Depositional history of the Ament Bay Assemblage in the Sturgeon Lake Greenstone Belt, Northwestern Ontario: implications for gold metallogeny
Bibliographic record
Abstract
The Sturgeon Lake greenstone belt makes up the easternmost portion of the western Wabigoon terrane of the Superior craton, and is comprised of mostly Neoarchean volcanic assemblages, minor siliciclastic successions, and subalkalic- to alkalic intrusions. The Ament Bay assemblage is the youngest supracrustal assemblage of the Sturgeon Lake greenstone belt with a newly determined maximum depositional age of 2695.2 ± 7.8 Ma. Ament Bay consists dominantly of polymictic conglomerates, subarkosic- to arkosic arenites and wacke-mudstone sequences, interpreted as a sub-aerial fan delta that is transitional into subaqueous turbidites. These lithofacies are intruded by syenites of the Sturgeon Narrows Alkalic Complex (ca: 2693.2 ± 0.9 Ma), which are also incorporated as clasts in conglomerates of the Ament Bay assemblage, indicating a coeval relationship between alkalic magmatism, uplift erosion and sedimentation. Both the Ament Bay assemblage and Sturgeon Narrows Alkalic Complex are cross-cut by the Sturgeon Lake fault zone. Coeval alkalic magmatism and sedimentation in a fault-controlled basin are features of the 2680-2670 Ma Timiskaming assemblage which controls much of the orogenic-style gold endowment in the Abitibi greenstone belt. The Ament Bay assemblage has similar features but gold mineralization is not recognized in the belt. The lack of gold endowment in the Ament Bay assemblage could be a result of crustal influence on the alkalic melts and shallow-penetrating faults, in contrast to the juvenile nature of alkalic magmatism and deep-penetrating faults associated with the Timiskaming assemblage.
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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 | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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 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".