Japan Geoscience Union Meeting 2018

Presentation information

[EE] Oral

S (Solid Earth Sciences) » S-IT Science of the Earth's Interior & Tectonophysics

[S-IT22] Interaction and Coevolution of the Core and Mantle in the Earth and Planets

Tue. May 22, 2018 1:45 PM - 3:15 PM International Conference Room (IC) (2F International Conference Hall, Makuhari Messe)

convener:Tsuyoshi Iizuka(University of Tokyo), Hidetoshi Shibuya(Department of Earth and Environmental Sciences, Faculty of Advanced Science and Technology, Kumamoto University), Taku Tsuchiya(愛媛大学地球深部ダイナミクス研究センター, 共同), Kenji Ohta(Department of Earth and Planetary Sciences, Tokyo Institute of Technology), Chairperson:Tsuchiya Taku, Sinmyo Ryosuke

2:45 PM - 3:00 PM

[SIT22-05] Deformation experiments of mixture of bridgmanite and ferropericlase using rotational diamond anvil cell

*Shintaro Azuma1, Ryuichi Nomura2, Kentaro Uesugi3, Yuki Nakashima4, Yohei Kojima2, Doi Shunta2, Sho Kakizawa2 (1.Department of Earth and Planetary Sciences, Faculty of Science, Kyushu University, 2.Geodynamics Research Center, Ehime University, 3.Japan Synchrotron Radiation Research Institute (JASRI/SPring-8), 4.Tokyo Institute of Technology)

Keywords:rotational diamond anvil cell, bridgmanite, ferropericlase, deformation experiment

Development of high-pressure (static compression) experiments enabled to increase pressure up to ~360 GPa, corresponding conditions to inner core of the Earth (e.g., Tateno et al., 2010). On the other hand, pressure is limited for a technical reason in high-pressure deformation experiments. Earth’s interior is dominated by ‘dynamic’ processes. Therefore, expansion of pressure range in deformation experiments is necessary to understanding the evolution of Earth’s deep interior. We developed rotational diamond anvil cell (rDAC) to conduct deformation experiments with large strain under ultra-high pressure conditions, corresponding to those of Earth’s core (Nomura et al., 2017; Azuma et al., 2018). We present the results of deformation experiments using rDAC and the status of development of rDAC.
In this study, existing diamond anvil cell (DAC) is modified to give torsional deformation to sample under ultra-high pressure conditions. In the developed rDAC, lower anvil is fixed and upper anvil can rotate relative to the lower anvil. The mixture of bridgmanite and ferropericlase was deformed using the rDAC. The experimental conditions are ranging 35–135 GPa, room temperature and strain-rate of 5.6×10-5–1.7×10-4 s-1. Starting material was grooved by FIB and the groove was deposited by Pt as strain-marker. Recovered samples were cut by FIB to observe the rotation angle of strain-marker, sample thickness, and shape of strain-marker in each cross-section. Deformation experiments were conducted also in Japan Synchrotron Radiation Research Institute (SPring-8) and 3D visualization of the internal structure of samples were performed using X-ray laminography (Nomura and Uesugi, 2016).
The geometry of strain-marker in recovered samples show nearly simple shear, indicating that this apparatus allows us to investigate the deformation with large strain under ultra-high pressure conditions, corresponding to those of core-mantle boundary (CMB). Recovered sample was observed using FE-SEM and we determined the 2D surface area and aspect ratio of each particle of ferropericlase. Microstructure of mixture of bridgmanite and ferropericlase showed that the ferropericlase highly deformed and connected each other, indicating that the ferropericlase dominate the deformation in the lower mantle. However, these deformation experiments were conducted under room temperature. We will carry on the development of rDAC for high-temperature deformation experiments.