| 1. |
Wang H., Lu W., Wang W., Liu Q. and Yamamoto J., High-precision analysis of carbon isotopic composition for individual CO2 inclusions via Raman spectroscopy: Addressing issues arising from the laser-heating effects, Chemical Geology, https://doi.org/10.1016/j.chemgeo.2024.122014, 651, 122014, 2024.02. |
| 2. |
Yamamoto J. and Hagiwara Y., Precision evaluation of Raman densimetry for carbon dioxide –improvement by correction for drift effect–., Applied Optics, in press, 2024.01. |
| 3. |
Hagiwara Y, Yokokura L, Yamamoto J, Unlocking ultimate precision of intensity and area ratio measurements in Raman spectroscopy: Insights from simulation, experimentation, and theory and implications for isotope ratio analysis, Journal of Raman Spectroscopy, 10.1002/jrs.6594, in press, 2023.09. |
| 4. |
Inoue Y., Okiyama R., Hagiwara Y.， Yamamoto J., Raman spectroscopic evaluation of precision of oxygen isotope ratio of carbon dioxide, Geochemical Journal, https://doi.org/10.2343/geochemj.GJ23007, 2023.04. |
| 5. |
Yamamoto J. and Kurz M.D., Noble gas isotopic compositions and abundance ratios of mantle xenoliths from Honolulu series volcanism, Oahu, Hawaii, EARTH AND PLANETARY SCIENCE LETTERS, https://doi.org/10.1016/j.epsl.2022.117979, 603, 117979, 2023.02. |
| 6. |
Mikuni K., Hirano N., Akizawa N., Yamamoto J., Machida S., Tamura A., Hagiwara Y. and Morishita T., Lithological structure of western Pacific lithosphere reconstructed from mantle xenoliths in a petit-spot volcano, PROGRESS IN EARTH AND PLANETARY SCIENCE, 10.1186/s40645-022-00518-y, 9, 1, 2022.11, The lithospheric mantle, formed at the mid-ocean ridge as a residue of crustal production, comprises theoretically depleted peridotite, but more fertile components (e.g., lherzolite and pyroxenite) have been reported, creating an enigmatic picture of the lithosphere. The oceanic lithosphere has also been found to be locally modified by intraplate magmatism as proposed from geochemistry of mantle xenolith. Petit-spot xenoliths are particularly notable as direct evidence of old lithospheric mantle and expected to retain essential information about oceanic lithosphere prior to its subduction. In this study, we report on the lithological structure of Pacific lithosphere aged at 160 Ma, just subducting into Mariana Trench, based on petrology and chemistry of ultramafic xenoliths from a petit-spot knoll, and then, we suggest the occurrence of petit-spot melt infiltration resulting in mantle metasomatism and formation of pyroxene- rich vein. Our petit-spot ultramafic xenoliths can be divided into three main types: a depleted peridotite as a residue of crust production, an enriched peridotite, and fertile pyroxenites as the product of melt–rock interactions prior to entrapment. Geothermobarometry also suggests that the depleted peridotite was derived from the uppermost lithospheric mantle, whereas the enriched peridotite and Al-augite pyroxenites were obtained from deeper layers of the lithosphere. Moreover, thermal gradient of the lithosphere estimated from these data is considerably hotter than pristine geotherm estimated on the basis of plate age. Hence, we could illustrate that the oldest portion of the Pacific lithosphere (160 Ma), which was not observed before, was locally fertilized and heated by prior multiple petit-spot magmatic events, and pyroxene-rich metasomatic veins penetrated from the base to the middle/upper lithosphere. Such local lithospheric fertilization is plausible at the plate-bending field, and the nature of Pacific Plate subducting into Mariana Trench may be partly different from what has been assumed so far.. |
| 7. |
Hagiwara Y., Angel R.J., Yamamoto J. and Alvaro M., Equation of state of spinel (MgAl2O4): constraints on self-consistent thermodynamic parameters and implications for elastic geobarometry of peridotites and chromitites, CONTRIBUTIONS TO MINERALOGY AND PETROLOGY, 10.1007/s00410-022-01975-w, 177, 11, 2022.11, Spinel is potentially one of the best minerals for elastic geobarometry, but the large uncertainties in the published equation of state (EoS) of spinel prevent the application of elastic geobarometry using spinel. We have determined the EoS of MgAl2O4 from literature data on the volume, elasticity, and isobaric heat capacity by paying particular attention to the consistency of the thermoelastic data within the dataset and the influence of the inversion degree (i; (Mg1-iAli)[MgiAl2-i]O4) on the physical properties. After appropriate data selection, normalization, and correction, the resulting dataset was fitted with various EoS. Thermal pressure EoS that combined the third-order Birch–Murnaghan EoS and the Mie–Grüneisen–Debye EoS explain the data most successfully. The analysis yielded the following six EoS parameters: V0 = 39.78 cm3/mol (fixed), KT0 = 196.43(12) GPa, K′T0 = 4.37(4), θD0 = 898(10) K, γ0 = 1.136(11), and q = 1.94(9). The EoS has the properties at room conditions of αV = 1.6765(10) × 10–5 K–1 and KS0 = 197.55(12) GPa.
