Mechanical and hydraulic properties of Nankai accretionary prism sediments; effect of stress path

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doi: 10.1029/2012GC004124
Author(s): Kitajima, Hiroko; Chester, Frederick M.; Biscontin, Giovanna
Author Affiliation(s): Primary:
Texas A&M University, Department of Geology and Geophysics, College Station, TX, United States
Volume Title: Geochemistry, Geophysics, Geosystems - G<sup>3</sup>
Source: Geochemistry, Geophysics, Geosystems - G>3`, 13(10). Publisher: American Geophysical Union and The Geochemical Society, United States. ISSN: 1525-2027
Note: In English. 85 refs.; illus., incl. 1 table
Summary: We have conducted triaxial deformation experiments along different loading paths on prism sediments from the Nankai Trough. Different load paths of isotropic loading, uniaxial strain loading, triaxial compression (at constant confining pressure, Pc), undrained Pc reduction, drained Pc reduction, and triaxial unloading at constant Pc, were used to understand the evolution of mechanical and hydraulic properties under complicated stress states and loading histories in accretionary subduction zones. Five deformation experiments were conducted on three sediment core samples for the Nankai prism, specifically from older accreted sediments at the forearc basin, underthrust slope sediments beneath the megasplay fault, and overthrust Upper Shikoku Basin sediments along the frontal thrust. Yield envelopes for each sample were constructed based on the stress paths of Pc-reduction using the modified Cam-clay model, and in situ stress states of the prism were constrained using the results from the other load paths and accounting for horizontal stress. Results suggest that the sediments in the vicinity of the megasplay fault and frontal thrust are highly overconsolidated, and thus likely to deform brittle rather than ductile. The porosity of sediments decreases as the yield envelope expands, while the reduction in permeability mainly depends on the effective mean stress before yield, and the differential stress after yield. An improved understanding of sediment yield strength and hydromechanical properties along different load paths is necessary to treat accurately the coupling of deformation and fluid flow in accretionary subduction zones.
Year of Publication: 2012
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 16 Structural Geology; Accretionary wedges; Brittle deformation; Compressive strength; Consolidation; Cores; Coupling; Critical load; Deformation; Experimental studies; Fluid phase; Hydraulic conductivity; Integrated Ocean Drilling Program; Marine sediments; Mechanical properties; NanTroSEIZE; Nankai Trough; North Pacific; Northwest Pacific; Overconsolidated materials; Pacific Ocean; Permeability; Physical properties; Sediments; Shikoku Basin; Stress; Subduction zones; Triaxial tests; West Pacific
Record ID: 2013088584
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from John Wiley & Sons, Chichester, United Kingdom, Reference includes data supplied by, and/or abstract, Copyright, American Geophysical Union

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