The petrogenesis and mantle source of Archaean ferropicrites from the Western Superior Province
Bibliographic record
Abstract
Archaean ferropicrites have been under-appreciated in the past because they have been frequently misidentified as enriched koma-tiites or Al-depleted komatiites. To investigate the nature of Archaean ferropicrite magmatism, we sampled ferropicrites from the Steep Rock, Lumby Lake, Grassy Portage Bay, and Dayohessarah Lake greenstone belts in the Western Superior Province, Ontario, Canada. Ferropicrite samples that are thought to approximate liquid compositions have 18 wt % Fe2O3 at 19 wt % MgO, and frequently contain less than 5 wt % Al2O3.They are enriched inTi and high field strength elements relative to koma-tiites, and have fractionated trace element profiles (La/Yb 11). These distinctive geochemical characteristics require that ferropi-crites and komatiites have different mantle sources, with that of the ferropicrites being Fe- and incompatible element-enriched compared with that of komatiites. A consideration of recent 5 GPa melting experiments on pyrolite and Fe-rich Martian mantle compositions indicates that Archaean ferropicrites could be generated by melting of an olivine-dominated mantle source with a Mg-number of 85 at 5 GPa. The high densities calculated for the ferropicrite magmas (e.g. 333 g/cm3) suggest that more Fe-rich magmas would have difficulty rising to the Earth’s surface and would tend to stagnate or sink within the mantle. KEY WORDS: Archaean; ferropicrite; Fe-rich; komatiite; mantle; petrogenesis
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 | 0.001 | 0.000 |
| 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".