Determination of the stress conditions of the ductile-to-brittle regime along the Asuke Shear Zone, SW Japan

Kanai, Takuto; Takahashi, Hideo

doi:10.1016/j.jsg.2016.02.009

Cited by 10 publications

(4 citation statements)

References 85 publications

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“…Therefore, the top-to-the-north normal faulting, the movement direction of which is normal to the trend of the proto-Southwest Japan arc (N75°E in the present orientation), could have been caused by the ridge subduction parallel to the arc. Kanai et al (2014); Kanai and Takagi (2016) estimated the paleostress orientations of the σ 3 axis trending nearly normal to the MTL based on the preferred orientation of healed microcracks in quartz from the Ryoke granite in Central Japan during the Late Cretaceous to Early Paleocene. The inferred orientation of the σ 3 axis indicates that the extensional stress field normal to the MTL is extensive during the Ichinokawa phase, supporting the tectonic interpretation mentioned above.…”

Section: 1029/2018tc005372mentioning

confidence: 99%

Kinematic Analyses and Radiometric Dating of the Large‐Scale Paleogene Two‐Phase Faulting Along the Median Tectonic Line, Southwest Japan

Kubota

Takeshita

Yagi³

et al. 2020

Tectonics

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The Median Tectonic Line (MTL) in Southwest Japan, a major east-west trending arc-parallel fault, has been defined as the boundary fault between the Cretaceous Sambagawa metamorphic rocks and the Ryoke granitic and metamorphic rocks, which are unconformably covered by the Upper Cretaceous Izumi Group. Based on the detailed fieldwork and microstructural studies of fault rocks, we reconstruct the kinematic history along the MTL during the Paleogene, which can be divided into the Ichinokawa and pre-Tobe phases. While the Ichinokawa phase is defined by large-scale, top-to-the-north normal faulting, the pre-Tobe phase is represented by large-scale, high-angle right-stepping en échelon faults almost parallel to the MTL in the Upper Cretaceous Izumi Group. We found that left-handed en échelon folds have developed along the right-stepping faults, which contain 25-60 m wide cataclasite and fault gouge. Both map scale en échelon folds and microstructures (e.g., composite planar structures) in the fault rocks suggest that they were formed by sinistral-reverse faulting with top-to-the-SW kinematics. Furthermore, based on the new K-Ar age dating of authigenic illite from the fault gouge along the MTL and right-stepping faults, it can be concluded that the MTL was activated in two discrete stages at approximately 59 Ma (Ichinokawa phase) and 47-46 Ma (pre-Tobe phase). Based on these results, we reappraise the kinematic framework of the MTL in the Paleogene, which can be interpreted as the record of the movements of the subducting oceanic plate relative to the continental plate.

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Section: 1029/2018tc005372mentioning

confidence: 99%

Kinematic Analyses and Radiometric Dating of the Large‐Scale Paleogene Two‐Phase Faulting Along the Median Tectonic Line, Southwest Japan

Kubota

Takeshita

Yagi³

et al. 2020

Tectonics

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“…Calcite‐twin data (pairs of adjacent twinned and untwinned c‐axis crystallographic orientations from EBSD analysis) were also used to invert for paleostress directions. The twinning data were recast into a form analogous to fault‐slip data using the following steps (e.g., Craddock & Magloughlin, 2005; Engelder, 1979; Kanai & Takagi, 2016; Kilsdonk & Wiltschko, 1988; Turner, 1962): (a) crystallographic orientation data from host calcite grains and their adjacent e‐twins were collected by EBSD (see above); (b) the crystallographic orientations from the e‐twin and the host calcite grains were used to determine the e‐twin plane, glide direction, and sense of shear for every twin pair based on the known angular relationships (e.g., Burkhard, 1993); and (c) the kinematic data (glide plane, direction, and shear sense) were converted from a sample coordinate system (relative to lineation, foliation, and top‐bottom) to a geographical one (N–S, E–W, and top–bottom; see Data Repository for the conversion MATLAB‐code).…”

Section: Methodsmentioning

confidence: 99%

Using Syntectonic Calcite Veins to Reconstruct the Strength Evolution of an Active Low‐Angle Normal Fault, Woodlark Rift, SE Papua New Guinea

et al. 2021

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Lithospheric or crustal strength is often expressed as the maximum differential stress that a rock can sustain before it fractures or flows. Most knowledge of brittle rock strength comes from laboratory experiments (e.g., Byerlee, 1978) and deep boreholes (e.g., Hickman & Zoback, 2004;Zoback & Harjes, 1997). These studies typically infer Coulomb frictional failure in the upper crust, in which the differential stress or shear stress (τ) is linearly related to the effective normal stress (σ e ) via a "Byerlee" coefficient of friction (μ = 0.6-0.85, Behr & Platt, 2014;Byerlee, 1978). Detachment faults-associated with regional extension-that may have formed and/or slipped as "low-angle normal faults" (<30°, LANFs), remain a controversial topic because Andersonian normal faults in Mohr-Coulomb materials with "Byerlee" frictional strength should form and slip at dips of 60-75° and frictionally lock-up at dips <30-45° (e.g.,

