Solution chemistry dependency on fluid-rock reactions within subduction zones and its hydrological responses

• Project Area: Science of Slow to Fast Earthquakes
• Project/Area Number: 22H05295
• Research Category: Grant-in-Aid for Transformative Research Areas (A)
• Allocation Type: Single-year Grants
• Review Section: Transformative Research Areas, Section (II)
• Research Institution: Tohoku University
• Principal Investigator: 岡本 敦 東北大学, 環境科学研究科, 教授 (40422092)
• Project Period (FY): 2022-06-16 – 2024-03-31
• Project Status: Completed (Fiscal Year 2023)
• Budget Amount: ¥9,880,000 (Direct Cost: ¥7,600,000、Indirect Cost: ¥2,280,000); Fiscal Year 2023: ¥4,940,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥1,140,000); Fiscal Year 2022: ¥4,940,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥1,140,000)
• Keywords: 沈み込み帯 / 地殻ーマントル境界 / 緑泥石化 / シリカ析出 / 水熱実験 / 交代作用 / 流体 / シリカ / 溶液組成 / 滑石 / 二酸化炭素 / 岩石ー流体反応 / 水熱反応実験 / スロー地震 / シーリング

Outline of Research at the Start

プレートの沈み込み境界の流体は多様な元素をイオンや錯体として含んでおり，鉱物の溶解・析出を引き起こす。しかし，岩石―流体反応が断層の水理学的・力学的特性や地震発生過程に与える影響はまだよくわかっていない。本課題では，スロー地震との関連が指摘される高圧変成帯の特徴的な岩石－流体反応（鉱物脈形成，交代作用）に着目し，流通式水熱反応実験により，元素移動や空隙構造・固体体積の変化を伴う反応進行の素過程とミクロな構造形成，それによる水理学的挙動の変化を明らかにする。また，鉱物―溶液平衡計算を軸に，天然組織と実験を結びつけ，沈み込み帯の地震現象に対する流体の化学的な役割について検討する。

Outline of Annual Research Achievements

三波川帯四国中央部の富郷蛇紋岩体と泥質片岩の境界の物質移動解析により、(1)泥質片岩では緑泥石化が起こり、蛇紋岩においては破砕を伴いながら滑石脈が発達すること、また、(2) 緑泥石は元の組織を残しながら反応が進むのに対して、変形は滑石レイヤーに集中することなどを明らかにした。このMgとSiの相対的な移動については他の変成帯についてもその系統性を調べ、２編の論文として公表した(Oyanagi, Okamoto et al. 2023, Contrib. Mineral. Petrol.; Okamoto and Oyanagi, 2023, Prog. Earth. Planet. Sci.)。また、CO2を導入すると滑石生成が大きく促進されることを平衡溶液計算と実験から明らかにしつつあり、溶液組成にコントロールされる交代作用によってプレート境界岩石のレオロジーが大きく変化することを示唆している。反応―透水反応装置を用いた実験では、短期間で反応がするMgOを用いた実験を行い、反応によって差応力が生じ、変形、亀裂形成、浸透率の増大が起こることを見出した。
高シリカ溶液を用いた析出実験では、X線CTとかソードルミネッセンス(CL)を用いた詳細な析出物と表面の観察を進めた。K, Na, Alなどの不純物が溶液の中に存在していることに起因して、同一の出発溶液を流しているにも関わらず石英中にCLの累帯構造が形成されることを明らかにし、これは、実験中の微小な圧力振動を記録している可能性もある。また、石英表面の結晶成長、核形成＋成長、アモルファスシリカなどの準安定鉱物の形成によって、基盤表面の荒さや析出物の分布が変わることを明らかにした。より制御した実験が必要であるが、シリカ析出による浸透率の低下も観察され、析出の条件による断層や亀裂の浸透率と強度に大きな変化を与えることが示唆された。

