Hydrogen solubility of stishovite provides insights into water transportation to deep Earth

Abstract. Water dissolved in nominally anhydrous minerals (NAMs) can be transported to deep regions of the Earth through subducting slabs, thereby significantly influencing the physicochemical properties of deep Earth materials and impacting dynamic processes in the deep Earth. Stishovite, a prominent mineral found in subducting slabs, remains stable at mantle conditions ranging from pressure of 9–50 GPa and can incorporate varying amounts of water (H⁺, OH⁻, and H₂O) within its crystal structure. Consequently, stishovite plays a crucial role in transporting water into deep Earth through subducting slabs. This paper provides a comprehensive review of the research progress concerning water (hydrogen) solubility in stishovite. The key factors that govern water solubility in stishovite are summarized as temperature, pressure, water fugacity and aluminum content. Combined with published results on the dependence of water solubility on the aforementioned parameters, this paper proposes a new equation for water solubility in Al-bearing stishovite can be described by the relationship. Calculation results based on this equation suggest that stishovite may effectively absorb water released from processes such as hydrous mineral breakdown, dehydration reactions, and volume reduction, ultimately contributing to the presence of a water-rich transition zone.