HOMOGENEOUS BUBBLE NUCLEATION IN RHYOLITIC MAGMAS: AN EXPERIMENTAL STUDY OF THE EFFECT OF H2O AND CO2
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dc.contributor.author | Mourtada-Bonnefoi C.C. | |
dc.contributor.author | Laporte D. | |
dc.date.accessioned | 2021-05-21T07:34:18Z | |
dc.date.available | 2021-05-21T07:34:18Z | |
dc.date.issued | 2002 | |
dc.identifier | https://www.elibrary.ru/item.asp?id=42261519 | |
dc.identifier.citation | Journal of Geophysical Research: Solid Earth, 2002, 107, 4, 2-1-2-21 | |
dc.identifier.issn | 2169-9356 | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/28467 | |
dc.description.abstract | Rapid decompression experiments were performed to study homogeneous bubble nucleation in a crystal-free rhyolitic liquid at 800°C. Bubble nucleation was produced by lowering the pressure at 1–10 MPa s−1 from an initial value between 200 and 295 MPa to a final value below the volatile saturation pressure PSat. Six volatile compositions with 4.1–7.7 wt % H2O and 10–1200 ppm CO2 were investigated. For each composition we determined the critical pressure PHoN below which homogeneous nucleation can proceed. The samples quenched below PHoN showed a nucleated core with a large number of uniformly spaced bubbles. With decreasing pressure, bubble number densities increased from 1015 m−3. The degree of supersaturation required for homogeneous nucleation, ΔPHoN (= PSat − PHoN), increased with decreasing H2O content or increasing CO2 content. Huge values of ΔPHoN, ≥135 to 310 MPa, were measured in the H2O-poor compositions (4.1–4.6 wt % H2O; 50–1100 ppm CO2); much lower values from ≈60 to 160 MPa were obtained in the H2O-rich compositions (7.0–7.7 wt % H2O; 10–630 ppm CO2). The high ΔPHoN in liquids with 4–5 wt % H2O should result in the buildup of large degrees of supersaturation during magma ascent, a very late nucleation event, and a rapid (explosive) vesiculation. By contrast, rhyolitic liquids with much larger water contents have higher saturation pressures and much lower ΔPHoN: bubble nucleation may therefore occur at depth in the volcanic conduit favoring a subsequent near-equilibrium degassing. | |
dc.title | HOMOGENEOUS BUBBLE NUCLEATION IN RHYOLITIC MAGMAS: AN EXPERIMENTAL STUDY OF THE EFFECT OF H2O AND CO2 | |
dc.type | Статья |
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