TOHOKU UNIVERSITY Researchers

Research History 3

2026/04 - Present

Tohoku University　Graduate School of Science Department of Earth Science　Assistant Professor
2024/04 - 2026/04

Chiba Institute of Technology　Ocean Resources Research Center of Next Generation　Research Scientist
2022/04 - 2024/04

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

Education 3

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

2018/04 - 2022/03
Tohoku University　Graduate School of Science　Department of Earth Science

2016/04 - 2018/03
Tohoku University　Faculty of Science　Division of Earth and Planetary Materials Sciences

2014/04 - 2016/03

Professional Memberships 3

The Geochemical Society of Japan

2022/04 - Present
日本地質学会

2018/04 - Present
Japan Geoscience Union

2016/04 - Present

Research Interests 3

Submarine hydrothermal activity
Paleoenvironment
Ferromanganese crust / nodule

Research Areas 1

Natural sciences / Solid earth science / Geochemistry

Awards 4

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 14

Temporal changes in Angkorian ironmaking technology in Northern Cambodia during the 10th–14th centuries

Keishiro Azami, Etsuo Uchida, Aoi Mizumori, Yoshimitsu Kobayashi, Kaito Kuriyama, Tamaki Nakamura, Yasuhiro Kato

Scientific Reports　2025/12/12

DOI： 10.1038/s41598-025-27581-x 　

ISSN： 2045-2322
Petit-spot hydrothermal systems simulated: Fluid evolution, chemical fluxes, and chemoautotrophic habitability

Keishiro Azami, Kanta Koyama, Takuya Saito, Takazo Shibuya, Syogo Kinoshita, Shiki Machida, Yasuhiro Kato, Etsuo Uchida

Geochimica et Cosmochimica Acta　2025/11

DOI： 10.1016/j.gca.2025.09.008 　
Magma Differentiation, Phase Separation, and Volatiles: Factors Controlling Chemistry of Submarine Hydrothermal Fluids

Keishiro Azami

Geochemistry, Geophysics, Geosystems　2025/10

DOI： 10.1029/2025GC012636 　
Origin of ferromanganese deposits in the Jurassic to Cretaceous accretionary complex: Implications for the deep-sea environment around ocean anoxic events

Keishiro Azami, Koichiro Fujinaga, Naoto Hirano, Yasuhiro Kato

Ore Geology Reviews　2025/05/07

DOI： 10.1016/j.oregeorev.2025.106661 　

ISSN： 0169-1368
Study on Stone Blocks Used for Resthouses Along the Northwest Royal Road Connecting Angkor in Cambodia and Phimai in Thailand Based on On-Site Magnetic Susceptibility Measurements and Chemical Composition Analyses

Etsuo Uchida, Yoshimitsu Kobayashi, Aoi Mizumori, Kaito Kuriyama, Keishiro Azami

Heritage　8　(3)　106-106　2025/03/14
Publisher: MDPI AG
DOI： 10.3390/heritage8030106 　

eISSN： 2571-9408

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The purpose of this paper was to identify the types of stone used in the “Resthouses” along the Northwest Royal Road connecting Angkor in Cambodia and Phimai in Thailand and to determine their sources through magnetic susceptibility measurements and chemical composition analyses. Laterite was the primary building material for the “Resthouses”, except for Pr. Ku Sila Khan in Thailand. Pr. Ku Sila Khan, located at the northernmost point of the Northwest Royal Road, was primarily built with fine-grained red sandstone. Based on the magnetic susceptibility and the V, Sr, and As contents of the laterite, the following pairs of “Resthouses” were likely sourced from the same quarries: Pr. Sampov and Pr. Saman Teng, Pr. Kok Ac Chring and Pr. Kok Mon, Pr. Ta Muan and Pr. Thamo, and Pr. Ban Bu and Pr. Non Kong. Fine-grained red sandstone, white siliceous sandstone, red siliceous sandstone, and gray sandstone were used for the frame material of the openings. The Rb vs. Ti diagram and magnetic susceptibility measurements suggest that the fine-grained red sandstone and siliceous white sandstone used in the “Resthouses” in Thailand were likely sourced from the Khok Kruat Formation and the Phu Phan Formation, respectively. However, the red siliceous sandstone and white siliceous sandstone used in the “Resthouses” in Cambodia are presumed to have been sourced from the Sao Khua Formation and the Phra Wihan Formation, respectively. Gray sandstone from the Phu Kradung Formation was uniquely used in the frame material of the openings of Pr. Sampov and Pr. Kok Mon in Cambodia. In conclusion, the sandstone used in the door and window frames of the “Resthouses” appears to have been determined by the surrounding geology. Laterite was used as the primary building material for the “Resthouses” along the Northwest Royal Road, whereas valuable sandstone was used for those along the East Royal Road. This suggests that the Northwest Royal Road was of lesser importance compared to the East Royal Road.
A study on the possible construction order of the temples in Mahendraparvata on the summit of Kulen Mountain, Cambodia, based on brick and sandstone materials

