Tectonic regime and major processes governing the chemistry of water and gas discharges from the rotorua geothermal field, New Zealand
1992; Elsevier BV; Volume: 21; Issue: 1-2 Linguagem: Inglês
10.1016/0375-6505(92)90073-i
ISSN1879-3576
AutoresWerner F. Giggenbach, R.B. Glover,
Tópico(s)earthquake and tectonic studies
ResumoThe chemical composition of water and gas discharges clearly shows that the Rotorua geothermal system produces several types of fluids having travelled distinctly different paths. A plume of high Cl (>1400 mg/kg), high temperature (>250°C) waters feeds a discharge area, possibly partly submerged in Lake Rotorua, in the east and centre of the field. A closely related secondary plume of slightly altered such waters supplies the Whakarewarewa thermal area. A third plume of lower temperature (≈220°C) and lower Cl (≈500 mg/kg), but high HCO3 waters, likely to have travelled underground more slowly or over longer distances, supplies the northern and western parts of the system. Cl, B, CO2, N2, Ar and He contents in the fluids encountered over the northern and western parts of the field resemble closely those produced from other geothermal systems along the western half of the Taupo Volcanic Zone, systems thought to be associated with extensional tectonics. Of all these "rift"-type discharges from the TVZ, those from the southern and eastern parts of the Rotorua geothermal field appear to represent fluids most directly derived from an environment dominated by basaltic magmatism.
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