Combining our EoS with the published EoS, it was found that MgAl2O4 inclusions trapped in olivine and orthopyroxene derived from the spinel-lherzolite stability field should always have positive residual pressures (Pinc) at room conditions. This implies that elastic geobarometry using these host-inclusion systems can be expected to be new methods for estimating the depth provenance of spinel-bearing peridotites. In contrast olivine, orthopyroxene, and clinopyroxene inclusions in MgAl2O4 are expected to have Pinc > 0 only when trapped (or re-equilibrated) in geological environments with geotherms corresponding to surface heat flows below about 50, 60 and 70 mW/m2, respectively.. |
| 8. |
Yamamoto J. and Hagiwara Y., Precision evaluation of nitrogen isotope ratios by Raman spectrometry, Analytical Science Advances, 10.1002/ansa.202200020, 3, 269-277, 2022.08. |
| 9. |
Yamamoto J. and Kurz M.D., Mantle noble gas abundance ratios inferred from oceanic basalts and model estimates, Physics of the Earth and Planetary Interiors, https://doi.org/10.1016/j.pepi.2022.106875, 327, 106875, 2022.04. |
| 10. |
Factors Affecting Overall Evaluation of a University Class : Exploring Factors Improving Learning Motivation. |
| 11. |
Yuuki Hagiwara, Junji Torimoto, Junji Yamamoto, Pressure measurement and detection of small H2O amounts in high-pressure H2O-CO2 fluid up to 141 MPa using Fermi diad splits and bandwidths of CO2, JOURNAL OF RAMAN SPECTROSCOPY, 10.1002/jrs.5865, 51, 6, 1003-1018, 2020.06. |
| 12. |
Lena Yokokura, Yuuki Hagiwara, Junji Yamamoto, Pressure dependence of micro-Raman mass spectrometry for carbon isotopic composition of carbon dioxide fluid, JOURNAL OF RAMAN SPECTROSCOPY, 10.1002/jrs.5864, 51, 997-1002, 2020.03. |
| 13. |
J. Yamamoto, T. Yoshino, D. Yamazaki, Y. Higo, Y. Tange, J. Torimoto, Thermal expansion of natural mantle spinel using in situ synchrotron X-ray powder diffraction, Journal of Materials Science, 10.1007/s10853-018-2848-5, 54, 1, 139-148, 2019.01. |
| 14. |
Yoshihiro Nakamura, Hidemi Ishibashi, Atsushi Yasuda, Natsumi Hokanishi, Junji Yamamoto, Ultra-magnesian olivine-bearing ultramafic lava blocks within Cenozoic accretionary sediments at Shizuoka, Japan: Implications for young, hot plume activity beneath the western Pacific Plate, LITHOS, 10.1016/j.lithos.2018.11.009, 324, 315-324, 2019.01. |
| 15. |
J. Yamamoto, T. Kawano, N. Takahata, Y. Sano, Noble gas and carbon isotopic compositions of petit-spot lavas from southeast of Marcus Island, Earth and Planetary Science Letters, 10.1016/j.epsl.2018.06.020, 497, 139-148, 2018.09. |
| 16. |
Hagiwara Y, Takahata K, Torimoto J, Yamamoto J, CO2 Raman thermometer improvement: comparing hot band and Stokes and anti-Stokes Raman scattering thermometers, Journal of Raman Spectroscopy, 10.1002/jrs.5461, 49, 1776-1781, 2018.07. |
| 17. |
Yuki Sato, Naoto Hirano, Shiki Machida, Junji Yamamoto, Masao Nakanishi, Teruaki Ishii, Arashi Taki, Kazutaka Yasukawa, Yasuhiro Kato, Direct ascent to the surface of asthenospheric magma in a region of convex lithospheric flexure, International Geology Review, 10.1080/00206814.2017.1379912, 60, 10, 1231-1243, 2018.07. |
| 18. |
Hagiwara Y., Sogo Y., Takahata K. and Yamamoto J., Temperature dependence of CO2 densimetry using micro-Raman Spectrometry at laboratory conditions, Geochemical Journal, 10.2343/geochemj.2.0523, 52, 379-383, 2018.04. |
| 19. |
Kenya Ono, Yuya Harada, Akira Yoneda, Junji Yamamoto, Akira Yoshiasa, Kazumasa Sugiyama, Hiroshi Arima, Tohru Watanabe, Determination of elastic constants of single-crystal chromian spinel by resonant ultrasound spectroscopy and implications for fluid inclusion geobarometry, PHYSICS AND CHEMISTRY OF MINERALS, 10.1007/s00269-017-0912-3, 45, 3, 237-247, 2018.03. |
| 20. |
Educational program exhibiting formation of dyke: An approach to magma study. |
| 21. |
Yusuke Shibano, Kohei Takahata, Jun Kawano, Tsuyoshi Watanabe, Daisuke Enomoto, Hiroyuki Kagi, Natsumi Kamiya, Junji Yamamoto, Raman spectroscopic determination of Sr/Ca ratios of calcite samples, JOURNAL OF RAMAN SPECTROSCOPY, 10.1002/jrs.5235, 48, 12, 1755-1761, 2017.12. |
| 22. |
Yamamoto J., Ishibashi H. and Nishimura K., Cooling rate responsiveness of pyroxene geothermometry, Geochemical Journal, 10.2343/geochemj.2.0477, 51, 457-467, 2017.04. |
| 23. |
Norikatsu Akizawa, Akihiro Tamura, Keisuke Fukushi, Junji Yamamoto, Tomoyuki Mizukami, Marie Python, Shoji Arai, High-temperature hydrothermal activities around suboceanic Moho: An example from diopsidite and anorthosite in Wadi Fizh, Oman ophiolite, LITHOS, 10.1016/j.lithos.2016.07.012, 263, 66-87, 2016.10. |
| 24. |
Shitaoka, Y, Moriwaki, H, Akai, F, Nakamura, N, Miyoshi, M, Yamamoto, J, Eruption age of Sakurajima-Satsuma tephra using thermoluminescence dating, 地球環境研究, 19, 18, 125-128, 2016.03. |
| 25. |
Kohei Takahata, Junji Torimoto, Junji Yamamoto, Improvement of Raman Spectroscopic Densimetry for Carbon Dioxide Fluid, CHEMISTRY LETTERS, 10.1246/cl.140782, 43, 12, 1924-1925, 2014.12. |
