O'Regan, A. Matthew and Moran, Kate (2007): Compressibility, permeability, and stress history of sediments from Demerara Rise

Leg/Site/Hole:
ODP 207
ODP 207 1257
ODP 207 1258
ODP 207 1259
ODP 207 1260
ODP 207 1261
Identifier:
2007-087734
georefid

10.2973/odp.proc.sr.207.114.2007
doi

Creator:
O'Regan, A. Matthew
University of Rhode Island, Granduate School of Oceanography, Narragansett, RI, United States
author

Moran, Kate
Bundesanstalt fuer Geowissenschaften und Rohstoffe, Federal Republic of Germany
author

Identification:
Compressibility, permeability, and stress history of sediments from Demerara Rise
2007
In: 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 2003
Texas A&M University, Ocean Drilling Program, College Station, TX, United States
207
The 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.
English
Coverage:Geographic coordinates:
North:9.2800
West:-54.4400East: -54.1100
South:9.0200

Sedimentary petrology; Engineering geology; Atlantic Ocean; boreholes; Cenozoic; consolidation; continental margin; cores; Cretaceous; Demerara Rise; deposition; diagenesis; Equatorial Atlantic; erosion; French Guiana; hydraulic conductivity; Leg 207; Mesozoic; North Atlantic; Northwest Atlantic; Ocean Drilling Program; ODP Site 1257; ODP Site 1258; ODP Site 1259; ODP Site 1260; ODP Site 1261; overconsolidated materials; Paleogene; permeability; pore water; porosity; soil mechanics; South America; stress; Surinam; Tertiary; western Equatorial Atlantic;

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