Research Progress Status

令和5年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

令和5年度が最終年度であるため、記入しない。

Research Products

• [Int'l Joint Research] ユトレヒト大学(オランダ)
• [Int'l Joint Research] ミネソタ大学(米国)
• [Int'l Joint Research] ユトレヒト大学(オランダ)
• [Int'l Joint Research] ミネソタ大学(米国)
• [Journal Article] Porosity generation via spatially uncoupled dissolution precipitation during plagioclase replacement in quartz undersaturated fluids (2024)
  • Author(s): Astin Nurdiana, Atsushi Okamoto, Masaoki Uno, Noriyoshi Tsuchiya
  • Journal Title: Contributions to Mineralogy and Petrology Volume: 179 Issue: 1 Pages: 10-10
  • DOI: 10.1007/s00410-023-02088-8
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Ultramafic rocks from the Sanbagawa belt: Records of mantle wedge processes (2024)
  • Author(s): Atsushi Okamoto, Takayoshi Nagaya, Shunsuke Endo, Tomoyuki Mizukami
  • Journal Title: Elements Volume: 20 Pages: 83-88
  • Peer Reviewed
• [Journal Article] Geological records of transient fluid drainage into the shallow mantle wedge (2023)
  • Author(s): Kazuki Yoshida, Ryosuke Oyanagi, Masao Kimura, Oliver Plumper, Mayuko Fukuyama, and Atsushi Okamoto
  • Journal Title: Sci. Adv. Volume: 9 Issue: 14 Pages: 6674-6674
  • DOI: 10.1126/sciadv.ade6674
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Super-resolution of X-ray CT images of rock samples by sparse representation: applications to the complex texture of serpentine (2023)
  • Author(s): Omori, T., Suzuki, S., Michibayashi, K., Okamoto, A.
  • Journal Title: Scientific Reports Volume: 13 Issue: 1 Pages: 6648-6648
  • DOI: 10.1038/s41598-023-33503-6
  • Peer Reviewed / Open Access
• [Journal Article] Metasomatism at a metapelite-ultramafic rock contact at the subduction interface: Insights into mass transfer and fluid flow at the mantle wedge corner (2023)
  • Author(s): Oyanagi Ryosuke、Uno Masaoki、Okamoto Atsushi
  • Journal Title: Contributions to Mineralogy and Petrology Volume: 178 Issue: 5 Pages: 27-27
  • DOI: 10.1007/s00410-023-02011-1
  • Peer Reviewed / Open Access
• [Journal Article] Mantle hydration initiated by Ca metasomatism in a subduction zone: An example from the Chandman meta-peridotite, western Mongolia (2023)
  • Author(s): Otgonbayar Dandar, Atsushi Okamoto, Masaoki Uno, Noriyoshi Tsuchiya
  • Journal Title: Lithos Volume: 452-453 Pages: 107212-107212
  • DOI: 10.1016/j.lithos.2023.107212
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Si- versus Mg-metasomatism at the crust-mantle interface: insights from experiments, natural observations and geochemical modeling (2023)
  • Author(s): Okamoto Atsushi、Oyanagi Ryosuke
  • Journal Title: Progress in Earth and Planetary Science Volume: 10 (39) Issue: 1 Pages: 39-39
  • DOI: 10.1186/s40645-023-00568-w
  • Peer Reviewed / Open Access
• [Journal Article] Role of mantle carbonation in trench outer‐rise region in the global carbon cycle (2023)
  • Author(s): Katayama, I., Okazaki, K., & Okamoto, A
  • Journal Title: Island Arc Volume: 32 Issue: 1
  • DOI: 10.1111/iar.12499
  • Peer Reviewed
• [Journal Article] Effects of hydrothermal alteration on shear localization and weakening in the mantle lithosphere (2023)
  • Author(s): Semba Maki、Hirauchi Ken-ichi、Ohuchi Tomohiro、Okamoto Atsushi、Kouketsu Yui
  • Journal Title: Tectonophysics Volume: 868 Pages: 230081-230081
  • DOI: 10.1016/j.tecto.2023.230081
  • Peer Reviewed
• [Journal Article] Multiphase-solid fluid inclusions in HP-LT eclogite facies rock (Zavkhan Terrane, Western Mongolia): evidence for the evolution from saline to hypersaline fluids during metamorphism in subduction zone (2023)
