日本地球惑星科学連合2022年大会

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[J] 口頭発表

セッション記号 S (固体地球科学) » S-CG 固体地球科学複合領域・一般

[S-CG52] 変動帯ダイナミクス

2022年5月27日(金) 09:00 〜 10:30 301A (幕張メッセ国際会議場)

コンビーナ:深畑 幸俊(京都大学防災研究所)、コンビーナ:岩森 光(東京大学・地震研究所)、大橋 聖和(山口大学大学院創成科学研究科)、座長:岩森 光(東京大学・地震研究所)、宇野 正起(東北大学大学院環境科学研究科)

10:00 〜 10:15

[SCG52-05] Evolution of quartz microstructure during dynamic recrystallisation

*Thomas Jing Yi Yeo1,2Norio Shigematsu2Takuma Katori3 (1.Department of Earth and Planetary Science, Graduate School of Science, Tokyo University 、2.Research Institute of Earthquake and Volcano Geology, Geological Survey of Japan, National Institute of Advance Industrial Science and Technology、3.Fossa Magna Museum)


キーワード:dynamic recrystallisation, crystallographic preferred orientation (CPO), electron backscattering diffraction (EBSD) , microstructure

It is known that the recrystallised fraction is dependent on the strain applied, and possibly can be used to evaluate strain (Cross and Skemer, 2019). Fabric intensity of quartz crystallographic preferred orientation (CPO) evolves with increasing strain (Heilbroner and Tullis, 2006; Muto et. al, 2011). Conversely, it is also documented that fabric intensity of quartz is very weak in strongly deformed ultramylonite (Okudaira and Shigematsu, 2012; Kilian et al., 2011).

The aim of this study is to investigate the effect of strain on fabric intensity of quartz CPO. We use the recrystallised fraction as a proxy of strain. The mylonite samples collected from the Median Tectonic Line, Mie, Japan display large variations in both recrystallized fraction and CPO fabric intensity within a short distance. We consider this phenomena to have occurred at similar deformational conditions.

Within this study, quartz crystallography data were collected from EBSD analysis whilst the dynamically recrystallised and relict grains are separated through applying a newly developed clustering technique. The M-index of both the relict and recrystallised grains are compared to discuss the changes in the fabric intensity in relation to recrystallised fraction. Evaluation of the effect of increasing recrystallised fraction on the possible changes in deformational mechanism will also be discussed.