The mantle source of REE-rich alkaline silicate magmas can be enriched by continent-derived sediment subduction
Bibliographic record
Abstract
Alkaline silicate intrusions host large rare-earth-element (REE) resources, yet the precise origin of the mantle enrichment that generates these magmas remains unresolved. Here, we use a combination of Li-Ba-Sr-Nd isotopic data to clarify the processes responsible for the metasomatic enrichment of the mantle source. We focus on alkaline complexes in the North China Craton that host giant REE deposits, which exhibit broadly similar Li-Ba-Sr-Nd isotopic signatures, despite forming in different tectonic settings. Neither recycling of altered oceanic crust nor serpentinite-related metasomatism can reproduce these coupled geochemical signatures; instead, they require the addition of subducted continent-derived sediment derived from weathered continental crust. Storage of these REE-rich sediments within the lithospheric mantle lowers its solidus and creates chemically fertile domains. Lithospheric extension subsequently triggers selective melting of these domains, generating REE-rich alkaline magmas. Our findings suggest that continent-derived sediment recycling plays an important role in shaping the critical-metal budget of the Earth.
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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 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 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".