Paleostress orientation from 3‐D orientation distribution of microcracks in quartz from the Cretaceous granodiorite core samples drilled through the Nojima Fault, south‐west Japan

Takeshita, Toru; Yagi, Koshi

doi:10.1111/j.1440-1738.2001.00348.x

Cited by 7 publications

(6 citation statements)

References 28 publications

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“…The presence of healed rather than sealed or open microcracks (Smith & Evans ) suggests that these samples underwent metamorphism at around 200 °C–300 °C (e.g. Takeshita ; Takeshita & Yagi ), consistent with temperatures inferred from metamorphic mineral assemblages ( P = ˜ 7 kb and T = 250 °C–300 °C; Sakakibara & Ota ). Accordingly, metamorphism in the study area did not reach temperatures greater than the closure temperature of FT in zircon ( ca.…”

Section: Discussionsupporting

confidence: 61%

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Fission track and U–Pb zircon ages of psammitic rocks from the Harushinai unit, Kamuikotan metamorphic rocks, central Hokkaido, Japan: constraints on metamorphic histories

Okamoto

Takeshita

Iwano³

et al. 2015

Island Arc

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Accurate pressure-temperature-time (P-T-t) paths of rocks from sedimentation through maximum burial to exhumation are needed to determine the processes and mechanisms that form high-pressure and low-temperature type metamorphic rocks. Here, we present a new method combining laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) U-Pb with fission track (FT) dates for detrital zircons from two psammitic rock samples collected from the Harushinai unit of the Kamuikotan metamorphic rocks. The concordant zircon U-Pb ages for these samples vary markedly, from 1980 to 95 Ma, with the youngest age clusters in both samples yielding Albian-Cenomanian weighted mean ages of 100.8 ± 1.1 and 99.3 ± 1.0 Ma (2σ uncertainties). The zircon U-Pb ages were not reset by high-P/T type metamorphism, because there is no indication of overgrowth within the zircons with igneous oscillatory zoning. Therefore, these weighted mean ages are indicative of the maximum age of deposition of protolithic material. By comparison, the zircon FT data yield a pooled age of ca. 90 Ma, which is almost the same as the weighted mean age of the youngest U-Pb age cluster. This indicates that the zircon FT ages were reset at ca. 90 Ma while still at their source, but have not been reset since. This conclusion is supported by recorded temperature conditions of less than about 300°C (the closure temperature of zircon FTs), as estimated from microstructures in the deformed detrital quartz grains in psammitic rocks, and no shortening of fission track lengths in the zircon. Combining these new data with previously reported white mica K-Ar ages indicates that the Harushinai unit was deposited after ca. 100 Ma, and underwent burial to its maximum depth before being subjected to a localized thermal overprint during exhumation at ca. 58 Ma.

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Section: Discussionsupporting

confidence: 61%

“…e, Smith & Evans ), which are inferred to have formed at temperatures of 200 °C–300 °C near the brittle–ductile transition conditions of quartz (e.g. Takeshita ; Takeshita & Yagi ). The other evidence of brittle deformation is the presence of pull‐apart microstructures (i.e.…”

Section: Petrography Of the Analysed Psammitic Rock Samplesmentioning

confidence: 99%

Fission track and U–Pb zircon ages of psammitic rocks from the Harushinai unit, Kamuikotan metamorphic rocks, central Hokkaido, Japan: constraints on metamorphic histories

Okamoto

Takeshita

Iwano³

et al. 2015

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“…The diagram in Figure 8 was rotated to a position in which the dominant set of faultrelated microfractures in quartz would have the roughly E-W (to NE-SW) orientation determined by TAKESHITA and YAGI (2001). This positioning also causes the minor shear to be oriented subparallel to the strike of the Nojima fault, consistent with the results of CÉLÉRIER et al, (2000).…”

Section: Microstructure Orientationssupporting

confidence: 77%

“…Relative strikes of microstructural elements in damage-zone sample GSJ 101-2. The figure was oriented such that the dominant fracture set in quartz has the roughly EW (to NE-SW) trend measured by TAKESHITA and YAGI (2000), and the minor shear is sub-parallel to the strike (&N36°E) of the Nojima fault (that is, a north arrow would point upwards in this interpretation).…”

Section: Microstructure Orientationsmentioning

confidence: 99%

Geometry of the Nojima Fault at Nojima-Hirabayashi, Japan – II. Microstructures and their Implications for Permeability and Strength

Moore

Lockner

Ito

et al. 2009

Pure appl. geophys.

