A paper on aqueous tungsten speciation, led by Dr. Takahashi, who was a JSPS Postdoctoral Fellow in our group through FY2024, has been published in Chemical Geology.
Tungsten plays an important role in hydrothermal ore formation and elemental transport in subduction zones, yet its chemical forms in high-temperature and high-pressure fluids deep within the Earth remain poorly understood. In this study, we investigated aqueous tungsten speciation at conditions of up to approximately 800°C and 1.4 GPa by combining in situ Raman spectroscopy using a hydrothermal diamond-anvil cell (HDAC) with density functional theory (DFT) calculations. The results show that, in high-temperature fluids, tungsten occurs primarily as mononuclear species such as the hydrogentungstate ion (HWO4-), rather than as species composed of multiple tungsten atoms. HWO4- is likely a major species responsible for tungsten transport in NaCl-bearing fluids. This result provides new insights into ore formation and fluid–rock interactions in deep subduction zones.
Takahashi N., Nakamura M., Yamashita S., and Kagi H. (2026) Tungsten(VI) speciation in aqueous fluids at high pressures and high temperatures: in-situ Raman spectroscopy supported by DFT calculations. Chemical Geology, 713, 123411.