Sea Floor Methane Hydrates at Hydrate Ridge, Cascadia Margin

摘要: The crest of Hydrate Ridge harbors a variety gas hydrates in near-surface sediments. formation and destruction continuously shape the ridge topography. Interstitial Cl-anomaly patterns conjunction with video-guided sampling have established that uppermost sediment column contains several distinct layers hydrate which are exposed at sea floor. A methane-oxidizing bacterial consortium populates exposures hydrate; colonies vent macro-fauna abundant as well. Discharge methane from destabilized seafloor stimulates high rates benthic oxygen consumption. These rates, however, vary by many orders magnitude spatially temporally, highlighting need for implementing observatories sites. Two types fabrics were observed: highly porous fabric an estimated pore space approx. 60 vol.-% massive type, no visible space. Both contain varying amounts chloride, to be taken into account when estimating volumes Cl-depletion waters. has low bulk density, may cause periodic release large chunks They float surface leave behind chaotic topography mounds depressions. pieces floating constitute important transport mechanism directly atmosphere.