Raman spectroscopic study of the transformation of nitrogen‐bearing K‐cymrite during heating experiments: Origin of kokchetavite in high‐pressure metamorphic rocks
Bibliographic record
Abstract
Abstract Nitrogen‐bearing K‐cymrite was synthesized in experiments at high pressures but so far has not been found/identified as inclusions in minerals subducted and subsequently exhumed from mantle depths. K‐cymrite is a potential carrier of nitrogen; it can store and transport up to 4 wt% of nitrogen in the deep mantle, thus contributing to the global nitrogen cycle. The stability of nitrogen‐bearing K‐cymrite synthesized at pressure of 6.3 GPa, upon exhumation to the Earth's surface, remains unknown. Here, we report an in situ Raman spectroscopic study of nitrogen‐bearing K‐cymrite, using Linkam heating and freezing microscope stage (THMS600). The transition induced in this experiment corresponds to the retrograde PT‐path of deeply subducted rocks. Our results demonstrate that (i) nitrogen‐bearing K‐cymrite structure is more stable upon heating than pure H2O bearing specimens (KAlSi3O8·H2O), (ii) phase transformation (e.g., H2O, N2, and NH3 release) starts at 550°C leading to the formation of kokchetavite (an anhydrous hexagonal polymorph of KAlSi3O8) frequently observed in high‐pressure metamorphic rocks, and (iii) Raman spectra of kokchetavite obtained from different precursors (e.g., nitrogen‐bearing and H2O‐bearing K‐cymrite) are identical. Thus, nitrogen‐bearing K‐cymrite can be considered a potential host phase for nitrogen in subduction‐related environments, and it can be preserved as inclusions in refractory minerals during the exhumation of deeply subducted rocks.
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".