Structural Controls on the Mary River Iron Ore Deposit, North Baffin Island, Nunavut
Bibliographic record
Abstract
The Mary River Fe-ore deposits of northern Baffin Island are hosted in the ArcheanMary River Group; Deposit 1 is the site of Canada’s northernmost active mine.Greenstone belts of the Mary River Group form discontinuous, 1–10 km scale, vari-ably deformed and metamorphosed panels within orthogneiss and granitoid rocksof the Rae Craton. Despite evidence for Archean deformation, two main tectonicevents, including the Paleoproterozoic collisional Trans-Hudson orogeny and theMesoproterozoic extensional events forming the Bylot basins were responsible forthe distribution of Fe-ore. North–south shortening during the Trans-Hudsonorogeny resulted in structural thickening of the primary Mary River banded iron for-mation (BIF), local metasomatic removal of chert layers, the development of foliat-ed and lineated, specularitic hematite ore, and finally crenulation of the speculariticore. Lineations and crenulations plunge regionally to the southeast across a series ofsynforms. The Mary River Group is structurally repeated along a series of steeplywest- to southwest-dipping listric normal faults, best observed at Glacier Lake ~20km east of the Deposit 1 Mary River mine. An appropriately oriented set of topo-graphic lineaments evident in digital topographic images is likely the surface mani-festation of the extensional faults. At Glacier Lake, development of normal faultswas accompanied by local brecciation and facilitated fluid flow responsible for themetasomatic removal of chert and the formation of blocky ore, which locally over-prints specular ore. The normal faults explain the consistent metamorphic gradeacross the region despite the consistent southeast structural plunge, the repetition ofthe Mary River Group stratigraphy, and the exposure of a series of synclines withoutintervening anticlines. The normal faults may be products of the Mesoproterozoicextensional event that gave rise to the more northerly Bylot basins.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.002 |
| Scholarly communication | 0.002 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.005 | 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".