Fluid chemistry of the waimangu geothermal system

The Waimangu geothermal area began discharging after the 1886 eruption of the Tarawera volcano, and currently consists of intense activity in the Waimangu and Lower Haumi Valleys, and on the western shore of the lake Rotomahana, with warm springs and seeps to the north and south. Variations in the chemical and isotopic compositions of water and gas discharges indicate that the deep water outflows near the lake, while large volumes of mixed origin, cooler waters are discharged in the Waimangu Valley. Large variations in the Cl : Cs, and apparent lack of mineral-solution equilibrium below 200°C indicate that the system has yet to arrive at a chemical equilibrium with the country rock at shallower levels. Cl : B and Cl : Cs ratios suggest a cogenetic relationship with geothermal systems to the south.