High-temperature contact metamorphism of calc-silicate xenoliths in the Kiglapait Intrusion, Labrador
Bibliographic record
Abstract
Calc-silicate xenoliths occur as part of a xenolith and autolith swarm in the Lower Zone of the Kiglapait Intrusion, Labrador. All xenoliths are lighter-colored than the local troctolite host rock, and are surrounded by a 1-2 cm thick reaction zone of clinopyroxenite. The typical mineral assemblage in calc-silicate xenoliths is diopside + forsterite + monticellite + spinel, and one also contains åkermanite. Reaction zones are dominated by diopside and spinel. All clinopyroxene compositions are “fassaitic,” with high concentrations of Al 2 O 3 (4-12 wt%), TiO 2 (1-4 wt%), and calculated Fe 2 O 3 (Fe 3+ > Fe 2+ ). In addition, clinopyroxene grains locally display extreme zoning in Si, Al, Ti, and X Mg . Åkermanite contains up to 1.5 wt% Na 2 O. Textures in the xenoliths are complex, with most containing highly irregular intergrowths of diopside, forsterite, and monticellite. Åkermanite and forsterite are separated locally by a coarse symplectic intergrowth of diopside and monticellite, which resulted from a retrograde reaction. The dominant assemblage probably represents the production of monticellite from calcite + clinopyroxene + forsterite, until calcite was consumed. These reactions require metamorphic temperatures of ~900 °C and pressures ≤ 0.4 kbar, such that the xenoliths were probably derived from the roof of the magma chamber. Whole-rock compositions reflect either substantial chemical exchange with the Kiglapait magma, or a very impure dolomitic protolith. The clinopyroxenite reaction zones were produced primarily by assimilation of carbonate by the Kiglapait magma, in combination with the effects of magma undercooling near the xenoliths
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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 | 0.000 |
| 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".