  • Author(s): Bayarbold Manzshir、Okamoto Atsushi、Uno Masaoki、Yoshida Kenta、Kotov Alexey、Agroli Geri、Dandar Otgonbayar、Niwa Yasuhiro、Kimura Masao、Tsuchiya Noriyoshi
  • Journal Title: Contributions to Mineralogy and Petrology Volume: 178 Issue: 11 Pages: 85-85
  • DOI: 10.1007/s00410-023-02055-3
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Continental arc-derived eclogite in the Zavkhan Terrane, western Mongolia: Implications for the suture zone in the northern part of the Central Asian Orogenic Belt (2022)
  • Author(s): Bayarbold Manzshir、Okamoto Atsushi、Dandar Otgonbayar、Uno Masaoki、Tsuchiya Noriyoshi
  • Journal Title: Journal of Asian Earth Sciences Volume: 229 Pages: 105150-105150
  • DOI: 10.1016/j.jseaes.2022.105150
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Dehydration of brucite + antigorite under mantle wedge conditions: insights from the direct comparison of microstructures before and after experiments (2022)
  • Author(s): Takayoshi Nagaya, Atsushi Okamoto, Masanori Kido, Jun Muto, Simon R. Wallis
  • Journal Title: Contributions to Mineralogy and Petrology Volume: 177 Issue: 9 Pages: 87-87
  • DOI: 10.1007/s00410-022-01956-z
  • Peer Reviewed / Open Access
• [Journal Article] Development of Open Transport of Aqueous Fluid from Pegmatite Revealed by Trace Elements in Garnet (2022)
  • Author(s): Nurdiana Astin、Okamoto Atsushi、Uno Masaoki、Tsuchiya Noriyoshi
  • Journal Title: Geofluids Volume: 2022 Pages: 1-21
  • DOI: 10.1155/2022/8786250
  • Peer Reviewed / Open Access
• [Journal Article] 沈み込み帯の含水マントルの炭酸塩化作用―自己促進的な反応―破壊―カップリング現象― (2022)
  • Author(s): 岡本敦
  • Journal Title: 月刊地球 Volume: 44 Pages: 566-572
• [Presentation] Plagioclase replacement by Epidote during hydrothermal alteration of gabbro from the Khantaishir ophiolite, western Mongolia (2023)
  • Author(s): Otgonbayar Dandar, Atsushi Okamoto, Masaoki Uno, Noriyoshi Tsuchiya
  • Organizer: 日本地球惑星科学連合（JpGU）
• [Presentation] Formation of the Silica Sealing Layer Above Supercritical Geothermal Reservoirs (2023)
  • Author(s): Edward L. Vinis, Jumpei Sugioka, Atsushi Okamoto, Flow-Through Experiments on the
  • Organizer: 日本地球惑星科学連合（JpGU）
• [Presentation] 沈み込み帯のCO2流体が引き起こす地殻-マントル境界のTalc生成に関する実験的制約 (2023)
  • Author(s): 沖野 峻也、岡本 敦、喜多 倖子、澤 燦道、武藤 潤
  • Organizer: 日本地球惑星科学連合（JpGU）
• [Presentation] Effects of fluid chemistry on metasomatic reactions at slab-mantle interfaces within the subduction zones: Significance of Si vs. Mg and CO2 (2023)
  • Author(s): Atsushi Okamoto, Ryosuke Oyanagi, Shunya Okino
  • Organizer: 日本地球惑星科学連合（JpGU）
• [Presentation] Two different zoned garnets in the Khungui eclogite induced by replacement of Ti-bearing minerals during P-T evolution (2023)
  • Author(s): Bayarbold Manzshir, Atsushi Okamoto, Masaoki Uno, Dandar Otgonbayar, Noriyoshi Tsuchiya
  • Organizer: 日本地球惑星科学連合（JpGU）
• [Presentation] Exploration of the Formation of Silica-Sealing Layers Above Supercritical Geothermal Reservoirs Using Flow-Through Experiments (2023)
  • Author(s): Edward L. Vinis, Jumpei Sugioka, Atsushi Okamoto
  • Organizer: Earth, Sea and Sky : International Joint Graduate Program Workshop in Earth and Environmental Sciences
  • Int'l Joint Research
• [Presentation] Mass transport and metasomatic reactions at crust-mantle interfaces induced by CHO fluids (2023)
  • Author(s): Atsushi Okamoto
  • Organizer: Serpentine days
  • Int'l Joint Research / Invited
