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doi:10.2204/iodp.proc.308.204.2008

Data report: consolidation characteristics of sediments from IODP Expedition 308, Ursa Basin, Gulf of Mexico¹

H. Long,^2, 3 P.B. Flemings,⁴ J.T. Germaine,⁵ D.M. Saffer,⁶ and B. Dugan⁷

Abstract

We conducted constant rate of strain consolidation tests on 9 samples from Integrated Ocean Drilling Program Site U1322 and 23 samples from Site U1324 in three laboratories (Massachusetts Institute of Technology, Pennsylvania State University, and Rice University) to obtain the consolidation properties of the sediment, as well as determine the stress history of the sites. The sediments recovered from above 200 meters below seafloor (mbsf) at both sites have similar consolidation properties. The compression index (C_c) ranges from 0.1508 to 0.5052. C_c decreases with void ratio at both sites. The expansion index (C_e) ranges from 0.0153 to 0.1144 and decreases with void ratio at both sites. The in situ hydraulic conductivity (K_i) ranges from 2.18 × 10^–11 to 6.38 × 10^–10 m/s. K_i decreases with depth. The e-log (K_i) relation has different slopes for sediments above and below 300 mbsf at Site U1324. The coefficient of consolidation (c_v) ranges from 1.5 × 10^–8 to 4.2 × 10^–7 m²/s. c_v increases with depth for the sediments above 200 mbsf at both sites and shows no clear trend for the sediments below 200 mbsf at Site U1324. The preconsolidation pressure (P′_c) is significantly less than the hydrostatic vertical effective stress (σ′_vh) at both sites, which suggests that Ursa sediments are overpressured.

¹Long, H., Flemings, P.B., Germaine, J.T., Saffer, D.M., and Dugan, B., 2008. Data report: consolidation characteristics of sediments from IODP Expedition 308, Ursa Basin, Gulf of Mexico. In Flemings, P.B., Behrmann, J.H., John, C.M., and the Expedition 308 Scientists, Proc. IODP, 308: College Station, TX (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/​iodp.proc.308.204.2008

²Department of Energy and Mineral Engineering, The Pennsylvania State University, University Park PA 16802, USA.

³Present address: ExxonMobil Upstream Research Company, Houston, TX 77098.

⁴John A. and Katherine G. Jackson School of Geosciences, The University of Texas at Austin, Austin TX 78712, USA. pflemings@jsg.utexas.edu

⁵Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge MA 02139, USA.

⁶Department of Geosciences, The Pennsylvania State University, University Park, PA 16802, USA.

⁷Department of Earth Science, Rice University, Houston TX 77005, USA.

Initial receipt: 22 June 2007
Acceptance: 31 January 2008
Web publication: 1 July 2008
MS 308-204

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