Magmatic evolution and subsolidus alteration of annite in nepheline syenites, Mont Saint-Hilaire, Québec
Bibliographic record
Abstract
Nepheline syenite represents the highly differentiated product of fractional crystallization in the Poudrette quarry at Mont Saint-Hilaire, Quebec. It also records a significant subsolidus overprint due to circulation of post-magmatic fluids. Annite, the ferrous-iron-dominant member of the biotite series, represents up to 20% of the typical nepheline syenites. Hand samples cover the complete range of freshness, from unaltered to hydrothermally modified rocks. Identification of minerals and estimation of their abundances and compositions were obtained with optical microscopy and electron-microprobe analysis. I also used a combined approach of X-ray diffraction and high-resolution transmission electron microscopy. With respect to annite composition, Fe/(Fe + Mg) varies from 0.74 (porphyntic nepheline syenite) to 0.98 (poikilitic nepheline syenite). Concerning the habit of annite, the melt composition controls the order of crystallization, which then in turn controls whether the annite is bladed and skeletal or oikocrystic. The rock from the Poudrette dyke is a hypersolvus nepheline syenite in which the bladed annite was a liquidus phase; therefore, the order of crystallization was "normal" (mafic mineral first), whereas in poikilitic nepheline syenite, this order was reverse. The proportion of Ti decreases with Fe/(Fe + Mg), whereas that of Mn increases; F and Cl contents are very low in spite of their availability. The application of n-alkylammonium cation exchange reveals the presence of planar structural defects as a result of dehydrogenation-type reactions. The annite records the results of oxidation during cooling, i.e., open-system behavior in this degassing pluton.
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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 | 0.002 | 0.001 |
| 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) | 0.004 | 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 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".