In this study, we executed constant-flow permeability tests in the horizontal (cross-core) and vertical (along-core) directions using 11 whole-round core specimens of mud(stone) from Integrated Ocean Drilling Program Nankai Trough Sites C0006 and C0007. The samples came from ~34 to 564 meters below seafloor and include lithostratigraphic Units II (accreted trench wedge) and III (upper Shikoku Basin facies). Effective isotropic confining stress during the tests was set at 0.55 MPa (80 psi). At Site C0006, the highest value of vertical hydraulic conductivity (K v) is 1.60 × 10-6 cm/s and the lowest value of vertical hydraulic conductivity is 2.63 × 10-10 cm/s. The highest value of horizontal hydraulic conductivity (K h) is 2.07 × 10-6 cm/s, and the lowest value of horizontal hydraulic conductivity is 3.25 × 10-10 cm/s. The average ratio of horizontal to vertical intrinsic permeability (k h /k v) is 4.27. At Site C0007, the highest value of vertical hydraulic conductivity is 1.24 × 10-9 cm/s and the lowest value of vertical hydraulic conductivity is 9.54 × 10-10 cm/s. Horizontal hydraulic conductivity reaches a maximum of 1.15 × 10-9 cm/s, and the lowest value of horizontal hydraulic conductivity is 8.09 × 10-10 cm/s. The average ratio k h /k v is 0.93 for specimens at Site C0007. Environmental scanning electron microscopy was used to evaluate the relation between sediment microstructure and anisotropy of permeability. The index of orientation does not vary significantly and shows a weak correlation with k h /k v values.
This report documents the results of constant-flow permeability tests in the horizontal (cross-core) and vertical (along-core) directions, administered at an effective isotropic confining stress of 0.55 MPa (80 psi). The whole-round specimens of mud(stone) were collected from depths of ~34 to 748 meters below seafloor at Integrated Ocean Drilling Program Sites C0011 and C0012 in the Shikoku Basin. Unfortunately, only ten samples were tested successfully; five samples failed because of drilling-induced core damage or friability. Most test results show minor anisotropy ef-
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