Occurrence of bleached mafic flows and their association with sockwork sulphides and banded iron-formation in the Crestaurum Formation of the late Archean Yellowknife Greenstone Belt, Northwest Territories
Bibliographic record
Abstract
In the northern part of the late Archean Yellowknife Greenstone Belt, tholeiitic basalt of the Crestaurum Formation is bleached along a 7 km strike length. Unbleached late volcanic gabbro dykes and sills transect the bleached mafic flows and constrain the alteration to synvolcanic processes. Bleaching is likely a result of silicification and Fe leaching with later chloritization of pillow selvages. These altered flows are intercalated with thinly layered, silica-rich, metavolcaniclastic rocks, which have been referred to as 'cherty tuff'. Petrographic and oxygen isotopic constraints indicate that the chert component is minor. An occurrence of discontinuous chert-magnetite iron-formation and discordant sulphide stockwork are indicative of synvolcanic hydrothermal activity. This hydrothermal activity is likely responsible for local alteration of the mafic flows, but does not explain the large-scale alteration. Stratigraphic considerations suggest that a hydrothermal alteration system existed within the Crestaurum Formation and preceded eruption of the overlying felsic metavolcanic rocks.
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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 | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 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".