The origin of Triassic/Jurassic kimberlite magmatism, Canada: Two mantle sources revealed from the Sr‐Nd isotopic composition of groundmass perovskite
Bibliographic record
Abstract
The crystallization ages and the Sr and Nd isotopic compositions of groundmass perovskite from a well‐established, SE trending, Triassic‐Jurassic corridor of kimberlite magmatism in central and eastern North America were determined to investigate the origin of this magmatism. The results obtained from kimberlite fields located along this corridor are interpreted to indicate that at least two distinct mantle sources contributed to this magmatism. The most primitive Rankin Inlet and Timiskaming kimberlites have a relatively unradiogenic strontium isotopic signature (0.7032–0.7036), interpreted to be derived from recycled and metasomatized oceanic lithosphere in the deep mantle. In contrast, the Attawapiskat and Kirkland Lake kimberlites have CHUR‐like (Chondritic Uniform Reservoir) signatures (0.7040–0.7042) interpreted to have an origin in the asthenosphere. The progressive decrease in the age of magmatism from the Triassic Rankin Inlet kimberlites to the Miocene Great Meteor seamount, combined with the similarity in the isotopic composition of these diverse magmas along the proposed >3000 km long hot spot track, provides strong evidence in support of a common mantle plume origin for both the continental and oceanic components.
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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".