Articles | Volume 35, issue 4
https://doi.org/10.5194/ejm-35-613-2023
https://doi.org/10.5194/ejm-35-613-2023
Research article
 | 
02 Aug 2023
Research article |  | 02 Aug 2023

H2O degassing triggered by alkali depletion in bimodal magma injection processes – a new experimental approach

Patricia Louisa Marks, Anja Allabar, and Marcus Nowak

Cited articles

Allabar, A. and Nowak, M.: Message in a bottle: Spontaneous phase separation of hydrous Vesuvius melt even at low decompression rates, Earth Planet. Sc. Lett., 501, 192–201, https://doi.org/10.1016/j.epsl.2018.08.047, 2018. 
Allabar, A., Dobson, K. J., Bauer, C. C., and Nowak, M.: Vesicle shrinkage in hydrous phonolitic melt during cooling, Contrib. Mineral. Petr. 175, 21, https://doi.org/10.1007/s00410-020-1658-3, 2020. 
Allabar, A., Petri, P. L., Eul, D., and Nowak, M.: An empirical H2O solubility model for peralkaline rhyolitic melts, Contrib. Mineral. Petr., 177, 52, https://doi.org/10.1007/s00410-022-01915-8, 2022. 
Arienzo, I., Moretti, R., Civetta, L., Orsi, G., and Papale, P.: The feeding system of Agnano–Monte Spina eruption (Campi Flegrei, Italy): Dragging the past into present activity and future scenarios, Chem. Geol., 270, 135–147, https://doi.org/10.1016/j.chemgeo.2009.11.012, 2010. 
Bachmann, O. and Bergantz, G.: The Magma Reservoirs That Feed Supereruptions, Elements, 4, 17–21, https://doi.org/10.2113/GSELEMENTS.4.1.17, 2008. 
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Short summary
These results represent the first high-pressure and high-temperature degassing experiments simulating the injection of basaltic melt into a hydrous rhyolitic melt reservoir. Diffusion processes in the contact zone of the melts lead to a depletion of alkalis in the rhyolitic melt interface. The reduced alkali concentration significantly decreases the H2O solubility of the rhyolitic melt and promotes enhanced H2O vesicle formation and further degassing, which can trigger volcanic eruptions.