Aqueous fluids derived from a subducting slab: Observed high 3He emanation and conductive anomaly in a non-volcanic region, Kii Peninsula southwest Japan

Umeda, Koji; Ogawa, Yasuo; Asamori, Koichi; Oikawa, Teruki

doi:10.1016/j.jvolgeores.2005.06.005

Cited by 57 publications

(47 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…They further suggested that the occurrences of non-volcanic deep tremors in the Kii Peninsula were caused by the movement of fluids derived from the subducting slab. Recently Umeda et al (2006) have reported again high-Ra emanation and conductive anomaly in the region. They have attributed these features into the aqueous fluids expelled from the Philippine Sea Plate.…”

Section: Magma Aging Effect On Helium Isotopesmentioning

confidence: 89%

“…However the magma aging effect indicates that it is difficult to maintain the high-Ra in the Philippine Sea Plate as discussed above. It is not likely that the high-Ra was derived from the dehydration suggested by Matsumoto et al (2003) and Umeda et al (2006). In addition the slab melting can not account for the high-Ra.…”

Section: Magma Aging Effect On Helium Isotopesmentioning

confidence: 93%

“…(a) Kinki, SW Japan. al., 1987;Matsumoto et al, 2003;Umeda et al, 2006) and plotted in the map based on the above definition (Fig. 9a).…”

Section: Helium Isotopes and Kinki Spot In Sw Japanmentioning

confidence: 99%

“…These data have provided new knowledge of geophysics and geochemistry of the subduction zone. However most of them were focused on the regional interest such as Hokkaido island , Kinki district Matsumoto et al, 2003;Umeda et al, 2006), Chugoku district (Sano et al, 2006), and Shikoku island (Dogan et al, 2006). The other data were related to single volcanoes such as Oshima , Hakone (Sakamoto et al, 1992), Kusatsu-Shirane (Sano et al, 1984) and Ontake (Sano et al, 1998) in Japan.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Geographical distribution of 3He/4He ratios and seismic tomography in Japan

Sano

Nakajima

2008

Geochem. J.

View full text Add to dashboard Cite

The 3 He/ 4 He ratios (Ra) of natural gas, volcanic fluid, and groundwater are compiled in the Japanese Islands and their geographical distributions are discussed in the tectonic frame work of subduction zone together with preciselydetermined seismic velocity structures. In Northeastern (NE) Japan where typical island arc signatures are developed, there is a clear contrast of 3 He/ 4 He ratios perpendicular to the trench axis, low-Ra in the frontal arc and high-Ra in the volcanic arc. This may reflect the presence or absence of magma with high-Ra in the shallow crust. As a carrier of primordial helium, source melt may be generated in low-V zone of the wedge mantle by dehydration of Pacific slab at about 150 km deep and may flow upward sub-parallel to the slab, which is well constrained by S-wave velocity perturbation. In the Chugoku and Shikoku districts of Southwestern (SW) Japan, there is a geographical contrast of Ra similar to NE Japan except for the region at about 100 km from the volcanic front where medium-Ra was found. High-Ra observed in volcanic arc of the Chugoku district may be attributable to the mantle helium derived from the magma source generated below the Philippine Sea slab. Medium-Ra in the Shikoku district is explained by dehydration of the young slab with a moderate aging effect. These features are again consistent with the results of seismic tomography. In the Kinki district of SW Japan, anomalously high-Ra was observed in the frontal arc region that was called by "Kinki Spot". Since the high-Ra is located at much wider region from the volcanic front when compared with NE Japan, the melt generated below the Philippine Sea slab may penetrate into the fissure of the slab tear and may arrive at the shallow crust by upwelling flow.

show abstract

Section: Magma Aging Effect On Helium Isotopesmentioning

confidence: 89%

Section: Magma Aging Effect On Helium Isotopesmentioning

confidence: 93%

“…(a) Kinki, SW Japan. al., 1987;Matsumoto et al, 2003;Umeda et al, 2006) and plotted in the map based on the above definition (Fig. 9a).…”

Section: Helium Isotopes and Kinki Spot In Sw Japanmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Geographical distribution of 3He/4He ratios and seismic tomography in Japan

Sano

Nakajima

2008

Geochem. J.

View full text Add to dashboard Cite

show abstract

“…He, Ne and Ar isotopic ratios and concentrations of Tables 1 and 3. noble gases in groundwaters in Japan have been analyzed and give us the information of their origin and formation process (e.g., Wakita, 1985, 1988;Umeda et al, 2006;Sano and Nakajima, 2008;Morikawa et al, 2008). In the studied area, the He and Ne isotopic ratios were analyzed for groundwaters in Horonobe (Nagao et al, 2003) and three thermal waters in northern Hokkaido (Sano and Wakita, 1985).…”

