Volcanic reconstruction of the paleoproterozoic powderhouse formation, Snow Lake, Manitoba, Canada: implications for controls on volcanogenic massive sulfide formation
Bibliographic record
Abstract
The Powderhouse formation of the Paleoproterozoic Snow Lake arc assemblage comprises the \nstratigraphic footwall to six volcanogenic massive sulfide deposits (VMS) at Snow Lake, \nManitoba, Canada. It is interpreted to be a product of voluminous pyroclastic eruptions and \nconcomitant subsidence followed by a period of relative volcanic quiescence that was dominated \nby suspension sedimentation, the reworking of these previously deposited pyroclastic units by \ndebris flows and bottom currents, and localized emplacement of rhyolite domes. The rhyolite \ndomes are spatially associated with the Chisel, Chisel North, Lost, Ghost, Photo and Lalor \ndeposits. \nThe Chisel, Lalor and Lost members comprise the Powderhouse formation and are \nsubdivided into thirteen lithologically and chemically distinct lithofacies and allows, for the first \ntime, correlation between the South Chisel basin and Lalor area. The Chisel and Lalor members \ncontain lithofacies and bedforms that are characteristic of emplacement by subaqueous \npyroclastic mass flows and concomitant subsidence. The Chisel member also contains coarse \nvolcaniclastic breccias emplaced by mass debris flows derived from movement along fault scarps \nafter early pyroclastic eruptions, and during continued subsidence. The Lost member consists of \nlithofacies deposited by mass flows generated from faults scraps during continued subsidence, \nbut also contains lithofacies reworked by bottom currents and those deposited by suspension \nsedimentation, and locally coherent rhyolite. The Lost member represents a time stratigraphic \ninterval, the “Ore Interval”, that marks contemporaneous rhyolite dome eruption, VMS \nformation, and a hiatus in explosive volcanism.
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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 | 0.002 |
| Science and technology studies | 0.002 | 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) | 0.002 | 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".