Experimental study of bubble growth in Stromboli basalt melts at 1 atmosphere
Bibliographic record
Abstract
In order to investigate bubble formation and growth at 1 atmosphere, degassing experiments using a Stromboli basalt with dissolved H2O or H2O + CO2 were performed in a custom furnace on a beamline at the Advanced Photon Source. The glasses were synthesized at 1250°C and 1000 MPa, with ~3.0 wt%, ~5.0 wt%, or ~7.0 wt% H2O or with mixtures of H2O + CO2, ~3.0 wt% H2O and ~440 ppm CO2, ~5.0 wt% H2O and 880 ppm CO2, ~7.0 wt% H2O and ~1480 ppm CO2, then heated on the beamline while recording the bubble growth. The 3D bubble size distributions in the quenched samples were then studied with synchrotron X-ray microtomography. The experimental results show that bubble nucleation and growth are volatile-concentration dependent. Bubbles can easily nucleate in melts initially containing high volatile concentrations. CO2 has no significant effect on bubble formation and growth because of low CO2 concentrations. Multiple nucleation events occur in most of these degassing samples, and they are more pronounced in more supersaturated melts. Bubble growth is initially controlled by viscosity near glass transition temperatures and by diffusion at higher temperatures where melt viscous relaxation occurs rapidly. Bubble foam forms when bubbles are highly connected due to coalescence, and bubbles begin pop, 10 to 20 seconds after the foam is developed. The degree of bubble coalescence increases with time, and bubble coalescence can significantly change the bubble size distribution. Bubble size distributions follow power-law relations at vesicularities of 1.0% to 65%, and bubble size distributions evolve from power-law relations to exponential relations at vesicularities of 65% to 83%. This evolution is associated with the change from far-from-equilibrium degassing to near-equilibrium degassing. The experimental results imply that during basaltic eruptions both far-from-equilibrium degassing and near-equilibrium degassing can occur. The far-from-equilibrium degassing generally generates the power-law bubble size distributions whereas the near-equilibrium degassing produces exponential bubble size distributions Bubbles begin to pop when the vesicularities attain 65% to 83%. Bubble expansion in the foam possibly accounts for the mechanism of magma fragmentation.
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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 | 0.001 |
| 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".