Champagne Pool

Champagne Pool is a prominent geothermal feature within the Waiotapu geothermal area in the North Island of New Zealand. The terrestrial hot spring is located about 30km southeast of Rotorua and about 50km northeast of Taupo. The name Champagne Pool is derived from the abundant efflux of carbon dioxide (CO2), similar to a glass of bubbling champagne. The hot spring was formed 900 years ago by a hydrothermal eruption, which makes it in geological terms a relatively young system. Its crater is around 65m in diameter with a maximum depth of approximately 62m and is filled with an estimated volume of 50000m3 of geothermal fluid.HydrochemistryThe deep geothermal water below Champagne Pool is of the order of 260°C but water temperature within the pool is maintained at 73°C to 75°C by losing heat to the atmosphere. The pH of 5.5 is relatively constant due to buffering by the flux of CO2. Gases are mainly CO2, but to less extent nitrogen (N2), methane (CH4), hydrogen (H2), hydrogen sulphide (H2S) and traces of oxygen (O2). The siliceous geothermal fluid is oversaturated with metalloid compounds such as orpiment (As2S3) and stibnite (Sb2S3), which precipitate and form orange subaqueous deposits. The colourful deposits are in sharp contrast to the grey-white silica sinter surrounding Champagne Pool.