Geobarometric evidence for a LM/TZ origin of CaSiO3 in a sublithospheric diamond
Bibliographic record
Abstract
Breyite is the second most abundant mineral inclusion in super-deep diamonds after ferropericlase.Though breyite stability extends to 300 km along typical mantle geotherm, this phase is often assumed to be the product of retrograde transformation of CaSiO 3 -perovskite, and thus has the potential to retain information from as deep as 800-1000 km.In this study, we determined the depth of formation of a breyite inclusion still enclosed in its host diamond from Juîna, Brazil, by X-ray diffraction.The measured >5 % smaller unit cell for breyite indicates a stored residual pressure showing that the breyite was entrapped between about 9(1) and 10(1) GPa.These are the highest estimates of formation pressure ever determined for a breyite inclusion.For ambient mantle temperatures higher than 1400-1500 °C, these pressures would exceed the maximum P of the breyite stability field.Breyite in this diamond cannot be primary but is rather a backtransformation product from CaSiO 3 -perovskite formed in the transition zone or the lower mantle.The co-existence magnesite in diamond JU55 and the slabassociation of sublithospheric diamonds is evidence of carbon transport to lower mantle depths.
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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) | 0.002 | 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".