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“…After the amalgamation of low-and high-P/T-type metamorphic belts at the subduction interface during 66-64 Ma, the paired metamorphic belts in most areas (Oshika, Yanai, Centrail Shikoku and Kii peninusula) were exhumed between 60 and 50 Ma, according to the revised cooling curve (Figure 14b; Narita et al, 1999;Wallis et al, 2004). Much structural evidence has suggested the occurrence of extensional exhumation related to normal fault movement in the Sanbagawa and Ryoke belts (Fukunari & Wallis, 2007;Kanai & Takagi, 2016;Kubota et al, 2020;Kubota & Takeshita, 2008;Osozawa & Pavlis, 2007). The timing of exhumation during brittle deformation is consistent with that of Izanagi-Pacific Ridge subduction (Figure 14b; Seton et al, 2015).…”

Section: Exhumation Of Paired Metamorphic Beltsmentioning

confidence: 99%

Amalgamation of the Ryoke and Sanbagawa metamorphic belts at the subduction interface: New insights from the Kashio mylonite along the Median Tectonic Line, Nagano, Japan

Nakamura

Miyazaki

Takahashi

et al. 2021

Journal Metamorphic Geology

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We present a detailed petrological, structural and geochronological study of the mylonitic Ryoke metamorphic rocks within the granitic mylonite (Kashio mylonite) and Sanbagawa metamorphic rocks along the Median Tectonic Line (MTL), Japan. Located in the Oshika area of the Chubu District, the Kashio mylonite is one of the few geologic units that can be used to determine detailed pressure-temperature-time-deformation (P-T-t-D) paths during mylonitization because it occurs as many small tectonic blocks of mylonitic metasediment. Detailed petrological analysis coupled with conventional thermobarometry and P-T pseudosection modelling give estimated peak P-T conditions (M1a) of 650-790 C at 4.6-5.6 kbar for the Ryoke metamorphic rocks. The gneissose Ryoke granitoids were emplaced subhorizontally at around 685-710 C and 4.6-5.8 kbar, after peak metamorphism. The Kashio shear zone developed immediately after the last igneous activity at ca. 71 Ma, and two stages of mylonitization (stages D1 and D2) can be identified from microstructural observations. The retrograde P-T conditions (M1b) recorded in the Kashio mylonite exhibit a systematic change in temperature from 710 C to 450 C at 5.2-2.6 kbar with decreasing distance from the MTL. By contrast, highly deformed mylonites with zoned garnets demonstrate a striking increase in pressure from 4.0 to 8.3 kbar with decreasing temperature from 590 C to 450 C after low-P/T-type metamorphism. Such a temperature range indicating isothermal compression is consistent with deformation temperatures of stage D1 determined from quartz microstructures and quartz c-axis fabric openingangle deformation thermometer. Moreover, the timing of the two mylonitization episodes during retrograde metamorphism are estimated to be 69-67 and 66-64 Ma, respectively, with a high cooling rate of $34 C/Ma using the revised time-temperature relationship of the host Ryoke granitoids. The rapid change in tectonic setting with strain localization occurred during the brief period between 69 and 64 Ma. Our field and petrological observations imply that a thick D1 mylonite zone was formed by rapid subsidence

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Determination of the stress conditions of the ductile-to-brittle regime along the Asuke Shear Zone, SW Japan

Cited by 10 publications

References 85 publications

Kinematic Analyses and Radiometric Dating of the Large‐Scale Paleogene Two‐Phase Faulting Along the Median Tectonic Line, Southwest Japan

Kinematic Analyses and Radiometric Dating of the Large‐Scale Paleogene Two‐Phase Faulting Along the Median Tectonic Line, Southwest Japan

Using Syntectonic Calcite Veins to Reconstruct the Strength Evolution of an Active Low‐Angle Normal Fault, Woodlark Rift, SE Papua New Guinea

Amalgamation of the Ryoke and Sanbagawa metamorphic belts at the subduction interface: New insights from the Kashio mylonite along the Median Tectonic Line, Nagano, Japan

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