Contrasting oxygen isotopes in garnet from diamondiferous and barren eclogitic parageneses
Bibliographic record
Abstract
Eclogite is a minor mantle lithology, present in subducted slivers in cratonic roots.Mantle eclogites carry O and C isotopic signatures from surface organic and inorganic carbon and also are modified by reaction with fluids in the lithosphere.One third of the diamonds mined worldwide are sourced from mantle eclogites, and individual eclogite xenoliths contain up to 20 vol.% diamond.It is critically important to understand where the diamond carbon comes from, and how the diamonds form, for insights on the carbon cycle, diamond exploration, and processes in the lithospheric mantle.Few samples and methods are available to constrain diamond formation in eclogites; in this work we focus on oxygen isotopes in eclogitic garnets.New analyses of garnet/majorite found as inclusions in the Cullinan diamonds reveal a statistically significant systematic difference between δ 18 O in garnet associated, and unassociated, with diamond.This contrast persists between garnet from diamondiferous and barren eclogite xenoliths and cannot be due to shielding of diamond inclusions from equilibrating with the common mantle values of δ 18 O.We propose that diamond-forming metasomatic reactions triggered by carbonatitic fluids may contribute up to 1.5 ‰ to the shift of δ 18 O to higher values in eclogitic diamondiferous paragenesis, but cannot fully account for the observed difference of 2.5 ‰.
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 | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 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".