| 26. |
Junji Yamamoto, Jun Korenaga, Naoto Hirano, Hiroyuki Kagi, Melt-rich lithosphere-asthenosphere boundary inferred from petit-spot volcanoes, GEOLOGY, 10.1130/G35944.1, 42, 11, 967-970, 2014.11, Young basaltic knolls have been discovered on the old oceanic lithosphere, namely petit-spot volcanoes. Based on their geochemical signatures, they have presumably originated from partial melts in the asthenosphere. However, there is no direct information on the depth provenance of petit-spot formation. Here we report new geothermobarometric data of rare mantle xenoliths discovered from petit-spot lavas exhibiting a geotherm much hotter than expected for the ca. 140 Ma seafloor on which petit-spots were formed. Such an anomalously hot geotherm indicates that melt porosity around the lithosphere-asthenosphere boundary (LAB) must be as high as a few percent. Such high melt porosity would be possible by continuous melt replenishment. Excess pressure induced by the outer-rise topography enables horizontal melt migration along the LAB and sustains a continuous melt supply to petit-spot magmatism. Given the general age-depth relationship of ocean basins, a melt-rich boundary region could also be a global feature.. |
| 27. |
Yoshitaka Kumagai, Tatsuhiko Kawamoto, Junji Yamamoto, Evolution of carbon dioxide-bearing saline fluids in the mantle wedge beneath the Northeast Japan arc, CONTRIBUTIONS TO MINERALOGY AND PETROLOGY, 10.1007/s00410-014-1056-9, 168, 4, DOI:10.1007/s00410-014-1056-9, 2014.10. |
| 28. |
Yorinao Shitaoka, Masaya Miyoshi, Junji Yamamoto, Tomoyuki Shibata, Tsuneto Nagatomo, Keiji Takemura, THERMOLUMINESCENCE AGE OF QUARTZ XENOCRYSTS IN BASALTIC LAVA FROM ONINOMI MONOGENETIC VOLCANO, NORTHERN KYUSHU, JAPAN, GEOCHRONOMETRIA, 10.2478/s13386-013-0144-3, 41, 1, 30-35, 2014.03. |
| 29. |
Masaya Miyoshi, Taro Shinmura, Hirochika Sumino, Takashi Sano, Yasuo Miyabuchi, Yasushi Mori, Hirohito Inakura, Kuniyuki Furukawa, Koji Uno, Toshiaki Hasenaka, Keisuke Nagao, Yoji Arakawa, Junji Yamamoto, Lateral magma intrusion from a caldera-forming magma chamber: Constraints from geochronology and geochemistry of volcanic products from lateral cones around the Aso caldera, SW Japan, Chemical Geology, 10.1016/j.chemgeo.2013.06.003, 352, 202-210, 2013.08, We investigated the K-Ar ages and the petrological and geochemical features of lava units from lateral cones and lava distributed around the Aso caldera in central Kyushu, Japan, in order to constrain the spatial range of lateral magma intrusion during the caldera-forming stage. The results of the K-Ar age determination showed that most of the analyzed lava units erupted almost simultaneously with the Aso caldera-forming pyroclastic eruptions (266 to 89. ka). In addition, the petrography, major and trace element compositions, and Sr isotope ratios of these lava units are indistinguishable from the caldera-forming pyroclastic products. The contemporaneous activities of compositionally similar magmas inside and outside of the caldera presumably indicate the occurrence of a lateral intrusion of caldera-forming magma, which had accumulated in a huge magma chamber beneath the caldera system. Our results suggest that a total of 6.3. vol.% of caldera-forming magma in the Aso volcano migrated more than 20. km along the faults from the center of the caldera. © 2013 Elsevier B.V.. |
| 30. |
Tomoyuki Kobayashi, Junji Yamamoto, Takao Hirajima, Hidemi Ishibashi, Naoto Hirano, Yong Lai, Vladimir S. Prikhod'ko, Shoji Arai, Conformity and precision of CO2 densimetry in CO2 inclusions: microthermometry versus Raman microspectroscopic densimetry, JOURNAL OF RAMAN SPECTROSCOPY, 10.1002/jrs.3134, 43, 8, 1126-1133, 2012.08. |
| 31. |
Junji Yamamoto, Koshi Nishimura, Hidemi Ishibashi, Hiroyuki Kagi, Shoji Arai, Vladimir S. Prikhod'ko, Thermal structure beneath Far Eastern Russia inferred from geothermobarometric analyses of mantle xenoliths: Direct evidence for high geothermal gradient in backarc lithosphere, TECTONOPHYSICS, 10.1016/j.tecto.2012.06.005, 554, 74-82, 2012.07, Based on pressure and temperature (P-T) information of mantle-derived xenoliths, this report describes a geotherm in Far Eastern Russia, which is situated in the backarc of volcanic chains in eastern Asia. The mantle xenoliths have abundant CO2 fluid inclusions. Accurate determination of the internal pressure of the CO2 fluid inclusions enables estimation of the depth provenance of the mantle xenoliths. The depth provenances obtained from five mantle xenoliths are correlated with equilibrium temperatures estimated using a geothermometer. Assuming that the correlation reflects the geotherm in this region, it corresponds to heat flow of around 100 mW/m(2), which is comparable to the surface heat flow in the volcanic arc. Such high heat flow implies a thin lithosphere and high temperature of the shallower upper mantle.
