Updated on 2023/11/28

写真a

 
AZAMI, Keishiro
 
Affiliation
Faculty of Science and Engineering, School of Creative Science and Engineering
Job title
Assistant Professor(non-tenure-track)
Degree
Ph.D. (Engineering) ( 2022.03 The University of Tokyo )
Master of Science ( 2018.03 Tohoku University )
Bachelor of Science ( 2016.03 Tohoku University )

Research Experience

  • 2022.04
    -
    Now

    Waseda University   Department of Resources and Environmental Engineering, School of Creative Science and Engineering

Education Background

  • 2018.04
    -
    2022.03

    The University of Tokyo   The Graduate School of Engineering   Department of System Innovation  

  • 2016.04
    -
    2018.03

    Tohoku University   Graduate School of Science   Department of Earth Science  

  • 2014.04
    -
    2016.03

    Tohoku University   Faculty of Science   Division of Earth and Planetary Materials Sciences  

Professional Memberships

  • 2022.04
    -
    Now

    The Geochemical Society of Japan

  • 2018.04
    -
    Now

    日本地質学会

  • 2016.04
    -
    Now

    Japan Geoscience Union

Research Areas

  • Solid earth sciences   Geochemistry

Research Interests

  • Ferromanganese crust / nodule

  • Submarine hydrothermal activity

  • Paleoenvironment

Awards

  • 若手奨励賞

    2019.03   ブルーアースサイエンス・テク2019  

  • 若手奨励賞

    2017.03   ブルーアースサイエンス・テク2017  

  • Silver medal

    2011.09   International Earth Science Olympiad  

  • Grand prize

    2011.06   Japan Earth Science Olympiad Committee  

 

Papers

  • Formation of hydrothermal ferromanganese oxides from the Daigo-Kume Knoll in the middle Okinawa Trough, Japan

    Keishiro Azami, Kanta Koyama, Shiki Machida, Kyoko Okino, Kazutaka Yasukawa, Yasuhiro Kato, Etsuo Uchida

    Marine Geology   463   107117 - 107117  2023.07

    DOI

    Scopus

  • Hydrothermal ferromanganese oxides around a petit-spot volcano on old and cold oceanic crust

    Keishiro Azami, Shiki Machida, Naoto Hirano, Kentaro Nakamura, Kazutaka Yasukawa, Tetsu Kogiso, Masao Nakanishi, Yasuhiro Kato

    Communications Earth & Environment   4 ( 1 )  2023.06

     View Summary

    Abstract

    Areas of old and cold oceanic plate lack conventional volcanism and have been assumed to be devoid of submarine hydrothermal activity. However, petit-spot volcanoes are common in areas of flexure of such oceanic plates. Here, we report hydrothermal ferromanganese oxides dredged from the vicinity of a petit-spot volcano at 5.7 km water depth in an area of oceanic plate flexure east of the Japan Trench. The bulk chemical, lead isotopic and mineralogical compositions of the samples indicate their formation by low-temperature hydrothermal activity, which can be interpreted as being caused by fluid–rock interactions at <200 °C. We propose that interaction of local marine sediments with volatile-rich petit-spot magmas may produce hydrothermal fluids containing not only iron and manganese but also enough amounts of carbon dioxide and methane to have implications for the global carbon cycle. However, contemporary hydrothermal activities at petit-spot volcanoes have not been confirmed yet.

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • Geochemistry of ferromanganese nodules in the soil of Okinawa Island, Japan: Paleoclimatic implications and discrimination scheme of the nodule origins

    Keishiro Azami, Kazutaka Yasukawa, Yasuhiro Kato

    Journal of Asian Earth Sciences: X   8   100127 - 100127  2022.12

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • 87Sr/86Sr Isotopic Ratio of Ferromanganese Crusts as a Record of Detrital Influx to the Western North Pacific Ocean

    Keishiro Azami, Naoto Hirano, Jun-Ichi Kimura, Qing Chang, Hirochika Sumino, Shiki Machida, Kazutaka Yasukawa, Yasuhiro Kato

    Minerals   12 ( 8 ) 943 - 943  2022.07

     View Summary

    In this study, the Sr isotope ratios (IRs; 87Sr/86Sr) of ferromanganese (Fe–Mn) crusts are analyzed through laser ablation inductively coupled plasma multiple-collector mass spectrometry. A sample collected from off Minamitorishima Island showed uniform Sr IRs (0.70906–0.70927) similar to that of present-day seawater with more than 36 mm thickness. Meanwhile, a detritus-rich sample collected from off northeast (NE) Japan showed a wide variation in Sr IRs (0.707761–0.709963). The Sr IR variation in the Fe–Mn crust from off NE Japan suggests detrital influx contributions from both the NE Japan arc (<0.708) and aeolian dust from China (>0.718). Detrital flux from the NE Japan arc increases from the bottom to middle layers, possibly due to the uplift of the Ou backbone range that occurred after ~2 Ma. The increased influx of the aeolian dust in the outer layer is attributable to global cooling in the Quaternary that increased the loess dust transportation from China to the western North Pacific Ocean. Meanwhile, the influence of the detrital influx on the sample from off Minamitorishima Island appeared to be negligible. The Sr IR analysis with high spatial resolution proposed in this study possibly improves the burial history of Fe–Mn nodules.

