Spatial variations in 3He/4He ratios along a high strain rate zone, central Japan

Umeda, Koji; Kusano, Tomohiro; Ninomiya, Atusi; Asamori, Koichi; Nakajima, Jun

doi:10.1016/j.jseaes.2013.04.016

Cited by 5 publications

(6 citation statements)

References 31 publications

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“…High attenuation in this area is also suggested from S-wave attenuation studies He ratios (~8 Ra) (Umeda et al 2013). The absence of apparent high-attenuation areas beneath the Moho is probably due to the insufficient number of rays propagating through the uppermost mantle, as a consequence of small number of deep-focus earthquakes with reliable f c estimates; this inference is supported by the poor recovery rates of the checkerboard patterns at depths of >60 km (Fig.…”

Section: Discussionsupporting

confidence: 55%

Anelastic properties beneath the Niigata–Kobe Tectonic Zone, Japan

Nakajima

Matsuzawa

2017

Earth Planets Space

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We estimate the three-dimensional (3D) P-wave attenuation structure beneath the Niigata-Kobe Tectonic Zone (NKTZ), central Japan, using high-quality waveform data from a large number of stations. The obtained results confirm the segmentation of the NKTZ into three regions, as suggested by 3D seismic velocity models, and reveal characteristic structures related to surface deformation, shallow subduction of the Philippine Sea slab, and magmatism. The lower crust beneath the NKTZ west of the Itoigawa-Shizuoka Tectonic Line (ISTL) is overall characterized by distinct high attenuation, whereas the upper crust shows marked high attenuation to the east of the ISTL. Differences in the depths of anelastically weakened parts of the crust probably result in a first-order spatial variation in surface deformation, forming wide (width of ~100 km) and narrow (width of 25-40 km) deformation zones on the western and eastern sides of the ISTL, respectively. Many M ≥ 6.5 earthquakes occur in the upper crust where seismic attenuation in the underlying lower crust varies sharply, suggesting that spatial variations in rates of anelastic deformation in the lower crust result in stress concentration in the overlying brittle crust. We interpret a moderate-to low-attenuation zone located in the lower crust at the northeast of Biwa Lake to reflect low-temperature conditions that are developed locally as a result of shallow subduction of the cold Philippine Sea slab.

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Section: Discussionsupporting

confidence: 55%

Anelastic properties beneath the Niigata–Kobe Tectonic Zone, Japan

Nakajima

Matsuzawa

2017

Earth Planets Space

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“…However it is possible that the effect of water coming from underlying formations may be different for each borehole. Some previous studies indicated the possibility that faults play an important role in transporting mantle fluid [62] and this may also be applicable to the present study. In Figure 12, measured [He] w and [He] aup are compared for each of the sampling points and the dashed line is the line of = .…”

Section: 23supporting

confidence: 59%

“…This indicates that not only He produced in situ (radiogenic) but also He from other origins accumulated in the porewater. He with a high 3 He/ 4 He (up to 1 × 10 −5 ) was observed in Japan and was ascribed to He affected by the mantle [61][62][63]. In the evaluation of porewater stagnancy with He, we will compare the measured He concentration and the He concentration calculated with in situ accumulation rate (Section 5.2.4).…”

Section: 23mentioning

confidence: 99%

An Evaluation of the Long-Term Stagnancy of Porewater in the Neogene Sedimentary Rocks in Northern Japan

et al. 2018

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A groundwater dating for very old porewater using 36 Cl and 4 He was applied to the Koetoi and Wakkanai formations distributed in the northernmost part in Japan. Measured 36 Cl/Cl in the Koetoi Formation was 2.6 ± 2.0 × 10 −15 and that in the Wakkanai Formation was 8.1 ± 2.5 × 10 −15 . These values are similar to 36 Cl/Cl in situ secular equilibrium calculated from chemical compositions of core suggesting that Cl − ions and porewater have remained in the formations for much longer than half-life of 36 Cl . He concentration in porewater ranged from 1.1 × 10 −6 to 2.6 × 10 −5 (cc STP g w −1 ) and it is much higher than water saturated with air indicating that both formations contain very old porewater. However, the possibility of mixing of young water was indicated because He concentration was lower than that calculated by multiplication of in situ He production and time after the uplift. This possibility was also supported by Cl − , D, and 18 O data. After combining information on 36 Cl/Cl, 4 He, and D and 18 O, it was inferred that the porewater in the deep part of the Wakkanai Formation might have been stagnant since the uplift. The porewater in the Koetoi Formation and the shallow part of the Wakkanai Formation were found to be affected by young surface water.

