2023/02/15 更新

写真a

フクダ ジュンイチ
福田 惇一
FUKUDA JUNICHI
担当
大学院理学研究科 地球学専攻 准教授
理学部 地球学科
職名
准教授
所属
理学研究院

担当・職階

  • 大学院理学研究科 地球学専攻 

    准教授  2022年04月 - 継続中

  • 理学部 地球学科 

    准教授  2022年04月 - 継続中

取得学位

  • 博士(理学) ( 大阪大学 )

研究分野

  • 自然科学一般 / 固体地球科学

研究キーワード

  • 地殻物質の変形

  • 変形微細組織

  • 天然変形岩

  • 岩石力学

  • 岩石変形実験

  • 岩石鉱物中の水

  • 構造地質学

所属学協会

  • 日本地質学会

    2009年06月 - 継続中

  • 米国地球物理学連合

    2007年08月 - 継続中

  • 日本鉱物科学会

    2006年06月 - 継続中

  • 日本地球惑星科学連合

    2006年01月 - 継続中

職務経歴(学外)

  • 大阪公立大学   理学部 地球学科

    2022年04月 - 継続中

  • 神戸大学   理学研究科 惑星学専攻

    2020年04月 - 2022年03月

  • 神戸大学   内海域環境教育研究センター   講師(研究機関研究員)

    2019年06月 - 2020年03月

  • 大阪市立大学   理学研究科 生物地球系専攻

    2018年04月 - 2019年05月

論文

  • Water release and homogenization by dynamic recrystallization of quartz

    Fukuda, J., Okudaira, T., Ohtomo, Y.

    EGUsphere [preprint]   2023年01月

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    担当区分:筆頭著者, 責任著者   掲載種別:研究論文(学術雑誌)   国際・国内誌:国際誌  

    DOI: 10.5194/egusphere-2022-1487

  • Enhancement of ductile deformation in polycrystalline anorthite due to the addition of water 査読

    Junichi Fukuda, Jun Muto, Sanae Koizumi, Sando Sawa, Hiroyuki Nagahama

    Journal of Structural Geology   156   104547 - 104547   2022年02月( ISSN:0191-8141

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1016/j.jsg.2022.104547

  • A centennial-resolution terrestrial climatostratigraphy and Matuyama–Brunhes transition record from a loess sequence in China 査読

    Masayuki Hyodo, Kenta Banjo, Tianshui Yang, Shigehiro Katoh, Meinan Shi, Yuki Yasuda, Jun-ichi Fukuda, Masako Miki, Balázs Bradák

    Progress in Earth and Planetary Science   7 ( 26 )   1 - 18   2020年12月

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    掲載種別:研究論文(学術雑誌)  

    <title>Abstract</title>Terrestrial records of the last geomagnetic reversal often have few age constraints. Chronostratigraphy using suborbital-scale paleoceanic events during marine isotope stage 19 may contribute to solving this problem. We applied the method to an 8 m long, high-resolution paleomagnetic record from a loess sequence in China and revealed millennial-to-sub-centennial scale features of the Matuyama–Brunhes (MB) transition. All samples were subjected to progressive thermal demagnetization with 14–15 steps up to 650–680 °C. As a result, 96% of the samples yielded a high-quality remanent magnetization. The MB transition terminated with a 75 cm thick zone with nine polarity flips. The polarity flip zone, dated at about 779–777 ka, began between the warm events “I” and “J” and terminated at the end of the cooling event coincident with the lowest axial-dipole strength interval. Most polarity flips occurred within 70 years. The virtual geomagnetic poles (VGPs) in the upper polarity flip zone clustered in the SW Pacific region, where the MB transitional VGPs from lavas of the Hawaiian and Canary Islands and lacustrine deposits of Java also clustered. These sites were probably dominated by dipolar fields. The absence of transitional fields across polarity flips implies a short time span for averaging fields due to a thin loess-magnetization lock-in zone. The reverse-to-normal polarity reversal dated at about 778 ka in Lingtai occurred at the end of the SW Pacific VGP zone, an important key bed for MB transition stratigraphy. The reversal is a good candidate for the main MB boundary. We found an excursion at about 766 ka spanning about 1 ka.

