Petrogenesis of the Labrieville Alkalic Anorthosite Massif, Grenville Province, Quebec
Bibliographic record
Abstract
The Labrieville massif (∼1010 Ma) is an eroded dome consisting of three zones: (1) a foliated inner core of pink anorthosite (∼An30Or13, ∼2100 ppm Sr, ∼1300 ppm Ba) with minor leuconorite; (2) a foliated outer core of pink anorthosite (∼An35Or10, ∼1900 ppm Sr, ∼850 ppm Ba) with more abundant leuconorite; (3) a border of foliated to massive green leucogabbro. Antiperthitic plagioclase, orthopyroxene, hemoilmenite, and small amounts of biotite are present in all rocks. The border zone contains additional clinopyroxene, magnetite, and apatite. Labrieville is more alkalic and Sr- and Ba-rich than almost all other massif anorthosites. The widespread presence of biotite and the high hematite content of hemoilmenite suggest crystallization from a relatively oxidizing and water-bearing magma. Collectively, these features imply that Labrieville originated from a magma that differed considerably from typical tholeiitic liquids. Major- and trace-element variations suggest that all rock types represent mixtures of cumulus minerals, with negligible trapped melt. The compositionally distinct zones imply differentiation during crystallization. Although plagioclase compositions become more evolved inward, other indicators (e.g. XMg in pyroxene) suggest differentiation outward from core to border. We favor the latter interpretation, and suggest that the increase in plagioclase An content reflects a decline in pressure during crystallization.
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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 | 0.001 |
| 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) | 0.008 | 0.001 |
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".