Petrogenesis of the ferrogabbroic intrusions and associated Fe-Ti-V-(P) mineralization within the McFaulds greenstone belt, Superior Province, northern Ontario
Bibliographic record
Abstract
The Thunderbird and Butler intrusions of the McFaulds Lake greenstone belt ("Ring of Fire") were studied to determine petrogenesis and associated Fe-Ti-V-(P) mineralization. These intrusions are characterized by variably well layered gabbro-anorthosite intrusions with abundant Fe-Ti oxides, broadly termed ferrogabbro. The layers are composed of partial to complete cycles that comprise basal massive oxide (magnetiteilmenite), which grade into semi-massive oxide units, followed by oxide-rich pyroxenite/melagabbro/gabbro, oxide-poor melagabbro/gabbro/leucogabbro, and topped with oxide-free leucogabbro/anorthosite. The cycles range from centimetres to metres in thickness and define the well layered portions of the intrusions that typically exhibit sharp upper and lower contacts with gradational internal contacts. Conversely, the intrusions contain broad intervals of disseminated magnetite-ilmenite (25%) hosted in melagabbro/gabbro/ leucogabbro/anorthosite, which range in thickness from metres to tens of metres. The layering and textures observed within the ferrogabbro units are thought to be dominantly produced by convection currents with intermittent periods of quiescence. The ferrogabbro intrusions are characterized by gently sloping LREE and flat HREE patterns. This geochemical signature most closely corresponds to an E-MORB source that is thought to have been the result of interaction of a mnalte plume with MORB-like mantle under the McFaulds Lake area. This plume-related magma is thought to have undergone differentiation, resulting in the abundant Cr-Ni-Cu-PGE-bearing ultramafic and evolved Fe-Ti-rich mafic suites in the McFaulds area. Additionally, the plume may have resulted in a thinned lithosphere and produced the coeval VMS occurrences. Also studied is the potential application of the TiO2/V2O5 ratio for the identification of prospective vanadium mineralization and to aid in the determination of magmatic stratigraphy.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| 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".