Physical properties of deep Earth minerals and the effect of water

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We have clarified the physical properties of deep Earth mantle minerals and the effect of water. Experiments were conducted by in situ X-ray measurements in addition to quench experiments.From our previous studies, it has been clarified that high pressure polymorphs of olivine, wadsleyite and ringwoodite, can contain 2-3 wt% of H_2O in their crystal structures, but the partitioning of H_2O among these minerals has not been clarified yet. In the present study, we have clarified the partitioning of H_2O to synthesize these coexisting phases, and found that mantle transition zone should be a strong water reservoir in the Earth's interior.In addition, the measurements of thermal expansion and elastic properties of hydrous wadsleyite and hydrous ringwoodite were conducted to clarify the H_2O content in the mantle. Combined these results with seismic observation, we estimated the H_2O content in the mantle. Further extensive studies have been conducted with seismologist.We also tried to observe dehydration and physical properties of high pressure hydrous phase with capsulation using relatively light metal capsule by in situ X-ray observation. We succeeded to get X-ray spectra of superhydrous phase B using AgPd capsule, and further improved capsule, which were made by a single crystal diamond sleeve and metal caps, were designed for in situ X-ray experiment. The capsule is quite successful, and the effective acquisition of X-ray spectra under high pressure has been achieved by in situ X-ray experiment. This technique has been adopted to determine hydrous melt structure and time-resolved experiment of dehydration.