A simplified analysis of parameters controlling dewatering in accretionary prisms

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doi: 10.1016/0012-821X(92)90092-A
Author(s): Bekins, Barbara A.; Dreiss, Shirley J.
Author Affiliation(s): Primary:
Univ. Calif. at Santa Cruz, Earth Sci. Board, Santa Cruz, CA, United States
Other:
Ec. Norm. Supér., France
Volume Title: Fluids in convergent margins
Volume Author(s): Kastner, M., editor; Le Pichon, Xavier
Source: Earth and Planetary Science Letters, 109(3-4), p.275-287; Fluids in subduction zones, Paris, France, Nov. 5-6, 1991, edited by M. Kastner and Xavier Le Pichon. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X CODEN: EPSLA2
Note: In English. 14 refs.; illus. incl. 3 tables
Summary: One of the many dynamic geological processes taking place at subduction zones is the compaction-driven dewatering of sea-floor sediments as they are accreted to the overriding plate. The rate of dewatering is equal to the divergence of the sediment matrix velocity field. This rate can be estimated analytically if simplifying assumptions are made about the geometry of the prism and the motion of the sediments. The analytical expression depends only on the sediment accretion velocity, thickness of the accreted section, prism taper angle, and sediment porosity distribution. A sensitivity analysis of the solution shows that the fluid production distribution is relatively insensitive to the sediment porosity distribution, but the solution is very sensitive to the taper angle of the wedge. High-angle wedges expel almost all of the incoming water within 20 km, while low-angle wedges may retain a significant fraction of the incoming water for >= 50 km. Thickness of the incoming section is also important. Dewatering of thin accreted sections is more concentrated near the toe of the wedge. Analyses of transects through the Northern Barbados, Makran, Vancouver and Nankai accretionary prisms illustrate a range of dewatering rates and spacial distributions of dewatering. [Authors' abstract]
Year of Publication: 1992
Research Program: ODP Ocean Drilling Program
Key Words: 07 Marine Geology and Oceanography; 18 Geophysics, Solid-Earth; Accretionary wedges; Compaction; Dehydration; Marine sediments; Plate tectonics; Pore water; Processes; Sediments; Subduction zones
Record ID: 1992024683
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom

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