Etsuo Uchida, Aoi Mizumori, Kaito Kuriyama, Keishiro Azami

npj Heritage Science　13　(1)　2025/02/19
Publisher: Springer Science and Business Media LLC
DOI： 10.1038/s40494-025-01576-3 　

eISSN： 3059-3220
Formation of hydrothermal ferromanganese oxides in the Daini-Nishi-Yamato Seamount, Sea of Japan: Do they really contain critical-metal particles?

Keishiro Azami, Tokio Doshita, Kanta Koyama, Shiki Machida, Kentaro Nakamura, Yasuhiro Kato, Etsuo Uchida

Ore Geology Reviews　2024/09

DOI： 10.1016/j.oregeorev.2024.106202 　
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
Publisher: Elsevier {BV}
DOI： 10.1016/j.margeo.2023.107117 　

ISSN： 0025-3227
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)　2023/06/01
Publisher: Springer Science and Business Media LLC
DOI： 10.1038/s43247-023-00832-3 　

eISSN： 2662-4435

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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.
Geochemistry of ferromanganese nodules in the soil of Okinawa Island, Japan: Paleoclimatic implications and discrimination scheme of the nodule origins

Kazutaka Yasukawa, Yasuhiro Kato

Journal of Asian Earth Sciences: X　8　100127-100127　2022/12
Publisher: Elsevier {BV}
DOI： 10.1016/j.jaesx.2022.100127 　

ISSN： 2590-0560
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　2022/07/27
Publisher: MDPI AG
DOI： 10.3390/min12080943 　

eISSN： 2075-163X

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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.
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　2021/03/06
Publisher: {MDPI} {AG}
DOI： 10.3390/min11030270 　

ISSN： 2075-163X

eISSN： 2075-163X

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<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>
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

DOI： 10.1016/j.oregeorev.2020.103805 　

ISSN： 0169-1368

eISSN： 1872-7360
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
Publisher: Elsevier {BV}
DOI： 10.1016/j.chemgeo.2018.05.045

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Misc. 7

X-ray diffraction intensities of the hydrothermal ferromanganese oxides obtained from a petit-spot volcano

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

figshare　2023

DOI： 10.6084/m9.figshare.22559851 　
Process of hydrothermal activity estimated from independent component analysis

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, 加藤泰浩

日本地質学会学術大会(Web)　129th　2022

ISSN： 2187-6665
Elucidating the timing and characteristics of a growth hiatus of the Minamitorishima ferromanganese nodules based on age dating through Os isotope stratigraphy and elemental mapping using μXRF

青柳颯汰, 大田隼一郎, 大田隼一郎, 矢野萌生, 見邨和英, 浅見慶志朗, 野崎達生, 野崎達生, 野崎達生, 野崎達生, 中村謙太郎, 中村謙太郎, 安川和孝, 町田嗣樹, 加藤泰浩, 加藤泰浩

日本地質学会学術大会(Web)　129th　2022

ISSN： 2187-6665
「よこすか」「しんかい6500」YK18-08, YK19-05S研究航海の概要 : 南鳥島海域プチスポット火山の「しんかい6500」潜航研究速報—Quick report of the R/V Yokosuka and Shinkai 6500 YK16-01, YK19-05S Cruise : Preliminary 6K dive report on "petit-spot" volcano around Minamitorishima Island