Backarc areas are universally characterized by both high surface heat flow and the occurrence of recent volcanic activities. Furthermore low seismic velocity anomaly is widely observed in the shallower upper mantle in the backarc, especially in eastern Asia. The present xenolith geotherm suggests that the seismic anomaly arises from high temperature of the shallower upper mantle. It would be direct evidence for warming of the lithospheric mantle and subsequent lithospheric thinning, which is likely attributable to asthenospheric upwelling. (C) 2012 Elsevier B.V. All rights reserved.. |
| 32. |
Toyama C., Muramatsu Y., Yamamoto J., Nakai S. and Kaneoka I., Sr and Nd isotope ratios and trace element concentrations in kimberlites from Shandong and Liaoning (China) and the Kimberley area (South Africa), Geochemical Journal, 46, 45-59, 2012.04. |
| 33. |
Study Program to Assess Hinterland Provenance Using Several Separation Methods for Beach Sand. |
| 34. |
Hidemi Ishibashi, Masashi Arakawa, Junji Yamamoto, Hiroyuki Kagi, Precise determination of Mg/Fe ratios applicable to terrestrial olivine samples using Raman spectroscopy, JOURNAL OF RAMAN SPECTROSCOPY, 10.1002/jrs.3024, 43, 2, 331-337, 2012.02. |
| 35. |
Junji Yamamoto, Kazuhiko Otsuka, Hiroaki Ohfuji, Hidemi Ishibashi, Naoto Hirano, Hiroyuki Kagi, Retentivity of CO2 in fluid inclusions in mantle minerals, EUROPEAN JOURNAL OF MINERALOGY, 10.1127/0935-1221/2011/0023-2150, 23, 5, 805-815, 2011.10, To assess the capacity of fluid inclusions in mantle minerals for CO2 retention, annealing experiments were conducted for two mantle xenoliths with CO2 inclusions for 8 days at 1000 degrees C under atmospheric pressure and fO(2) of 10(-11) MPa. The results show no marked decrease in the CO2 density of the CO2 inclusions for any examined minerals - olivine, orthopyroxene, clinopyroxene, or spinel. The CO2 density of CO2 inclusions in olivine in the present mantle xenoliths is lower than that in pyroxenes or spinel. Results of previous studies indicate that the low CO2 density in olivine is attributable to plastic deformation of olivine around CO2 inclusions during annealing in ascending magma.
Results of this study present fundamental implications for deformation mechanisms that arise from internal pressure of fluid inclusions in silicate minerals. We calculated the stress field in minerals having a CO2 inclusion. Results show a steep stress gradient in the host around the inclusion. Such local stress in the mineral induces a local rise in the density of dislocations around the CO2 inclusions. The orthopyroxene used for this study showed a sparse distribution of dislocations around a CO2 inclusion, whereas olivine showed dense dislocations around CO2 inclusions, implying that the low CO2 density of the CO2 inclusions in olivine results from volume expansion of the CO2 inclusions through plastic deformation of the host mineral during annealing of the xenoliths in ascending magma.
In this respect, constancy of CO2 density during the annealing experiments for all minerals is an interesting finding. Regarding olivines, the reduction of internal pressure of the CO2 inclusions or interaction of the dense dislocations possibly inhibits decrepitation or further volume expansion of the CO2 inclusions during annealing experiments. However, pyroxenes and spinel show higher and similar CO2 density, which reflects the resistance to plastic deformation and which indicates the effectiveness of CO2 inclusions in these minerals as a depth probe for mantle xenoliths.. |
| 36. |
Observation of Magma Formation Using Portable Clay Cooking Stove and Familiar Products. |
| 37. |
Yoshikawa M., Kawamoto T., Shibata T. and Yamamoto J., Petrology and Sr-Nd isotopic geochemistry of ultramafic xenoliths from the French Massif Central, Geological Society of London, Special Publications, 337, 153-175, 2010.04. |
| 38. |
Takaharu Yasuzuka, Hidemi Ishibashi, Masashi Arakawa, Junji Yamamoto, Hiroyuki Kagi, Simultaneous determination of Mg# and residual pressure in olivine using micro-Raman spectroscopy, JOURNAL OF MINERALOGICAL AND PETROLOGICAL SCIENCES, 10.2465/jmps.090615, 104, 6, 395-400, 2009.12. |
| 39. |
Junji Yamamoto, Naoto Hirano, Natsue Abe, Takeshi Hanyu, Noble gas isotopic compositions of mantle xenoliths from northwestern Pacific lithosphere, CHEMICAL GEOLOGY, 10.1016/j.chemgeo.2009.09.009, 268, 3-4, 313-323, 2009.11, We measured noble gas isotopic compositions of mantle xenoliths and xenocrystic olivines sampled from seamounts-so-called petit-spot volcanoes-on the 135-million-year-old northwestern Pacific Plate. The xenoliths are spinel lherzolites originating from suboceanic lithospheric mantle. The samples' He-3/He-4 ratios are 7.0-8.5 Ra, where Ra signifies atmospheric He-3/He-4. The Ar-40/Ar-36 ratios are as high as 7000. These observations suggest that the noble gas isotopic compositions of suboceanic lithospheric mantle resemble those of mid-ocean ridge basalt (MORB). A mantle source with a He/U ratio as high as an assumed value for MORB source is necessary to maintain the MORB-like He-3/He-4 over 135 million years, implying that melt extraction at mid-ocean ridges only slightly alters the He/U ratio of the oceanic upper mantle.
