The marine gas hydrate stability zone (GHSZ) occurs in the slope environment along many active and passive continental margins. In this environment, slope failures are common and can occur near the shelf slope break, within submarine canyons, or on the flanks of bathymetric highs, resulting in a spectrum of slope failure deposits from landslides to turbidites. On the Cascadia margin, the GHSZ occurs within the bathymetric thrust ridges and slope basins of the accretionary wedge. Here, the ridges are composed of uplifted abyssal plain deposits associated with submarine fans and/or paleoslope basin deposits formed during the evolution of the accretionary wedge (Johnson et al., 2006; Torres et al., 2008). The adjoining slope basins contain the deposits from slope failure of the ridges. Both ridges and slope basins offshore Central Oregon and Vancouver Island were sampled by drilling during ODP Leg 204 and IODP Expedition 311, respectively (Figure 1). The recovered cores document the distribution and abundance of gas hydrate in these regions within a stratigraphy that is dominated by silt and sand turbidites, debris flows, and intervals of silty clay, separated by hemipelagic clay.
Fire in the Ice, The National Energy Technology Laboratory Methane Hydrate Newsletter
U.S. Department of Energy
Johnson, J.E., Solway, D., Disenhof, C., Torres, M.E., Hong, W-L., Rose, K., 2010, Identifying Slope Failure Deposits from a Potentially Mixed Magnetic Susceptibility Signal in Gas Hydrate Bearing Regions. Fire in the Ice, The National Energy Technology Laboratory Methane Hydrate Newsletter, vol. 10, issue 3, p. 20-24. http://www.netl.doe.gov/research/oil-and-gas/methane-hydrates/fire-in-the-ice