Mineralisation of fractured granites along the Cobequid Fault Zone: West Moose River Pluton, Cumberland County, Nova Scotia
Bibliographic record
Abstract
The West Moose River Pluton in the Cobequid Highlands is a late Paleozoic A-type granitic intrusion, emplaced and highly deformed during the evolution of the Cobequid Shear Zone. Pervasive fractures in these granites provide record of several hydrothermal events characterized by distinct mineral assemblages that correlate with known dated fluid circulations throughout the shear zone. The types of hydrothermal alteration identified in this pluton include albitisation, biotisation, chloritisation, calcitefilled fractures, and Fe-rich alteration expressed as stringers in hand specimen. This study presents geochemical, and mineralogical data, as well as magnetic susceptibility measurements on selected fractured samples from the West Moose Pluton. Petrographic investigation of these granites revealed that they contain a large variety of exclusively hydrothermal REE-minerals that include thorite, xenotime, Fe-rich hingganite-(Y), cerianite, samarskite-(Y), nioboaeschynite-(Y), tantaeuxenite-(Y), allanite-(Ce), bastnäsite-(Ce) and synchysite-(Ce). Associated Fe-oxyhydroxides include magnetite, hematite, goethite, and limonite, while ilmenite and TiO2 minerals are also present in varying amounts. The amounts of hydrothermal REE-minerals correlate positively with the volume of fractures measured in the samples, with the highest amounts measured in calcite-filled veins. Samples in the southwestern part of the pluton show high amounts of Fe-oxides, high magnetic susceptibility, and positive Ce anomalies, here interpreted as the result of Ce scavenging and oxidation during oxide precipitation. Therefore the mineral cerianite along with Fe-rich hingganite-(Y) are interpreted as synchronous with the Fe-oxides. The distribution of hydrothermal REE-phases suggests that REE-rich circulation and precipitation was initiated after biotisation (343 Ma) and was probably ongoing until 323 Ma, during the IOCG mineralizing event along the Cobequid-Chedubucto Fault Zone.
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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".