Shrinkage Bubbles: The C–O–H–S Magmatic Fluid System at San Cristóbal Volcano
Bibliographic record
Abstract
New analytical results for the composition of shrinkage bubbles (09–70 vol. %) in olivine-hosted (Fo <80%) primary melt inclusions (MIs) have been incorporated into a novel geochemical model for San Cristobal volcano, Nicaragua. The vapour, liquid, and mineral components found inside shrinkage bubbles may represent relics of early C–O–H–S fluids exsolved from a magmatic-hydrothermal system. This conclusion is supported by high-resolution Raman microspectroscopy revealing: (1) gaseous CO2 (d1⁄4017–031 g/cm3 in 31 samples) coexisting with liquid H2O (in seven samples) at ambient temperature (<22C) inside the shrinkage bubbles of naturally quenched inclusions; (2) several mineral phases (i.e. Fe, Cu-sulfides, Ca-sulfates, and Mg-carbonates) formed along the bubble–glass interface, as confirmed by electron backscattered/energy-dispersive spectroscopy. The presence of liquid water was revealed by applying a novel subtraction method to fitted Raman spectra that isolated an isosbestic liquid-water band at 3460660/cm-1 (mean6SD). In MIs, the major oxide composition of glasses containing shrinkage bubbles were analysed by electron microprobe, whereas glass volatile contents were measured with nanoscale secondary-ion mass spectroscopy. According to the water content of the glass inclusions ( 33wt %) and the presence of liquid water at the bubble–glass interface, only small amounts of water (03wt %) appear to have migrated inside the bubbles. From pre-eruptive (up to 1200C) to post-eruptive temperatures, aqueous fluids represent the principal agents for chemical reactions inside MI bubbles involving dissolved ionic species (e.g. SO42-, CO32-, and Cl- ) and major and/or trace elements from the inclusion glass (e.g. Mg, Fe, Cu, Si, Al, Na, and K). After the initiation of nucleation (1009–1141C), the volume of shrinkage bubbles expands and the surrounding glass contracts (at <530C). The Fe–Mg–Cu-rich (vapour) shrinkage-bubble paragenetic mineral sequence formed during different cooling stages: (A) high-temperature sulfide precipitation at 500–700C; (B) lowtemperature magnesite precipitation at hydrothermal conditions <350C; and finally (C) low-toambient temperature precipitation of carbonates and sulfates in liquid water at <150C. Our findings indicate that the C–O–H–S fluids in shrinkage bubbles can represent an ideal preserved/closed magmatic-hydrothermal system evolving after the exsolution of magmatic fluids during cooling
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 | 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) | 0.019 | 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; both teacher heads agree on what is shown here.
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".