Water diffusion in natural potassic melts
Bibliographic record
Abstract
Abstract Water diffusion experiments were performed on a trachytic melt from the Agnano-Monte Spina explosive eruption (Phlegrean Fields, South Italy). Experiments were run in a piston cylinder apparatus at 1 GPa pressure, at temperatures from 1373 to 1673 K and for durations of 0 to 255 s, using the diffusion-couple technique. Water concentration profiles were measured by Fourier transform infrared spectrometry. Water diffusion coefficients at different temperatures and water concentrations were calculated from the total water profiles, using the Boltzmann-Matano technique. Over the investigated range of temperatures and water concentrations, the diffusivity of water in potassic melts ( D water ), m 2 /s can be described by Arrhenius equations that can be generalized for water concentrations between 0.25 and 2 wt% as follows: D water = exp ( − 11.924 − 1.003 ln C H 2 O ) exp ( − ( exp ( 11.836 − 0.139 ln C H 2 O ) ) RT ) where C H 2 O is the water concentration in wt%, R is 8.3145 (J K −1 mol. −1 ) and T is the temperature in Kelvin. Water diffusivities in trachytic melts were compared with water diffusivities in rhyolitic and basaltic melts. The activation energies for water diffusivity in trachyte and basalt are comparable, and higher than the haplogranitic melt. This results in a convergence of water diffusion coefficients in all melts at lower (magmatic) temperatures.
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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 | 0.000 | 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".