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“…Previously published helium isotope data used in this study are from Craig et al [1978], Doğan et al [2006], Kita et al [1993], Kusakabe et al [2003], Marty et al [1989], Matsumoto et al [2003], Morikawa et al [2005], Murakami [2010], Nagao [2004], Nagao et al [1981], New Energy and Industrial Technology Development Organization [1988, 1990], Notsu et al [2001], Ohno et al [2011], Ohwada et al [2007], Okada et al [1994], Ono et al [1993], Sakamoto et al [1992], Sakata et al [1987], Sano and Wakita [1985], Sano and Marty [1995], Sano et al [1982, 1984, 1986, 1998a, 1998b, 2006, 2009], Sato et al [2002], Sturchio et al [1996], Takahata et al [2003], Umeda and Ninomiya [2009], Umeda et al [2006a, 2006b, 2007a, 2007b, 2009a, 2009b, 2011a, 2011b, 2012], Wakita et al [1987], and K. Asamori et al (unpublished data, 2012). The majority of samples measured in the previous studies were collected from wells and bubbling natural springs, the remainder are from volcanic gases.…”

Section: Discussionmentioning

confidence: 99%

“…The mantle helium components of samples collected from the northern Chugoku region are relatively higher than those from northern Kyushu Island (Figure 3). [2007], Okada et al [1994], Ono et al [1993], Sakamoto et al [1992], Sakata et al [1987], Sano and Wakita [1985], Sano and Marty [1995], Sano et al [1982Sano et al [ , 1984Sano et al [ , 1986Sano et al [ , 1998aSano et al [ , 1998bSano et al [ , 2006Sano et al [ , 2009, Sato et al [2002], Sturchio et al [1996], Takahata et al [2003], Umeda and Ninomiya [2009], Umeda et al [2006aUmeda et al [ , 2006bUmeda et al [ , 2007aUmeda et al [ , 2007bUmeda et al [ , 2009aUmeda et al [ , 2009bUmeda et al [ , 2011aUmeda et al [ , 2011bUmeda et al [ , 2012, Wakita et al [1987], and K. Asamori et al (unpublished data, 2012). The majority of samples measured in the previous studies were collected from wells and bubbling natural springs, the remainder are from volcanic gases.…”

Section: Hydrogen Oxygen and Helium Isotopesmentioning

confidence: 99%

Relationship between ³He/⁴He ratios and subduction of the Philippine Sea plate beneath southwest Japan

Umeda¹,

Kusano²,

Asamori³

et al. 2012

J. Geophys. Res.

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[1] Regional and local variations in mantle helium provide insight into the coupling of mantle-crust tectonics, and heat and/or mass transfer from the Earth's interior. In order to further elucidate the geographic distribution of 3 He/ 4 He ratios in southwest Japan, the data from a total of 924 sites were compiled and synthesized. These include data from 48 additional hot spring and drinking water well sites on the northern Kyushu Island and in the northern Chugoku region. There appears to be good correlation between variations in helium isotope ratios and the geophysical evidence used to determine the configuration of the subducting Philippine Sea plate (PHS). Seismological studies reveal that the leading edge of the aseismic slab does not extend to the northern Chugoku region nor to the Osaka Bay area, where gas samples with significantly elevated 3 He/ 4 He ratios occur. This is consistent with a mantle-derived helium in these areas, from melts and/or mantle fluids ascribed to upwelling asthenosphere without being hindered by the descending PHS slab. In contrast, gas samples in the regions where the overriding crust comes into direct contact with the subducting PHS are dominated by radiogenic helium derived from the crust because of the absence of a mantle wedge, the most plausible source of mantle helium. Owing to the abrupt changes in the seismicity and focal mechanisms of intraplate earthquakes, the PHS is considered to have slab tears beneath the Kii Channel and/or the eastern Kii Peninsula oriented in a NW-SE direction. However, the lenear alignment of anomalously high 3 He/ 4 He ratios does not appear to be NW-SE trending along the assumed slab tears but rather forms an broad, ENE-WSW trending zone between the tears where low-frequency events occur. The emanation of gas with elevated 3 He/ 4 He ratios in the central peninsula can be explained by the upward mobilization of mantle volatiles derived from the mantle wedge above the PHS and/or transferred from the hydrated slab mantle through the N-S trending fractured medium within the PHS. Accordingly, the helium isotopes observed on the Earth's surface may be efficient geochemical indicators of the configuration of a relatively younger, warm aseismic slab, and be especially useful in seismically inactive areas.

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Spatial variations in 3He/4He ratios along a high strain rate zone, central Japan

Cited by 5 publications

References 31 publications

Anelastic properties beneath the Niigata–Kobe Tectonic Zone, Japan

Anelastic properties beneath the Niigata–Kobe Tectonic Zone, Japan

An Evaluation of the Long-Term Stagnancy of Porewater in the Neogene Sedimentary Rocks in Northern Japan

Relationship between ³He/⁴He ratios and subduction of the Philippine Sea plate beneath southwest Japan

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Spatial variations in 3He/4He ratios along a high strain rate zone, central Japan

Cited by 5 publications

References 31 publications

Anelastic properties beneath the Niigata–Kobe Tectonic Zone, Japan

Anelastic properties beneath the Niigata–Kobe Tectonic Zone, Japan

An Evaluation of the Long-Term Stagnancy of Porewater in the Neogene Sedimentary Rocks in Northern Japan

Relationship between 3He/4He ratios and subduction of the Philippine Sea plate beneath southwest Japan

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Relationship between ³He/⁴He ratios and subduction of the Philippine Sea plate beneath southwest Japan