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • Stratigraphic Variations of Fe–Mn Micronodules and Implications for the Formation of Extremely REY-Rich Mud in the Western North Pacific Ocean

    Kazutaka Yasukawa, Satoshi Kino, Junichiro Ohta, Keishiro Azami, Erika Tanaka, Kazuhide Mimura, Koichiro Fujinaga, Kentaro Nakamura, Yasuhiro Kato

    Minerals   11 ( 3 ) 270 - 270  2021.03

     View Summary

    <jats:p>The origin of deep-sea sediments in the western North Pacific Ocean, which are significantly enriched in rare-earth elements and yttrium (REY), and its paleoceanographic implications have been poorly constrained. Here, we investigated stratigraphic variations in the chemical compositions and textures of ferromanganese (Fe–Mn) micronodules separated from western North Pacific sediments. The characteristics of the micronodules of an extremely REY-rich mud layer vary from almost purely diagenetic to relatively hydrogenetic. This indicates the abundant supply of organic matter to the sediment together with fish debris that accumulates REY at the onset of the REY-enrichment of the mud, followed by the exposure of the seafloor to oxic water masses during the latter half of the formation of the REY-rich mud. These results support a previously proposed formation mechanism based on which enhanced bottom water currents caused pelagic fish proliferation via the upwelling of nutrients and fish debris was physically sorted and selectively accumulated on the seafloor. After the main REY-enrichment, the micronodules exhibit varying diagenetic signatures, suggesting changes in the bottom current intensities after the main REY-enrichment. However, the bulk REY contents do not increase. This implies that a sufficient increase in the fish productivity is an essential factor affecting the formation of REY-rich mud.</jats:p>

    DOI

    Scopus

    8
    Citation
    (Scopus)
  • Geochemical features of Fe-Mn micronodules in deep-sea sediments of the western North Pacific Ocean: Potential for co-product metal extraction from REY-rich mud

    Kazutaka Yasukawa, Satoshi Kino, Keishiro Azami, Erika Tanaka, Kazuhide Mimura, Junichiro Ohta, Koichiro Fujinaga, Kentaro Nakamura, Yasuhiro Kato

    Ore Geology Reviews   127   103805 - 103805  2020.12

     View Summary

    Rare earth element and yttrium (REY)-rich mud around Minamitorishima Island, Japan, in the western North Pacific Ocean has received significant attention as a novel REY resource. In REY-rich muds, industrially critical metals such as Co, Ni, and Mo occur in relatively high concentrations. We show that Fe-Mn micronodules separated from REY-rich muds are significantly enriched in these elements; we measured Co contents of almost 3000 ppm and Ni contents that exceed 39,000 ppm. Through experiments, we demonstrated that reductive chemical leaching can be used to extract major portions (generally >80%) of the metals associated with Fe-Mn (oxyhydr)oxides from REY-rich muds. The Fe-Mn micronodules were of an oxic diagenetic origin. A simple mass balance calculation indicated that the contribution of the Fe-Mn micronodules to the bulk Fe-Mn (oxyhydr)oxides in the sediment can amount to 8%-50% (median: 18%). The other metals associated with Fe-Mn (oxyhydr)oxides seem to be hosted in Mn-microparticles, probably of a hydrogenetic origin. We estimate that the most promising site for REY-rich mud development contains (9.3 +/- 0.6) x 10(2) t, (1.6 +/- 0.1) x 10(3) t, and (2.8 +/- 0.2) x 10(2) t of leachable Co, Ni, and Mo, respectively, in 1 km(2) x 0-10 m below seafloor. These amounts account for 0.66 +/- 0.04%, 0.061 +/- 0.004%, and 0.097 +/- 0.007% of present annual global productions of Co, Ni, and Mo, respectively. The feasibility of extracting these metals as co-products during REY-rich mud development depends on the cost-efficiency of the recovery process, which ultimately depends on their market price in the near future.y

    DOI

    Scopus

    26
    Citation
    (Scopus)
  • Rare earth elements and yttrium (REY) variability with water depth in hydrogenetic ferromanganese crusts

    K. Azami, N. Hirano, S. Machida, K. Yasukawa, Y. Kato

    Chemical Geology   493   224 - 233  2018.08

    DOI

    Scopus

    23
    Citation
    (Scopus)

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Presentations

  • Geochemistry of hydrothermal ferromanganese oxides from Daigo-Kume Knoll in the Okinawa Trough

