Collaborative Research: Geochemical Consequences of Extensive Gas Hydrate Formuation in Sediments of the Cascadia Accretionary Prism

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9731463 Brown To quantify the exchange of fluids and dissolved constituents from the Cascadia margin hydrate field to the overlying water column a multi-investigator program is designed to measure this exchange under a variety of conditions within the Cascadia region. A 2-year field program will deploy benthic devices that sample fluid discharge. Gravity, push and multicores will be used to assess how near-surface formation and decomposition of a mixed CH4-H2S hydrate in continental margin sediments influences benthic fluxes and early diagenetic reactions. The data collected during the first year will be used to assess the spatial variations of constituent release from the hydrate field, variations that are likely to be most significant at active venting sites. These results will 1) identify ideal sites for temporal variability studies to be conducted during two subsequent visits to the area, and 2) define the length and number of deployments in the following field programs. The different environments present in the Cascadia margin, along with the spatial-temporal experimental design will enable assessment of the effect of widespread hydrate formation in the Cascadia margin on element mobilization, transport, and release at the seafloor. This knowledge has applications for broader issues on a global scale, as hydrate geochemistry is of significant relevance in global carbon budgets, climate change models, sediment slope stability, and energy resource issues.