CHEMISTRY AND EMISSION RATE OF VOLATILES FROM WHITE ISLAND VOLCANO (NEW-ZEALAND)

Gases and a water condensate have been sampled at White Island volcano in two selected fumaroles (100 and 495-degrees-C). They have been analysed for major, minor and trace elements. Both the chemical composition of gases and thermodynamic calculations suggest that the fluids feeding high and low temperature fumaroles have the same origin, but that they follow different evolutions while ascending to the surface. Very low CO/CO2 ratios with respect to White Island previous results suggest that White Island is now in stage of reduced activity. According to the very low solubility of CO in silicate melts, an increase in activity due to a magmatic pulse should cause a significant increase of CO in the released gas phase. Long term fluxes of gases and metals have been estimated on the basis of COSPEC SO2 flux measurements performed during a medium activity stage. Our data concerning some heavy metals are similar to previous data, suggesting a constancy of the emissions during quiescent periods.