Proceedings of the International workshop on the Nojima Fault core and borehole data analysis

Fujimoto, Koichiro; Tanaka, Hidemi; Lockner, D. A.

doi:10.3133/ofr00129

Cited by 4 publications

(1 citation statement)

References 142 publications

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“…Nojima Fault Projects, Japan: Soon after the Kobe earthquake in 1995 (M6.9), several research teams drilled multiple boreholes into and across the shallow portion of the Nojima fault (the locus of that event) from ~750 m to ~1800 m depth (Ito et al, 1999;Omura, this issue,). Detailed compositional and structural analyses identified a narrow fault core of gouge and surrounding damage zone, with asymmetric structure in the footwall and hanging wall (Boullier et al, 2001;Fujimoto et al, 2001;Ito et al, 1996;Ohtani et al, 2001;Tanaka et al, 2001).…”

Section: Nankai Trough Accretionary Wedge Muroto Region Westernmentioning

confidence: 99%

Joint IODP-ICDP Workshop Examines Challenges of Fault Zone Drilling

Tobin

Ito

Behrmann

et al. 2007

Scientific Drilling

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Section: Nankai Trough Accretionary Wedge Muroto Region Westernmentioning

confidence: 99%

Joint IODP-ICDP Workshop Examines Challenges of Fault Zone Drilling

Tobin

Ito

Behrmann

et al. 2007

Scientific Drilling

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Grain size distributions of fault rocks: A comparison between experimentally and naturally deformed granitoids

Keulen

Heilbronner

Stünitz

et al. 2007

Journal of Structural Geology

144

105

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Healing microstructures of experimental and natural fault gouge

2008

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[1] The healing of fault gouge was studied by examining microstructures of naturally and experimentally produced granitoid fault rock. We performed deformation experiments on intact granitoid rock samples at T = 300-500°C, P c = 500 MPa, and _ e = 1.2 Â 10 À4 -1.3 Â 10 À7 s À1 with 0.2 wt% H 2 O added. Healing experiments were carried out on deformed samples at T = 200-500°C, P c = 500 MPa, for 4 h to 14 days under hydrostatic and nonhydrostatic conditions. The grain size distributions (GSD) of the deformed samples were quantified using the D > value (slope of log(frequency) -log(radius) of the GSD) for quartz and feldspar fault gouge. Healing causes a decrease in the D > value from >2.0 to $1.5. The time dependence of the D > decrease is described by a hydrostatic healing law of the form DD = D > (t) À D f = A Á e (ÀlÁt) . The results of the laboratory experiments were compared to three natural fault systems, (1) Nojima Fault Zone (Japan), (2) fault zones in the Black Forest (Germany), and (3) Orobic Thrust (Italian Alps). Natural and experimental gouges have similar D > values. Healing is only observed in monomineralic aggregates; polymineralic (i.e., mixed) fault gouges retain their high D > value after extended healing times because grain growth is inhibited. Healing under nonhydrostatic conditions is more rapid than hydrostatic healing. The low strain rates, which were measured during nonhydrostatic healing, are temperature-dependent and suggest that diffusive mass transfer processes take place during deformation. Thus, fault rocks at upper to midcrustal depth may deform by combined cataclasis and diffusive mass transfer.

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Proceedings of the International workshop on the Nojima Fault core and borehole data analysis

Abstract: Vll similar studies of their core materials.All groups have completed a number of downhole measurements, particularly in the holes across the Nojima fault. The research activities on the GSJ Hirabayashi borehole are described in Fig. 2 and the publication list is shown in the Appendix.

Cited by 4 publications

References 142 publications

Joint IODP-ICDP Workshop Examines Challenges of Fault Zone Drilling

Joint IODP-ICDP Workshop Examines Challenges of Fault Zone Drilling

Grain size distributions of fault rocks: A comparison between experimentally and naturally deformed granitoids

Healing microstructures of experimental and natural fault gouge

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