Elucidation for behavior of pore fluid in a sediment resulted in wet-sedimet deformation

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Two deformation styles, the brittle and ductile deformations, are recognized in wet-sediment deformation. The former is represented by a healted fault or planeless fault, and the latter is characterized by deformation that have modified the primary sedimentary structure. Based on the specific image of X-ray CAT scan tomogram, SEM observation and the pore distribution detected by Mercury injection type porosimeter, it enables to examine the detailed bulk-density distribution in a healt fault plane, that is complicated rather than expected. In the brittle deformation, the pore distribution pattern is changed by formation of fracture (secondary pore) and shearing of preexisting pores. In a part of the same fault plane, the clay minerals are obviously deformed (imbricated) and the associated pores are often broken and makes porosity smaller than htat of the non-deformed surrounds. On the other hand, fractures are developed in the adjacent part within the same fault plane, where any change in pore distribution is not identified, that cause the porosity larger than the non-deformed surrounds. Hence, the positive and negative anomaries in porosity can be recognized in the same plane of a healt fault, suggesting that the imbricated domain should play important role to expell the pore water whereas the fractured is likely to behave as a reservior of the pore water, then the developments of the both is important factor in controlling flow behavior along a fault in a brittle deformation stage. Significant difference in pore distribution pattern is identified between the ductile-deromed and the adjacent non-deformed sediments although any differences in porosity can not be detected. The ductile deformation is likely to make the pore distribution Gaussian-like unimodal distribution, suggesting that the ductile defromation should cause reorganization of the pore distributuion to be more simple pattern than the primary non-deformed one.