Water and Oxygen Fugacity in the Lithospheric Mantle Wedge beneath the Northern Canadian Cordillera (Alligator Lake)
Bibliographic record
Abstract
Abstract Assessing water contents of subduction zone mantle peridotites can gain insight into the compositions of slab‐derived fluids/melts and the active margin water cycle. Here eight mantle xenoliths from Alligator Lake (northern Canadian Cordillera) are examined to address these issues. The harzburgites have less water, on average, but are more oxidized (ΔFMQ ~ 0.1) than the lherzolites (ΔFMQ ~ −1.0). The lherzolites have major and trace element compositions close to primitive mantle, while the harzburgite major element and heavy rare earth element compositions are indicative of higher degrees of melt depletion but with light rare earth element‐enriched profiles. Correlations between lherzolite pyroxene water contents and bulk rock Ba/Nb and Ba/Yb ratios likely result from interaction with subduction related fluids. The trace element compositions of the harzburgite clinopyroxenes are successfully modeled by melting of a fertile mantle lithosphere and interaction with a carbonatite melt. Correlations between the harzburgite water contents and clinopyroxene Ca/Al ratios and Mg# are also consistent with the influence of carbonatite metasomatism. Metasomatism likely resulted from opening of a slab window beneath the region, detected as a low‐velocity seismic anomaly, which heated and mobilized a heterogeneous mantle lithosphere veined with carbonatite. This study confirms that subduction zone mantle lithosphere is not necessarily more water‐rich or more oxidized than oceanic lithosphere or other off‐cratonic settings. Moreover, local oxidation is not necessarily related to the ingress of subduction zone fluids but can also be related to melting of a heterogeneous lithosphere following heating above a slab window.
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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 | 0.002 | 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) | 0.001 | 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".