    JpGU Meeting 2023 

    Presentation date: 2023.05

  • Geochemistry of terrestrial ferromanganese nodules in soils as a potential paleoclimate indicator

    JpGU Meeting 2023 

    Presentation date: 2023.05

  • プチスポット火山による海洋地殻に対する熱水変質の影響

    浅見慶志朗, 町田嗣樹, 平野直人, 小木曽哲, 中村謙太郎, 加藤泰浩

    日本地球化学会 第69回年会 

    Presentation date: 2022.09

    Event date:
    2022.09
     
     
  • 独立成分分析に基づく低温熱水活動の推移

    浅見慶志朗, 町田嗣樹, 平野直人, 中村謙太郎, 安川和孝, 小木曽哲, 加藤泰浩

    日本地質学会 第129年学術大会 

    Presentation date: 2022.09

    Event date:
    2022.09
     
     
  • Geochemical features of Fe-Mn micronodules in deep-sea sediments around Minamitorishima Island: Potential for co-product metal extraction from REY-rich mud

    Yasukawa Kazutaka, Kino Satoshi, Azami Keishiro, Tanaka Erika, Mimura Kazuhide, Ohta Junichiro, Fujinaga Koichiro, Nakamura Kentaro, Kato Yasuhiro

    Presentation date: 2021.09

  • High-resolution dating of ferromanganese nodules around Minamitorishima Island based on osmium isotopic ratio

    Aoyagi Sota, Ohta Junichiro, Azami Keishiro, Nakamura Kentaro, Yasukawa Kazutaka, Nozaki Tatsuo, Machida Shiki, Kimura Jun-ichi, Kato Yasuhiro

    Presentation date: 2021.09

  • Geochemical features of Fe-Mn micronodules in deep-sea sediments around Minamitorishima Island: Implications for the formation process of extremely REY-rich mud

    Yasukawa Kazutaka, Kino Satoshi, Ohta Junichiro, Azami Keishiro, Tanaka Erika, Mimura Kazuhide, Fujinaga Koichiro, Nakamura Kentaro, Kato Yasuhiro

    Presentation date: 2021.09

  • Chemostratigraphy of ferromanganese crusts based on Independent Component Analysis

    Azami, K, Chang, Q, Kimura, J-I, Yasukawa, K, Nakamura, K, Kato, Y

    JpGU 2020 

    Presentation date: 2020.07

  • 鉄マンガンクラストの微細化学層序

    浅見慶志朗, 常青, 木村純一, 安川和孝, 中村謙太郎, 加藤泰浩

    日本地質学会第126年学術大会 

    Presentation date: 2019.09

  • High-resolution chemostratigraphy of Fe-Mn crusts

    Azami, K, Chang, Q, Kimura, J-I, Yasukawa, K, Nakamura, K, Kato, Y

    Goldschmidt 

    Presentation date: 2019.08

  • The first report of the evidence for hydrothermal activity in old oceanic plate

    Azami, K, Machida, S, Hirano, N, Kogiso, T, Kato, Y

    JpGU 2019 

    Presentation date: 2019.05

  • 鉄マンガンクラストのREE組成の水深依存性:海水中溶存REEの地球化学に対する示唆

    浅見慶志朗, 平野直人, 町田嗣樹, 安川和孝, 加藤泰浩

    日本地質学会第125年学術大会 

    Presentation date: 2018.12

  • Origin of Diagenetic Signal in Hydrogenetic Ferromanganese Crusts from Petit-spot Volcanoes

    Azami, K, Hirano, N, Takahashi, N, Watanabe, T

    AOGS (Asia Oceania Geoscience Society) 14th Annual Meeting 

    Presentation date: 2017.08

  • REE and Y Distribution in Deep Submarine Ferromanganese Crusts

    Azami, K, Hirano, N, Machida, S, Yasukawa, K, Kato, Y

    Goldschmidt 

    Presentation date: 2016.06

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Research Projects

  • Establishment of ferromanganese crust stratigraphy: from environment change to plate motion

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for JSPS Fellows

    Project Year :

    2018.04
    -
    2021.09
     

Misc

 

Syllabus

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Internal Special Research Projects

  • 全球的な銀循環の理解に向けた海洋銀同位体比の解明

    2022  

     View Summary

    海洋銀同位体比の解明に向け,本研究では高精度の銀同位体比測定手法の開発を試みた.マルチコレクター型の質量分析計を用いて銀標準試料の銀同位体比を測定したところ,分析機器中に銀が残存しやすい事が明らかになった.そこで,銀を高濃度で含む可能性のある試料との併用を防ぐために,分析機器の試料導入系を新たに購入し,銀同位体比測定専用とした.また,先行研究に倣い銀のカラム分離を実施し,銀が分離抽出出来る事を確認した.以上により,高精度の銀同位体比測定に必要な環境が概ね整った.