The He-4/Ar-40* ratios of the samples described herein are much lower than the theoretical radiogenic production ratio, where an asterisk denotes correction for atmospheric contribution. The low He-4/Ar-40* is inferred to result from kinetic fractionation in the mantle. When magma migrates through a mantle source, lighter noble gases in the mantle source diffuse selectively into magma channels. The MORB generation does not cause low He-4/Ar-40*, however. If a mantle source is depleted in lighter noble gases during ancient MORB generation, then noble gas isotopic compositions of the mantle source are affected over time by accumulation of radiogenic nuclides. Thereby, the mantle source adopts a radiogenic or nucleogenic noble gas isotopic composition. Recent kinetic fractionation contributes to the low He-4/Ar-40* in the samples. Based on the diffusive fractionation model, more than 100 years are necessary to produce a residual mantle source with He-4/Ar-40*, as observed in the samples. However, petit-spot volcanoes. found as small knolls, seem to erupt within a short period. The low He-4/Ar-40* of the samples implies prior volcanism in this region. No recent volcanism has occurred near this region aside from petit-spot volcanism, indicating that petit-spot volcanoes are polygenetic with a long active period.
Petit-spot volcanoes are regarded as common magmatism on the subducting oceanic plate. Consequently, the thermal structure and temperature-dependent physical properties of the oceanic plate are, at least partly, affected by remnant heat of the magmatism. (C) 2009 Elsevier B.V. All rights reserved.. |
| 40. |
Yuji Sano, Ayano Kameda, Naoto Takahata, Junji Yamamoto, Junichi Nakajima, Tracing extinct spreading center in SW Japan by helium-3 emanation, CHEMICAL GEOLOGY, 10.1016/j.chemgeo.2008.10.020, 266, 1-2, 50-56, 2009.08. |
| 41. |
Melt extraction and multiple metasomatism beneath French Massif Central: Geochemical and isotopic signatures of ultramafic xenoliths. |
| 42. |
Junji Yamamoto, Koshi Nishimura, Takeshi Sugimoto, Keiji Takemura, Naoto Takahata, Yuji Sano, Diffusive fractionation of noble gases in mantle with magma channels: Origin of low He/Ar in mantle-derived rocks, EARTH AND PLANETARY SCIENCE LETTERS, 10.1016/j.epsl.2009.01.029, 280, 1-4, 167-174, 2009.04, By crushing olivine and pyroxene phenocrysts in volcanic rocks from Kyushu Island, Japan, we determined (3)He/(4)He of 3-7 Ra and (40)Ar/(36)Ar of up to 1750. These values are lower than those of MORB. (4)He/(40)Ar* (down to 0.1) is much lower than the production ratio of (4)He/(40)Ar* (1-5), where an asterisk denotes correction for the atmospheric contribution. Such values are typical of mantle-derived samples from the island arcs and active continental margins. Although the origin of the low (3)He/(4)He and (40)Ar/(36)Ar of subcontinental mantle has been widely discussed, low (4)He/(40)Ar* has been given little attention. Actually, (3)He/(4) He and (4)He/(40)Ar* of phenocrysts overlap with those of subcontinental mantle xenoliths. Although noble gas compositions of phenocrysts are affected considerably by diffusive fractionation in ascending magma, they have little effect on the noble gases in the mantle xenoliths because it takes 100 years for He/Ar fractionation of ca. 15% for a mantle xenolith with 5 cm diameter. Therefore, the low (4)He/(40)Ar* of the mantle xenoliths is inferred to result from another kinetic fractionation in the mantle.
During generation and migration of magma in the mantle, lighter noble gases diffuse rapidly out into the magma. This diffusive fractionation can explain low (4)He/(40)Ar* and somewhat low (3)He/(4)He in the residual mantle. Furthermore, the combination of the diffusive fractionation and subsequent radiogenic ingrowth explain the fact that data from subcontinental mantle xenoliths have extremely low (3)He/(4)He and various (4)He/(40)Ar*. Consequently, (4)He/(40)Ar* and (3)He/(4) He in mantle-derived materials are proposed as indicators of the degree of noble gas depletion of the source mantle. (C) 2009 Elsevier B.V. All rights reserved.. |
| 43. |
Junji Yamamoto, Shun'ichi Nakai, Koshi Nishimura, Ichiro Kaneoka, Hiroyuki Kagi, Keiko Sato, Tasuku Okumura, Vladimir S. Prikhod'ko, Shoji Arai, Intergranular trace elements in mantle xenoliths from Russian Far East: Example for mantle metasomatism by hydrous melt, ISLAND ARC, 10.1111/j.1440-1738.2008.00642.x, 18, 1, 225-241, 2009.03, Based on both major and trace element chemistry, the occurrence of the intergranular component in mantle-derived xenoliths from far eastern Russia has been constrained. Whole-rock trace element measurements of one xenolith show apparent negative anomalies in Ce, Th, and high field strength elements on normalized trace element patterns. The trace element pattern of the whole rock differs from those of constituent minerals, indicating that the anomalies in the whole rock are attributable to the presence of an intergranular component. That assumption was confirmed using in situ analysis of trace elements in the intergranular substance and melt inclusion using laser ablation inductively coupled plasma-mass spectrometry. Both the intergranular component and the melt inclusions have identical trace element patterns, which mean that these materials are a cognate metasomatizing agent. The anomalies are regarded as mantle metasomatism related to an aqueous fluid. Hydrous minerals were observed on the wall of the melt inclusions using micro-Raman spectroscopy, indicating that the melt inclusions contained a large amount of water. Thus, this study reveals a trace element composition of a hydrous metasomatizing agent in the mantle.. |
