THE ROLE OF NON-CONDENSABLE GASES IN GEYSER ERUPTIONS IN YELLOWSTONE NATIONAL PARK
In November 2013, we sampled five hot water geysers and springs in Yellowstone. In order to understand the evolution of geyser waters and non-condensable gases on an eruption interval time-scale, we collected continuous in situ water quality data between eruptions and took time series water samples for major element chemistry, isotope, and dissolved gas analysis. Chemical geothermometry determined that the studied geyser and spring waters ascend from temperatures of 170 - 200°C. Subsurface steam separation is estimated to majorly contribute to the cooling of waters to their surface temperatures of around ~90°C, which concurrently strips dissolved CO2 from the water. Using surface CO2 concentrations in Spouter Geyser, which increase leading up to an eruption, subsurface temperatures, and CO2 partition coefficients, we calculated subsurface CO2 concentrations in Spouter Geyser. Although dissolved gas analysis shows that CO2 concentration is a minor component in surface waters of Spouter Geyser, subsurface concentrations may reach levels greater than solubility preceding an eruption at corresponding pressures and temperatures. We propose that ebullition of CO2 may induce boiling to drive an eruption in hot water systems.