石井輝秋, 金子誠, 町田嗣樹, 金子純二, 浅見慶志朗, 平野直人, 秋澤紀克, 松本亜沙子, 田中えりか, 油谷拓, 進士優朱琿, 小長谷智哉, 長谷川貴章, 木野聡志, 大嶋ちひろ, 坂本衣里, 井和丸光

公益財団法人深田地質研究所年報 = Annual report　(21)　103-126　2020
Publisher: 東京 : 深田地質研究所
Dredge cruise on petit-spot volcanoes and IODP drilling earth science-Great discovery: explosion crater (Maar) in the abyssal plane, off Tohoku-

石井輝秋, 金子誠, 平野直人, 町田嗣樹, 松本亜沙子, 秋澤紀克, 佐藤勇輝, 油谷拓, 油谷拓, 浅見慶志朗, 桂木悠希, 坂井俊太, 中野幸彦, 松崎琢也

日本地球惑星科学連合大会予稿集(Web)　2020　2020
アセノスフェアから速やかに上昇したプチスポット「直プチ」調査

平野直人, 町田嗣樹, 油谷拓, 油谷拓, 秋澤紀克, 浅見慶志朗, 佐藤勇輝, 桂木悠希, 坂井俊太, 中野幸彦, 松本亜沙子, 金子誠, 中西正男, 石井輝秋

ブルーアースサイエンス・テク要旨集　2019　2019
「新青丸」KS-18-9航海,プチスポット火山ドレッジ研究速報と展望 : 歴史的大発見 : 東北沖太平洋超深海底の爆裂火口(マール)—Quick report of the R/V Shinsei-maru KS-18-9 dredge cruise on petit-spot volcanoes : Historical great discovery : explosion crater (Maar) in the Pacific abyssal plane, off Tohoku

石井輝秋, 金子誠, 平野直人, 町田嗣樹, 松本亜沙子, 秋澤紀克, 佐藤勇輝, 油谷拓, 浅見慶志朗, 桂木悠希, 坂井俊太, 中野幸彦, 松崎琢也

公益財団法人深田地質研究所年報 = Annual report　(20)　105-128　2019
Publisher: 深田地質研究所

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Presentations 14

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

JpGU Meeting 2023　2023/05
Geochemistry of terrestrial ferromanganese nodules in soils as a potential paleoclimate indicator

JpGU Meeting 2023　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　2022/09/07
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　2022/09/05
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

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

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

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　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　2019/09
High-resolution chemostratigraphy of Fe-Mn crusts

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

Goldschmidt　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　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　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　2017/08
REE and Y Distribution in Deep Submarine Ferromanganese Crusts

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

Goldschmidt　2016/06

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Research Projects 6

海底鉱物資源生成史の解明による地球表層システム変動の新たな描像

加藤泰浩, 安川和孝, 桑原佑典, 岩森光, 矢野萌生, 浅見慶志朗, 見邨和英, 野崎達生

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 基盤研究(S)

Institution: 東京大学

2025/04 - 2030/03
Co-evolution of REE-rich mud and Earth system decoded from the Phanerozoic accretionary complexes and deep-sea sediments of the northern and southern hemispheres

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (A)

Institution: The University of Tokyo

2025/04/01 - 2029/03/31
鉄マンガンクラストのLu-Hf絶対年代測定法の開発：真に全球的な地球史解読を目指して

浅見慶志朗

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 若手研究

Institution: 千葉工業大学

2025/04/01 - 2028/03/31
Construction of a new view of the Earth that integrates the environment, life and resources based on the understanding of the phenomenon of asteroid impacts in oceans

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (S)

Institution: The University of Tokyo

2023/04/12 - 2028/03/31
Petrological study on stone materials and their deterioration in the Khmer monuments including the Angkor monuments

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Fund for the Promotion of Joint International Research (Fostering Joint International Research (B))

Institution: Waseda University

2019/10/07 - 2025/03/31
Establishment of ferromanganese crust stratigraphy: from environment change to plate motion

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for JSPS Fellows

Category: Grant-in-Aid for JSPS Fellows

Institution: The University of Tokyo

2018/04/25 - 2021/03/31

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