Mantle Structure Beneath the SW Slave Craton, Canada: Constraints from Garnet Geochemistry in the Drybones Bay Kimberlite
Bibliographic record
Abstract
This study describes the petrography of peridotite xenoliths, and the major and trace element geochemistry of garnets in both xenoliths and coarse concentrate from the Drybones Bay kimberlite. The temperature and depth of equilibration of clinopyroxene and garnet show that the mantle lithosphere beneath the SW margin of the Slave Province was at least 160 km thick at the time of kimberlite emplacement (∼450 Ma). The garnet population is dominated by grains with sinuous light rare earth element (LREE)-enriched trace element patterns many of which are ultra-depleted in Zr, Y and Ti. Normal heavy REE (HREE)-enriched garnets make up a small proportion of the garnet population. The spectrum in garnet geochemistry may be explained by heating and percolation of a metasomatic fluid from through an ultra-depleted mantle protolith before kimberlite eruption. A shallow ultra-depleted layer of mantle lithosphere recognized in garnets from the central Slave Province may exist beneath the SW margin of the craton, but the layer has been modified or overprinted by the metasomatic front, which has caused enrichment in Ca and incompatible elements in garnets. The changes in garnet chemistry in the Drybones Bay garnets are coincident with a unique seismic discontinuity exhibiting multiple layer anisotropy commencing at 110 km depth ∼50 km north of Drybones Bay; correlation of the two features is, however, tenuous.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.039 | 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 teacher head, 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".