Oxygen isotope shifts reveal fluid-fluxed melting in continental anatexis
Bibliographic record
Abstract
Abstract Fluid-flux melting is increasingly recognised as a key mechanism for continental crust growth and recycling, but the abundance and sources of the external fluids involved in this process are typically uncertain. Here we use zircon and garnet oxygen isotope data, geochronology, and petrological analysis of mid- to lower-crustal rocks from the Georgetown Inlier, Australia, to explore the composition and origin of anatexis-triggering fluids. Tonalite veins and garnetite residues show higher zircon δ 18 O values (~6‰) than their amphibolite source (~2–3‰), whereas sediment-derived granites show lower values (6‰) than those of typical siliciclastic sources (10–20‰). Mass balance modelling suggests that these isotopic shifts result from the interaction with mantle-derived fluids. Asthenospheric mantle upwelling beneath the Georgetown crust during slab rollback or break-off provided heat and fluids, generating hydrous mafic underplates that exsolved mantle-derived water, promoting crustal anatexis. This process may have been key in shaping Earth’s early buoyant sodic continental crust.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 0.001 |
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 teacher head, 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".