9706693 Magenheim Crater lakes, perched atop active volcanoes, act as natural condensers of magmatic volatiles and integrate volatile element (Cl, S, F, among others) and heat fluxes over periods of passive degassing. This study will assess the chlorine stable isotope ratios associated with the volcanogenic flux of Cl to EarthOs surface through the analysis of crater lake fluids. A survey of geographically and tectonically distinct crater lakes, as well as, an assessment of the temporal variations in several well studies caldera lakes (Yugama, Poas, and Ruapehu) will be included. The primary objectives are: 1) to estimate the isotopic ratios of Cl presently being degassed to EarthOs Surface reservoir through the survey of Cl trapped in crater lake systems from around the world, 2) to investigate the potential for isotope fractionation occurring during magmatic degassing through the time-series studies, and 3) to address the origin of the Cl being supplied to the crater lakes, specifically whether the Cl is derived from the surface reservoirs or from deeper, within the mantle.
