The concentrations and isotopic compositions of volatiles like CO2, CH4, and H2 in hydrothermal fluids provide crucial information concerning the nature of the heat source underlying hydrothermal systems and the high temperature water-rock reactions that occur deep in the ocean crust. These chemical species are also a vital link between the mantle, magmas, and the biological communities that thrive at deep-sea hydrothermal vents. This research focuses on determining the concentration of CO2, methane, and C2 hydrocarbons in long-term (~20 year) time-series fluid samples from hydrothermal vents on the Endeavour Segment of the Juan de Fuca Ridge off the northwestern coast of the US. Work also involves analyzing the associated carbon and hydrogen isotopes. These data will be used to discriminate between magmatic, thermal, and sedimentary/biological processes controlling the targeted carbon-bearing species and identify the source of the anomalous carbon gradient that is found in the Endeavour hydrothermal vent area. The primary broader impact of the work is completing a major hydrothermal fluid dataset for the NSF-funded Ridge 2000 Program to allow studies of integration and synthesis to take place. There is also international collaboration with a Swiss scientist.