| 44. |
Hidemi Ishibashi, Masashi Arakawa, Shugo Ohi, Junji Yamamoto, Akira Miyake, Hiroyuki Kagi, Relationship between Raman spectral pattern and crystallographic orientation of a rock-forming mineral: a case study of Fo(89)Fa(11) olivine, JOURNAL OF RAMAN SPECTROSCOPY, 10.1002/jrs.2094, 39, 11, 1653-1659, 2008.11. |
| 45. |
Junji Yamamoto, Hiroyuki Kagi, Application of densimetry using micro-Raman spectroscopy for CO(2) fluid inclusions: a probe for elastic strengths of mantle minerals, EUROPEAN JOURNAL OF MINERALOGY, 10.1127/0935-1221/2008/0020-1825, 20, 4, 529-535, 2008.07, Micro-Raman spectroscopy enables precise non-destructive analyses of CO(2) density in a very small volume. By applying this method to CO(2) fluid inclusions in minerals, a contrast is apparent in the CO(2) density specific to mineral species in a mantle-derived spinel lherzolite xenolith entrained by ascending magma. The rock investigated in this study comprises four mineral species: olivine, orthopyroxene (opx), clinopyroxene (cpx), and chromian-spinel (spinel). The CO(2) densities in the fluid inclusions in these minerals are 1.006-1.035, 1.148-1.154, 1.150-1.154 and 1.189-1.194 g/cm(3), respectively. During transport of the rock by magma and subsequent cooling, the CO(2) fluid inclusions change their volume due to both elastic and plastic properties of the host mineral, which are sensitive to differential pressure between internal pressure of the CO(2) fluid inclusion, and stress in surrounding crystal lattice. We tested the possibility that the Volume Of CO(2) fluid inclusion changes by the differential pressure. Existing models dealing with the volume change of fluid inclusion in response to deformation of host mineral do not explain the density gradation, particularly that between pyroxenes and spinel. We propose that combination of precise determination of fluid density in mantle-derived minerals and observation of microstructure in the host mineral provides a deep insight into the deformation mechanism of natural minerals under high differential pressure and temperature.. |
| 46. |
Junji Yamamoto, Jun-ichi Ando, Hiroyuki Kagi, Toru Inoue, Akihiro Yamada, Daisuke Yamazaki, Tetsuo Irifune, In situ strength measurements on natural upper-mantle minerals, PHYSICS AND CHEMISTRY OF MINERALS, 10.1007/s00269-008-0218-6, 35, 5, 249-257, 2008.06, Using in situ strength measurements at pressures up to 10 GPa and at room temperature, 400, 600, and 700 degrees C, we examined rheological properties of olivine, orthopyroxene, and chromian-spinel contained in a mantle-derived xenolith. Mineral strengths were estimated using widths of X-ray diffraction peaks as a function of pressure, temperature, and time. Differential stresses of all minerals increase with increasing pressure, but they decrease with increasing temperature because of elastic strain on compression and stress relaxation during heating. During compression at room temperature, all minerals deform plastically at differential stress of 4-6 GPa. During subsequent heating, thermally induced yielding is observed in olivine at 600 degrees C. Neither orthopyroxene nor spinel shows complete stress relaxation, but both retain some stress even at 700 degrees C. The strength of the minerals decreases in the order of chromian-spinel approximate to orthopyroxene > olivine for these conditions. This order of strength is consistent with the residual pressure of fluid inclusions in mantle xenoliths.. |
| 47. |
Masashi Arakawa, Junji Yamamoto, Hiroyuki Kagi, Micro-Raman thermometer for CO2 fluids: Temperature and density dependence on Raman spectra of CO2 fluids, CHEMISTRY LETTERS, 10.1246/cl.2008.280, 37, 3, 280-281, 2008.03. |
| 48. |
プチスポット総合調査. |
| 49. |
Masashi Arakawa, Junji Yamamoto, Hiroyuki Kagi, Developing micro-Raman mass spectrometry for measuring carbon isotopic composition of carbon dioxide, APPLIED SPECTROSCOPY, 10.1366/000370207781393244, 61, 7, 701-705, 2007.07. |
| 50. |
Junji Yamamoto, Hiroyuki Kagi, Yoko Kawakami, Naoto Hirano, Masaki Nakamura, Paleo-Moho depth determined from the pressure of CO2 fluid inclusions: Raman spectroscopic barometry of mantle- and crust-derived rocks, EARTH AND PLANETARY SCIENCE LETTERS, 10.1016/j.epsl.2006.10.038, 253, 3-4, 369-377, 2007.01, The density, and therefore the pressure, Of CO2 fluid inclusions in minerals can be estimated from the Fermi diad splitting of Raman spectra Of CO2. An accurate determination of the pressure Of CO2 fluid inclusions enables the estimation of the depth origin of rocks from the deep Earth. A micro-Raman densimeter was applied to ultramafic-mafic xenoliths sampled along the Ohku coast of Oki-Dogo Island in the Sea of Japan (East Sea). The density Of CO2 fluid inclusions in the mafic granulite was 1.02-1.05 g/cm(3), while those of Iherzolites were 0.98-1.02 g/cm. In contrast, the density Of CO2 fluid inclusions measured in olivine gabbro, clinopyroxenite, and harzburgite were lower ranging from 0.86- to 0.99 g/cm(3). Taking into account the temperature condition estimated using a pyroxene thermometer, the mafic granulite originated from a depth of 27-30 km and the lherzolites from 2529 km. The overlapping depth of 27-29 km can be interpreted as the depth including the Moho discontinuity under Oki-Dogo Island 3.3 Ma. This estimation is consistent with geophysical observations. (c) 2006 Elsevier B.X. All rights reserved.. |
