Fluid-rock interaction recorded in black fault rocks in the Kodiak accretionary complex, Alaska

Yamaguchi, Asuka; Ishikawa, Tsuyoshi; Kato, Yasuhiro; Nozaki, Tatsuo; Meneghini, Francesca; Rowe, C. D.; Moore, J. Casey; Tsutsumi, Akito; Kimura, Gaku

doi:10.1186/1880-5981-66-58

Cited by 15 publications

(14 citation statements)

References 33 publications

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“…Although this result is different from that obtained in previous studies, it is in agreement, in terms of increasing Li concentration, with Yamaguchi et al (2014). Regarding the enrichment of Li, Yamaguchi et al (2014) estimate that reactions with fluids containing a high content of Li occurred at seismogenic depths. In this study, it is suggested that Li and Cs are concentrated due to the similarity of temperatures experienced by the Kodiak accretionary complex and the Nobeoka Thrust.…”

Section: Comparison With Previous Researchescontrasting

confidence: 53%

“…Fluid-rock interactions along the Chelungpu fault, Taiwan, were investigated by Ishikawa et al (2008), while the Emi accretionary complex, Boso, the Kure Mélange of the Shimanto belt, and the Pasagshak Point thrust in the Kodiak accretionary prism were studied by Hamada et al (2011), Honda et al (2011), and Yamaguchi et al (2014), respectively. Table 1 compares the element redistribution patterns derived from this work to those obtained from previous researches.…”

Section: Comparison With Previous Researchesmentioning

confidence: 99%

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Postseismic fluid discharge chemically recorded in altered pseudotachylyte discovered from an ancient megasplay fault: an example from the Nobeoka Thrust in the Shimanto accretionary complex, SW Japan

Hasegawa

Yamaguchi

Fukuchi

et al. 2019

Prog Earth Planet Sci

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Megasplay fault branching from plate boundaries of subduction zones is thought to be important sources of earthquakes and tsunamis. In this study, we performed structural and geochemical analyses on a fossilized megasplay fault (the Nobeoka Thrust of the Shimanto accretionary complex) to understand fluid-rock interaction and how the splay fault plays a role in fluid flow in the seismogenic zone. As a result of structural observations, we report that the principal slip zone (PSZ) of the Nobeoka Thrust is composed of foliated cataclasite originating from a sandstone-shale mélange and includes a thin (~1.5 mm thick) pseudotachylyte layer. Major and trace element composition analysis and EPMA element mapping revealed that the pseudotachylyte is enriched in Li and Cs within the PSZ, as well as in the slip zone of a minor fault in the footwall. Li and Cs enrichment in pseudotachylyte is interpreted as a result of fluid-rock interaction in the postseismic stage, because such an anomaly only results from a large fluid/rock ratio (R > 512-24 at 250-350°C) under the influence of Li-and Cs-enriched fluids. The amount of fluid that reacted with the pseudotachylyte is estimated to be 1.78 × 10 0 to 7.61 × 10 3 m 3 .

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Section: Comparison With Previous Researchescontrasting

confidence: 53%

Section: Comparison With Previous Researchesmentioning

confidence: 99%

Postseismic fluid discharge chemically recorded in altered pseudotachylyte discovered from an ancient megasplay fault: an example from the Nobeoka Thrust in the Shimanto accretionary complex, SW Japan

Hasegawa

Yamaguchi

Fukuchi

et al. 2019

Prog Earth Planet Sci

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“…Rocks in the slip zone of the Taiwan Chelungpu fault showed distinct depletion of or enrichment in fluid-mobile trace elements consistent with coseismic fluid-rock interactions at >350°C and the occurrence of thermal pressurization during the 1999 Chi-Chi earthquake as the permeability of the fault zone is low [Ishikawa et al, 2008;Tanikawa et al, 2009]. Similar geochemical anomalies have been reported in fault rocks from accretionary prisms and another on-land active fault [Hamada et al, 2011;Honda et al, 2011;Ishikawa et al, 2014;Yamaguchi et al, 2014]. However, Ishikawa et al [2008] based their interpretation of geochemical data on the results of laboratory hydrothermal experiments carried out in an autoclave apparatus and obtained after a long reaction time of at least a few days [You et al, 1996;James et al, 2003].…”

Section: Introductionsupporting

confidence: 69%

“…Rocks in the slip zone of the Taiwan Chelungpu fault showed distinct depletion of or enrichment in fluid‐mobile trace elements consistent with coseismic fluid‐rock interactions at >350°C and the occurrence of thermal pressurization during the 1999 Chi‐Chi earthquake as the permeability of the fault zone is low [ Ishikawa et al , ; Tanikawa et al , ]. Similar geochemical anomalies have been reported in fault rocks from accretionary prisms and another on‐land active fault [ Hamada et al , ; Honda et al , ; Ishikawa et al , ; Yamaguchi et al , ]. However, Ishikawa et al .…”

