The Lithospheric Mantle beneath Continental Margins: Melting and Melt–Rock Reaction in Canadian Cordillera Xenoliths
Bibliographic record
Abstract
Abstract Seven alkali basalt centers in the southern Canadian Cordillera contain mantle xenolith suites that comprise spinel Cr-diopside peridotites, spinel augite-bearing wehrlites and orthopyroxene-poor lherzolites, and minor pyroxenites. The Cr-diopside peridotites appear to be residues of the extraction of Mg-rich basalts by up to 15% partial melting (median 5–10%) of a pyrolite-like source in the spinel stability field. The xenoliths are similar to other mantle xenolith suites derived from beneath convergent continental margins, but are less depleted, less oxidized, and have lower spinel mg-number than peridotites found in fore-arc settings. Their dominant high field strength element depleted character, however, is typical of arc lavas, and may suggest that fluids or melts circulating through the Canadian Cordillera lithosphere were subduction related. Modeling using MELTS is consistent with the augite-bearing xenoliths being formed by interaction between crystallizing alkaline melts and peridotite. Assimilation–fractional crystallization modeling suggests that the trace element patterns of liquids in equilibrium with the augite xenoliths may represent the initial melts that reacted with the peridotite. Moreover, the compositions of these melts are similar to those of some glasses observed in the mantle xenoliths. Melt–rock interaction may thus be a viable mechanism for the formation of Si- and alkali-rich glass in peridotites.
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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 | 0.002 | 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) | 0.003 | 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".