Petrogenesis and Geodynamic Evolution of the Paleoproterozoic (~1878 Ma) Trout Lake Volcanogenic Massive Sulfide Deposit, Flin Flon, Manitoba, Canada
Bibliographic record
Abstract
The Trout Lake deposit (1878 ± 1 Ma) is a rhyolite-hosted, bimodal-mafic, volcanogenic massive sulfide (VMS) deposit. It is one of the largest VMS deposits in the Flin Flon mining district, containing 21.8 Mt of Cu-Zn rich ore. The deposit underwent greenschist facies metamorphism and polyphase synvolcanic to postvolcanic hydrothermal alteration. Footwall and hanging-wall lithostratigraphic units of the Trout Lake deposit occur as an upright, steeply NE dipping, homoclinal succession of thrust-repeated volcanic and siliciclastic sedimentary units. The deposit consists of several massive sulfide ore lenses hosted within a felsic volcanic unit that represents a localized felsic eruptive center composed of flows, synvolcanic sills, and volcaniclastic lithofacies with an FIIIb-type tholeiitic to transitional rhyolite composition (Zr = 213–385 ppm; Ybcn = 47–100; La/Ybcn = 0.97–2.33). The felsic unit occurs along strike of an andesitic unit comprising an intercalation of high-MgO andesite (MgO > 5.0 wt %) and Nb-enriched andesite (Nb = 10–13 ppm) flows that are underlain by a footwall basaltic unit composed of flow lithofacies with a low-Ti tholeiitic basaltic composition (TiO2 < 0.48 wt %; Zr = 15–17 ppm; Al2O3/TiO2 = 37–45). Postvolcanic gabbros with back-arc basin basalt composition intrude the volcanic units, which are unconformably covered by a younger argillite unit deposited at ca. <1843 ± 9 Ma. The felsic volcanic and argillite units were repeated and structurally interleaved during west-directed thrusting. The presence of low-Ti tholeiitic basalts indicates high-temperature melting (1,200°–1,500°C) of strongly depleted refractory mantle sources (Nb/Yb 1.45) variably affected by slab-derived hydrous melts. These petrologic characteristics suggest a geochemically heterogeneous mantle wedge that underwent metasomatism by slab-derived components. In addition, zircon saturation thermometry indicates that FIIIb-type rhyolites formed at temperatures >900°C during partial melting of mafic lower crust. Collectively, the occurrence of high-temperature melts indicates that the Trout Lake VMS deposit formed in a hot, intraoceanic, extensional-arc geodynamic setting. Intra-arc rifting, asthenospheric upwelling, and subduction of young and hot oceanic crust are mechanisms that explain the high-temperature magmatism and are features consistent with the formation of the massive sulfide ore lenses. The back-arc basalt geochemical signatures of the postvolcanic gabbros suggest that the tectonic environment of the Trout Lake area evolved from an intra-arc rift, during the deposition of the ore lenses, to an incipient back-arc basin during the intrusion of the gabbros.
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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 | 0.000 | 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) | 0.004 | 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".