Melting of Bridgmanite Under Hydrous Shallow Lower Mantle Conditions

High pressure and temperature experiments were carried out on the oxide mixtures corresponding to bridgmanite stoichiometry under hydrous shallow lower mantle conditions (24–25 GPa 1673–1873 K with 5–10 wt. % of water in starting material). Oxide investigated correspond MgSiO3, (Mg, Fe)SiO3, Al, Si)O3, Fe, Si)O3. Melting was observed all runs. Partitioning various elements, including Mg, Si, H is investigated. leads increased (Mg + Fe)O/SiO2 melt compared residual solids. The solids often contain a large amount stishovite, contains higher (Mg,Fe)O/SiO2 ratio than initial material. Fe)O-rich could explain low-velocity anomalies stishovite solid may be responsible for scattering seismic waves mid-lower “stishovite paradox." Since stishovite-rich materials are formed only when silica-rich source rock (MORB) melted (not typical peridotitic [bulk silicate Earth]), provides clue circulation subducted MORB materials. To estimate hydrogen content, we use new method estimating content unquenchable melts, also propose interpretation significance superhydrous phase B inclusions bridgmanite. results provide revised values partitioning between minerals melts that substantially previous estimates.