Istituto di Geoscienze e Georisorse     
Brombach T., Caliro S., Chiodini G., Fiebig J., Hunziker J., Raco B. Geochemical evidence for mixing of magmatic fluids with seawater, Nisyros hydrothermal system, Greece. In: Bulletin of Volcanology, vol. 65 (7) pp. 505 - 516. Springer, 2003.
The chemical and isotopic compositions (dD H2O, d 18O H2O, d 18O CO2, d 13C CO2, d 34S, and He/N 2 and He/Ar ratios) of fumarolic gases from Nisyros, Greece, indicate that both arc-type magmatic water and local seawater feed the hydrothermal system. Isotopic composition of the deep fluid is estimated to be +4.90.5 for d 18O and -115 for dD corresponding to a magmatic water fraction of 0.7. Interpretation of the stable water isotopes was based on liquid-vapor separation conditions obtained through gas geothermometry. The H 2-Ar, H 2-N 2, and H 2-H 2O geothermometers suggest reservoir temperatures of 34515 C, in agreement with temperatures measured in deep geothermal wells, whereas a vapor/liquid separation temperature of 26030 C is indicated by gas equilibria in the H 2O-H 2-CO 2-CO-CH 4 system. The largest magmatic inputs seem to occur below the Stephanos-Polybotes Micros crater, whereas the marginal fumarolic areas of Phlegeton-Polybotes Megalos craters receive a smaller contribution of magmatic gases.
URL: http://www.springerlink.com/openurl.asp?genre=journal&issn=0258-8900
Subject fluid geochemistry
hydrothermal system

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