Primitive Magma From the Jericho Pipe, N.W.T., Canada: Constraints on Primary Kimberlite Melt Chemistry
Bibliographic record
Abstract
We report the first estimates of primary kimberlite melt composition from the Slave craton, based on samples of aphanitic kimberlite from the Jericho kimberlite pipe, N.W.T., Canada. Three samples derive from the margins of dykes where kimberlite chilled against wall rock (JD51, JD69 and JD82) and are shown to be texturally consistent with crystallization from a melt. Samples JD69 and JD82 have geochemical characteristics of primitive melts: they have high MgO (20–25 wt %), high mg-numbers (86–88), and high Cr (1300–1900 ppm) and Ni (800–1400 ppm) contents. They also have high contents of CO2 (10–17 wt %). Relative to bulk macrocrystal kimberlite, they have lower mg-numbers and lower MgO but are enriched in incompatible elements (e.g. Zr, Nb and Y), because the bulk kimberlite compositions are strongly controlled by accumulation of mantle olivine and other macrocrysts. The compositions of aphanitic kimberlite from Jericho are similar to melts produced experimentally by partial melting of a carbonate-bearing garnet lherzolite. On the basis of these experimental data, we show that the primary magmas from the Jericho kimberlite could represent 0·7–0·9% melting of a carbonated lherzolitic mantle source at pressures and temperatures found in the uppermost asthenosphere to the Slave craton. The measured CO2 contents for samples JD69 and JD82 are only slightly lower than the CO2 contents of the corresponding experimental melts; this suggests that the earliest hypabyssal phase of the Jericho kimberlite retained most of its original volatile content. As such these samples provide a minimum CO2 content for the primary kimberlite magmas from the Slave craton.
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 | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".