Constraints on the Trace Element Composition of the Archean Mantle Root beneath Somerset Island, Arctic Canada
Bibliographic record
Abstract
Peridotites that sample Archean mantle roots are frequently incompatible trace element enriched despite their refractory major element compositions. To constrain the trace element budget of the lithosphere beneath the Canadian craton, trace element and rare earth element (REE) abundances were determined for a suite of garnet peridotites and garnet pyroxenites from the Nikos kimberlite pipe on Somerset Island, Canadian Arctic, their constituent garnet and clinopyroxene, and the host kimberlite. These refractory mantle xenoliths are depleted in fusible major elements, but enriched in incompatible trace elements, such as large ion lithophile elements (LILE), Th, U and light rare earth elements (LREE). Mass balance calculations based on modal abundances of clinopyroxene and garnet and their respective REE contents yield discrepancies between calculated and analyzed REE contents for the Nikos bulk rocks that amount to LREE deficiencies of 70–99%, suggesting the presence of small amounts of interstitial kimberlite liquid (0·4–2 wt %) to account for the excess LREE abundances. These results indicate that the peridotites had in fact depleted or flat LREE patterns before contamination by their host kimberlite. LREE and Sr enrichment in clinopyroxene and low Zr and Sr abundances in garnet in low-temperature peridotites (800–1100°C) compared with high-temperature peridotites (1200–1400°C) suggest that the shallow lithosphere is geochemically distinct from the deep lithosphere beneath the northern margin of the Canadian craton. The Somerset mantle root appears to be characterized by a depth zonation that may date from the time of its stabilization in the Archean.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".