| 51. |
Naoto Hirano, Eiichi Takahashi, Junji Yamamoto, Natsue Abe, Stephanie P. Ingle, Ichiro Kaneoka, Takafumi Hirata, Jun-Ichi Kimura, Teruaki Ishii, Yujiro Ogawa, Shiki Machida, Kiyoshi Suyehiro, Volcanism in response to plate flexure, SCIENCE, 10.1126/science.1128235, 313, 5792, 1426-1428, 2006.09. |
| 52. |
Junji Yamamoto, Hiroyuki Kagi, Extended micro-Raman densimeter for CO2 applicable to mantle-originated fluid inclusions, CHEMISTRY LETTERS, 10.1246/cl.2006.610, 35, 6, 610-611, 2006.06, Micro-Raman spectroscopy enables nondestructive analyses Of CO2 fluid density in a very small volume. For application of the method to CO2 fluid inclusions in minerals originated from the deep Earth having widely various densities, we extended the relational expression between the density and Raman spectra Of CO2 up to the density corresponding to the boundary between liquid and solid.. |
| 53. |
J Yamamoto, PG Burnard, Solubility controlled noble gas fractionation during magmatic degassing: Implications for noble gas compositions of primary melts of OIB and MORB, GEOCHIMICA ET COSMOCHIMICA ACTA, 10.1016/j.gca.2004.07.014, 69, 3, 727-734, 2005.02, Noble gas abundances in basaltic glasses from ocean islands (OIBs) are generally lower than those of mid-oceanic ridge basalts (MORBs), contrary to most geodynamic models which usually require that the source of OIBs is less degassed (resulting in higher primordial noble gas abundances) and more trace element enriched (resulting in higher radiogenic noble gas abundances) than the MORB source. Therefore, noble gas abundances in OIBs are often thought to have been reduced by extensive gas loss from the magma before eruption.
The extent of magmatic degassing can be tested as it will cause characteristic changes in the composition of the volatiles; notably the He-4/Ar-40* ratio (where Ar-40* is Ar-40 corrected for atmospheric contamination) will increase in residual volatiles due to the higher solubility of He relative to Ar. The degree of He-As fractionation for a given fraction of gas loss depends on the ratio of the solubilities, S-He/S-Ar, which is sensitive to (among other things) the CO2 and H2O content of the basalt at the time of degassing.
From a global database of OIB and MORB glasses, we show that He-4/Ar-40* ratios of MORB glasses are broadly consistent with degassing of a magma with an initial Ar-40 of approximate to1.5 x 10(-5) ccSTP/g, i.e., similar to that of the "popping rock." However, OIB glasses generally have lower Ar-40* concentration for a given He-4/Ar-40*. While this would appear to require lower Ar-40* abundances in the undegassed OIB magmas, the higher volatile contents of OIBs will reduce S-He/S-Ar (relative to MORBs) during degassing. By modeling S-He/S-Ar in OIBs, it is possible to show that extensive degassing of OIBs can occur without dramatically increasing the He-4/Ar-40* ratio. We show that undegassed Ar-40 concentrations of OEB magmas were probahl. similar to those of MORBs. Copyright (C) 2005 Elsevier Ltd.. |
| 54. |
K Notsu, K Sugiyama, M Hosoe, A Uemura, Y Shimoike, F Tsunomori, H Sumino, J Yamamoto, T Mori, PA Hernandez, Diffuse CO2 efflux from Iwojima volcano, Izu-Ogasawara arc, Japan, JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, 10.1016/j.jvolgeores.2004.08.003, 139, 3-4, 147-161, 2005.01. |
| 55. |
N Hirano, J Yamamoto, H Kagi, T Ishii, Young, olivine xenocryst-bearing alkali-basalt from the oceanward slope of the Japan Trench, CONTRIBUTIONS TO MINERALOGY AND PETROLOGY, 10.1007/s00410-004-0593-z, 148, 1, 47-54, 2004.09. |
| 56. |
J Yamamoto, Kaneoka, I, S Nakai, H Kagi, VS Prikhod'ko, S Arai, Evidence for subduction-related components in the subcontinental mantle from low He-3/He-4 and Ar-40/(36) Ar ratio in mantle xenoliths from Far Eastern Russia, CHEMICAL GEOLOGY, 10.1016/j.chemgeo.2004.03.007, 207, 3-4, 237-259, 2004.07, By applying both vacuum crushing and stepwise heating methods for the extraction of the noble gases, we have discovered He-3/He-4 ratios much lower than the atmospheric ratio (similar to 0.3 R-A; R-A is the atmospheric He-3/He-4 ratio of 1.4 x 10(-6)) and relatively low Ar-40/Ar-36 ratios (Spectroscopic and petrographic observations confirm that there are at least two compositionally distinct fluids in these xenoliths; liquid CO2 inclusions and melt inclusions with shrinkage bubbles. Based on the crushing experiments, it is inferred that the inclusions of liquid CO2 have a He-3/He-4 ratio similar to that of MORB, and the component with the low He-3/He-4 ratio is derived from the shrinkage bubbles in the melt inclusions.
