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

2020 Fiscal Year Final Research Report

• 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
• Keywords: 岩石磁気 / 三次元構造 / X線CT

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.

Free Research Field

古地磁気学

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。