ABSTRACT
Three categories of C-enriched springs were considered in this study: hot springs, CO2-rich soda springs, and dilute springs. Springs of all three types occur throughout the arc, but only springs discharging on or at the base of a volcanic edifice were used in this study. The spring waters should thus drain only volcanic rocks, ruling out dissolution of shallow marine carbonate rocks as a source of DIC. The 3He/4He ratios have been determined for many of these springs, and ratios of 2-8 RA demonstrate a magmatic gas component.
