georefid:2006-021474SEDIS 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=10.1130/G22008.12006-01-01publicationgeorefid:2006-021474doi:10.1130/G22008.1Musgrave, Robert J.Monash University, School of Geosciences, Clayton, Victoria, AustraliaauthorBangs, Nathan L.University of Texas, United StatesauthorLarrasoana, Juan CruzUniversitat de Barcelona, SpainauthorGracia, EulaliaCentre Mediterrani d'Investigacions Marines i Ambientals, SpainauthorHollamby, Jennifer A.La Trobe University, AustraliaauthorVega, Marta E.authorGeological Society of America (GSA), Boulder, CO, United StatespublisherdocumentHardcopyGeology (Boulder)34 (2)117-120Gas hydrate, a clathrate of methane and water widespread on continental margins, has been implicated as a trigger of climate change and submarine slides as a result of methane release when the base of its stability zone moves upward rapidly. Direct tests of these hypotheses are made difficult by the ephemeral record of gas hydrate in sediment. In places, a seismic reflector (double bottom simulating reflector, BSR) appears to mark the old base of the gas hydrate layer, but the occurrence of this feature is patchy and its interpretation is controversial. Microbial activity is stimulated in the presence of gas hydrate, and results in the production of magnetic iron sulfides; the base of the gas hydrate interval is marked by a sharp reduction in the magnetic hysteresis parameter D (sub JH) . At Hydrate Ridge on the Cascadia margin, sampled during Ocean Drilling Program Leg 204, this signature occurs between 20 and 65 m below the present-day base of the gas hydrate zone, at a depth consistent with predictions for the base of gas hydrate stability given water depths and bottom-water temperatures appropriate for the last glacial maximum. Seismic evidence for a double BSR over part of Hydrate Ridge corroborates the rock magnetic interpretation.completedQuaternary geologyaliphatic hydrocarbonsalkanesapplicationsbottom-simulating reflectorsCenozoicclimate changecontinental margindepthEast Pacificgas hydratesgeophysical methodsgeophysical profilesgeophysical surveysglacial environmentglaciomarine environmenthigh-resolution methodsHydrate Ridgehydrocarbonslast glacial maximumLeg 204magnetic hysteresismarine environmentmarine sedimentsmethaneNorth PacificNortheast PacificOcean Drilling Programorganic compoundsPacific OceanpaleoclimatologypaleomagnetismporosityQuaternarysedimentsseismic methodsseismic profilessurveystechniquesupper Quaternaryurn:org.iodp:exp:204urnlargerWorkCitationcampaignEnglishgeoscientificInformation-125.1000-125.060044.330044.3600With GSA Data Repository Item 2006025