Kiglapait magma evolution: mantle to Labrador to lab
Bibliographic record
Abstract
Field relations of the Kiglapait Intrusion (KI) show a large (~81 %) troctolitic Lower Zone (LZ) grading upward by addition of augite to a strongly evolving Upper Zone (UZ) culminating in fayalite-ferrohedenbergite-mesoperthite syenite. The simplest hypothesis for the intrusion is emplacement of a single batch of magma and fractionation in a closed system (at ~1.3 Ga and ~3 kb), except for an olivine-rich basal LZ. A successful experimental test for consistency would yield the observed mineral compositions in the observed proportions. We carry out this test for the LZ-LLD (liq. line of descent) using separated minerals and a contact rock from the KI, mixing them in proportions to yield the observed cotectic L(OL, PL), and the observed crystal compositions at the liquidus. LZ experiments were run in graphite at 5 kb in 19-mm pistoncylinder apparatus. The LZ cotectic runs from 1245 deg C to 1203 deg C. Oxy-norm Liq comps. in the the AUG-PL-OL ternary run from AUG(5%) PL(73%) OL(22%) to AUG(24%)PL(62%)OL(14%) where AUG saturation occurs. The crystal compositions found are An67, Fo 74 to An53, Fo 62. The trend mimics that in Di-An-Fo and runs close to that determined previously from modal data. The cotectic is gently concave toward the PL apex, and its position depends solely on AUG, being indifferent to An, Fo, and minor variations in Ti & P. AUG saturation occurs at the same OL:(OL+AUG) ratio = 0.38 as in the modal data. The lever rule applied to the ternary curve shows AUG+ at 81% solidified, as in the modal result. The experiments are consistent with the simplest hypothesis. The source region was explored via the liquidus phases found in the bulk composition mix at higher pressures. L(OL,PL) persists to ~11 kb but the cotectic moves slightly toward OL; the Clapeyron slope is 7.75 deg C /kb. At 13 kb, SP, Al-CPX, Al-OPX, and GT all occur with 90%L at 1300 deg C. The SP field is narrow, possibly <2kb wide. The setting of KI and other late troctolitic magmas in the anorthositic Nain Plutonic Suite suggests crustal extension and a locally shallow depth to mantle (Olson & Morse, Nature 344, 76
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.007 | 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".