Permeabilities, fluid pressures, and flow rates in the Barbados Ridge Complex

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doi: 10.1029/JB095iB06p08997
Author(s): Screaton, Elizabeth J.; Wuthrich, Dennis R.; Dreiss, Shirley J.
Author Affiliation(s): Primary:
Univ. Calif. at Santa Cruz., Earth Sci. Board, Santa Cruz, CA, United States
Other:
Univ. Calif. at Santa Cruz, United States
Volume Title: Special section on the Role of fluids in sediment accretion, deformation, diagenesis, and metamorphism in subduction zones
Volume Author(s): Langseth, Marcus G., editor; Moore, J. Casey
Source: Journal of Geophysical Research, 95(B6), p.8997-9007; Workshop on the Role of fluids in accretionary complexes, Il Ciocco, Tuscany, Italy, 1988, edited by Marcus G. Langseth and J. Casey Moore. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0148-0227
Note: In English. 48 refs.; illus. incl. 2 tables, sketch map
Summary: Recent measurements from Ocean Drilling Program leg 110 and Deep Sea Drilling Project leg 78a indicate that pore pressures near the toe of the Barbados accretionary prism may be close to lithostatic and that the décollement is a zone with relatively high rates of fluid flow and methane transport. We used a numerical model of fluid flow to estimate intrinsic permeabilities, pore pressures, and flow velocities that are consistent with these observations. Model results suggest that the permeability of the décollement may be 3-5 orders of magnitude greater than that of adjacent prism sediments. If permeabilities in the prism vary with depth in a manner similar to those in sedimentary basins, the average intrinsic permeability of the décollement, k d , must be about 10-14 m2. When kd is 10-13 m2, high pore pressures do not develop near the deformation front in the model. If kd is 10-15 m2, simulated pressures are unrealistically high in both the prism and underthrust sediments arcward of the deformation front. Water originating from compaction in the décollement and underthrust sediments flows laterally seaward, while water expelled from prism sediments flows upward to the ocean floor. However, flow velocities are small, and the net motion of pore water in prism and underthrust sediments is arcward relative to the deformation front because of tectonic transport. Pore water migrates seaward in spite of tectonic transport only in discrete zones with higher permeability, in this case the décollement. Copyright 1990 by the American Geophysical Union.
Year of Publication: 1990
Research Program: DSDP Deep Sea Drilling Project
ODP Ocean Drilling Program
Key Words: 07 Marine Geology and Oceanography; 18 Geophysics, Solid-Earth; Accretionary wedges; Atlantic Ocean; Barbados Ridge; Decollement; Deep Sea Drilling Project; Fluid pressure; Leg 110; Leg 78; Marine sediments; North American Atlantic; North Atlantic; Numerical models; Ocean Drilling Program; Oceanography; Permeability; Plate tectonics; Pore water; Properties; Sediments
Coordinates: N152000 N154500 W0582000 W0590500
Record ID: 1990053591
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