    DOI: 10.1186/s40645-020-00337-z

    その他URL: https://link.springer.com/article/10.1186/s40645-020-00337-z/fulltext.html

  • Water distribution in quartz schists of the Sanbagawa Metamorphic Belt, Japan: infrared spectroscopic mapping and comparison of the calibrations proposed for determining water contents 査読

    Jun-ichi Fukuda, Ichiko Shimizu

    Earth, Planets and Space   71 ( 136 )   1 - 14   2019年12月

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    担当区分:筆頭著者, 責任著者   掲載種別:研究論文(学術雑誌)  

    <title>Abstract</title>We evaluated water distributions in deformed quartz in schists along the Asemi River, Central Shikoku, in the Sanbagawa Metamorphic Belt, Japan, using infrared spectroscopic (IR) mapping. The water trapped in quartz as molecular H<sub>2</sub>O showed a broad IR absorption band at 2800–3750 cm<sup>−1</sup>. A necessary step before assessing the quartz water content was to evaluate and compare six previously proposed IR calibrations in terms of the molar absorption coefficients of H<sub>2</sub>O (L/mol H<sub>2</sub>O cm<sup>2</sup>). The coefficients vary from 24,100 to 89,000 L/mol H<sub>2</sub>O cm<sup>2</sup>, and the values of the coefficients show a rough increase with increasing component of structural –OH in the IR spectra. We used Paterson’s calibration, which does not require input regarding the mineral species, but which was modified in his paper for measurements of molecular H<sub>2</sub>O in quartz. The absorption coefficient is 38,000 L/mol H<sub>2</sub>O cm<sup>2</sup>. IR mapping was performed on Sanbagawa metamorphic rocks with increasing grades of metamorphism, where the mean grain size of quartz increases from ~ 40 to ~ 120 µm. The absorption bands that are only from the quartz can be distinguished on the basis of microstructural observations and the corresponding mapping results. The IR spectra of quartz commonly show dominant molecular H<sub>2</sub>O bands at 2800–3750 cm<sup>−1</sup> with no additional bands associated with crystalline –OH when only quartz is measured. The water contents of quartz in all our samples were 40–310 ppm, and these values are about one-third of previously reported values measured using point analyses with the unified Paterson’s calibration. This difference seems to reflect the incorporation of phyllosilicates in previous measurements that showed a broad band around 3600 cm<sup>−1</sup>. The lowest and highest water contents in our quartz samples are associated with intragranular water and grain boundary water, respectively. We estimated the grain boundary widths to be at most ~ 10 nm on the basis of the water contents at grain boundaries.

    DOI: 10.1186/s40623-019-1117-4

    その他URL: http://link.springer.com/article/10.1186/s40623-019-1117-4/fulltext.html

  • Experimental grain growth of quartz aggregates under wet conditions and its application to deformation in nature 査読

    Junichi Fukuda, Hugues Raimbourg, Ichiko Shimizu, Kai Neufeld, Holger Stünitz

    Solid Earth   10 ( 3 )   621 - 636   2019年05月

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    担当区分:筆頭著者, 責任著者   掲載種別:研究論文(学術雑誌)  

    Abstract. Grain growth of quartz was investigated using two quartz samples
    (powder and novaculite) with water under pressure and temperature
    conditions of 1.0–2.5 GPa and 800–1100 ∘C. The compacted powder
    preserved a substantial porosity, which caused a slower grain growth than in
    the novaculite. We assumed a grain growth law of
    dn-d0n=k0fH2Orexp⁡(-Q/RT)t
    with grain size d (µm) at time t (seconds), initial grain size
    d0 (µm), growth exponent n, a constant k0 (µmn MPa−r s−1), water fugacity
    fH2O (MPa) with the exponent r,
    activation energy Q (kJ mol−1),
    gas constant R, and temperature T in
    Kelvin. The parameters we obtained were n=2.5±0.4, k0=10-8.8±1.4, r=2.3±0.3, and Q=48±34 for the powder and n=2.9±0.4, k0=10-5.8±2.0, r=1.9±0.3, and Q=60±49 for the novaculite. The grain growth parameters obtained for
    the powder may be of limited use because of the high porosity of the powder
    with respect to crystalline rocks (novaculite), even if the differences
    between powder and novaculite vanish when grain sizes reach ∼70 µm. Extrapolation of the grain growth laws to natural conditions
    indicates that the contribution of grain growth to plastic deformation in the
    middle crust may be small. However, grain growth might become important for
    deformation in the lower crust when the strain rate is &lt; 10−12 s−1.

    DOI: 10.5194/se-10-621-2019