Papers by Hirochika Sumino
Annual Meeting of the Geological Society of Japan, 2018
Meeting Abstracts of the Physical Society of Japan (Nihon Butsuri Gakkai koen gaiyoshu), 2015
Meeting Abstracts of the Physical Society of Japan (Nihon Butsuri Gakkai koen gaiyoshu), 2014
Programme and Abstracts the Volocanological Society of Japan, 2018
Japan Geoscience Union, 2015
An extension of the Ar-Ar and I-Xe dating methods enables us to determine trace amount of halogen... more An extension of the Ar-Ar and I-Xe dating methods enables us to determine trace amount of halogens (Cl, Br, and I), K, Ca, Ba, and U. These elements are converted to corresponding isotopes of Ar, Kr, and Xe by neutron irradiation in a nuclear reactor. Noble gases in the irradiated samples are analyzed by noble gas mass spectrometry and the conversion factors from parent elements to noble gas isotopes are determined by analyses of standard samples [1]. The detection limits of this technique for Cl, Br, and I are 10 −10 to 10−11, 10−13 to 10−14, and 10−14 to 10−15 mol, respectively, which are several orders of magnitude lower than those of conventional methods. Using this method, we are investigating halogen geochemistry in the mantle. Halogens, except for F, are incompatible elements that are strongly partitioned into aqueous fluids. They are concentrated at the Earth’s surface in distinct compositions and scarce in the mantle. These features enable us to trace water subducted into t...
Japan Geoscience Union, 2018
Fluids released from dehydration reactions of a subducting slab have been considered to play an i... more Fluids released from dehydration reactions of a subducting slab have been considered to play an important role on fluid circulation and slow earthquakes in subduction zones. Mantle-derived helium was reported for surface spring waters above non-volcanic long-period deep tremors in Shikoku Island [1] and bottom seawater close to the Japan Trench after the Tohoku-Oki earthquake [2], indicating that the dehydrated fluid migrates from the mantle to the surfaces. However, it remains poorly understood how mantle-derived fluids migrate toward shallow depths. Fluid inclusions in mineral veins in subduction mé langes provide an opportunity to study the process of fluid migration, as they preserve the fluid that was present in the subduction plate boundary. In this study, we measured helium isotope ratio of fluid inclusions in shear veins distributed in the Makimine mélange in the Shimanto accretionary complex of southwest Japan, which was deformed at 10–15 km depth and 300–350 °C. The measur...
Japan Geoscience Union, 2016
He/He ratios in terrestrial samples vary more than three orders of magnitude, because primordial ... more He/He ratios in terrestrial samples vary more than three orders of magnitude, because primordial helium with He/He of (1.4–4.6) x 10 has been diluted by addition of radiogenic He produced by decay of Uand Th-series elements in different degrees depending on He/(U+Th) ratio of each reservoir. This feature makes He/He ratio a powerful tracer in geochemistry and cosmochemistry. Though atmospheric helium with He/He ratio of 1.4 x 10 is used to calibrate He/He measurement with a noble gas mass spectrometer, relatively low concentration and He/He ratio of the atmospheric helium cause many difficulties to use it as a working standard for daily measurements. Thus noble gas laboratories often use their own working standards prepared from a natural gas sample with high He/He ratio or by mixing of isotopically pure He and He. "He Standard of Japan" (HESJ) is one of the latter originally prepared by four noble gas laboratories in Japan [1] and now distributed worldwide as an interlabo...
Proceedings of the International Conference on Neutron Optics (NOP2017), 2018
Goldschmidt2021 abstracts, 2021
Goldschmidt2021 abstracts, 2021
Goldschmidt2021 abstracts, 2021
Chemical Geology, 2021
Abstract We determined the heavy halogen (Cl, Br, and I) concentrations of fourteen powdered geol... more Abstract We determined the heavy halogen (Cl, Br, and I) concentrations of fourteen powdered geological reference materials distributed by the Geological Survey of Japan (GSJ) and the US Geological Survey, and seven original blocks of GSJ geological reference materials, using neutron irradiation noble gas mass spectrometry (NI-NGMS). The halogen concentrations obtained from the powder and original blocks of geological reference materials are systematically lower than their reference values for low-concentration samples. This discrepancy can be explained by contamination on the sample surface during the preparation of the reference materials. Contaminated halogen-derived noble gases were, at least partially, removed before analysis during preheating of the samples under vacuum after sample loading. The presence of the contaminated component in the reference materials is not a matter for other analytical methods as long as the contaminated component is completely homogenized in the powder reference materials and not removed before analysis. However, the present results indicate that the standard materials used in NI-NGMS should be selected more carefully than those used in other methods. In addition, we propose an F-determination method using NI-NGMS based on Ne systematics of neutron-irradiated samples.
Goldschmidt Abstracts, 2020
Goldschmidt Abstracts, 2020
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Papers by Hirochika Sumino