Geothermal fluid chemistry of the Orakeikorako field, New Zealand

Abstract

Abstract Samples of water and steam from natural discharges in the Orakeikorako geothermal area of the Taupo Volcanic Zone have been analyzed for their chemical and stable isotopic components. The waters are near neutral, with chloride contents less than 400 mg/kg. A model of the subsurface hydrology, based upon well measurements and chemical and isotopic measurements has been developed, in which the dilute waters discharged at the surface are considered to result from the dilution of deeper fluids which may have temperatures as high as 280°C. In the northern parts of the field waters with relatively lower chloride and higher bicarbonate composition have further diluted the rising fluid. There is no evidence that local lake or river waters have changed the field character or water composition significantly since the river water level was raised.