The Flux of Carbon from a Modern Accretionary Prism: In Situ Measurements of Hydrocarbon Sequestration as Gas Hydrates and Diagenetic Carbonate Deposits

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9712174 Carson At accretionary margins sedimentary carbon is recycled as pore waters are squeezed from the compacting sediments. These pore waters are discharged at natural seeps where some of the carbon is deposited as thick surface and subsurface layers, additional carbon may be sequestered in gas hydrates, and some of the carbon is lost to the water column in gaseous form. The relative proportions and magnitude of these processes, however, are poorly understood. The present project will begin an in situ , experimental approach to examining and quantifying these processes on the Oregon margin. Sampling chambers will be fitted to sealed borehole drilled by the Ocean Drilling Program and will be used to collect precipitate and fluid flow out of the sedimentary section. Samples from the year long experiment will be subsequently analyzed to provide information on the kinetics of carbon sequestration during fluid expulsion. Not only will the research define chemistry of the fluids and associated digenetic deposits, it also will relate the mass deposited over time to a known volume of fluid, and measure the affect of that deposition on sediment permeability. Microbial research will examine the potential role and importance of organisms in controlling the carbon partitioning. ***