The Significance of Hypermagnesian Clinopyroxene in the Yanisvaara Ultrabasic Complex, Kola Peninsula, Russia
Bibliographic record
Abstract
Abstract Two generations of hypermagnesian clinopyroxene [92 < Mg# < 98] are found in the Yanisvaara ultrabasic complex in the northwestern Lapland–Belomorian Belt, Kola Peninsula, Russia. Grains of a first generation (Wo47.3–50.7En46.5–49.4Fs2.5–3.5), 0.2–0.4 mm across, are attributed to a reaction in which tremolite + clinopyroxene replaced orthopyroxene. The second generation generally attains even more strongly magnesian compositions (Wo46.5–50.9En47.5–50.8Fs1.0–3.2). It is sporadically developed as submicrometric rim- or veinlet-like grains associated with tremolite and domains of fresh olivine with Mg# in the range 80.5–82.5 to 87.7–88.0. The later generation of clinopyroxene crystallized at elevated values of fO2 under closed-system autometasomatic conditions rather than during regional metamorphism. The compositions attained in three representative samples are highly magnesian, but characteristically poor in Cr compared to primary clinopyroxene. Compositions of the accompanying silicate, oxide, and sulfide minerals are provided. A novel Ni-Mn oxyspinel may be related to hausmannite. Yanisvaara and coeval subvolcanic komatiitic complexes are inferred to have degassed, which promoted the rapid rise in fO2 and indirectly promoted the buildup of Mg in the late clinopyroxene.
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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 | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".