• [Presentation] 海洋リソスフェアの変質作用：元素移動とエネルギー生成について (2023)
  • Author(s): 岡本敦
  • Organizer: 海底拡大系観測から探る地球内部と表層のリンケージ ～InterRidge-Japan研究集会～
  • Invited
• [Presentation] Dynamics of breccia formation underpin the series of co-seismic slip (EQ), elevated fluid activity, and mineralization (2023)
  • Author(s): Geri Agroli, Atsushi Okamoto, Masaoki Uno,Noriyoshi Tsuchiya
  • Organizer: Water-Rock Interaction WRI-17
  • Int'l Joint Research
• [Presentation] emporal variation of silica precipitation along seismogenic subduction zones (2023)
  • Author(s): Hanae Saishu, Makoto Otsubo, Atsushi Okamoto, Kohtaro Ujiie
  • Organizer: Water-Rock Interaction WRI-17
  • Int'l Joint Research
• [Presentation] Experimental constraints on talc formation at slab-mantle interface induced by CO2 fluids within the subduction zones (2023)
  • Author(s): Shunya Okino, Atsushi Okamoto, Yukiko Kita, Jun Muto
  • Organizer: Water-Rock Interaction WRI-17
  • Int'l Joint Research
• [Presentation] Shape evolution of micro-scale porosities during feldspar alteration and its implications to supercritical geothermal reservoir (2023)
  • Author(s): Atsushi Okamoto, Shuhei Fujiwara, Masaoki Uno, Kazuki Yoshida, Tomohiro Ishii, Masao Kimura, Noriyoshi Tsuchiya
  • Organizer: Water-Rock Interaction WRI-17
  • Int'l Joint Research
• [Presentation] Formation of bi-pyramidal quartz in response to density drop of hydrothermal fluids (2023)
  • Author(s): Atsushi Okamoto, Junpei Sugioka, Ryoichi Yamada
  • Organizer: Water-Rock Interaction WRI-17
  • Int'l Joint Research
• [Presentation] Multiphase-solid fluid inclusion in eclogitic garnets of the Melange zone, western Mongolia (2023)
  • Author(s): Bayarbold Manzshir, Atsushi Okamoto, Masaoki Uno, Kenta Yoshida, Alexey Kotov, Geri Agroli, Otgonbayar Dandar, Yasuhiro Niwa, Masao Kimura, Noriyoshi Tsuchiya
  • Organizer: Water-Rock Interaction WRI-17
  • Int'l Joint Research
• [Presentation] Progressive release of trace elements from subducting slab and enrichment in the overlying crust: Trace element budget at the plate boundary elucidated from the Sanbagawa metamorphic belt, Japan (2023)
  • Author(s): Satoshi Matsuno, Masaoki Uno, Atsushi Okamoto
  • Organizer: Water-Rock Interaction WRI-17
  • Int'l Joint Research
• [Presentation] Super-resolution of X-ray CT images of rock samples by sparse representation: applications to the complex texture of serpentinite (2023)
  • Author(s): Toshiaki Omori, Shoi Suzuki, Katsuyoshi Michibayashi, Atsushi Okamoto
  • Organizer: Water-Rock Interaction WRI-17
  • Int'l Joint Research
• [Presentation] Mantle wedge serpentinization in subduction zones: Effects of reaction-induced and tectonic stresses on fracture propagation and fluid flow (2023)
  • Author(s): Jeremiah McElwee, Ikuko Wada, Kazuki Yoshida, Hiroyuki Shimizu, Atsushi Okamoto
  • Organizer: Water-Rock Interaction WRI-17
  • Int'l Joint Research
• [Presentation] Exploration of the Silica-Sealing Layer Above Supercritical Geothermal Reservoirs Using Flow-Through Experiments (2023)
  • Author(s): Edward L. Vinis, Jumpei Sugioka, Atsushi Okamoto
  • Organizer: Water-Rock Interaction WRI-17
  • Int'l Joint Research
• [Presentation] マントル岩石における二酸化炭素固定ーそのメカニズムと地球科学的重要性ー (2023)
  • Author(s): 岡本敦
  • Organizer: 第６６回粘土科学討論会
  • Invited
• [Presentation] Fluid flow and fluid-rock interactions at shallow mantle wedge (2023)
  • Author(s): Atsushi Okamoto, Kazuki Yoshida, Shunya Okino, Ryosuke Oyanagi
  • Organizer: International Joint Wrokshop on Slow-to-Fast Earthquakes