Section: Introductionmentioning

confidence: 99%

Trace element anomaly in fault rock induced by coseismic hydrothermal reactions reproduced in laboratory friction experiments

Tanikawa

Ishikawa

Honda

et al. 2015

Geophysical Research Letters

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Friction experiments at high velocities (0.1 to 0.4 m/s) at room temperature under high pore fluid pressures (2 or 5 MPa) and trace element analyses of the run products were carried out on simulated fault gouge derived from the Chelungpu fault, Taiwan. The friction coefficient decreased to ~0.1 during sliding, and the slip surface temperature reached 300°C by 6 m of slip displacement. The slip caused a small, but distinct decrease of Li in the deformed gouge when the slip surface temperature exceeded 300°C. The observed Li depletion agreed with calculated results, indicating that it resulted from a hydrothermal reaction at a high temperature produced by short‐duration (up to 40 s) frictional heating. The geochemical data suggest a small fluid/rock ratio and low reaction temperature in the simulated fault, which is explained by higher normal stress or repeated earthquakes which elevated fluid‐rock ratios in the natural fault.

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“…Interestingly, feldspar breakdown in fault core is opposite to some other thrusts in subduction setting. For example, plagioclase was newly formed by >350°C water-rock interaction in the fault core of the Pasagshak Point Thrust in the Kodiak accretionary complex, Alaska (Yamaguchi et al 2014), although both the Nobeoka Thrust and the Pasagshak Point Thrust were active at similar background temperatures of approximately 250°C.…”

Section: Factors Controlling Illite Crystallinity Within Fault Zonementioning

confidence: 99%

Changes in illite crystallinity within an ancient tectonic boundary thrust caused by thermal, mechanical, and hydrothermal effects: an example from the Nobeoka Thrust, southwest Japan

Fukuchi

Fujimoto

Kameda

et al. 2014

Earth, Planets and Space

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Illite crystallinity (IC), the full width at half maximum of the illite (001) peak in clay-fraction X-ray diffraction (XRD), is a common geothermometer widely applied to various tectonic settings. Paleotemperature estimation using IC presents methodological ambiguity because IC is not only affected by background temperature but also by mechanical, hydrothermal, and surface weathering effects. To clarify the influences of these effects on IC in the fault zone, we analyzed the IC and the illite 001 peak intensity of continuous borehole core samples from the Nobeoka Thrust, a fossilized tectonic boundary thrust in the Shimanto Belt, the Cretaceous-Paleogene Shimanto accretionary complex in southwest Japan. We also carried out grinding experiments on borehole core samples and sericite standard samples as starting materials and investigated the effect of mechanical comminution on the IC and illite peak intensity of the experimental products. We observed the following: (1) the paleotemperatures of the hanging wall and footwall of the Nobeoka Thrust are estimated to be 288°C to 299°C and 198°C to 249°C, respectively, which are approximately 20°C to 30°C lower than their previously reported temperatures estimated by vitrinite reflectance; (2) the fault core of the Nobeoka Thrust does not exhibit IC decrease; (3) the correlation of IC and illite peak intensity in the hanging wall damage zone were well reproduced by the grinding experiment, suggesting that the effect of mechanical comminution increases toward the fault core and; (4) the abrupt increase in IC value accompanied by high illite peak intensity is explained by hydrothermal alterations including plagioclase breakdown and the formation of white micas. Our results indicate that IC has potential for quantifying the effects of mechanical comminution and hydrothermal alteration within a fault zone.

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Fluid-rock interaction recorded in black fault rocks in the Kodiak accretionary complex, Alaska

Abstract: Ultrafine-grained black fault rocks (BFRs)

Cited by 15 publications

References 33 publications

Postseismic fluid discharge chemically recorded in altered pseudotachylyte discovered from an ancient megasplay fault: an example from the Nobeoka Thrust in the Shimanto accretionary complex, SW Japan

Postseismic fluid discharge chemically recorded in altered pseudotachylyte discovered from an ancient megasplay fault: an example from the Nobeoka Thrust in the Shimanto accretionary complex, SW Japan

Trace element anomaly in fault rock induced by coseismic hydrothermal reactions reproduced in laboratory friction experiments

Changes in illite crystallinity within an ancient tectonic boundary thrust caused by thermal, mechanical, and hydrothermal effects: an example from the Nobeoka Thrust, southwest Japan

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