georefid:2001-025804georefid:2001-025795SEDIS 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=10.2973/odp.proc.sr.164.214.20002000-01-01publicationgeorefid:2001-025804doi:10.2973/odp.proc.sr.164.214.2000Borowski, Walter S.University of North Carolina at Chapel Hill, Geology Department, Chapel Hill, NC, United StatesauthorHoehler, Tori M.University of Tokyo, JapanauthorAlperin, Marc J.Ocean Drilling Program, United StatesauthorRodriguez, Nancy M.U. S. Geological Survey, United StatesauthorPaull, Charles K.University of Texas at Arlington, United StatesauthorTexas A & M University, Ocean Drilling Program, College Station, TX, United StatespublisherdocumentHardcopyIn: Paull, Charles K., Matsumoto, Ryo, Wallace, Paul J., Black, Nancy R., Borowski, Walter S., Collett, Timothy S., Damuth, John E., Dickens, Gerald R., Egeberg, Per Kristian, Goodman, Kim, Hesse, Reinhard F., Hiroki, Yoshihisa, Holbrook, W. Steven, Hoskins, Hartley, Ladd, John, Lodolo, Emanuele, Lorenson, Thomas D., Musgrave, Robert J., Naehr, Thomas H., Okada, Hisatake, Pierre, Catherine, Ruppel, Carolyn D., Satoh, Mikio, Thiery, Regis, Watanabe, Yoshio, Wehner, Hermann, Winters, William J., Wood, Warren T., Miller, Christine M. (editor), Reigel, Ruth (editor), Proceedings of the Ocean Drilling Program; volume 164; scientific results; gas hydrate sampling on the Blake Ridge and Carolina Rise; covering Leg 164 of the cruises of the drilling vessel JOIDES Resolution, Halifax, Nova Scotia, to Miami, Florida, sites 991-997, 31 October-19 December 199516487-99A unique set of geochemical pore-water data, characterizing the sulfate reduction and uppermost methanogenic zones, has been collected at the Blake Ridge (offshore southeastern North America) from Ocean Drilling Program (ODP) Leg 164 cores and piston cores. The delta (super 13) C values of dissolved CO (sub 2) (Sigma CO (sub 2) ) are as (super 13) C-depleted as -37.7 per mil PDB (Site 995) at the sulfate-methane interface, reflecting a substantial contribution of isotopically light carbon from methane. Although the geochemical system is complex and difficult to fully quantify, we use two methods to constrain and illustrate the intensity of anaerobic methane oxidation in Blake Ridge sediments. An estimate using a two-component mixing model suggests that approximately 24% of the carbon residing in the Sigma CO (sub 2) pool is derived from biogenic methane. Independent diagenetic modeling of a methane concentration profile (Site 995) indicates that peak methane oxidation rates approach 0.005 mu mol cm (super -3) yr (super -1) , and that anaerobic methane oxidation is responsible for consuming approximately 35% of the total sulfate flux into the sediments. Thus, anaerobic methane oxidation is a significant biogeochemical sink for sulfate, and must affect interstitial sulfate concentrations and sulfate gradients. Such high proportions of sulfate depletion because of anaerobic methane oxidation are largely undocumented in continental rise sediments with overlying oxic bottom waters. We infer that the additional amount of sulfate depleted through anaerobic methane oxidation, fueled by methane flux from below, causes steeper sulfate gradients above methane-rich sediments. Similar pore water chemistries should occur at other methane-rich, continental-rise settings associated with gas hydrates.completedGeneral geochemistryaliphatic hydrocarbonsalkanesanaerobic environmentAtlantic Oceanbiogenic processesBlake-Bahama Outer RidgeC-13/C-12carbonchemical reactionsconcentrationgas hydrateshydrocarbonsisotope ratiosisotopesLeg 164marine sedimentsmethaneNorth AtlanticNorthwest AtlanticOcean Drilling ProgramODP Site 995organic compoundsoxidationsedimentary organic mattersedimentsstable isotopessulfatesurn:org.iodp:exp:164urnlargerWorkCitationcampaignurn:org.iodp:exp:164:site:995urnlargerWorkCitationstudyurn:org.iodp:exp:164urnlargerWorkCitationcampaignEnglishgeoscientificInformation-75.3118-75.311831.481231.4812