Consolidation and overpressure near the seafloor in the Ursa Basin, deepwater Gulf of Mexico

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doi: 10.1016/j.epsl.2011.02.007
Author(s): Long, H.; Flemings, P. B.; Germaine, J. T.; Saffer, D. M.
Author Affiliation(s): Primary:
ExxonMobil Upstream Research Company, Houston, TX, United States
University of Texas, United States
Massachusetts Institute of Technology, United States
Pennsylvania State University, United States
Volume Title: Earth and Planetary Science Letters
Source: Earth and Planetary Science Letters, 305(1-2), p.11-20. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X CODEN: EPSLA2
Note: In English. Supplementary data available in online version. 44 refs.; illus., incl. sects., sketch map
Summary: In mudstones of the Ursa Basin, Gulf of Mexico, the volume of voids to solids, or void ratio, ranges from 4 (porosity=80%) at the seafloor to 0.6 (porosity=37%) at 600 m below seafloor. This seven-fold change in void ratio can only be described by a compaction model that includes greater sediment stiffening with stress than has commonly been used in geotechnical or geological approaches. Through uniaxial consolidation experiments, we show that specific volume (v=1+void ratio) declines as an exponential function of effective stress. We use this relationship to successfully predict in-situ overpressures at Integrated Ocean Drilling Program (IODP) Sites U1322 and U1324. This technique can be used around the world to describe sediment compaction and predict pore pressure in the first 1000 m below seafloor. Rapid sediment consolidation near the seafloor provides the fluid source that generates overpressure despite the fact that these sediments have high permeability. Ultimately sediment consolidation is a first order control on when and at what depth overpressure will be generated in the subsurface. This in turn will impact whether submarine landslides are expected and the regional gradient of continental margins. Abstract Copyright (2011) Elsevier, B.V.
Year of Publication: 2011
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 06 Petrology, Sedimentary; 07 Marine Geology and Oceanography; Atlantic Ocean; Clastic rocks; Compaction; Compression; Consolidation; Continental margin; Expedition 308; Experimental studies; Gulf of Mexico; Hydrostatic pressure; IODP Site U1322; IODP Site U1324; Integrated Ocean Drilling Program; Marine geology; Marine sediments; Mass movements; Mudstone; North Atlantic; Ocean floors; Overpressure; Pore pressure; Porosity; Sedimentary rocks; Sediments; Slope stability; Slumping; Uniaxial tests; Ursa Basin
Coordinates: N280600 N280600 W0890100 W0890200
N280500 N280500 W0890800 W0890800
Record ID: 2011061206
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands