 mg/L), likely formed as a result of dilution of acidic H2S-rich gases in near surface oxygenated groundwater, and have experienced limited water-rock interaction.