日本地球惑星科学連合2019年大会

講演情報

[E] ポスター発表

セッション記号 S (固体地球科学) » S-IT 地球内部科学・地球惑星テクトニクス

[S-IT21] 核-マントルの相互作用と共進化

2019年5月27日(月) 17:15 〜 18:30 ポスター会場 (幕張メッセ国際展示場 8ホール)

コンビーナ:河合 研志(東京大学大学院理学系研究科地球惑星科学専攻)、飯塚 毅(東京大学)、太田 健二(東京工業大学大学院理工学研究科地球惑星科学専攻)、土屋 卓久(愛媛大学地球深部ダイナミクス研究センター)

[SIT21-P05] Lattice thermal conductivity of wadsleyite and ringwoodite at the mantle transition zone pressures

*木村 清二1太田 健二6川添 貴章2廣瀬 敬3鍵 裕之4八木 貴志5 (1.東京工業大学理学院地球惑星科学系、2.広島大学大学院理学研究科地球惑星システム学専攻、3.東京工業大学大学 地球生命研究所、4.東京大学大学院理学系研究科附属地殻化学実験施設 、5.国立研究開発法人産業技術総合研究所、6.東京工業大学大学院理工学研究科地球惑星科学専攻)

キーワード:ウォズレアイト、リングウッダイト、マントル遷移層、含水鉱物、熱伝導率

The lattice thermal conductivities of wadsleyite (Wd) and ringwoodite (Rw), which predominantly occupy the Earth's mantle transition zone, are important transport properties to understand the dynamics and thermal structure of the mantle. In particular, the temperature in the subducting slab is mainly controlled by the thermal conduction of Wd and Rw. Wd and Rw are both thought to preserve a large amount of hydrogen ions, thus should play an important role as the main water reservoir in the Earth. Furthermore, it has been reported that the hydration affects the physical properties of minerals including thermal conductivity, and it is necessary to measure the lattice thermal conductivity of Wd and Rw considering their water content. However, so far, the reported lattice thermal conductivities of Wd and Rw has not been considered their water content (Xu et al., 2004). Here we measured the room temperature lattice thermal conductivity of (Mg0.89Fe0.11)2SiO4 Wd and (Mg0.91Fe0.09)2SiO4 Rw up to 27 GPa, respectively, to clarify their hydration dependence using the pulsed light heating thermoreflectance technique in a diamond anvil cell.The obtained results show similar pressure dependence of the lattice thermal conductivity to the previous study (Xu et al., 2004). However, the absolute values of the thermal conductivity are different; the lattice conductivities of hydrous Wd and Rd are ~52% and ~40% lower than the results of Xu et al. (2004), respectively. Our results suggest strong water content dependence of lattice thermal conductivities of Wd and Rw, implying that the water content in the mantle minerals is key factor for calculating the thermal structure in a subducting slab, mantle dynamics.