Temporal and spatial evolution of a gas hydrate–bearing accretionary ridge on the Oregon continental margin

摘要: A seismic-reflection survey on the Oregon continental margin conducted in 1989 indicates widespread presence of gas hydrate beneath middle and lower slope this accretionary margin. The seismic signature hydrate, a bottom simulating reflector (BSR) with negative polarity that locally cuts across stratigraphic horizons, is especially well developed Hydrate Ridge. This anomalously shallow ridge was drilled during Ocean Drilling Program Leg 146 to study fluid venting. In paper we focus data from southern part Ridge, where little evidence active venting has previously been reported but indicate complicated subsurface plumbing system. Apparent disruptions BSR western flank suggest dissociation response slumping. double crest suggests destabilization tectonic uplift folding. On basis these other observations, propose qualitative model for evolution hydrate-bearing an complex which initially stabilizes sea floor, permitting construction large ridges are then eaten away by slumps along their margins. north-to-south variation sea-floor structure Ridge may reflect different stages temporal one ridges.