Hydrothermal CO2 emission from the Taupo Volcanic Zone, New Zealand

The CO2 flux to the atmosphere from active geothermal systems in the back-arc marginal basin environment of the Taupo Volcanic Zone (TVZ), North Island, New Zealand, has been estimated. The fluxes for individual systems refer to pre-exploitation (i.e. natural) hydrothermal discharge and have been calculated from heat flow data (predominantly convective), together with reservoir temperature and CO2 concentrations. The integrated CO2 flux for 20 geothermal systems in the TVZ is estimated to be approximately 1010 mol yr−1. It is concluded that the global hydrothermal CO2 flux from subareal environments alone may be comparable to that estimated for direct volcanic emanations.