Presentation Information
[R3-P-09]Stability and solid solution relationship between high-pressure hydrous phases in subducting slabs
*Makoto Bisaiji1, Toru Inoue1, Goru Takaichi1, Takaaki Kawazoe1, Toru Shinme2, Tetsuo Irihune2 (1. Hiroshima Univ. Sci., 2. Ehime Univ. GRC)
Keywords:
subducting slab,high-pressure hydrous phase,phase Egg,phase H,mantle-crustal material reaction
The transport of water into the Earth's interior is facilitated by subduction of slabs. Phase Egg (AlSiO4H) is a high-pressure hydrous phase derived from sedimentary rocks (continental crust materials) that forms under the pressure conditions of the mantle transition zone and is thermally stable up to 1700C (Ono, 1988; Sano et al., 2004; Fukuyama et al., 2017). This phase Egg has been discovered as an inclusion in diamond (Wirth et al., 2007) and is regarded as evidence that both continental crust materials and H2O components subduct down to the mantle transition zone. Recently, it was shown through experiments at 24GPa and 1400C that phase H (MgSiO4H2), a high-pressure hydrous magnesium silicate stable in the lower mantle, can dissolve into phase Egg (Al0.65Mg0.35SiO4H1.35 phase Egg: Bindi et al., 2023). This finding suggests the importance of water-mediated crust-mantle material reactions occurring between the mantle transition zone and the uppermost lower mantle. However, systematic studies to clarify this solid solution relationship have not yet been conducted. This study aims to experimentally investigate the solid solution relationship of phase H components into phase Egg under conditions corresponding to the mantle transition zone to the uppermost lower mantle.
