| Abstract |
The 'mixed' model of water-rock interaction (1980 Workshop) is explained in detail. magnitude of the oxygen isotope shifts of their recharge water, different geothermal systems can be placed in an evolutionary series, from incipient (large shift of water) to mature (small shift of water). Isotopes of different chemical elements may be combined, to yield a stringent test of whether or not a given change in rock composition may be ascribed to interaction with water (L-shaped trajectories). For the acidic eruptives of the Taupo Volcanic Zone, available strontium oxygen isotope data practically rule out an origin by ti ng of greywacke basement. |