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Samples of damage-zone granodiorite and fault core from two drillholes into the active, strikeslip Nojima fault zone display microstructures and alteration features that explain their measured present-day strengths and permeabilities and provide insight on the evolution of these properties in the fault zone. The least deformed damage-zone rocks contain two sets of nearly perpendicular (60-90°angles), roughly vertical fractures that are concentrated in quartz-rich areas, with one set typically dominating over the other. With increasing intensity of deformation, which corresponds generally to increasing proximity to the core, zones of heavily fragmented rock, termed microbreccia zones, develop between prominent fractures of both sets. Granodiorite adjoining intersecting microbreccia zones in the active fault strands has been repeatedly fractured and locally brecciated, accompanied by the generation of millimeter-scale voids that are partly filled with secondary minerals. Minor shear bands overprint some of the heavily deformed areas, and small-scale shear zones form from the pairing of closely spaced shear bands. Strength and permeability measurements were made on core collected from the fault within a year after a major (Kobe) earthquake. Measured strengths of the samples decrease regularly with increasing fracturing and fragmentation, such that the gouge of the fault core and completely brecciated samples from the damage zone are the weakest. Permeability increases with increasing disruption, generally reaching a peak in heavily fractured but still more or less cohesive rock at the scale of the laboratory samples. Complete loss of cohesion, as in the gouge or the interiors of large microbreccia zones, is accompanied by a reduction of permeability by 1-2 orders of magnitude below the peak values. The core samples show abundant evidence of hydrothermal alteration and mineral precipitation. Permeability is thus expected to decrease and strength to increase somewhat in active fault strands between earthquakes, as mineral deposits progressively seal fractures and fill pore spaces.

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“…3 HC SC OC Kranz 1983Anders et al 2014Plumb et al, 1984Lespinasse and Pecher, 1986;Vollbrecht et al, 1991;Takeshita and Yagi, 2001;Nadan and Engelder, 2009;HC SC Hay et al, 1988Evans, 1995;Lespinasse, 1999;Laubach, 2003;Fischer et al, 2009 σ 3 σ 3 σ 1 σ 2 Yamaji et al, 2010;Yamaji and Sato, 2011;Yamaji, 2016Yamaji, 2014Yamaji, 2008 HC MTL Nakai, 1976;, 2016 Fig …”

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confidence: 99%

Paleostress directions estimated from healed microcracks in the Cretaceous granitoids:

Kanai

Takahashi

2017

Jour. Geol. Soc. Japan

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Paleostress analyses using the three-dimensional orientation distribution of healed microcracks (HCs) in quartz from Cretaceous granitoids have been performed along a ca. km transect normal to the Median Tectonic Line (MTL), central Japan. The paleostress was determined by fitting mixed Bingham distributions to the HC distribution for each sample. As a result, the orientations of the HCs in each data set were grouped into -clusters, and the group with the maximum density of HCs was regarded as the dominant stress for the data set. The nonparametric correlation coefficients of angular differences of stress for each axis (σ , σ , and σ ) were projected onto best-fit great circles on a stereoplot, yielding distances from the MTL of . , . , and . , respectively. The σ axis is orthogonal to the MTL strike in the vicinity of the MTL, but rotates counterclockwise in areas away from the MTL and is roughly parallel to the MTL strike at ca.km from the MTL. The dominant σ axis (NW-SE), which is normal to the MTL in the vicinity of the MTL (southeastern area), is considered to be related to extensional faulting on the MTL at -Ma (Ichinokawa Phase), whereas the dominant σ axis (NE-SW) parallel to the MTL at a distance from the MTL suggests the influence of the plate convergence direction (NW) at about -Ma, rather than the influence of MTL-normal extension. The orientations of σ and σ show no correlation with distance from the MTL, indicating that their orientations depend on the local stress state within the granitic body.

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Paleostress orientation from 3‐D orientation distribution of microcracks in quartz from the Cretaceous granodiorite core samples drilled through the Nojima Fault, south‐west Japan

Cited by 7 publications

References 28 publications

Fission track and U–Pb zircon ages of psammitic rocks from the Harushinai unit, Kamuikotan metamorphic rocks, central Hokkaido, Japan: constraints on metamorphic histories

Fission track and U–Pb zircon ages of psammitic rocks from the Harushinai unit, Kamuikotan metamorphic rocks, central Hokkaido, Japan: constraints on metamorphic histories

Geometry of the Nojima Fault at Nojima-Hirabayashi, Japan – II. Microstructures and their Implications for Permeability and Strength

Paleostress directions estimated from healed microcracks in the Cretaceous granitoids:

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