Behavior of volatiles in arc volcanism : geochemical and petrologic evidence from active volcanoes in Indonesia
Bibliographic record
Abstract
Large amounts of material are recycled along subduction zones by uprising magmas, of which volcanoes are the surface expression. This thesis focuses on the behavior of volatiles elements (S, Cl, H) during these recycling processes. The study area is the Indonesian arc system, which hosts many active volcanoes. Application of whole-rock and in situ analytical techniques on material collected from nine volcanoes provided a large data set including the chemical and stable isotope compositions of bulk lavas, and chemical compositions of minerals, melt inclusions and soluble material adsorbed on ashes from eruption plumes. Evidence is presented that sulfur is enriched in the sub-arc mantle by slab-derived additions. Magma sources in the mantle wedge are metasomatized by material enriched in heavy sulfur, most likely in the form of hydrous fluids, that is derived from subducted sediments rather than from subducted altered oceanic crust. Among the chalcophile elements, lead, and possibly copper, must have been added as well, whereas cobalt and nickel are largely controlled by the composition of the pre-subduction mantle. Furthermore, it is demonstrated that large sulfur fluxes at the onset of the 1982-83 eruptions of Galunggung volcano were derived from degassing of non-erupted deep-seated magma, whereas most of the chlorine must have been released directly from erupting magma. The presence the rare mineral zirconolite in vesicle fillings in the lavas of Lewotolo volcano provides strong evidence that high field-strength elements (e.g., Nb, Zr, Ti), rare earth elements (e.g., Ce, La, Nd) and actinides (Th, U) can be mobilized during fluid-driven processes in fluorine-rich shallow magmatic environments. This finding lends support to the hypothesis that HFSE, REE and actinide-bearing ore deposits in island arcs are preferentially formed around potassic magma bodies.
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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 | 0.000 | 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".