Relationship between fault growth mechanism and permeability variations with depth of siliceous mudstones in northern Hokkaido, Japan

Ishii, Eiichi; Funaki, Hironori; Tokiwa, Tetsuya; Ota, Ken Ichiro

doi:10.1016/j.jsg.2009.10.012

Cited by 38 publications

(34 citation statements)

References 48 publications

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“…The sedimentary sequence passes upwards from Wakkanai Formation (massive siliceous diatomaceous mudstones including opal-CT), through the Koetoi Formation (massive diatomaceous mudstones including opal-A, but not opal-CT) to the Yuchi Formation (fine to medium grained sandstones) and to the Sarabetsu Formation (alternating beds of conglomerate, sandstone and mudstone, intercalated with coal seams) which is overlain by late Pleistocene to Holocene deposits (Ishii et al, 2010).…”

Section: Geological Backgroundmentioning

confidence: 99%

Microbiological influences on fracture surfaces of intact mudstone and the implications for geological disposal of radioactive waste

et al. 2011

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The significance of the potential impacts of microbial activity on the transport properties of host rocks for geological repositories is an area of active research. Most recent work has focussed on granitic environments. This paper describes pilot studies investigating changes in transport properties that are because of microbial activity in sedimentary rock environments in northern Japan. For the first time, these short experiments (39 days maximum) have shown that the denitrifying bacteria, Pseudomonas denitrificans, can survive and thrive when injected into flowthrough column experiments containing fractured diatomaceous mudstone material and synthetic groundwater under pressurised conditions. Although there were few significant changes in the fluid chemistry, changes in the Microbiological impacts -mudstone 2 permeability of the biotic column were quantitatively monitored. These same methodologies could also be adapted to obtain information from cores originating from a variety of geological environments including oil reservoirs, aquifers and toxic waste disposal sites to provide an understanding of the impact of microbial activity on the transport of a range of solutes, such as groundwater contaminants and gases (e.g. injected carbon dioxide).

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Section: Geological Backgroundmentioning

confidence: 99%

Microbiological influences on fracture surfaces of intact mudstone and the implications for geological disposal of radioactive waste

et al. 2011

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“…Tectonic deformation structures, such as compactional shear bands (i.e., shear bands with volumetric compaction), faults, and joints, are observed in outcrops and in drill cores from the Wakkanai and Koetoi formations [ Funaki et al , 2009; Ishii et al , 2010; E. Ishii, Microstructure and origin of faults in siliceous mudstone at the Horonobe Underground Research Laboratory site, Japan, submitted to Journal of Structural Geology , 2011]. However, they are seldom observed in the Yuchi Formation.…”

Section: Structural Datamentioning

confidence: 99%

“…However, even where the bands are very thin, their presence is indicated by darkish planes on the faults (Figures 3b and 5c). Fault breccia and/or fault gouge are associated with some of the faults [ Funaki et al , 2009; Ishii et al , 2010]. …”

Section: Structural Datamentioning

confidence: 99%

“…The joints are unhealed and incohesive open fractures, characterized by natural plumose structure on the joint walls. Many of the joints observed in outcrops of the Wakkanai Formation are splays, propagating from faults associated with fault rocks [ Ishii et al , 2010]. …”

Section: Structural Datamentioning

confidence: 99%

“…The results are in the range of 10 −19 to 10 −12 m 2 (10 −12 to 10 −5 m/s) (Figure 11). Highly permeable packer sections (>10 −14 m 2 or >10 −7 m/s) are limited to shallower depths in the Wakkanai Formation [ Ishii et al , 2010]. …”

Section: Hydrogeological Datamentioning

confidence: 99%

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The relationships among brittleness, deformation behavior, and transport properties in mudstones: An example from the Horonobe Underground Research Laboratory, Japan

et al. 2011

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[1] Mudstones are low-permeability sedimentary rocks; however, when shear stresses induced by tectonic movement or nonhydrostatic stresses exceed the shear strength of the rock, brittle or ductile deformation occurs. The nature of this deformation is controlled by the brittleness of the mudstone. If brittle deformation occurs, the resulting dilatant structures may increase the permeability and change the transport properties of the strata. This paper addresses the relationships among brittleness, deformation behavior, and transport properties in mudstones at the Horonobe Underground Research Laboratory, Japan. Geological, mechanical, and hydrogeological data from borehole investigations and laboratory tests were systematically interpreted using a brittleness index (BRI), which is the ratio of the unconfined compressive strength to the effective vertical stress. For mudstones under natural strain rates and low temperatures, ductile deformation occurs when BRI <2, brittle/ductile deformation occurs when BRI is 2-8, and brittle deformation occurs when BRI >8, although semibrittle behavior may also occur at the brittle-ductile boundary. When BRI >8 and faulting is well developed, the mudstone behaves hydrogeologically as a fractured medium at the mesoscopic scale, whereas for BRI <8 the mudstone behaves hydrogeologically as a porous medium, even if faulting is extensive. The BRI concept is a useful tool for systematically characterizing the hydromechanical behavior of mudstones; for example, when assessing the effectiveness of mudstone as a long-term barrier in disposal repositories for radioactive waste.Citation: Ishii, E., H. Sanada, H. Funaki, Y. Sugita, and H. Kurikami (2011), The relationships among brittleness, deformation behavior, and transport properties in mudstones: An example from the Horonobe Underground Research Laboratory, Japan,

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Predictions of the highest potential transmissivity of fractures in fault zones from rock rheology: Preliminary results

Ishii

2015

JGR Solid Earth

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Fracture transmissivity in a fault zone is a significant parameter when solving certain geoscientific and geotechnical problems. However, the transmissivities are difficult to predict quantitatively owing to the complexity of in situ conditions such as the apertures of fractures. This study analyzes extensive data sets on flow anomalies (transmissive zones) detected from fluid/flow logs of boreholes in fault zones in the light of rock rheology, fracture mineralization/dissolution, and fracture orientation at six sites, namely Horonobe (Japan; siliceous mudstone), Wellenberg (Switzerland; argillaceous marl), Forsmark (Sweden; granite/granodiorite), Olkiluoto (Finland; gneiss), Northern Switzerland (granite/gneiss), and Sellafield (UK; volcaniclastic rocks and sandstone). The flow anomalies are correlated to fractures in fault zones. The data sets show that the transmissivities of the flow anomalies are strongly controlled by the ductility index, defined as the effective mean stress normalized to the tensile strength of the intact rock. An empirically derived power law relationship exists between the transmissivity and the ductility index, allowing predictions of the highest potential transmissivities of fractures in possible fault zones with maximum errors of about 2 orders of magnitude, due to the inevitable heterogeneity of a fault zone. The actual transmissivities may be further reduced by mineral precipitation in the fractures, or increased by mineral dissolution. Fracture orientation has no discernable influence on the transmissivity. The results may prove helpful for understanding and predicting the long-term transport properties of fault zones in the upper crust.

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Relationship between fault growth mechanism and permeability variations with depth of siliceous mudstones in northern Hokkaido, Japan

Cited by 38 publications

References 48 publications

Microbiological influences on fracture surfaces of intact mudstone and the implications for geological disposal of radioactive waste

Microbiological influences on fracture surfaces of intact mudstone and the implications for geological disposal of radioactive waste

The relationships among brittleness, deformation behavior, and transport properties in mudstones: An example from the Horonobe Underground Research Laboratory, Japan

Predictions of the highest potential transmissivity of fractures in fault zones from rock rheology: Preliminary results

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