Noble gases in the mantle wedge and lower crust: an inference from the isotopic analyses of xenoliths from Oki-Dogo and Ichinomegata, Japan.

Nagao, Keisuke; Takáhashi, Eiichi

doi:10.2343/geochemj.27.229

Cited by 44 publications

(28 citation statements)

References 32 publications

(71 reference statements)

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“…The ratios of 40 Ar/ 36 Ar in the mantle-derived minerals are 336 to 2325 [25,27,29] in northeastern China, 269 to 548 in Hannuoba [25,27] ，and 251 to 1234 in Jiangsu, Anhui and Zhejiang [25] . All the ratios of 40 Ar/ 36 Ar in the mantle-derived minerals in eastern China are lower than those in the mainland of western America [37] , European Continent [39,41,42] and eastern Australia [39,40] , and even much lower than those in the middle ocean ridge basalts (MORB) [43] , but close to the same kind of samples in Oki-Dogo Island and Ichinomegata [44] Volcano in Japan.…”

Section: Isotopic Compositions Of the Noble Gas And Their Originsmentioning

confidence: 66%

“…Ratios of 3 He/ 4 He (2.8-10.3 Ra) and 40 Ar/ 36 Ar (344-612) in the mantle-derived xenoliths from Oki Island, Japan, are very similar to those from the Yishu area too. Nagao et al [44] thought that 40 Ar/ 36 Ar variation was primarily attributed to the admixtures of tectonic subduction belts, while 3 He/ 4 He variation was primarily attributed to the influence of radiogenic ingredients. Another typical example is Chile on the east Pacific Ocean verge.…”

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confidence: 99%

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Characteristics and origins of primary fluids and noble gases in mantle-derived minerals from the Yishu area, Shandong Province, China

Jin-long

Tao

2006

SCI CHINA SER D

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Fluids and noble gases of mantle-derived materials are important tracers for the mantle information. Compositions of primary fluids and noble gases in mantle-derived minerals from the Yishu area, Shandong Province, China, were tested by the methods of heat-bursting and heat-melting respectively. The fluids are mainly composed of CO 2 , CO and H 2 , which account for about 90% of the total, and are similar to the mantle-derived rocks from other areas of eastern China; ratios of 3 He/ 4 He in almost all samples range from 0.82 Ra to 2.74 Ra, whereas 40 Ar/ 36 Ar from 299.5 to 758.8. Both ranges are much lower than those of the typical ocean mantle-derived samples (such as MORB) and primarily reflect the influences of the atmospheric components and the radiogenic isotopes. Ratios of C/ 3 He range from 27.6×10 9 to 1050×10 9 , N 2 /Ar from 927 to 56612, and N 2 / 3 He from 2.5×10 9 to 27×10 9 , similar to those in western United States and New Zealand which belong to the tectonic plate collision regions. The ratios fall in the intersect of mantle-crust-atmosphere in the comprehensive tracer-charts, reflecting the influences of the atmosphere and the crusts with organic components. Our results suggest that the composition of the primary fluids and the isotopic ratios of the noble gases may either reflect the evolution process of mantle-derived rocks connected with the rise and eruption of magma, or the influence of the ancient subduction-plate on the continental mantle of this region.

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Section: Isotopic Compositions Of the Noble Gas And Their Originsmentioning

confidence: 66%

mentioning

confidence: 99%

Characteristics and origins of primary fluids and noble gases in mantle-derived minerals from the Yishu area, Shandong Province, China

Jin-long

Tao

2006

SCI CHINA SER D

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“…The 40 Ar*/ 4 He depends on many factors, such as K/(U+Th) ratio of crustal rocks (e.g., Ballentine and Burnard 2002), degree of previous degassing events, and noble gas fractionation due to compositional variations of the emitted lavas (Motyka et al 1989;Poreda et al 1988;Tedesco et al 2010, and references therein). Although 40 Ar* is considered to be nonhomogeneously distributed within the mantle (Poreda and Farley 1992;Farley and Poreda 1993;Nagao and Takahashi 1993), reliable 40 Ar*/ 4 He ratios for MORB range from 0.05-1 (Graham 2002). Lower 40 Ar*/ 4 He ratios are expected in gasses from arc volcanoes, where crustal contamination may cause a relative 4 He enrichment at the fluid source compared with a relatively atmospheric 40 Ar from the entrainment of air-saturated groundwater (e.g., Torgersen et al 1988;Hu et al 1998).…”

Section: Fluid Source Regionsmentioning

confidence: 98%

Geochemical model of a magmatic–hydrothermal system at the Lastarria volcano, northern Chile

et al. 2011

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“…Highest ratio of over 10 -5 was observed in the Arima area, northern slope of Rokko Mountains. This value is overlapping with the highest value of mantle wedge beneath Japan (Nagao and Takahashi, 1993) and is identical to the MORB value (Graham, 2002). The samples of the Arima area have been collected from artesian wells, located along the large tectonic line (Arima-Takatsuki Tectonic Line).…”

Section: Relationship Between Geological Structure and He Isotopesmentioning

confidence: 59%

Relationship between geological structure and helium isotopes in deep ground-water from the Osaka Basin: Application to deep groundwater hydrology

et al. 2008

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The relationship between geological structure and helium isotopes is discussed for deep groundwaters from the Osaka sedimentary basin, southwest Japan, to understand dissolved He in groundwater for hydrological application. Although this area shows no Quaternary volcanic activity, nearly upper mantle-like 3 He/ 4 He ratio (1.1 × 10 -5 ) has been observed in the area along the fault system where the basement rocks are outcropped. In contrast, deep groundwaters from the lowest part of the aquifers beneath the Osaka Basin showed a wide variation in 3 He/ 4 He ratio (0.27-8 × 10 -6 ), which seems to reflect the geological structure. The moderately high 3 He/ 4 He ratios, not as high as those in the mantle value, are due to a contribution of radiogenic 4 He within the aquifer. The flux of mantle He through the Uemachi thrust fault into the aquifers in the east block (hanging wall of the fault) of the Osaka Basin will be smaller than those in the west block (foot wall), because mantle He through this fault encountered the aquifers in the west block and dissolved in this aquifer. The model for the Osaka Basin presented in this study implies that there are at least two different sources of He flux into an aquifer; mantle He flux through the fault system and crustal He from the underlying formation. The former should be spatially heterogeneous, while crustal 4 He flux is rather spatially constant throughout the lowermost part of the Osaka Basin.

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Noble gases in the mantle wedge and lower crust: an inference from the isotopic analyses of xenoliths from Oki-Dogo and Ichinomegata, Japan.

Cited by 44 publications

References 32 publications

Characteristics and origins of primary fluids and noble gases in mantle-derived minerals from the Yishu area, Shandong Province, China

Characteristics and origins of primary fluids and noble gases in mantle-derived minerals from the Yishu area, Shandong Province, China

Geochemical model of a magmatic–hydrothermal system at the Lastarria volcano, northern Chile

Relationship between geological structure and helium isotopes in deep ground-water from the Osaka Basin: Application to deep groundwater hydrology

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