Geochemistry, geochronology, and radiogenic isotopes of the Balmer and Confederation assemblages of the Laird Lake Area, Red Lake greenstone belt, Canada: implications for Archean tectonic evolution
Bibliographic record
Abstract
The Laird Lake property, southwest Red Lake greenstone belt, straddles the contact between the Balmer (2.99–2.96 Ga) and the Confederation (2.74–2.73 Ga) assemblages. The property is 10 km along strike from the Madsen and Starrat–Olsen Au mines that are hosted near the contact. The Balmer assemblage consists of fine-grained, aphyric, locally pillowed mafic volcanic rocks, ultramafic intrusive and volcanic rocks with flow breccia textures hosting local spinifex-bearing clasts, and banded-iron formations. In contrast, the Confederation assemblage comprises porphyritic mafic volcanic rocks intercalated with intermediate to felsic volcanic rocks that include crystal lapilli tuffs, crystal tuffs, and tuffs. The Balmer assemblage is composed of tholeiitic mafic volcanic rocks with minor Al-undepleted komatiites, whereas the Confederation assemblage is calc–alkalic. Neodymium isotopes, in conjunction with trace element geochemistry, suggests that parts of the Balmer assemblage were weakly contaminated by an older intermediate basement. Both arc and back-arc volcanism occurs in the Confederation assemblage, with the arc rocks showing a stronger crustal component than the back-arc rocks. A maximum U–Pb age of 2741 ± 19 Ma for a crystal tuff and an age of 2737.68 ± 0.79 Ma for a diorite are consistent with a Confederation assemblage affinity for the intermediate calc–alkaline rocks south of the Au-bearing horizon. The Balmer assemblage represents an oceanic plateau formed by plume magmatism on the margins of the North Caribou Terrane, whereas the Confederation assemblage at Laird Lake formed in an oceanic arc setting where both arc and back-arc volcanism occurred simultaneously.
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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 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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".