Editors’ Highlights are summaries of recent papers by AGU’s journal editors.
Source: Journal of Geophysical Research: Solid Earth
Understanding how deep continental rocks can be subducted into the Earth’s mantle is essential to understand lithospheric recycling, reconstructing deep subduction and exhumation processes. Minerals formed at great depths often preserve microscopic “exsolution” features, where one mineral separates out from another during cooling or decompression, but their interpretation has remained debated.
Li et al. [2025] performed the first systematic laboratory experiments on kyanite exsolution from aluminiferous stishovite, a high-pressure polymorph of SiO2 (silicon dioxide) stable at depths exceeding 300 kilometers. The experiments show that aluminum almost completely separates from stishovite to form kyanite during decompression, producing distinctive microscopic textures. These findings address a long-standing debate about whether a specific crystallographic relationship between exsolved phases and their host mineral is required to identify exsolution microstructures.
Importantly, the study demonstrates that a strict crystallographic alignment between the host mineral and exsolved phases is helpful but not always required to identify true exsolution. These results provide a robust experimental framework for interpreting similar microstructures observed in natural rocks. Overall, the findings offer compelling new evidence that continental rocks can undergo ultra-deep subduction into the mantle depths of at least about 300 kilometers and later be exhumed back to the Earth’s surface.
Citation: Li, X., Wang, C., Liu, L., Kang, L., Xu, H. J., Zhang, J., et al. (2025). Kyanite exsolution from aluminiferous stishovite in laboratory experiments: New insights into continental ultra-deep subduction. Journal of Geophysical Research: Solid Earth, 130, e2025JB031612. https://doi.org/10.1029/2025JB031612
—Jun Tsuchiya, Editor; and Sujoy Ghosh, Associate Editor, JGR: Solid Earth
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