Temperature Dependence of H₂O Solubility in Al-Free Stishovite

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Purevjav, Narangoo ; Fei, Hongzhan ; Ishii, Takayuki ; Criniti, Giacomo ; Lin, Yanhao ; Mao, Ho-Kwang ; Katsura, Tomoo:
Temperature Dependence of H₂O Solubility in Al-Free Stishovite.
In: Geophysical Research Letters. Bd. 51 (2024) Heft 3 . - e2023GL104029.
ISSN 1944-8007
DOI: https://doi.org/10.1029/2023GL104029

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Abstract

The role of stishovite in transporting water in subducting slabs has been a subject of debate for several decades. Here we investigated stishovite's water solubility and its potential role in water transportation as a function of temperature from 1300 to 2100°C at 22 GPa. Under water-saturated conditions, high-quality, Al-free stishovite single crystals were synthesized with multi-anvil press, and their water contents were measured using infrared spectroscopy. The H2O solubility in stishovite increases from 128(20) to 521(47) wt. ppm with increasing temperature from 1300 to 1700°C and decreased to 145(26) wt. ppm at 2100°C. The maximum H2O content was about seven times larger than earlier high-temperature multi-anvil studies but significantly lower than recent laser-heated diamond anvil cell and low-temperature multi-anvil studies. We suggest that Al-free stishovite may not be a significant H2O carrier in subducting slabs, at least at the topmost lower mantle corresponding to our experimental conditions.