georefid:1999-066520SEDIS Publication Catalogue

ana.macario@awi.de

http://sedis.iodp.org/pub-catalogue/informationpointOfContact2011-06-23T00:00:00Zhttp://sedis.iodp.org/pub-catalogue/index.php?id=1999-0665201999-01-01publicationgeorefid:1999-066520Trehu, Anne M.Oregon State University, College of Oceanic and Atmospheric Sciences, Corvallis, OR, United StatesauthorTorres, Marta E.University of Hawaii, United StatesauthorMoore, Gregory F.GEOMAR, Research Center for Marine Geosciences, Federal Republic of GermanyauthorSuess, ErwinauthorBohrmann, GerhardauthorGeological Society of America (GSA), Boulder, CO, United StatespublisherdocumentHardcopyGeology (Boulder)27 (10)939-942A seismic-reflection survey on the Oregon continental margin conducted in 1989 indicates the widespread presence of gas hydrate beneath the middle and lower slope of this accretionary margin. The seismic signature of gas hydrate, a bottom simulating reflector (BSR) with negative polarity that locally cuts across stratigraphic horizons, is especially well developed beneath Hydrate Ridge. This anomalously shallow accretionary ridge was drilled during Ocean Drilling Program Leg 146 to study fluid venting. In this paper we focus on the seismic data from the southern part of Hydrate Ridge, where little evidence of active venting has previously been reported but where the seismic data indicate a complicated subsurface plumbing system. Apparent disruptions of the BSR beneath the western ridge flank suggest dissociation of gas hydrate in response to slumping. A double BSR beneath the southern crest suggests hydrate destabilization in response to tectonic uplift and folding. On the basis of these and other observations, we propose a qualitative model for the evolution of a hydrate-bearing ridge in an active accretionary complex in which gas hydrate initially stabilizes the sea floor, permitting construction of large ridges that are then eaten away by slumps along their margins. The north-to-south variation in sea-floor venting and subsurface seismic structure along Hydrate Ridge may reflect different stages in the temporal evolution of one of these ridges.completedSolid-earth geophysicsOceanographyaccretionary wedgesbathymetrybottom-simulating reflectorscontinental marginEast Pacificgas hydratesgeophysical methodsgeophysical profilesgeophysical surveysHydrate RidgeLeg 146marine environmentmarine sedimentsmass movementsmid-ocean ridgesNorth PacificNortheast PacificOcean Drilling Programocean floorsOregonoverpressurePacific Oceanplate tectonicsreflection methodssedimentsseismic methodsseismic profilesslope stabilityslumpingspatial distributionsubmarine environmentsurveystemporal distributionUnited Statesvertical seismic profilesurn:org.iodp:exp:146urnlargerWorkCitationcampaignEnglishgeoscientificInformation-125.3000-124.300044.240045.5000With GSA Data Repository Item 9977