Development of an Ancient Back‐Arc Basin Overlying Continental Crust: The Archean Peltier Formation, Northwest Territories, Canada
Bibliographic record
Abstract
The 2.67–2.69‐Ga Peltier Formation of the Point Lake volcanic belt, central Slave Province, Canada, is a mafic‐dominated succession that erupted in a back‐arc basin overlying sialic crust. The formation overlies the 3.22‐Ga Augustus Granite, is interstratified with the >2.65‐Ga turbiditic Contwoyto Formation, and is associated with 2.68‐Ga felsic and intermediate volcaniclastic rocks of the Samandre and Beauparlant Formations. Mafic rocks in the Peltier Formation range from N‐MORB (mid‐ocean ridge basalt) with flat to slightly LREE‐ (light rare earth element) enriched patterns, to tholeiitic LREE‐enriched E‐MORB with Nb and Ti depletions, and finally to strongly LREE‐enriched calc‐alkaline compositions with marked Nb and Ti depletions. The ϵNd values are between −2.94 and +3.06 and increase with decreasing (La/Yb)n ratios. Insulation of the conduit walls during ascent of early magmas may have limited the effects of crustal contamination over time. A possible tectonic model for the Point Lake belt evolution involves eruption of tholeiitic basalts between 2700 and 2680 Ma and calc‐alkaline basalts and andesites between 2680 and 2660 Ma into a back‐arc that developed following extension and rifting of an older remnant arc overlying continental crust. Construction of a new arc and subsequent mass wasting resulted in the deposition of felsic‐intermediate volcaniclastic material. Continuous erosion of the continental crust during volcanic activity is represented by the interstratification of turbidites and volcanic rocks.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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 teacher head, 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".