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| Titel |
The stability and spacing of crustal magma chambers |
| VerfasserIn |
Leif Karlstrom, Josef Dufek, Michael Manga |
| 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 |
250033209
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| Zusammenfassung |
| The development of discrete volcanic centers reflects a focusing of magma ascending from
the source region to the surface. We suggest that this organization occurs via mechanical
interactions between the magma chamber, volcanic edifice and dikes, and that the stresses
generated by these features may localize crustal magma transport before the first eruption
occurs. We develop a model for the focusing or “lensing” of rising dikes by magma
chambers, and show that it dominates focusing by volcanic edifices in most cases. We then
test the stability of chambers that grow through dike lensing, by dynamically simulating the
thermal evolution of basaltic composition magma chambers in country rock composed
of either tonalite or amphibolite, as end member proxies for arc and continental
crustal magma chambers. These simulations allow us to map out the parameter
space in which magma chambers erupt, freeze out, or exist stably in a geothermal
gradient, as well as the averaged bulk melt fraction and degree of country rock
assimilation in each scenario. We find that for reasonable lower crustal melt flux
(10-4 - 10-2m3-m2-yr) there is a regime of stable magma chambers, as well as the
possibility for rapid but stable chamber growth. This model suggests a general framework for
the formation of volcanic centers and for the incremental growth of large crustal
intrusions. |
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