Section: Introductionmentioning

confidence: 99%

Stable and noble gas isotopic study of thermal and groundwaters in northwestern Hokkaido, Japan and the occurrence of geopressured fluids

et al. 2010

View full text Add to dashboard Cite

owing to interaction with the surrounding rocks. In several areas, fossil sea water was found to have δ 18 O values of +5 to +8‰ due to the oxygen isotopic shift caused by the interaction, but to retain almost the same Cl concentration as fresh sea water (e.g., Sakai and Matsubaya, 1974;Mizukami et al., 1977;Shibata et al., 2005).At depths below ca. 2 km in sedimentary regions associated with oil and/or natural gas, formation waters tend to be geopressured fluid with pressures between hydrostatic and lithostatic values (e.g., Myers, 1968;Jones, 1970;Oki et al., 1999;Xu et al., 2006). The δD and δ 18 O data show that most geopressured fluid can be explained as a mixture of fossil sea water and local meteoric water, with an oxygen isotope shift due to rock-water interaction. Recently, fluids that have oilfield-like characteristic, with unusually high δD (-20‰) and low Cl concentrations (ca. 6,000 mg/L) have been observed along faults in the Horonobe area (Ishii et al., 2006). These fluids might have originated as a mixture between sea water and Stable and noble gas isotopic study of thermal and groundwaters in northwestern Hokkaido, Japan and the occurrence of geopressured fluids (Received July 14, 2009; Accepted June 7, 2010) Thermal and groundwaters are distributed along the west coast and in the inland region of Northwestern Hokkaido, Japan. The waters in the latter group have relatively high temperatures. Stable (D, O) and noble gas isotopic compositions of 23 thermal and groundwaters were analyzed to investigate their origins. The Cl concentrations vary from 45 to 19,300 mg/L and the δD values are in the range of -90 to -8‰. The δD-δ 18 O plots show a linear relationship which can be explained by a simple mixing of local meteoric waters and altered sea water, with oxygen isotopic shift of 5‰. However, a δD-Cl plot shows that there is also a contribution of an additional water component of different origin. This 3rd component has a δD value of -20‰ and Cl concentration of 6,000 mg/L. Multivariate statistical analysis of the observed chemical and isotopic compositions using the code M3 (M; multivariate mixing and mass balance) also supports the view that the Toyotomi thermal water has the composition closest to that of the 3rd groundwater component. This component is regarded as a geopressured fluid.The 3 He/ 4 He ratios in these waters are in the range of (0.1-5) × 10 -6 , which indicate contributions of both mantle and crustal He to the thermal and groundwaters in the studied area. The Toyotomi thermal water has a 3 He/ 4 He ratio of 5.5 × 10 -7 , and a high 3 He/ 20 Ne ratio (~700). These results indicate a crustal He input with a small amount of mantle-derived He and imply that the 3rd groundwater component is of deep origin. On the basis of isotopic and chemical compositions, 5 of 23 samples studied groundwater and thermal waters are contributed by a geopressured fluid component. The results show that geopressured fluids with a δD value of -20‰ and Cl concentration of 6,000 mg/L are widely distributed ...

show abstract

Segmentation of plate coupling, fate of subduction fluids, and modes of arc magmatism in Cascadia, inferred from magnetotelluric resistivity

Wannamaker

Evans

Bedrosian

et al. 2014

Geochem Geophys Geosyst

101

106

View full text Add to dashboard Cite

Five magnetotelluric (MT) profiles have been acquired across the Cascadia subduction system and transformed using 2-D and 3-D nonlinear inversion to yield electrical resistivity cross sections to depths of 200 km. Distinct changes in plate coupling, subduction fluid evolution, and modes of arc magmatism along the length of Cascadia are clearly expressed in the resistivity structure. Relatively high resistivities under the coasts of northern and southern Cascadia correlate with elevated degrees of inferred plate locking, and suggest fluid-and sediment-deficient conditions. In contrast, the north-central Oregon coastal structure is quite conductive from the plate interface to shallow depths offshore, correlating with poor plate locking and the possible presence of subducted sediments. Low-resistivity fluidized zones develop at slab depths of 35-40 km starting 100 km west of the arc on all profiles, and are interpreted to represent prograde metamorphic fluid release from the subducting slab. The fluids rise to forearc Moho levels, and sometimes shallower, as the arc is approached. The zones begin close to clusters of low-frequency earthquakes, suggesting fluid controls on the transition to steady sliding. Under the northern and southern Cascadia arc segments, low upper mantle resistivities are consistent with flux melting above the slab plus possible deep convective backarc upwelling toward the arc. In central Cascadia, extensional deformation is interpreted to segregate upper mantle melts leading to underplating and low resistivities at Moho to lower crustal levels below the arc and nearby backarc. The low-to high-temperature mantle wedge transition lies slightly trenchward of the arc.

show abstract

Aqueous fluids derived from a subducting slab: Observed high 3He emanation and conductive anomaly in a non-volcanic region, Kii Peninsula southwest Japan

Cited by 57 publications

References 43 publications

Geographical distribution of 3He/4He ratios and seismic tomography in Japan

Geographical distribution of 3He/4He ratios and seismic tomography in Japan

Stable and noble gas isotopic study of thermal and groundwaters in northwestern Hokkaido, Japan and the occurrence of geopressured fluids

Segmentation of plate coupling, fate of subduction fluids, and modes of arc magmatism in Cascadia, inferred from magnetotelluric resistivity

Contact Info

Product

Resources

About