Temperature and compositional dependences of H₂O solubility in majorite

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Liu, Dan ; Purevjav, Narangoo ; Fei, Hongzhan ; Withers, Anthony ; Ye, Yu ; Katsura, Tomoo:
Temperature and compositional dependences of H₂O solubility in majorite.
In: American Mineralogist. Bd. 109 (2024) Heft 9 . - S. 1646-1652.
ISSN 1945-3027
DOI: https://doi.org/10.2138/am-2023-9130

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Abstract

We systematically investigated H2O solubility in majorite as a function of temperature from 1670–2270 K under a pressure of 20 GPa using multi-anvil techniques. The H2O solubility in majorite decreases with increasing temperature. In addition, the H2O content is relatively independent of the concentrations of Al2O3 and SiO2 in majorite. Majorite can store more H2O than bridgmanite in the lower mantle. Therefore, when a slab sinks into the lower mantle, hydrous melt could be produced not only by the phase transformation from ringwoodite to bridgmanite + ferropericlase near 660 km depth but also by the majorite to bridgmanite transformation over a wide range of depths from 660 km up to ~800 km, at which majorite dissolves completely in bridgmanite.