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| Titel |
Numerical simulation of magma chamber dynamics. |
| VerfasserIn |
Antonella Longo, Paolo Papale, Chiara Paola Montagna, Melissa Vassalli, Salvatore Giudice, Andrea Cassioli |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250039588
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| Zusammenfassung |
| Magma chambers are characterized by periodic arrivals of deep magma batches that give
origin to complex patterns of magma convection and mixing, and modify the distribution of
physical quantities inside the chamber. We simulate the transient, 2D, multi-component
homogeneous dynamics in geometrically complex dyke+chamber systems, by means of
GALES, a finite element parallel C++ code solving mass, momentum and energy
equations for multi-component homogeneous gas-liquid (± crystals) mixtures in
compressible-to-incompressible flow conditions. Code validation analysis includes several
cases from the classical engineering literature, corresponding to a variety of subsonic to
supersonic gas-liquid flow regimes (see http://www.pi.ingv.it/~longo/gales/gales.html).
The model allows specification of the composition of the different magmas in the
domain, in terms of ten major oxides plus the two volatile species H2O and CO2.
Gas-liquid thermodynamics are modeled by using the compositional dependent,
non-ideal model in Papale et al. (Chem.. Geol., 2006). Magma properties are defined in
terms of local pressure, temperature, and composition including volatiles. Several
applications are performed within domains characterized by the presence of one
or more magma chambers and one or more dykes, with different geometries and
characteristic size from hundreds of m to several km. In most simulations an initial
compositional interface is placed at the top of a feeding dyke, or at larger depth,
with the deeper magma having a lower density as a consequence of larger volatile
content. The numerical results show complex patterns of magma refilling in the
chamber, with alternating phases of magma ingression and magma sinking from
the chamber into the feeding dyke. Intense mixing takes place in feeding dykes,
so that the new magma entering the chamber is always a mixture of the deep and
the initially resident magma. Buoyant plume rise occurs through the formation of
complex convective patterns, giving origin to a density-stratified magma chamber. |
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