Quantifying the Pressure, Temperature, and Timing of Metamorphism in the Montresor Belt, Nunavut, Canada
Bibliographic record
Abstract
P-T-t conditions are determined for the Montresor belt (Rae Province, Nunavut) using modern thermodynamic modeling and in-situ U-Th-Pb monazite geochronology.Phase equilibrium modeling yields peak P-T estimates of 355 -455°C and <4200 bar for the upper Montresor belt and 500 -580°C and <4000 bar for the lower Montresor belt, with a high geothermal gradient of ca.57°C/km during metamorphism.Forward modeling of garnet crystallization suggests growth along a clockwise, nearly isobaric P-T path from ca. 539 -544°C and 3090 -3140 bar.Chemical age dating of metamorphic monazite indicates peak P-T conditions occurred at ca. 1837 ± 8.6 Ma.Altered monazite domains suggest a fluid-mediated alteration event during cooling at ca. 1792 ± 10.1 Ma, associated with the emplacement of dykes into the lower Montresor group.These fluids increased the bulk rock K and caused modification to garnet growth zoning and mechanical fracturing of garnet.First and foremost I would like to thank my supervisors Fred Gaidies and John Percival for all the support and guidance over the completion of this project.It was a pleasure to work with both of you over the past two years.Thanks to Victoria Tschirhardt and Angela Ford who were great company during fieldwork and the endless search for garnet, and to everyone at the Geological Survey of Canada who made this project possible.Thank you to Mike Jercinovic and Mike Williams at the University of Massachusetts for allowing me to use your microprobe for the monazite geochronology and for all the discussions about the results.To Peter Jones for the hours spent on the garnet EPMA traverses and mineral ID.Thanks to Glenn Poirier at the University of Ottawa for the garnet compositional maps, to Pat Hunt at the GSC for the time spent locating the smallest of monazite grains, and to Tim Mount for the help in preparing the garnet central sections.Special thanks to my office mates Freya
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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 | 0.002 | 0.002 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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".