Characterizing 3D texture of magnetite nanorods to read geomagnetic paleointensity records

• Project/Area Number: 17H04855
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Single-year Grants
• Research Field: Solid earth and planetary physics
• Research Institution: Japan Agency for Marine-Earth Science and Technology
• Principal Investigator: Usui Yoichi 国立研究開発法人海洋研究開発機構, 海域地震火山部門(火山・地球内部研究センター), 研究員 (20609862)
• Project Period (FY): 2017-04-01 – 2021-03-31
• Project Status: Completed (Fiscal Year 2020)
• Budget Amount: ¥25,480,000 (Direct Cost: ¥19,600,000、Indirect Cost: ¥5,880,000); Fiscal Year 2020: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000); Fiscal Year 2019: ¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000); Fiscal Year 2018: ¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000); Fiscal Year 2017: ¥15,730,000 (Direct Cost: ¥12,100,000、Indirect Cost: ¥3,630,000)
• Keywords: 岩石磁気 / 三次元構造 / X線CT / マイクロ磁気シミュレーション / 古地磁気層序 / 南鳥島 / 磁性細菌 / 古地磁気 / 地球電磁気 / 磁気記録 / 地球史 / 磁鉄鉱 / インクルージョン / 3次元構造 / 3次元構造観察

Outline of Final Research Achievements

I examine three-dimensional geometry of exsolved magnetite in plagioclase crystals. I measured and analyzed the distributions of elongation directions and particle volumes of magnetite using laser-confocal microscopy and X-ray CT at SPring-8. When I assumed uniform magnetization of each grain (single magnetic domain state), the estimated magnetization efficiency was higher than the actual values. Computer simulations indicated that many exsolved magnetite is of vortex magnetic state.

Academic Significance and Societal Importance of the Research Achievements

マグマの冷却固化に伴う磁気記録の獲得は最も基本的な古地磁気記録であり、過去の地球惑星磁場を知る基礎である。粒子形状の分布を実測することで、この磁気記録の獲得効率を磁気測定とは独立に推定する道筋をつけたことは学術的価値が大きい。非破壊三次元測定の磁気測定への応用は、深海や宇宙の貴重な試料への応用も考えられる。

Research Products

• [Int'l Joint Research] リーズ大学(英国)
• [Int'l Joint Research] ベオグラード大学(セルビア)
• [Int'l Joint Research] リーズ大学(英国)
• [Int'l Joint Research] ソフィア自然史博物館(ブルガリア)
• [Journal Article] Magnetostratigraphic evidence for post-depositional distortion of osmium isotopic records in pelagic clay and its implications for mineral flux estimates (2021)
  • Author(s): Usui Yoichi、Yamazaki Toshitsugu
  • Journal Title: Earth, Planets and Space Volume: 73 Issue: 1 Pages: 1-9
  • DOI: 10.1186/s40623-020-01338-4
  • Peer Reviewed / Open Access
• [Journal Article] Unmixing biogenic and terrigenous magnetic mineral components in red clay of the Pacific Ocean using principal component analyses of first-order reversal curve diagrams and paleoenvironmental implications (2020)
  • Author(s): Yamazaki Toshitsugu、Fu Wei、Shimono Takaya、Usui Yoichi
  • Journal Title: Earth, Planets and Space Volume: 72 Issue: 1 Pages: 1-15
  • DOI: 10.1186/s40623-020-01248-5
  • Peer Reviewed / Open Access
• [Journal Article] Identification of paleomagnetic remanence carriers in ca. 3.47 Ga dacite from the Duffer Formation, the Pilbara Craton (2020)
  • Author(s): Usui, Y., Saitoh, M., Tani, K., Nishizawa, M., Shibuya, T., Kato, C., Okumura, T. and Kashiwabara, T.
  • Journal Title: Physics of the Earth and Planetary Interiors Volume: 299 Pages: 106411-106411
  • DOI: 10.1016/j.pepi.2019.106411
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Inverse Magnetic Susceptibility Fabrics in Pelagic Sediment: Implications for Magnetofossil Abundance and Alignment (2019)
  • Author(s): Yoichi Usui, Toshitsugu Yamazaki, Toshitaka Oka, Yuho Kumagai
  • Journal Title: Journal of Geophysical Research: Solid Earth Volume: 124 Issue: 11 Pages: 10672-10686
  • DOI: 10.1029/2019jb018128
  • Peer Reviewed
• [Journal Article] Rock magnetism of quartz and feldspars chemically separated from pelagic red clay: a new approach to provenance study (2018)
  • Author(s): Yoichi Usui, Takaya Shimono, Toshitsugu Yamazaki
  • Journal Title: Earth, Planets and Space Volume: 70 Issue: 1 Pages: 153-153
  • DOI: 10.1186/s40623-018-0918-1
  • Peer Reviewed / Open Access
• [Journal Article] Changing Abundance of Magnetofossil Morphologies in Pelagic Red Clay Around Minamitorishima, Western North Pacific (2017)
  • Author(s): Usui Yoichi、Yamazaki Toshitsugu、Saitoh Masafumi
  • Journal Title: Geochemistry Geophysics Geosystems Volume: 18 Issue: 12 Pages: 4558-4572
  • DOI: 10.1002/2017gc007127
  • Peer Reviewed / Open Access
• [Presentation] X線CTによる遠洋性粘土中の堆積構造および生物源アパタイト分布の観察 (2019)
  • Author(s): 臼井洋一、飯島耕一、町山 栄章、市山 祐司、田中 えりか、藤永 公一郎、安川 和孝
  • Organizer: 日本地球惑星科学連合2019年大会
• [Presentation] 帯磁率異方性による赤色泥中の生物源磁鉄鉱の定向配列推定 (2019)
  • Author(s): 臼井 洋一 、山崎 俊嗣 、岡 壽崇 、熊谷 祐穂
  • Organizer: 地球電磁気・地球惑星圏学会 第１４６回総会及び講演会
• [Presentation] Paleomagnetism of the Cherni Vrah massif, Balkan-Carpathian ophiolite: preliminary results (2018)
  • Author(s): Yoichi Usui, Ivan Savov
  • Organizer: 16th Castle Meeting - New Trends on Paleo, Rock and Environmental Magnetism
  • Int'l Joint Research
• [Presentation] Changing abundance of magnetofossil morphologies in pelagic red clay (2018)
  • Author(s): Yoichi Usui, Toshitsugu Yamazaki, Masafumi Saitoh
  • Organizer: 2018 American Geophysical Union Fall Meeting
  • Int'l Joint Research
• [Presentation] Nondestructive microscale texture observation of exsolved magnetite in silicate using laser confocal microscopy (2018)
  • Author(s): 臼井洋一
  • Organizer: European Geosciences Union General Assembly 2018
  • Int'l Joint Research