georefid:2007-087734georefid:2007-087719SEDIS Publication Catalogueana.macario@awi.dehttp://sedis.iodp.org/pub-catalogue/informationpointOfContact2011-06-23T00:00:00Zhttp://sedis.iodp.org/pub-catalogue/index.php?id=10.2973/odp.proc.sr.207.114.2007<gco:CharacterString>Compressibility, permeability, and stress history of sediments from Demerara Rise</gco:CharacterString>2007-01-01publicationgeorefid:2007-087734doi:10.2973/odp.proc.sr.207.114.2007O'Regan, A. MatthewUniversity of Rhode Island, Granduate School of Oceanography, Narragansett, RI, United StatesauthorMoran, KateBundesanstalt fuer Geowissenschaften und Rohstoffe, Federal Republic of GermanyauthorTexas A&M University, Ocean Drilling Program, College Station, TX, United StatespublisherdocumentDigitalIn: Mosher, David C., Erbacher, Jochen, Malone, Mitchell J., Berti, Debora, Bice, Karen L., Bostock, Helen, Brumsack, Hans-Juergen, Danelian, Taniel, Forster, Astrid, Glatz, Christine, Heidersdorf, Felix, Henderiks, Jorijntje, Janecek, Thomas R., Junium, Christopher, Le Callonnec, Laurence, MacLeod, Kenneth G., Meyers, Philip A., Mutterlose, H. Joerg, Nishi, Hiroshi, Norris, Richard D., Ogg, James G., O'Regan, A. Matthew, Rea, Brice, Sexton, Philip, Sturt, Helen, Suganuma, Yusuke, Thurow, Juergen W., Wilson, Paul A., Wise, Sherwood W., Jr., Proceedings of the Ocean Drilling Program; scientific results; Demerara Rise; equatorial Cretaceous and Paleogene paleoceanographic transect, western Atlantic; covering Leg 207 of the cruises of the Drilling Vessel JOIDES Resolution; Bridgetown, Barbados, to Rio de Janeiro, Brazil; sites 1257-1261; 11 January-6 March 2003207The stress history, permeability, and compressibility of sediments from Demerara Rise recovered during Ocean Drilling Program Leg 207 were determined using one-dimensional incremental load consolidation and low-gradient flow pump permeability tests. Relationships among void ratio, effective stress, and hydraulic conductivity are presented for sampled lithologic units and used to reconstruct effective stress, permeability, and in situ void ratio profiles for a transect of three sites across Demerara Rise. Results confirm that a significant erosional event occurred on the northeastern flank of the rise during the late Miocene, resulting in the removal of approximately 220 m of upper Oligocene- Miocene deposits. Although Neogene and Paleogene sediments tend to be overconsolidated, Cretaceous sediments are normally consolidated to underconsolidated, suggesting the presence of overpressure. A pronounced drop in permeability occurs at the transition from the Cretaceous black shales into the overlying Maastrichtian-upper Paleocene chalks and clays. The development of a hydraulic seal at this boundary may be responsible for overpressure in the Cretaceous deposits, leading to the lower overconsolidation ratios of these sediments. Coupled with large regional variations in sediment thickness (overburden stresses), the higher permeability overpressured Cretaceous sediments represent a regional lateral fluid conduit on Demerara Rise, possibly venting methane-rich fluids where it outcrops on the margin's northeastern flank.completedSedimentary petrologyEngineering geologyAtlantic OceanboreholesCenozoicconsolidationcontinental margincoresCretaceousDemerara RisedepositiondiagenesisEquatorial AtlanticerosionFrench Guianahydraulic conductivityLeg 207MesozoicNorth AtlanticNorthwest AtlanticOcean Drilling ProgramODP Site 1257ODP Site 1258ODP Site 1259ODP Site 1260ODP Site 1261overconsolidated materialsPaleogenepermeabilitypore waterporositysoil mechanicsSouth AmericastressSurinamTertiarywestern Equatorial Atlanticurn:org.iodp:exp:207urnlargerWorkCitationcampaignurn:org.iodp:exp:207:site:1257urnlargerWorkCitationstudyurn:org.iodp:exp:207urnlargerWorkCitationcampaignurn:org.iodp:exp:207:site:1258urnlargerWorkCitationstudyurn:org.iodp:exp:207urnlargerWorkCitationcampaignurn:org.iodp:exp:207:site:1259urnlargerWorkCitationstudyurn:org.iodp:exp:207urnlargerWorkCitationcampaignurn:org.iodp:exp:207:site:1260urnlargerWorkCitationstudyurn:org.iodp:exp:207urnlargerWorkCitationcampaignurn:org.iodp:exp:207:site:1261urnlargerWorkCitationstudyurn:org.iodp:exp:207urnlargerWorkCitationcampaignEnglishgeoscientificInformation-54.4400-54.11009.02009.2800application/pdfunknownSEDIS Publication Catalogueana.macario@awi.dehttp://sedis.iodp.org/pub-catalogue/informationpointOfContacthttp://www-odp.tamu.edu/publications/207_SR/VOLUME/CHAPTERS/114.PDFdownload