For the present samples, the Ar-40/Ar-36 ratios obtained by crushing were less than 1060, suggesting incorporation of atmospheric components in the source materials. Since low Ar-40/Ar-36 ratios were observed irrespective of the occurrence of the liquid CO, inclusions, the atmospheric component exists in the melt inclusions. Ne and Xe isotopes are also consistent with incorporation of atmospheric components.
Since the Far Eastern Russia area was located at a subduction zone in the Jurassic-early Cretaceous Period, it is most likely that the melt inclusions displaying atmospheric noble gas characteristics together with low He-3/He-4 ratios have been derived from the Jurassic-Cretaceous subducted slab. Although we cannot exclude the possibility that low He-3/He-4 ratios are due to the existence of minor U-bearing minerals in the lithospheric continental mantle caused by metasomatism, we have no petrographical evidence for such minerals in this area. On the other hand, He-3/He-4 ratios observed in the liquid CO2 inclusions, which are similar to the MORB-like value, might reflect the general character of the upper mantle. The Far Eastern Russian mantle may therefore be a MORB-like source that has been partly infiltrated by subduction-related fluids. (C) 2004 Elsevier B.V. All rights reserved.. |
| 57. |
Glasby G. P., Yamanaka T., Yamamoto J., Sato H. and Notsu K., Kuroko and Hydrocarbon Deposits from Northern Honshu, Japan: A Possible Common Hydrothermal/Magmatic Origin?, Resource Geology, 54, 413-424, 2004.07. |
| 58. |
Y Nishio, N Shun'ichi, J Yamamoto, H Sumino, T Matsumoto, VS Prikhod'ko, S Arai, Lithium isotopic systematics of the mantle-derived ultramafic xenoliths: implications for EM1 origin, EARTH AND PLANETARY SCIENCE LETTERS, 10.1016/S0012-821X(03)00606-X, 217, 3-4, 245-261, 2004.01. |
| 59. |
T Mizukami, Wallis, SR, J Yamamoto, Natural examples of olivine lattice preferred orientation patterns with a flow normal a-axis maximum, NATURE, 10.1038/nature02179, 427, 6973, 432-436, 2004.01. |
| 60. |
Y Kawakami, J Yamamoto, H Kagi, Micro-raman densimeter for CO2 inclusions in mantle-derived minerals, APPLIED SPECTROSCOPY, 10.1366/000370203322554473, 57, 11, 1333-1339, 2003.11. |
| 61. |
Kaneoka I., Hanyu T., Yamamoto J. and Miura N. Y., Noble gas systematics of the Hawaiian volcanoes based on the analysis of Loihi, Kilauea and Koolau submarine rocks, Hawaiian Volcanoes: Deep Underwater Perspectives (AGU Geophysical Monograph), 128, 373-389, 2002.06. |
| 62. |
Matsuda J., Matsumoto T., Sumino H., Nagao K., Yamamoto J., Miura Y. N., Kaneoka I., Takahata N. and Sano Y., The 3He/4He ratio of the new internal He standard of Japan (HESJ), Geochemical Journal, 36, 191-195, 2002.06. |
| 63. |
J Yamamoto, H Kagi, Kaneoka, I, Y Lai, VS Prikhod'ko, S Arai, Fossil pressures of fluid inclusions in mantle xenoliths exhibiting rheology of mantle minerals: implications for the geobarometry of mantle minerals using micro-Raman spectroscopy, EARTH AND PLANETARY SCIENCE LETTERS, 10.1016/S0012-821X(02)00528-9, 198, 3-4, 511-519, 2002.05, Micro-Raman spectroscopic analysis allows us to estimate the internal pressure of small fluid inclusions. We applied this method to CO2-dominated fluid inclusions in mantle-derived xenoliths. The pressures estimated from the equilibration temperature and density of the fluid range from 0.96 to 1.04 GPa corresponding to depths of up to 30 km, which confirms that these rocks and fluids are of uppermost mantle origin. Furthermore, the inclusions show pressures specific to the individual host minerals (spinel greater than or equal to orthopyroxene approximate to clinopyroxene much greater than olivine). In particular. the densities of CO2 in pyroxenes are 10% higher than in olivine. Such an enormous difference cannot be explained by elastic deformation of the minerals during ascent of the xenoliths, although the process may explain the slightly higher density of CO2 in spinel. During the ascent. the strain rate of orthopyroxene calculated using the 'constitutive equation' is several orders of magnitude lower than that of olivine. The difference in densities of CO2 among the host mineral species is therefore attributable to the rheological properties of the minerals. Present internal pressures of fluid inclusions can be a sensitive strength marker of mantle minerals. Conversely, the density of CO2 inclusions in pyroxene (and spinel) may be a useful geobarometer. (C) 2002 Elsevier Science B.V. All rights reserved.. |
| 64. |
J Yamamoto, M Watanabe, Y Nozaki, Y Sano, Helium and carbon isotopes in fluorites: implications for mantle carbon contribution in an ancient subduction zone, JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, 10.1016/S0377-0273(00)00315-2, 107, 1-3, 19-26, 2001.06, The concentrations of helium and carbon in fluorite associated with Cretaceous to Neogene (90-13 Ma) granitic magmatism in the Japanese are have been measured. Concentrations of Li, U, Th and Gd were measured to correct for secondary generated He-3. The CO2/He-3 of fluorites are almost uniform (1.5 x 10(10)-4 x 10(10)) and in fair agreement with the range of present island are volcanic gases. The calculated mantle C contribution in the Mesozoic subduction zone appear to have been identical to the present one (7-19%) indicating that the C flux from the mantle in supra-subduction zone environments has remained fairly constant during the past 70 million years. (C) 2001 Elsevier Science B.V. All rights reserved.. |