  • Int'l Joint Research / Invited
• [Presentation] マントルウェッジのCO2交代作用による滑石生成プロセスとすべり挙動に対する実験的制約 (2023)
  • Author(s): 沖野 峻也、岡本 敦、喜多 倖子、澤 燦道、武藤 潤
  • Organizer: 日本地質学会（GSJ）第130年学術大会
• [Presentation] Investigating the Formation of the Silica-Sealing Layer Above Supercritical Geothermal Reservoirs Using Flow-Through Experiments (2023)
  • Author(s): Edward L. Vinis, Atsushi Okamoto
  • Organizer: 日本地熱学会
• [Presentation] 沈み込み帯深部の地殻-マントル境界におけるCO2流体の重要性と反応 の多様性がもたらすレオロジーへの実験的推察 (2023)
  • Author(s): 沖野 峻也、岡本 敦、喜多 倖子、澤 燦道、武藤 潤
  • Organizer: 変成岩などシンポジウム
• [Presentation] 沈み込み帯の流体で形成されたアンチゴライト脈に記録された過渡的な流体移動 (2022)
  • Author(s): 吉田 一貴、大柳 良介、木村 正雄、 Plumper Oliver、福山 繭子、岡本 敦
  • Organizer: 日本地質学会（GSJ）
• [Presentation] マントルー地殻境界におけるマグネシウムとシリカの相対的移動度 (2022)
  • Author(s): 岡本敦、吉田一貴、大柳良介
  • Organizer: 日本地質学会（GSJ）
• [Presentation] 黒鉱鉱床における両錐石英の形成メカニズム (2022)
  • Author(s): 杉岡純平、山田亮一、岡本敦
  • Organizer: 日本鉱物科学会（JAMS）
• [Presentation] 超臨界条件および飽和蒸気圧条件下におけるシリカ粒子の形成 (2022)
  • Author(s): 杉岡純平、山田亮一、岡本敦
  • Organizer: 日本地熱学会（GRSJ）
• [Presentation] Temperature Estimation Profiles of Contact Metamorphism and Heat Source Granite in Kakkonda Geothermal Field Using Deep Hole Drilling Cuttings (2022)
  • Author(s): Nizar Nurdin, Geri Agroli, Atsushi Okamoto, Masaoki Uno, Noriyoshi Tsuchiya
  • Organizer: 日本地熱学会（GRSJ）
• [Presentation] 葛根田地熱地域の熱履歴から示唆される超臨界貯留槽の熱輸送メカニズム (2022)
  • Author(s): 宇野正起，岡本敦，土屋範芳，赤塚貴史，松本和人，佐々木惇
  • Organizer: 日本地熱学会（GRSJ）
• [Presentation] Formation and transport of silica particles in supercritical and vapor conditions and its implications to fracture sealing (2022)
  • Author(s): Atsushi Okamoto, Junpei Sugioka, Takamasa Niibe
  • Organizer: International Joint Workshop on Slow-to-Fast Earthquakes
  • Int'l Joint Research
• [Presentation] Transient fluid infiltration in the shallow mantle wedge recorded in the Oman Ophiolite (2022)
  • Author(s): Kazuki Yoshida, Ryosuke Oyanagi, Masao Kimura, Oliver Plumper, Mayuko Fukuyama, Atsushi Okamoto
  • Organizer: International Joint Workshop on Slow-to-Fast Earthquakes
  • Int'l Joint Research
• [Presentation] Precise evaluation of element transfer in metabasalt with sample-based predictive uncertainty estimation using machine-learning (2022)
  • Author(s): Satoshi Matsuno, Masaoki Uno, Atsushi Okamoto
  • Organizer: International Joint Workshop on Slow-to-Fast Earthquakes
  • Int'l Joint Research
• [Presentation] 長石の変質による3次元空隙構造の特徴抽出 (2022)
  • Author(s): 岡本敦，藤原秀平、吉田一貴、宇野正起、石井友弘、木村正雄
  • Organizer: 変成岩などシンポジウム (Metamorphic rock symposium)
• [Presentation] XRDによる変成履歴の定量化:リートベルト解析の検証と沈み込み帯岩相境界への適用 (2022)
  • Author(s): 松野哲士，宇野正起，平野伸夫, 岡本敦
  • Organizer: 変成岩などシンポジウム (Metamorphic rock symposium)
• [Presentation] Serpentinization in a stressed mantle wedge corner (2022)
  • Author(s): Jeremiah McElwee, Ikuko Wada, Kazuki Yoshida, Hiroyuki Shimizu, Atsushi Okamoto
  • Organizer: American Geophysical Union（AGU）
  • Int'l Joint Research
• [Presentation] Elucidating parameters governing elemental transfer during seafloor alteration: Application of machine-learning based Protolith Reconstruction Model (PRM) to seafloor altered basalt, the South and Northwest Pacific regions. (2022)
  • Author(s): Satoshi Matsuno, Masaoki Uno, Atsushi Okamoto
  • Organizer: American Geophysical Union（AGU）
  • Int'l Joint Research
• [Presentation] 沈み込み帯のCO2流体が引き起こす地殻ーマントル境界のTalc生成に関する実験的研究 (2022)
  • Author(s): 沖野峻也、岡本敦、喜多倖子、武藤潤
  • Organizer: 変成岩などシンポジウム (Metamorphic rock symposium)
• [Remarks] 東北大学 岡本・宇野研究室
  • URL: https://geo.kankyo.tohoku.ac.jp/gmel2/