The Rae Province at 2.6 Ga: a sanukitoid storm on the Canadian Shield, Nunavut
Bibliographic record
Abstract
Between 2.62 and 2.58 Ga, Rae Province was intruded from Lake Athabasca to Melville Peninsula (more than 1700 km) by mafic to felsic plutons (Snow Island Suite), and overlain by volcanic rocks that are now mostly preserved beneath Paleoproterozoic basins. The Snow Island Suite was preceded by offshore arc volcanism and possible back-arc basin activity, with a U-Pb age peak at 2.635 Ga (Marjorie peak). About 50% of the Snow Island Suite is an infracrustal granitoid with K-enriched and tonalitic subtypes; the remainder lies on a sanukitoid spectrum. The sanukitoidal rocks are dominantly orthopyroxene-bearing magnesian diorite and monzodiorite with Mesoarchean Nd model ages. Some isotopically juvenile Snow Island Suite and Marjorie peak mafic rocks also have strong sanukitoid or adakite trace-element signatures. Four important features in the data are: 1) Marjorie peak mafic assemblages are prominent on the southeastern edge of Rae Province. Related nickel showings are present in south Rae Province Marjorie peak and early Snow Island Suite rocks; 2) U-Pb ages in the Snow Island Suite young toward the west edge of the province; 3) the Committee Bay Block (north-central Rae Province) is distinctively rich in infracrustal Snow Island Suite migmatite and poor in Snow Island Suite sanukitoid rocks and in tonalite of any age; and 4) there is a marked shift from tonalite-rich infracrustal sources in south Rae Province to more tonalite-poor sources in central Rae Province. The data are consistent with the Snow Island Suite, representing a continental magmatic arc segment, verging westward, with ponding of mafic magmas, inducing melting in the lower lithosphere to generate intermediate melts that ascended and induced additional melting in the middle to upper crust to generate granite.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.005 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".