17:15 〜 18:45
[SCG44-P01] rDACによるカンラン石多結晶体の大歪変形実験の予察的結果
キーワード：地球、マントル、レオロジー、カンラン石
To understand the dynamics of the plate tectonics, it is important to constrain the rheology of olivine in the mantle peridotites, and how it evolves under high-strain deformation imposed during plate motions and mantle flows. We performed a series of high-strain deformation experiments on olivine aggregates using a rotational diamond anvil cell (rDAC).
All experiments were conducted at the beamline BL47XU, SPring-8. The experimental conditions are the confining pressure of 12–22 GPa, the temperature of 20–500 degC, and the equivalent shear strain rate of ~10–4 1/s. During the deformation experiments, X-ray diffraction (XRD) patterns and X-ray radiographs were taken every 2–5 minutes. Stresses in the olivine aggregates were calculated from the lattice strain estimated from XRD. Since we applied a torsional deformation to the sample, there are some stress and strain gradients in the sample. We adopted the stress at the position 2/3 of the radius from the center of the sample as a representative stress in the sample, because this position is the area-averaged radius of the sample.
As the shear strain increased, the stress increased and then reached a steady-state condition. The steady-state shear stress and equivalent stress at the temperature of 400 degC and the pressure of 12 GPa were about 1.2 GPa and 3.0 GPa, respectively. The steady-state stress obtained in the present study is consistent with a Peierls’s flow law reported in a previous study. We will also present data on crystallographic preferred orientations of olivine aggregates in this presentation.
All experiments were conducted at the beamline BL47XU, SPring-8. The experimental conditions are the confining pressure of 12–22 GPa, the temperature of 20–500 degC, and the equivalent shear strain rate of ~10–4 1/s. During the deformation experiments, X-ray diffraction (XRD) patterns and X-ray radiographs were taken every 2–5 minutes. Stresses in the olivine aggregates were calculated from the lattice strain estimated from XRD. Since we applied a torsional deformation to the sample, there are some stress and strain gradients in the sample. We adopted the stress at the position 2/3 of the radius from the center of the sample as a representative stress in the sample, because this position is the area-averaged radius of the sample.
As the shear strain increased, the stress increased and then reached a steady-state condition. The steady-state shear stress and equivalent stress at the temperature of 400 degC and the pressure of 12 GPa were about 1.2 GPa and 3.0 GPa, respectively. The steady-state stress obtained in the present study is consistent with a Peierls’s flow law reported in a previous study. We will also present data on crystallographic preferred orientations of olivine aggregates in this presentation.