Metal scavenging by sulfide oxidation in porphyry copper deposit root zones
Bibliographic record
Abstract
Abstract Porphyry copper (-gold) deposits in both arc and non-arc settings are hosted by oxidized magmatic rocks, but the exact mechanism by which the source magmas of these non-arc deposits become oxidized remains obscure. Through whole-rock geochemistry, mineral chemistry, and zircon isotopic analyses, here we show that the Neoproterozoic root of the Cretaceous Shaxi porphyry copper-gold deposit in the Jiangnan orogen is reduced and copper-sulfide rich, whereas the Cretaceous ore-forming magmas are oxidized. An oxidized mafic melt flushed the Neoproterozoic root zone, extracted copper and gold, and transported them to the upper crust where the Cretaceous Shaxi deposit formed. Evidence is recorded in growth zones of clinopyroxene, zircon, spinel, and plagioclase. Our results indicate that the relatively reduced, sulfide-enriched sub-continental lithospheric mantle or lower crust is essential but not sufficient for the formation of fertile non-arc porphyry magmas. Addition of a newer oxidized magma is crucial for the formation of this mineralization style.
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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".