Rutile's pressure-temperature-time evolution dictates its role as a depth-dependent subduction-zone water regulator
Bibliographic record
Abstract
The deep Earth water cycling is critically regulated by hydrogen storage capabilities of nominally anhydrous minerals (NAMs). Rutile TiO 2 , a prevalent NAM in subduction zones, incorporates measurable hydrogen via defect-mediated mechanisms. However, its molecular-level structural evolution and hydrogen content variations under subduction-relevant conditions remain poorly constrained. This study integrates spatially resolved Raman imaging and Fourier transform infrared spectroscopy to quantitatively elucidate the microstructural and hydrogen dynamics in rutile across various pressure-temperature-time (P-T-t) trajectories. The results reveal that during prolonged cold subduction (geothermal gradient of ∼5 °C/km), pressure enhances microstructural ordering and crystallinity in rutile, leading to hydrogen loss. Conversely, thermal activation generates microstructural defects, which serves as additional sites for hydrogen incorporation. Quantitative hydrogen tracking demonstrates that rutile undergoes ∼50 % dehydration in anhydrous environments, which is inhibited by the rutile-to-akaogiite transformation. This transformation initiates at ∼8 GPa due to molecular heterogeneity, yet the kinetic stability provided by polar covalent Ti O bonds enables rutile to persist up to ∼20 GPa. Notably, rutile exhibits ∼12 % hydrogen uptake upon prolonged fluid infiltration along cold-to-hot subduction pathways (geothermal gradients of ∼5–20 °C/km). In the continuous aqueous environments typical of subduction zones, these findings establish rutile as a depth-dependent water regulator. It can transport water beyond its initial content to mantle depths exceeding ∼300 km, thus advancing our understanding of how NAMs modulate water cycling in subduction zones. • Pressure-induced crystallinity optimization and H + loss in the NAM rutile. • Thermal activation facilitates structural defects and H + incorporation in rutile. • Polar covalent Ti O bonds kinetically stabilize rutile. • Rutile acts as a depth-dependent water regulation in subduction zones. • Raman imaging offers extensive data for accurate characterization of rutile.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".