[SCG69-01] Torsional deformation experiments at Mbar pressures toward understanding deep Earth rheology
★Invited Papers
キーワード：高圧高温変形実験、回転式ダイヤモンドアンビル装置、地球深部
The rheological properties of deep Earth materials are key to understanding the dynamics and evolution of the Earth’s interior. Recent technological developments in deformation experiments under high pressures and temperatures combined with the use of synchrotron X-rays have facilitated a qualitative understanding of the rheological properties. For instance, through the use of the D-DIA and the rotational Drickamer apparatuses, it is possible to determine stress-strain relationships at high pressures (P) and temperatures (T) to those in the uppermost part of the lower mantle[Girard et al., 2016; Tsujino et al., 2016].
In this study, we introduced a rotational diamond anvil cell [Blank et al., 1984] to extend the pressure range of large-strain steady-state deformation experiments. High experimental pressures covering those in the whole of the lower mantle were achieved using nano-polycrystalline diamond as the anvil material with a high experimental success rate [Nomura et al., 2017]. Additionally, pressures up to multi-Mbar were observed using single crystal diamond anvils, although the success rate was not high. A simple detachable external heating system with a vacuum chamber was introduced to generate temperatures greater than 1000 K. The high-pressure in-situ X-ray laminography technique [Nomura and Uesugi, 2016] was introduced to determine the strain state within a sample under high-pressure conditions. The X-ray diffraction measurement system was introduced to determine the stress state of the sample under high-pressure and high-temperature deformation conditions. A combined X-ray diffraction and X-ray imaging measurement system was set up in an identical beamline (BL47XU of SPring-8, Japan). Through this combined measurement technique with the rotational diamond anvil cell, we succeeded in extending the P-T range of the quantitative experimental studies to understand the rheological properties of the deep Earth materials. We present recent technical developments and their relevant applications.
In this study, we introduced a rotational diamond anvil cell [Blank et al., 1984] to extend the pressure range of large-strain steady-state deformation experiments. High experimental pressures covering those in the whole of the lower mantle were achieved using nano-polycrystalline diamond as the anvil material with a high experimental success rate [Nomura et al., 2017]. Additionally, pressures up to multi-Mbar were observed using single crystal diamond anvils, although the success rate was not high. A simple detachable external heating system with a vacuum chamber was introduced to generate temperatures greater than 1000 K. The high-pressure in-situ X-ray laminography technique [Nomura and Uesugi, 2016] was introduced to determine the strain state within a sample under high-pressure conditions. The X-ray diffraction measurement system was introduced to determine the stress state of the sample under high-pressure and high-temperature deformation conditions. A combined X-ray diffraction and X-ray imaging measurement system was set up in an identical beamline (BL47XU of SPring-8, Japan). Through this combined measurement technique with the rotational diamond anvil cell, we succeeded in extending the P-T range of the quantitative experimental studies to understand the rheological properties of the deep Earth materials. We present recent technical developments and their relevant applications.